Pulmonology

NEW ORLEANS – In patients with interstitial lung diseases at risk of pulmonary hypertension, inhaled nitric oxide produced meaningful improvements in activity that have been maintained over the long term, an investigator reported here.

Inhaled nitric oxide, which improved moderate to vigorous physical activity by 34% versus placebo in an 8-week controlled trial, has demonstrated long-term maintenance of activity parameters in open-label extension data, presented at the annual meeting of the American College of Chest Physicians.

SOURCE: Nathan SD et al. CHEST 2019. Abstract, doi: 10.1016/j.chest.2019.08.308.

NEW ORLEANS – In patients with interstitial lung diseases at risk of pulmonary hypertension, inhaled nitric oxide produced meaningful improvements in activity that have been maintained over the long term, an investigator reported here.

Inhaled nitric oxide, which improved moderate to vigorous physical activity by 34% versus placebo in an 8-week controlled trial, has demonstrated long-term maintenance of activity parameters in open-label extension data, presented at the annual meeting of the American College of Chest Physicians.

SOURCE: Nathan SD et al. CHEST 2019. Abstract, doi: 10.1016/j.chest.2019.08.308.

NEW ORLEANS – In patients with interstitial lung diseases at risk of pulmonary hypertension, inhaled nitric oxide produced meaningful improvements in activity that have been maintained over the long term, an investigator reported here.

Inhaled nitric oxide, which improved moderate to vigorous physical activity by 34% versus placebo in an 8-week controlled trial, has demonstrated long-term maintenance of activity parameters in open-label extension data, presented at the annual meeting of the American College of Chest Physicians.

SOURCE: Nathan SD et al. CHEST 2019. Abstract, doi: 10.1016/j.chest.2019.08.308.

NEW ORLEANS – A novel electromagnetic navigation bronchoscopy system can improve targeting of peripheral lung lesions, according to an industry-sponsored, prospective study.

The system, which incorporates fluoroscopic navigation, increased the percentage of cases in which the target overlapped with the lesion, from 60% to 83%. The percentage of cases without any target overlap decreased from 32% to 5%.

“Tomosynthesis-based fluoroscopic navigation … improves the three-dimensional convergence between the virtual target and the actual target,” said Krish Bhadra, MD, of CHI Memorial Medical Group in Chattanooga, Tenn.

Dr. Bhadra presented results with this system at the annual meeting of the American College of Chest Physicians.

He and his colleagues conducted a study of Medtronic’s superDimension navigation system (version 7.2), which provides real-time imaging with three-dimensional fluoroscopy. The system has a “local registration” feature, which uses fluoroscopy and an algorithm to update the virtual target location during the procedure. This allows the user to reposition the catheter based on the location of the lesion.

The researchers tested the system in 50 patients from two centers (NCT03585959). Patients’ lesions had to be larger than 10 mm, not visible endobronchially, and not reachable by convex endobronchial ultrasound. Lesions within 10 mm of the diaphragm were excluded.

The median lesion size was 17.0 mm, 61.2% were smaller than 20 mm, 65.3% were in the upper lobe, and 53.1% had a bronchus sign present. The median distance from lesion to pleura was 5.9 mm.

Dr. Bhadra said the system performed as designed in all cases, and the protocol-defined technical success rate was 95.9% (47/49). Local registration was attempted in 49 patients and was successful in 47 patients (95.9%). In the unsuccessful cases, local registration was not completed based on the system design because the correction distance was greater than 3.0 cm.

The study’s primary endpoint was three-dimensional overlap of the virtual target and the actual lesion, as confirmed by cone-beam computed tomography. Success was defined as greater than 0% overlap after location correction. Target overlap was achieved in 59.6% (28/47) of cases before local registration and 83.0% (39/47) of cases after.

There were six cases in which local registration was successful, but these subjects weren’t evaluable because of failed procedure recording. When those subjects were excluded, target overlap was achieved in 95.1% (39/41) of cases after local registration.

The median percent overlap between the virtual target and the actual lesion was 11.4% before local registration and 32.8% after. The percentage of cases without any target overlap decreased from 31.7% (13/41) before local registration to 4.9% (2/41) after.

Focusing on the two cases without target overlap, Dr. Bhadra noted that he was able to get a biopsy that proved a malignancy in one of those patients. In the other patient, Dr. Bhadra was able to identify features of organizing pneumonia.

“Even though we did not have overlap, we must have been close enough that we were able to get malignant tissue in one [patient] and features of organizing pneumonia in a patient who’s got no history of organizing pneumonia,” Dr. Bhadra said.

He and his colleagues did not evaluate diagnostic yield in this study, but they did assess complications up to 7 days after the procedure.

The team reported one case of pneumothorax, but the patient didn’t require a chest tube. Additionally, there were two cases of bronchopulmonary hemorrhage, but the patients didn’t require any interventions.

This study was sponsored by Medtronic. Dr. Bhadra disclosed relationships with Medtronic, Boston Scientific, BodyVision, Auris Surgical Robotics, Intuitive Surgical, Veracyte, Biodesix, Merit Medical Endotek, and Johnson & Johnson.

[email protected]

SOURCE: Bhadra K et al. CHEST 2019. doi: 10.1016/j.chest.2019.08.314.

NEW ORLEANS – A novel electromagnetic navigation bronchoscopy system can improve targeting of peripheral lung lesions, according to an industry-sponsored, prospective study.

The system, which incorporates fluoroscopic navigation, increased the percentage of cases in which the target overlapped with the lesion, from 60% to 83%. The percentage of cases without any target overlap decreased from 32% to 5%.

“Tomosynthesis-based fluoroscopic navigation … improves the three-dimensional convergence between the virtual target and the actual target,” said Krish Bhadra, MD, of CHI Memorial Medical Group in Chattanooga, Tenn.

Dr. Bhadra presented results with this system at the annual meeting of the American College of Chest Physicians.

He and his colleagues conducted a study of Medtronic’s superDimension navigation system (version 7.2), which provides real-time imaging with three-dimensional fluoroscopy. The system has a “local registration” feature, which uses fluoroscopy and an algorithm to update the virtual target location during the procedure. This allows the user to reposition the catheter based on the location of the lesion.

The researchers tested the system in 50 patients from two centers (NCT03585959). Patients’ lesions had to be larger than 10 mm, not visible endobronchially, and not reachable by convex endobronchial ultrasound. Lesions within 10 mm of the diaphragm were excluded.

The median lesion size was 17.0 mm, 61.2% were smaller than 20 mm, 65.3% were in the upper lobe, and 53.1% had a bronchus sign present. The median distance from lesion to pleura was 5.9 mm.

Dr. Bhadra said the system performed as designed in all cases, and the protocol-defined technical success rate was 95.9% (47/49). Local registration was attempted in 49 patients and was successful in 47 patients (95.9%). In the unsuccessful cases, local registration was not completed based on the system design because the correction distance was greater than 3.0 cm.

The study’s primary endpoint was three-dimensional overlap of the virtual target and the actual lesion, as confirmed by cone-beam computed tomography. Success was defined as greater than 0% overlap after location correction. Target overlap was achieved in 59.6% (28/47) of cases before local registration and 83.0% (39/47) of cases after.

There were six cases in which local registration was successful, but these subjects weren’t evaluable because of failed procedure recording. When those subjects were excluded, target overlap was achieved in 95.1% (39/41) of cases after local registration.

The median percent overlap between the virtual target and the actual lesion was 11.4% before local registration and 32.8% after. The percentage of cases without any target overlap decreased from 31.7% (13/41) before local registration to 4.9% (2/41) after.

Focusing on the two cases without target overlap, Dr. Bhadra noted that he was able to get a biopsy that proved a malignancy in one of those patients. In the other patient, Dr. Bhadra was able to identify features of organizing pneumonia.

“Even though we did not have overlap, we must have been close enough that we were able to get malignant tissue in one [patient] and features of organizing pneumonia in a patient who’s got no history of organizing pneumonia,” Dr. Bhadra said.

He and his colleagues did not evaluate diagnostic yield in this study, but they did assess complications up to 7 days after the procedure.

The team reported one case of pneumothorax, but the patient didn’t require a chest tube. Additionally, there were two cases of bronchopulmonary hemorrhage, but the patients didn’t require any interventions.

This study was sponsored by Medtronic. Dr. Bhadra disclosed relationships with Medtronic, Boston Scientific, BodyVision, Auris Surgical Robotics, Intuitive Surgical, Veracyte, Biodesix, Merit Medical Endotek, and Johnson & Johnson.

[email protected]

SOURCE: Bhadra K et al. CHEST 2019. doi: 10.1016/j.chest.2019.08.314.

NEW ORLEANS – A novel electromagnetic navigation bronchoscopy system can improve targeting of peripheral lung lesions, according to an industry-sponsored, prospective study.

The system, which incorporates fluoroscopic navigation, increased the percentage of cases in which the target overlapped with the lesion, from 60% to 83%. The percentage of cases without any target overlap decreased from 32% to 5%.

“Tomosynthesis-based fluoroscopic navigation … improves the three-dimensional convergence between the virtual target and the actual target,” said Krish Bhadra, MD, of CHI Memorial Medical Group in Chattanooga, Tenn.

Dr. Bhadra presented results with this system at the annual meeting of the American College of Chest Physicians.

He and his colleagues conducted a study of Medtronic’s superDimension navigation system (version 7.2), which provides real-time imaging with three-dimensional fluoroscopy. The system has a “local registration” feature, which uses fluoroscopy and an algorithm to update the virtual target location during the procedure. This allows the user to reposition the catheter based on the location of the lesion.

The researchers tested the system in 50 patients from two centers (NCT03585959). Patients’ lesions had to be larger than 10 mm, not visible endobronchially, and not reachable by convex endobronchial ultrasound. Lesions within 10 mm of the diaphragm were excluded.

The median lesion size was 17.0 mm, 61.2% were smaller than 20 mm, 65.3% were in the upper lobe, and 53.1% had a bronchus sign present. The median distance from lesion to pleura was 5.9 mm.

Dr. Bhadra said the system performed as designed in all cases, and the protocol-defined technical success rate was 95.9% (47/49). Local registration was attempted in 49 patients and was successful in 47 patients (95.9%). In the unsuccessful cases, local registration was not completed based on the system design because the correction distance was greater than 3.0 cm.

The study’s primary endpoint was three-dimensional overlap of the virtual target and the actual lesion, as confirmed by cone-beam computed tomography. Success was defined as greater than 0% overlap after location correction. Target overlap was achieved in 59.6% (28/47) of cases before local registration and 83.0% (39/47) of cases after.

There were six cases in which local registration was successful, but these subjects weren’t evaluable because of failed procedure recording. When those subjects were excluded, target overlap was achieved in 95.1% (39/41) of cases after local registration.

The median percent overlap between the virtual target and the actual lesion was 11.4% before local registration and 32.8% after. The percentage of cases without any target overlap decreased from 31.7% (13/41) before local registration to 4.9% (2/41) after.

Focusing on the two cases without target overlap, Dr. Bhadra noted that he was able to get a biopsy that proved a malignancy in one of those patients. In the other patient, Dr. Bhadra was able to identify features of organizing pneumonia.

“Even though we did not have overlap, we must have been close enough that we were able to get malignant tissue in one [patient] and features of organizing pneumonia in a patient who’s got no history of organizing pneumonia,” Dr. Bhadra said.

He and his colleagues did not evaluate diagnostic yield in this study, but they did assess complications up to 7 days after the procedure.

The team reported one case of pneumothorax, but the patient didn’t require a chest tube. Additionally, there were two cases of bronchopulmonary hemorrhage, but the patients didn’t require any interventions.

This study was sponsored by Medtronic. Dr. Bhadra disclosed relationships with Medtronic, Boston Scientific, BodyVision, Auris Surgical Robotics, Intuitive Surgical, Veracyte, Biodesix, Merit Medical Endotek, and Johnson & Johnson.

[email protected]

SOURCE: Bhadra K et al. CHEST 2019. doi: 10.1016/j.chest.2019.08.314.

A new study has uncovered how the measles virus (MeV) can induce immunosuppression by delaying the reconstitution of B cells.

CDC/ Cynthia S. Goldsmith; William Bellini, Ph.D.

“Our findings provide a biological explanation for the observed increase in childhood mortality and secondary infections several years after an episode of measles,” said Velislava N. Petrova, PhD, of the Wellcome Sanger Institute in Cambridge, England, and coauthors. The study was published in Science Immunology.

To determine if B-cell impairment can lead to measles-associated immunosuppression, the researchers investigated genetic changes in 26 unvaccinated children from the Netherlands who previously had measles. Their antibody genes were sequenced before any symptoms of measles developed and roughly 40 days after rash. Two control groups also were sequenced accordingly: vaccinated adults and three unvaccinated children from the same community who were not infected with measles.

Naive B cells from individuals in the vaccinated and uninfected control groups showed high correlation of immunoglobulin heavy chain (IGHV-J) gene frequencies across time periods (R² = 0.96 and 0.92, respectively) but no significant differences in gene expression (P greater than .05). At the same time, although B cell frequencies in measles patients recovered to levels before infection, they had significant changes in IGHV-J gene frequencies (P = .01) and decreased correlation in gene expression (R² = 0.78).

In addition, individuals in the control groups had “a stable genetic composition of B memory cells” but no significant changes in the third complementarity-determining region (CDR3) lengths or mutational frequency of IGHV genes (P greater than .05). B memory cells in measles patients, however, showed increases in mutational frequency (P = .0008) and a reduction in CDR3 length (P = .017) of IGHV genes, Dr. Petrova and associates said.

Finally, the researchers confirmed a hypothesis about the depletion of B memory cell clones during measles and a repopulation of new cells with less clonal expansion. The frequency of individual IGHV-J gene combinations before infection was correlated with a reduction after infection, “with the most frequent combinations undergoing the most marked depletion” and the result being an increase in genetic diversity.

To further test their findings, the researchers vaccinated two groups of four ferrets with live-attenuated influenza vaccine (LAIV) and at 4 weeks infected one of the groups with canine distemper virus (CDV), a surrogate for MeV. At 14 weeks after vaccination, the uninfected group maintained high levels of influenza-specific neutralizing antibodies while the infected group saw impaired B cells and a subsequent reduction in neutralizing antibodies.
 

Understanding the impact of measles on the immune system

“How measles infection has such a long-lasting deleterious effect on the immune system while allowing robust immunity against itself has been a burning immunological question,” Duane R. Wesemann, MD, PhD, of Brigham and Women’s Hospital in Boston, said in an accompanying editorial. The research from Petrova et al. begins to answer that question.

Among the observations he found most interesting was how “post-measles memory cells were more diverse than the pre-measles memory pool,” despite expectations that measles immunity would be dominant. He speculated that the void in memory cells is filled by a set of clones binding to unidentified or nonnative antigens, which may bring polyclonal diversity into B memory cells.

More research is needed to determine just what these findings mean, including looking beyond memory cell depletion and focusing on the impact of immature immunoglobulin repertoires in naive cells. But his broad takeaway is that measles remains both a public health concern and an opportunity to understand how the human body counters disease.

“The unique relationship measles has with the human immune system,” he said, “can illuminate aspects of its inner workings.”

The study was funded by grants to the investigators the Indonesian Endowment Fund for Education, the Wellcome Trust, the German Centre for Infection Research, the Collaborative Research Centre of the German Research Foundation, the German Ministry of Health, and the Royal Society. The authors declared no conflicts of interest. Dr. Wesemann reported receiving support from National Institutes of Health grants and an award from the Burroughs Wellcome Fund; he also reports being a consultant for OpenBiome.

SOURCE: Petrova VN et al. Sci Immunol. 2019 Nov 1. doi: 10.1126/sciimmunol.aay6125; Wesemann DR. Sci Immunol. 2019 Nov 1. doi: 10.1126/sciimmunol.aaz4195.

A new study has uncovered how the measles virus (MeV) can induce immunosuppression by delaying the reconstitution of B cells.

CDC/ Cynthia S. Goldsmith; William Bellini, Ph.D.

“Our findings provide a biological explanation for the observed increase in childhood mortality and secondary infections several years after an episode of measles,” said Velislava N. Petrova, PhD, of the Wellcome Sanger Institute in Cambridge, England, and coauthors. The study was published in Science Immunology.

To determine if B-cell impairment can lead to measles-associated immunosuppression, the researchers investigated genetic changes in 26 unvaccinated children from the Netherlands who previously had measles. Their antibody genes were sequenced before any symptoms of measles developed and roughly 40 days after rash. Two control groups also were sequenced accordingly: vaccinated adults and three unvaccinated children from the same community who were not infected with measles.

Naive B cells from individuals in the vaccinated and uninfected control groups showed high correlation of immunoglobulin heavy chain (IGHV-J) gene frequencies across time periods (R² = 0.96 and 0.92, respectively) but no significant differences in gene expression (P greater than .05). At the same time, although B cell frequencies in measles patients recovered to levels before infection, they had significant changes in IGHV-J gene frequencies (P = .01) and decreased correlation in gene expression (R² = 0.78).

In addition, individuals in the control groups had “a stable genetic composition of B memory cells” but no significant changes in the third complementarity-determining region (CDR3) lengths or mutational frequency of IGHV genes (P greater than .05). B memory cells in measles patients, however, showed increases in mutational frequency (P = .0008) and a reduction in CDR3 length (P = .017) of IGHV genes, Dr. Petrova and associates said.

Finally, the researchers confirmed a hypothesis about the depletion of B memory cell clones during measles and a repopulation of new cells with less clonal expansion. The frequency of individual IGHV-J gene combinations before infection was correlated with a reduction after infection, “with the most frequent combinations undergoing the most marked depletion” and the result being an increase in genetic diversity.

To further test their findings, the researchers vaccinated two groups of four ferrets with live-attenuated influenza vaccine (LAIV) and at 4 weeks infected one of the groups with canine distemper virus (CDV), a surrogate for MeV. At 14 weeks after vaccination, the uninfected group maintained high levels of influenza-specific neutralizing antibodies while the infected group saw impaired B cells and a subsequent reduction in neutralizing antibodies.
 

Understanding the impact of measles on the immune system

“How measles infection has such a long-lasting deleterious effect on the immune system while allowing robust immunity against itself has been a burning immunological question,” Duane R. Wesemann, MD, PhD, of Brigham and Women’s Hospital in Boston, said in an accompanying editorial. The research from Petrova et al. begins to answer that question.

Among the observations he found most interesting was how “post-measles memory cells were more diverse than the pre-measles memory pool,” despite expectations that measles immunity would be dominant. He speculated that the void in memory cells is filled by a set of clones binding to unidentified or nonnative antigens, which may bring polyclonal diversity into B memory cells.

More research is needed to determine just what these findings mean, including looking beyond memory cell depletion and focusing on the impact of immature immunoglobulin repertoires in naive cells. But his broad takeaway is that measles remains both a public health concern and an opportunity to understand how the human body counters disease.

“The unique relationship measles has with the human immune system,” he said, “can illuminate aspects of its inner workings.”

The study was funded by grants to the investigators the Indonesian Endowment Fund for Education, the Wellcome Trust, the German Centre for Infection Research, the Collaborative Research Centre of the German Research Foundation, the German Ministry of Health, and the Royal Society. The authors declared no conflicts of interest. Dr. Wesemann reported receiving support from National Institutes of Health grants and an award from the Burroughs Wellcome Fund; he also reports being a consultant for OpenBiome.

SOURCE: Petrova VN et al. Sci Immunol. 2019 Nov 1. doi: 10.1126/sciimmunol.aay6125; Wesemann DR. Sci Immunol. 2019 Nov 1. doi: 10.1126/sciimmunol.aaz4195.

A new study has uncovered how the measles virus (MeV) can induce immunosuppression by delaying the reconstitution of B cells.

CDC/ Cynthia S. Goldsmith; William Bellini, Ph.D.

“Our findings provide a biological explanation for the observed increase in childhood mortality and secondary infections several years after an episode of measles,” said Velislava N. Petrova, PhD, of the Wellcome Sanger Institute in Cambridge, England, and coauthors. The study was published in Science Immunology.

To determine if B-cell impairment can lead to measles-associated immunosuppression, the researchers investigated genetic changes in 26 unvaccinated children from the Netherlands who previously had measles. Their antibody genes were sequenced before any symptoms of measles developed and roughly 40 days after rash. Two control groups also were sequenced accordingly: vaccinated adults and three unvaccinated children from the same community who were not infected with measles.

Naive B cells from individuals in the vaccinated and uninfected control groups showed high correlation of immunoglobulin heavy chain (IGHV-J) gene frequencies across time periods (R² = 0.96 and 0.92, respectively) but no significant differences in gene expression (P greater than .05). At the same time, although B cell frequencies in measles patients recovered to levels before infection, they had significant changes in IGHV-J gene frequencies (P = .01) and decreased correlation in gene expression (R² = 0.78).

In addition, individuals in the control groups had “a stable genetic composition of B memory cells” but no significant changes in the third complementarity-determining region (CDR3) lengths or mutational frequency of IGHV genes (P greater than .05). B memory cells in measles patients, however, showed increases in mutational frequency (P = .0008) and a reduction in CDR3 length (P = .017) of IGHV genes, Dr. Petrova and associates said.

Finally, the researchers confirmed a hypothesis about the depletion of B memory cell clones during measles and a repopulation of new cells with less clonal expansion. The frequency of individual IGHV-J gene combinations before infection was correlated with a reduction after infection, “with the most frequent combinations undergoing the most marked depletion” and the result being an increase in genetic diversity.

To further test their findings, the researchers vaccinated two groups of four ferrets with live-attenuated influenza vaccine (LAIV) and at 4 weeks infected one of the groups with canine distemper virus (CDV), a surrogate for MeV. At 14 weeks after vaccination, the uninfected group maintained high levels of influenza-specific neutralizing antibodies while the infected group saw impaired B cells and a subsequent reduction in neutralizing antibodies.
 

Understanding the impact of measles on the immune system

“How measles infection has such a long-lasting deleterious effect on the immune system while allowing robust immunity against itself has been a burning immunological question,” Duane R. Wesemann, MD, PhD, of Brigham and Women’s Hospital in Boston, said in an accompanying editorial. The research from Petrova et al. begins to answer that question.

Among the observations he found most interesting was how “post-measles memory cells were more diverse than the pre-measles memory pool,” despite expectations that measles immunity would be dominant. He speculated that the void in memory cells is filled by a set of clones binding to unidentified or nonnative antigens, which may bring polyclonal diversity into B memory cells.

More research is needed to determine just what these findings mean, including looking beyond memory cell depletion and focusing on the impact of immature immunoglobulin repertoires in naive cells. But his broad takeaway is that measles remains both a public health concern and an opportunity to understand how the human body counters disease.

“The unique relationship measles has with the human immune system,” he said, “can illuminate aspects of its inner workings.”

The study was funded by grants to the investigators the Indonesian Endowment Fund for Education, the Wellcome Trust, the German Centre for Infection Research, the Collaborative Research Centre of the German Research Foundation, the German Ministry of Health, and the Royal Society. The authors declared no conflicts of interest. Dr. Wesemann reported receiving support from National Institutes of Health grants and an award from the Burroughs Wellcome Fund; he also reports being a consultant for OpenBiome.

SOURCE: Petrova VN et al. Sci Immunol. 2019 Nov 1. doi: 10.1126/sciimmunol.aay6125; Wesemann DR. Sci Immunol. 2019 Nov 1. doi: 10.1126/sciimmunol.aaz4195.

Here are 5 articles from the November issue of Clinician Reviews (individual articles are valid for one year from date of publication—expiration dates below):

1. Poor response to statins hikes risk of cardiovascular events

To take the posttest, go to: https://bit.ly/2MVHlDR
Expires April 17, 2020

2. Postvaccination febrile seizures are no more severe than other febrile seizures

To take the posttest, go to: https://bit.ly/2VUJzaE
Expires April 19, 2020

3. Hydroxychloroquine adherence in SLE: worse than you thought

To take the posttest, go to: https://bit.ly/2oT00Z9
Expires April 22, 2020

4. Long-term antibiotic use may heighten stroke, CHD risk

To take the posttest, go to: https://bit.ly/2OUUVu5
Expires April 28, 2020

5. Knowledge gaps about long-term osteoporosis drug therapy benefits, risks remain large

To take the posttest, go to: https://bit.ly/2Msgqkb
Expires May 1, 2020

Here are 5 articles from the November issue of Clinician Reviews (individual articles are valid for one year from date of publication—expiration dates below):

1. Poor response to statins hikes risk of cardiovascular events

To take the posttest, go to: https://bit.ly/2MVHlDR
Expires April 17, 2020

2. Postvaccination febrile seizures are no more severe than other febrile seizures

To take the posttest, go to: https://bit.ly/2VUJzaE
Expires April 19, 2020

3. Hydroxychloroquine adherence in SLE: worse than you thought

To take the posttest, go to: https://bit.ly/2oT00Z9
Expires April 22, 2020

4. Long-term antibiotic use may heighten stroke, CHD risk

To take the posttest, go to: https://bit.ly/2OUUVu5
Expires April 28, 2020

5. Knowledge gaps about long-term osteoporosis drug therapy benefits, risks remain large

To take the posttest, go to: https://bit.ly/2Msgqkb
Expires May 1, 2020

Here are 5 articles from the November issue of Clinician Reviews (individual articles are valid for one year from date of publication—expiration dates below):

1. Poor response to statins hikes risk of cardiovascular events

To take the posttest, go to: https://bit.ly/2MVHlDR
Expires April 17, 2020

2. Postvaccination febrile seizures are no more severe than other febrile seizures

To take the posttest, go to: https://bit.ly/2VUJzaE
Expires April 19, 2020

3. Hydroxychloroquine adherence in SLE: worse than you thought

To take the posttest, go to: https://bit.ly/2oT00Z9
Expires April 22, 2020

4. Long-term antibiotic use may heighten stroke, CHD risk

To take the posttest, go to: https://bit.ly/2OUUVu5
Expires April 28, 2020

5. Knowledge gaps about long-term osteoporosis drug therapy benefits, risks remain large

To take the posttest, go to: https://bit.ly/2Msgqkb
Expires May 1, 2020

ST. LOUIS – A brain abscess in the presence of a lung infection should raise suspicion for Nocardia whether patients are immunocompromised or not, according to University of California, San Francisco, investigators.

M. Alexander Otto/MDedge News

Nocardia – an ubiquitous gram-positive rod normally found in standing water, decaying plants, and soil, that can cause problems when it is inhaled as dust or introduced through a nick in the skin – is an underappreciated cause of brain abscess that is not covered by standard empiric therapy targeting the more common causes: Staphylococcus and Streptococcus bacteria, said senior investigator Megan Richie, MD, an assistant neurology professor at UCSF.

“Patients that have a lung infection with a new brain abscess should be started on empiric therapy not just for pyogenic organisms, but also for Nocardia pending biopsy and operative culture data, especially given that empiric therapy of high-dose Bactrim for Nocardia is relatively benign,” she said at the annual meeting of the American Neurological Association.

The advice comes from a comparison of 14 Nocardia cases with 42 randomly selected Staph/Strep cases in a university radiologic database. Nine Nocardia cases were confirmed by operative specimen culture, the rest by lung, blood, or other tissue cultures.

Dr. Richie and colleagues suspected an association with lung infection, which has been reported anecdotally in the literature. The researchers wanted to take a quantitative look to see if it held up statistically after pushback on a brain abscess patient with a lung infection. “We were concerned this patient had Nocardia, but it took quite some time to convince other doctors that we really needed to start [Bactrim]. The patient was not immunocompromised and the infectious disease team said ‘Nocardia brain infections don’t happen in immunocompetent patients,’” Dr. Richie said,

The man did, however, turn out to have Nocardia, and of the 14 cases in the series, four patients (29%) were not immunosuppressed. “I think this would surprise [physicians] who have a little bit less experience with this organism,” Dr. Richie said.Patients with a Nocardia brain abscess were far more likely to have a concomitant lung infection (86% vs. 2%; odds ratio, 246; 95% confidence interval, 21-2953; P less than .0001). Staph/Strep brain abscess patients were more likely to have concomitant ear or sinus infections (40% versus 0%; P = .005). Immunosuppression did turn out to be more common in the Nocardia group, as well (71% vs. 19%; OR, 11; 95% CI, 3-43; P = .001), as did diabetes (36% vs. 10%; P = .03).

Nocardia patients were older (median age, 61 yrs vs. 46 yrs: P = .01) and more likely to be Hispanic (36% vs. 10%; P = .04). There were no differences in sex; neurosurgery history; intravenous drug use; or endocarditis.

On imaging, Nocardia brain abscesses were poorly circumscribed and tended to have multiple lobes, “often two in a figure-eight pattern,” Dr. Richie said. Nocardia diagnosis took longer (median, 7 vs. 4 days; P = .04), “which makes sense because it is a harder diagnosis to make,” she said.

Operative specimen culture was the most potent diagnostic tool. Blood cultures were positive in just one Nocardia patient and a few controls.

There was no external funding, and the investigators did not have any relevant disclosures.

[email protected]

ST. LOUIS – A brain abscess in the presence of a lung infection should raise suspicion for Nocardia whether patients are immunocompromised or not, according to University of California, San Francisco, investigators.

M. Alexander Otto/MDedge News

Nocardia – an ubiquitous gram-positive rod normally found in standing water, decaying plants, and soil, that can cause problems when it is inhaled as dust or introduced through a nick in the skin – is an underappreciated cause of brain abscess that is not covered by standard empiric therapy targeting the more common causes: Staphylococcus and Streptococcus bacteria, said senior investigator Megan Richie, MD, an assistant neurology professor at UCSF.

“Patients that have a lung infection with a new brain abscess should be started on empiric therapy not just for pyogenic organisms, but also for Nocardia pending biopsy and operative culture data, especially given that empiric therapy of high-dose Bactrim for Nocardia is relatively benign,” she said at the annual meeting of the American Neurological Association.

The advice comes from a comparison of 14 Nocardia cases with 42 randomly selected Staph/Strep cases in a university radiologic database. Nine Nocardia cases were confirmed by operative specimen culture, the rest by lung, blood, or other tissue cultures.

Dr. Richie and colleagues suspected an association with lung infection, which has been reported anecdotally in the literature. The researchers wanted to take a quantitative look to see if it held up statistically after pushback on a brain abscess patient with a lung infection. “We were concerned this patient had Nocardia, but it took quite some time to convince other doctors that we really needed to start [Bactrim]. The patient was not immunocompromised and the infectious disease team said ‘Nocardia brain infections don’t happen in immunocompetent patients,’” Dr. Richie said,

The man did, however, turn out to have Nocardia, and of the 14 cases in the series, four patients (29%) were not immunosuppressed. “I think this would surprise [physicians] who have a little bit less experience with this organism,” Dr. Richie said.Patients with a Nocardia brain abscess were far more likely to have a concomitant lung infection (86% vs. 2%; odds ratio, 246; 95% confidence interval, 21-2953; P less than .0001). Staph/Strep brain abscess patients were more likely to have concomitant ear or sinus infections (40% versus 0%; P = .005). Immunosuppression did turn out to be more common in the Nocardia group, as well (71% vs. 19%; OR, 11; 95% CI, 3-43; P = .001), as did diabetes (36% vs. 10%; P = .03).

Nocardia patients were older (median age, 61 yrs vs. 46 yrs: P = .01) and more likely to be Hispanic (36% vs. 10%; P = .04). There were no differences in sex; neurosurgery history; intravenous drug use; or endocarditis.

On imaging, Nocardia brain abscesses were poorly circumscribed and tended to have multiple lobes, “often two in a figure-eight pattern,” Dr. Richie said. Nocardia diagnosis took longer (median, 7 vs. 4 days; P = .04), “which makes sense because it is a harder diagnosis to make,” she said.

Operative specimen culture was the most potent diagnostic tool. Blood cultures were positive in just one Nocardia patient and a few controls.

There was no external funding, and the investigators did not have any relevant disclosures.

[email protected]

ST. LOUIS – A brain abscess in the presence of a lung infection should raise suspicion for Nocardia whether patients are immunocompromised or not, according to University of California, San Francisco, investigators.

M. Alexander Otto/MDedge News

Nocardia – an ubiquitous gram-positive rod normally found in standing water, decaying plants, and soil, that can cause problems when it is inhaled as dust or introduced through a nick in the skin – is an underappreciated cause of brain abscess that is not covered by standard empiric therapy targeting the more common causes: Staphylococcus and Streptococcus bacteria, said senior investigator Megan Richie, MD, an assistant neurology professor at UCSF.

“Patients that have a lung infection with a new brain abscess should be started on empiric therapy not just for pyogenic organisms, but also for Nocardia pending biopsy and operative culture data, especially given that empiric therapy of high-dose Bactrim for Nocardia is relatively benign,” she said at the annual meeting of the American Neurological Association.

The advice comes from a comparison of 14 Nocardia cases with 42 randomly selected Staph/Strep cases in a university radiologic database. Nine Nocardia cases were confirmed by operative specimen culture, the rest by lung, blood, or other tissue cultures.

Dr. Richie and colleagues suspected an association with lung infection, which has been reported anecdotally in the literature. The researchers wanted to take a quantitative look to see if it held up statistically after pushback on a brain abscess patient with a lung infection. “We were concerned this patient had Nocardia, but it took quite some time to convince other doctors that we really needed to start [Bactrim]. The patient was not immunocompromised and the infectious disease team said ‘Nocardia brain infections don’t happen in immunocompetent patients,’” Dr. Richie said,

The man did, however, turn out to have Nocardia, and of the 14 cases in the series, four patients (29%) were not immunosuppressed. “I think this would surprise [physicians] who have a little bit less experience with this organism,” Dr. Richie said.Patients with a Nocardia brain abscess were far more likely to have a concomitant lung infection (86% vs. 2%; odds ratio, 246; 95% confidence interval, 21-2953; P less than .0001). Staph/Strep brain abscess patients were more likely to have concomitant ear or sinus infections (40% versus 0%; P = .005). Immunosuppression did turn out to be more common in the Nocardia group, as well (71% vs. 19%; OR, 11; 95% CI, 3-43; P = .001), as did diabetes (36% vs. 10%; P = .03).

Nocardia patients were older (median age, 61 yrs vs. 46 yrs: P = .01) and more likely to be Hispanic (36% vs. 10%; P = .04). There were no differences in sex; neurosurgery history; intravenous drug use; or endocarditis.

On imaging, Nocardia brain abscesses were poorly circumscribed and tended to have multiple lobes, “often two in a figure-eight pattern,” Dr. Richie said. Nocardia diagnosis took longer (median, 7 vs. 4 days; P = .04), “which makes sense because it is a harder diagnosis to make,” she said.

Operative specimen culture was the most potent diagnostic tool. Blood cultures were positive in just one Nocardia patient and a few controls.

There was no external funding, and the investigators did not have any relevant disclosures.

[email protected]

NEW ORLEANS – Up to 50% of children with asthma struggle to control their condition, yet fewer than 5% of pediatric asthma is severe and truly resistant to therapy, according to Susan Laubach, MD.

Other factors may make asthma difficult to control and may be modifiable, especially nonadherence to recommended treatment. In fact, up to 70% of patients report poor adherence to recommended treatment, Dr. Laubach said at the annual meeting of the American Academy of Pediatrics.

“Barriers to adherence may be related to the treatments themselves,” she said. “These include complex treatment schedules, lack of an immediately discernible beneficial effect, adverse effects of the medication, and prohibitive costs.”

Dr. Laubach, who directs the allergy clinic at Rady Children’s Hospital in San Diego, said that clinician-related barriers also influence patient adherence to recommended treatment, including difficulty scheduling appointments or seeing the same physician, a perceived lack of empathy, or failure to discuss the family’s concerns or answer questions. Common patient-related barriers include poor understanding of how the medication may help or how to use the inhalers.

“Some families have a lack of trust in the health care system, or certain beliefs about illness or medication that may hamper motivation to adhere,” she added. “Social issues such as poverty, lack of insurance, or a chaotic home environment may make it difficult for a patient to adhere to recommended treatment.”

In 2013, researchers led by Ted Klok, MD, PhD, of Princess Amalia Children’s Clinic in the Netherlands, explored practical ways to improve treatment adherence in children with pediatric respiratory disease (Breathe. 2013;9:268-77). One of their recommendations involves “five E’s” of ensuring optimal adherence. They include:

Ensure close and repeated follow-up to help build trust and partnership. “I’ll often follow up every month until I know a patient has gained good control of his or her asthma,” said Dr. Laubach, who was not involved in developing the recommendations. “Then I’ll follow up every 3 months.”

Explore the patient’s views, beliefs, and preferences. “You can do this by inviting questions or following up on comments or remarks made about the treatment plan,” she said. “This doesn’t have to take long. You can simply ask, ‘What are you concerned might happen if your child uses an inhaled corticosteroid?’ Or, ‘What have you heard about inhaled steroids?’ ”

Express empathy using active listening techniques tailored to the patient’s needs. Consider phrasing like, “I understand what you’re saying. In a perfect world, your child would not have to use any medications. But when he can’t sleep because he’s coughing so much, the benefit of this medication probably outweighs any potential risks.”

Exercise shared decision making. For example, if the parent of one of your patients has to leave for work very early in the morning, “maybe find a way to adjust to once-daily dosing so that appropriate doses can be given at bedtime when the parent is consistently available,” Dr. Laubach said.

Evaluate adherence in a nonjudgmental fashion. Evidence suggests that most patients with asthma miss a couple of medication doses now and then. She makes it a point to ask patients, “If you’re supposed to take 14 doses a week, how many do you think you actually take?” Their response “gives me an idea about their level of adherence and it opens a discussion into why they may miss doses, so that we can find a solution to help improve adherence.”

gpointstudio/Thinkstock

[email protected]

NEW ORLEANS – Up to 50% of children with asthma struggle to control their condition, yet fewer than 5% of pediatric asthma is severe and truly resistant to therapy, according to Susan Laubach, MD.

Other factors may make asthma difficult to control and may be modifiable, especially nonadherence to recommended treatment. In fact, up to 70% of patients report poor adherence to recommended treatment, Dr. Laubach said at the annual meeting of the American Academy of Pediatrics.

“Barriers to adherence may be related to the treatments themselves,” she said. “These include complex treatment schedules, lack of an immediately discernible beneficial effect, adverse effects of the medication, and prohibitive costs.”

Dr. Laubach, who directs the allergy clinic at Rady Children’s Hospital in San Diego, said that clinician-related barriers also influence patient adherence to recommended treatment, including difficulty scheduling appointments or seeing the same physician, a perceived lack of empathy, or failure to discuss the family’s concerns or answer questions. Common patient-related barriers include poor understanding of how the medication may help or how to use the inhalers.

“Some families have a lack of trust in the health care system, or certain beliefs about illness or medication that may hamper motivation to adhere,” she added. “Social issues such as poverty, lack of insurance, or a chaotic home environment may make it difficult for a patient to adhere to recommended treatment.”

In 2013, researchers led by Ted Klok, MD, PhD, of Princess Amalia Children’s Clinic in the Netherlands, explored practical ways to improve treatment adherence in children with pediatric respiratory disease (Breathe. 2013;9:268-77). One of their recommendations involves “five E’s” of ensuring optimal adherence. They include:

Ensure close and repeated follow-up to help build trust and partnership. “I’ll often follow up every month until I know a patient has gained good control of his or her asthma,” said Dr. Laubach, who was not involved in developing the recommendations. “Then I’ll follow up every 3 months.”

Explore the patient’s views, beliefs, and preferences. “You can do this by inviting questions or following up on comments or remarks made about the treatment plan,” she said. “This doesn’t have to take long. You can simply ask, ‘What are you concerned might happen if your child uses an inhaled corticosteroid?’ Or, ‘What have you heard about inhaled steroids?’ ”

Express empathy using active listening techniques tailored to the patient’s needs. Consider phrasing like, “I understand what you’re saying. In a perfect world, your child would not have to use any medications. But when he can’t sleep because he’s coughing so much, the benefit of this medication probably outweighs any potential risks.”

Exercise shared decision making. For example, if the parent of one of your patients has to leave for work very early in the morning, “maybe find a way to adjust to once-daily dosing so that appropriate doses can be given at bedtime when the parent is consistently available,” Dr. Laubach said.

Evaluate adherence in a nonjudgmental fashion. Evidence suggests that most patients with asthma miss a couple of medication doses now and then. She makes it a point to ask patients, “If you’re supposed to take 14 doses a week, how many do you think you actually take?” Their response “gives me an idea about their level of adherence and it opens a discussion into why they may miss doses, so that we can find a solution to help improve adherence.”

gpointstudio/Thinkstock

[email protected]

NEW ORLEANS – Up to 50% of children with asthma struggle to control their condition, yet fewer than 5% of pediatric asthma is severe and truly resistant to therapy, according to Susan Laubach, MD.

Other factors may make asthma difficult to control and may be modifiable, especially nonadherence to recommended treatment. In fact, up to 70% of patients report poor adherence to recommended treatment, Dr. Laubach said at the annual meeting of the American Academy of Pediatrics.

“Barriers to adherence may be related to the treatments themselves,” she said. “These include complex treatment schedules, lack of an immediately discernible beneficial effect, adverse effects of the medication, and prohibitive costs.”

Dr. Laubach, who directs the allergy clinic at Rady Children’s Hospital in San Diego, said that clinician-related barriers also influence patient adherence to recommended treatment, including difficulty scheduling appointments or seeing the same physician, a perceived lack of empathy, or failure to discuss the family’s concerns or answer questions. Common patient-related barriers include poor understanding of how the medication may help or how to use the inhalers.

“Some families have a lack of trust in the health care system, or certain beliefs about illness or medication that may hamper motivation to adhere,” she added. “Social issues such as poverty, lack of insurance, or a chaotic home environment may make it difficult for a patient to adhere to recommended treatment.”

In 2013, researchers led by Ted Klok, MD, PhD, of Princess Amalia Children’s Clinic in the Netherlands, explored practical ways to improve treatment adherence in children with pediatric respiratory disease (Breathe. 2013;9:268-77). One of their recommendations involves “five E’s” of ensuring optimal adherence. They include:

Ensure close and repeated follow-up to help build trust and partnership. “I’ll often follow up every month until I know a patient has gained good control of his or her asthma,” said Dr. Laubach, who was not involved in developing the recommendations. “Then I’ll follow up every 3 months.”

Explore the patient’s views, beliefs, and preferences. “You can do this by inviting questions or following up on comments or remarks made about the treatment plan,” she said. “This doesn’t have to take long. You can simply ask, ‘What are you concerned might happen if your child uses an inhaled corticosteroid?’ Or, ‘What have you heard about inhaled steroids?’ ”

Express empathy using active listening techniques tailored to the patient’s needs. Consider phrasing like, “I understand what you’re saying. In a perfect world, your child would not have to use any medications. But when he can’t sleep because he’s coughing so much, the benefit of this medication probably outweighs any potential risks.”

Exercise shared decision making. For example, if the parent of one of your patients has to leave for work very early in the morning, “maybe find a way to adjust to once-daily dosing so that appropriate doses can be given at bedtime when the parent is consistently available,” Dr. Laubach said.

Evaluate adherence in a nonjudgmental fashion. Evidence suggests that most patients with asthma miss a couple of medication doses now and then. She makes it a point to ask patients, “If you’re supposed to take 14 doses a week, how many do you think you actually take?” Their response “gives me an idea about their level of adherence and it opens a discussion into why they may miss doses, so that we can find a solution to help improve adherence.”

gpointstudio/Thinkstock

[email protected]

Is the relationship between A-fib and sleep apnea more than a coincidence stemming from the number of shared associated comorbidities? Significantly, the treatment of obstructive sleep apnea with continuous positive airway pressure (CPAP) has been shown to decrease the recurrence of A-fib after pharmacologic or electrical conversion and after interventional pulmonary vein interruption.¹ This suggests that at least in some cases, sleep apnea plays an active role in initiating and possibly also maintaining A-fib. The immediate culprit mediators that come to mind are hypoxia and hypercapnea; both are at least partially ameliorated by the successful use of CPAP, and both are reasonable physiologic candidates for induction of A-fib. Hypoxia is supported by clinical observation, and hypercapnea by experimental modeling.²

It is easy for clinicians to conceptualize the organ effects of hypoxia and hypercapnea. We are accustomed to seeing clinical ramifications of these in the emergency department and intensive care unit, particularly those affecting the brain and heart, organs critically dependent on transmembrane ion flow. We may recall from biochemistry classes the effects of hypoxia on intracellular metabolism and the implications on energy stores, mitochondrial function, and ion translocation. Recent work on the cellular effects of hypoxia, including research that resulted in a Nobel prize, has drawn major attention to patterned cellular responses to intermittent and persistent hypoxia. This includes recognition of epigenetic changes resulting in localized cardiac remodeling and fibrosis,³ factors that clearly affect the expression of arrhythmias, including A-fib.

But the interrelationship between A-fib and sleep apnea may be even more convoluted and intriguing. It now seems that most things cardiac are associated with inflammation in some guise, and the A-fib connection with sleep apnea may not be an exception. Almost 20 years ago, it was recognized that A-fib is associated with an elevation in circulating C-reactive protein (CRP),⁴ a biomarker of “inflammation,” although not necessarily an active participant. Recent reviews of this connection have been published,⁵ and successful anti-inflammatory approaches to preventing A-fib using colchicine have been described.⁶ So how does this tie in with sleep apnea?

A number of papers have now demonstrated that sleep apnea is also associated with an elevation in CRP,⁷ perhaps due to increases in tumor necrosis factor (TNF)-alpha in response to the intermittent hypoxia of sleep apnea. TNF can drive the inflammatory response through increased expression of genes regulated by nuclear factor kappa-B.⁸ While it certainly warrants consideration that the elevated biomarkers of inflammation in patients with sleep apnea actually reflect the presence of the frequent comorbidities, including visceral obesity, treating sleep apnea with CPAP (comparable to what I noted above in patients with A-fib) has been shown to reduce circulating CRP levels.⁹

As our understanding of the biologic underpinnings of A-fib and sleep apnea continue to grow, the practical clinical implications of the relationship between them, as described by Ayache et al, may achieve greater clarity. The two conditions commonly coexist, and treating the sleep apnea results in better rhythm-directed outcomes in the A-fib.

Stay tuned, there is certainly more to learn about this.

Is the relationship between A-fib and sleep apnea more than a coincidence stemming from the number of shared associated comorbidities? Significantly, the treatment of obstructive sleep apnea with continuous positive airway pressure (CPAP) has been shown to decrease the recurrence of A-fib after pharmacologic or electrical conversion and after interventional pulmonary vein interruption.¹ This suggests that at least in some cases, sleep apnea plays an active role in initiating and possibly also maintaining A-fib. The immediate culprit mediators that come to mind are hypoxia and hypercapnea; both are at least partially ameliorated by the successful use of CPAP, and both are reasonable physiologic candidates for induction of A-fib. Hypoxia is supported by clinical observation, and hypercapnea by experimental modeling.²

It is easy for clinicians to conceptualize the organ effects of hypoxia and hypercapnea. We are accustomed to seeing clinical ramifications of these in the emergency department and intensive care unit, particularly those affecting the brain and heart, organs critically dependent on transmembrane ion flow. We may recall from biochemistry classes the effects of hypoxia on intracellular metabolism and the implications on energy stores, mitochondrial function, and ion translocation. Recent work on the cellular effects of hypoxia, including research that resulted in a Nobel prize, has drawn major attention to patterned cellular responses to intermittent and persistent hypoxia. This includes recognition of epigenetic changes resulting in localized cardiac remodeling and fibrosis,³ factors that clearly affect the expression of arrhythmias, including A-fib.

But the interrelationship between A-fib and sleep apnea may be even more convoluted and intriguing. It now seems that most things cardiac are associated with inflammation in some guise, and the A-fib connection with sleep apnea may not be an exception. Almost 20 years ago, it was recognized that A-fib is associated with an elevation in circulating C-reactive protein (CRP),⁴ a biomarker of “inflammation,” although not necessarily an active participant. Recent reviews of this connection have been published,⁵ and successful anti-inflammatory approaches to preventing A-fib using colchicine have been described.⁶ So how does this tie in with sleep apnea?

A number of papers have now demonstrated that sleep apnea is also associated with an elevation in CRP,⁷ perhaps due to increases in tumor necrosis factor (TNF)-alpha in response to the intermittent hypoxia of sleep apnea. TNF can drive the inflammatory response through increased expression of genes regulated by nuclear factor kappa-B.⁸ While it certainly warrants consideration that the elevated biomarkers of inflammation in patients with sleep apnea actually reflect the presence of the frequent comorbidities, including visceral obesity, treating sleep apnea with CPAP (comparable to what I noted above in patients with A-fib) has been shown to reduce circulating CRP levels.⁹

As our understanding of the biologic underpinnings of A-fib and sleep apnea continue to grow, the practical clinical implications of the relationship between them, as described by Ayache et al, may achieve greater clarity. The two conditions commonly coexist, and treating the sleep apnea results in better rhythm-directed outcomes in the A-fib.

Stay tuned, there is certainly more to learn about this.

Is the relationship between A-fib and sleep apnea more than a coincidence stemming from the number of shared associated comorbidities? Significantly, the treatment of obstructive sleep apnea with continuous positive airway pressure (CPAP) has been shown to decrease the recurrence of A-fib after pharmacologic or electrical conversion and after interventional pulmonary vein interruption.¹ This suggests that at least in some cases, sleep apnea plays an active role in initiating and possibly also maintaining A-fib. The immediate culprit mediators that come to mind are hypoxia and hypercapnea; both are at least partially ameliorated by the successful use of CPAP, and both are reasonable physiologic candidates for induction of A-fib. Hypoxia is supported by clinical observation, and hypercapnea by experimental modeling.²

It is easy for clinicians to conceptualize the organ effects of hypoxia and hypercapnea. We are accustomed to seeing clinical ramifications of these in the emergency department and intensive care unit, particularly those affecting the brain and heart, organs critically dependent on transmembrane ion flow. We may recall from biochemistry classes the effects of hypoxia on intracellular metabolism and the implications on energy stores, mitochondrial function, and ion translocation. Recent work on the cellular effects of hypoxia, including research that resulted in a Nobel prize, has drawn major attention to patterned cellular responses to intermittent and persistent hypoxia. This includes recognition of epigenetic changes resulting in localized cardiac remodeling and fibrosis,³ factors that clearly affect the expression of arrhythmias, including A-fib.

But the interrelationship between A-fib and sleep apnea may be even more convoluted and intriguing. It now seems that most things cardiac are associated with inflammation in some guise, and the A-fib connection with sleep apnea may not be an exception. Almost 20 years ago, it was recognized that A-fib is associated with an elevation in circulating C-reactive protein (CRP),⁴ a biomarker of “inflammation,” although not necessarily an active participant. Recent reviews of this connection have been published,⁵ and successful anti-inflammatory approaches to preventing A-fib using colchicine have been described.⁶ So how does this tie in with sleep apnea?

A number of papers have now demonstrated that sleep apnea is also associated with an elevation in CRP,⁷ perhaps due to increases in tumor necrosis factor (TNF)-alpha in response to the intermittent hypoxia of sleep apnea. TNF can drive the inflammatory response through increased expression of genes regulated by nuclear factor kappa-B.⁸ While it certainly warrants consideration that the elevated biomarkers of inflammation in patients with sleep apnea actually reflect the presence of the frequent comorbidities, including visceral obesity, treating sleep apnea with CPAP (comparable to what I noted above in patients with A-fib) has been shown to reduce circulating CRP levels.⁹

As our understanding of the biologic underpinnings of A-fib and sleep apnea continue to grow, the practical clinical implications of the relationship between them, as described by Ayache et al, may achieve greater clarity. The two conditions commonly coexist, and treating the sleep apnea results in better rhythm-directed outcomes in the A-fib.

Stay tuned, there is certainly more to learn about this.

Yes. The prevalence of sleep apnea is exceedingly high in patients with atrial fibrillation—50% to 80% compared with 30% to 60% in respective control groups.^1–3 Conversely, atrial fibrillation is more prevalent in those with sleep-disordered breathing than in those without (4.8% vs 0.9%).⁴

Sleep-disordered breathing comprises obstructive sleep apnea and central sleep apnea. Obstructive sleep apnea, characterized by repetitive upper-airway obstruction during sleep, is accompanied by intermittent hypoxia, rises in carbon dioxide, autonomic nervous system fluctuations, and intrathoracic pressure alterations.⁵ Central sleep apnea may be neurally mediated and, in the setting of cardiac disease, is characterized by alterations in chemosensitivity and chemoresponsiveness, leading to a state of high loop gain—ie, a hypersensitive ventilatory control system leading to ventilatory drive oscillations.⁶

Both obstructive and central sleep apnea have been associated with atrial fibrillation. Experimental data implicate obstructive sleep apnea as a trigger of atrial arrhythmogenesis,^7,8 and epidemiologic studies support an association between central sleep apnea, Cheyne-Stokes respiration, and incident atrial fibrillation.⁹

HOW SLEEP APNEA COULD LEAD TO ATRIAL FIBRILLATION

In experiments in animals, intermittent upper-airway obstruction led to forced inspiration, substantial negative intrathoracic pressure, subsequent left atrial distention, and increased susceptibility to atrial fibrillation.¹⁰ The autonomic nervous system may be a mediator of apnea-induced atrial fibrillation, as apnea-induced atrial fibrillation is suppressed with autonomic blockade.¹⁰

Emerging data also support the hypothesis that intermittent hypoxia⁷ and resolution of hypercapnia,⁸ as observed in obstructive sleep apnea, exert atrial electrophysiologic changes that increase vulnerability to atrial arrhythmogenesis.

In a case-crossover study,¹¹ the odds of paroxysmal atrial fibrillation occurring after a respiratory disturbance were 17.9 times higher than after normal breathing (95% confidence interval [CI] 2.2–144.2), though the absolute rate of overall arrhythmia events (including both atrial fibrillation and nonsustained ventricular tachycardia) associated with respiratory disturbances was low (1 excess arrhythmia event per 40,000 respiratory disturbances).

EFFECT OF SLEEP APNEA ON ATRIAL FIBRILLATION MANAGEMENT

Sleep apnea also seems to affect the efficacy of a rhythm-control strategy for atrial fibrillation. For example, patients with obstructive sleep apnea have a higher risk of recurrent atrial fibrillation after cardioversion (82% vs 42% in controls)¹² and up to a 25% greater risk of recurrence after catheter ablation compared with those without obstructive sleep apnea (risk ratio 1.25, 95% CI 1.08–1.45).¹³

Several observational studies showed a higher rate of atrial fibrillation after pulmonary vein isolation in obstructive sleep apnea patients who do not use continuous positive airway pressure (CPAP) than in those who do.^14–17 CPAP therapy appears to exert beneficial effects on cardiac structural remodeling;  cardiac magnetic resonance imaging shows that patients with sleep apnea who received less than 4 hours of CPAP per night had larger left atrial dimensions and increased left ventricular mass compared with those who received more than 4 hours of CPAP at night.¹⁷ However, a need remains for high-quality, large randomized controlled trials to eliminate potential unmeasured biases due to differences that may exist between CPAP users and non-users, such as general adherence to medical therapy and healthcare interventions.

An additional consideration is that the overall utility and value of obtaining a diagnosis of obstructive sleep apnea strictly as it pertains to atrial fibrillation management is affected by whether a rhythm- or rate-control strategy is pursued. In other words, if a patient is deemed to be in permanent atrial fibrillation and a rhythm-control strategy is therefore not pursued, the potential effect of untreated obstructive sleep apnea on atrial fibrillation recurrence could be less important. In this case, however, the other beneficial cardiovascular and systemic effects of diagnosing and treating underlying obstructive sleep apnea would remain.

Epidemiologic and clinic-based studies have supported an association between sleep apnea (mostly central, but also obstructive) and atrial fibrillation.^4,18

Community-based studies such as the Sleep Heart Health Study⁴ and the Outcomes of Sleep Disorders in Older Men Study (MrOS Sleep),¹⁸ involving thousands of participants, have found the strongest cross-sectional associations of both obstructive and central sleep apnea with nocturnal atrial fibrillation. The findings included a 2 to 5 times higher odds of nocturnal atrial fibrillation, particularly in those with a moderate to severe degree of sleep-disordered breathing—even after adjusting for confounding influences (eg, obesity) and self-reported cardiac disease such as heart failure.

In MrOS Sleep, in an older male cohort, both obstructive and central sleep apnea were associated with nocturnal atrial fibrillation, though central sleep apnea and Cheyne-Stokes respirations had a stronger magnitude of association.¹⁸

Further insights can be drawn specifically from patients with heart failure. Sin et al,¹⁹ in a 1999 study, found that in 450 patients with systolic heart failure (85% men), the prevalence of sleep-disordered breathing was 25% to 33% (depending on the apnea-hypopnea index cutoff used) for central sleep apnea, and similarly 27% to 38% for obstructive sleep apnea. The prevalence of atrial fibrillation in this group was 10% in women and 15% in men. Atrial fibrillation was reported as a significant risk factor for central sleep apnea, but not for obstructive sleep apnea (for which only male sex and increasing body mass index were significant risk factors). Directionality was not clearly reported in this retrospective study in terms of timing of sleep studies and other assessments: ie, the report did not clearly state which came first, the atrial fibrillation or the sleep apnea. Therefore, the possibility that central sleep apnea is a predictor of atrial fibrillation cannot be excluded.  

Yumino et al,²⁰ in a study published in 2009, evaluated 218 patients with heart failure (with a left ventricular ejection fraction of ≤ 45%) and reported a prevalence of moderate to severe sleep apnea of 21% for central sleep apnea and 26% for obstructive sleep apnea. In multivariate analysis, atrial fibrillation was independently associated with central sleep apnea but not obstructive sleep apnea.

In recent cohort studies, central sleep apnea was associated with 2 to 3 times higher odds of developing atrial fibrillation, while obstructive sleep apnea was not a predictor of incident atrial fibrillation.^9,21

Although most available studies associate sleep apnea with atrial fibrillation, findings of a case-control study²² did not support a difference in the prevalence of sleep apnea syndrome (defined as apnea index ≥ 5 and apnea-hypopnea index ≥ 15, and the presence of sleep symptoms) in patients with lone atrial fibrillation (no evident cardiovascular disease) compared with controls matched for age, sex, and cardiovascular morbidity.

But observational studies are limited by the potential for residual unmeasured confounding factors and lack of objective cardiac structural data, such as left ventricular ejection fraction and atrial enlargement. Moreover, there can be significant differences in sleep apnea definitions among studies, thus limiting the ability to reach a definitive conclusion about the relationship between sleep apnea and atrial fibrillation.

SCREENING AND DIAGNOSIS

The 2014 joint guidelines of the American Heart Association, American College of Cardiology, and Heart Rhythm Society for the management of atrial fibrillation state that a sleep study may be useful if sleep apnea is suspected.²³ The 2019 focused update of the 2014 guidelines²⁴ state that for overweight and obese patients with atrial fibrillation, weight loss combined with risk-factor modification is recommended (class I recommendation, level of evidence B-R, ie, data derived from 1 or more randomized trials or meta-analysis of such studies). Risk-factor modification in this case includes assessment and treatment of underlying sleep apnea, hypertension, hyperlipidemia, glucose intolerance, and alcohol and tobacco use.

Laboratory polysomnography has long been considered the gold standard for sleep apnea diagnosis. In one study,¹³ obstructive sleep apnea was a greater predictor of atrial fibrillation when diagnosed by polysomnography (risk ratio 1.40, 95% CI 1.16–1.68) compared with identification by screening using the Berlin questionnaire (risk ratio 1.07, 95% CI 0.91–1.27). However, a laboratory sleep study is associated with increased patient burden and limited availability.

Home sleep apnea testing is being increasingly used in the diagnostic evaluation of obstructive sleep apnea and may be a less costly, more available alternative. However, since a home sleep apnea test is less sensitive than polysomnography in detecting obstructive sleep apnea, the American Academy of Sleep Medicine guidelines²⁸ state that if a single home sleep apnea test is negative or inconclusive, polysomnography should be done if there is clinical suspicion of sleep apnea. Moreover, current guidelines from this group recommend that patients with significant cardiorespiratory disease should be tested with polysomnography rather than home sleep apnea testing.²²

Further study is needed to determine the optimal screening method for sleep apnea in patients with atrial fibrillation and to clarify the role of home sleep apnea testing. While keeping in mind the limitations of a screening questionnaire in this population, as a general approach it is reasonable to use a screening questionnaire for sleep apnea. And if the screen is positive, further evaluation with a sleep study is merited, whether by laboratory polysomnography, a home sleep apnea test, or referral to a sleep specialist.

MULTIDISCIPLINARY CARE MAY BE IDEAL

Overall, given the high prevalence of sleep apnea in patients with atrial fibrillation, the deleterious effects of sleep apnea in general, the influence of sleep apnea on atrial fibrillation, and the cardiovascular and other beneficial effects of adequate treatment of sleep apnea, patients with atrial fibrillation should be assessed for sleep apnea.

While the optimal strategy in evaluating for sleep apnea in these patients needs to be further defined, a multidisciplinary approach to care involving a primary care provider, cardiologist, and sleep specialist may be ideal.

Yes. The prevalence of sleep apnea is exceedingly high in patients with atrial fibrillation—50% to 80% compared with 30% to 60% in respective control groups.^1–3 Conversely, atrial fibrillation is more prevalent in those with sleep-disordered breathing than in those without (4.8% vs 0.9%).⁴

Sleep-disordered breathing comprises obstructive sleep apnea and central sleep apnea. Obstructive sleep apnea, characterized by repetitive upper-airway obstruction during sleep, is accompanied by intermittent hypoxia, rises in carbon dioxide, autonomic nervous system fluctuations, and intrathoracic pressure alterations.⁵ Central sleep apnea may be neurally mediated and, in the setting of cardiac disease, is characterized by alterations in chemosensitivity and chemoresponsiveness, leading to a state of high loop gain—ie, a hypersensitive ventilatory control system leading to ventilatory drive oscillations.⁶

Both obstructive and central sleep apnea have been associated with atrial fibrillation. Experimental data implicate obstructive sleep apnea as a trigger of atrial arrhythmogenesis,^7,8 and epidemiologic studies support an association between central sleep apnea, Cheyne-Stokes respiration, and incident atrial fibrillation.⁹

HOW SLEEP APNEA COULD LEAD TO ATRIAL FIBRILLATION

In experiments in animals, intermittent upper-airway obstruction led to forced inspiration, substantial negative intrathoracic pressure, subsequent left atrial distention, and increased susceptibility to atrial fibrillation.¹⁰ The autonomic nervous system may be a mediator of apnea-induced atrial fibrillation, as apnea-induced atrial fibrillation is suppressed with autonomic blockade.¹⁰

Emerging data also support the hypothesis that intermittent hypoxia⁷ and resolution of hypercapnia,⁸ as observed in obstructive sleep apnea, exert atrial electrophysiologic changes that increase vulnerability to atrial arrhythmogenesis.

In a case-crossover study,¹¹ the odds of paroxysmal atrial fibrillation occurring after a respiratory disturbance were 17.9 times higher than after normal breathing (95% confidence interval [CI] 2.2–144.2), though the absolute rate of overall arrhythmia events (including both atrial fibrillation and nonsustained ventricular tachycardia) associated with respiratory disturbances was low (1 excess arrhythmia event per 40,000 respiratory disturbances).

EFFECT OF SLEEP APNEA ON ATRIAL FIBRILLATION MANAGEMENT

Sleep apnea also seems to affect the efficacy of a rhythm-control strategy for atrial fibrillation. For example, patients with obstructive sleep apnea have a higher risk of recurrent atrial fibrillation after cardioversion (82% vs 42% in controls)¹² and up to a 25% greater risk of recurrence after catheter ablation compared with those without obstructive sleep apnea (risk ratio 1.25, 95% CI 1.08–1.45).¹³

Several observational studies showed a higher rate of atrial fibrillation after pulmonary vein isolation in obstructive sleep apnea patients who do not use continuous positive airway pressure (CPAP) than in those who do.^14–17 CPAP therapy appears to exert beneficial effects on cardiac structural remodeling;  cardiac magnetic resonance imaging shows that patients with sleep apnea who received less than 4 hours of CPAP per night had larger left atrial dimensions and increased left ventricular mass compared with those who received more than 4 hours of CPAP at night.¹⁷ However, a need remains for high-quality, large randomized controlled trials to eliminate potential unmeasured biases due to differences that may exist between CPAP users and non-users, such as general adherence to medical therapy and healthcare interventions.

An additional consideration is that the overall utility and value of obtaining a diagnosis of obstructive sleep apnea strictly as it pertains to atrial fibrillation management is affected by whether a rhythm- or rate-control strategy is pursued. In other words, if a patient is deemed to be in permanent atrial fibrillation and a rhythm-control strategy is therefore not pursued, the potential effect of untreated obstructive sleep apnea on atrial fibrillation recurrence could be less important. In this case, however, the other beneficial cardiovascular and systemic effects of diagnosing and treating underlying obstructive sleep apnea would remain.

Epidemiologic and clinic-based studies have supported an association between sleep apnea (mostly central, but also obstructive) and atrial fibrillation.^4,18

Community-based studies such as the Sleep Heart Health Study⁴ and the Outcomes of Sleep Disorders in Older Men Study (MrOS Sleep),¹⁸ involving thousands of participants, have found the strongest cross-sectional associations of both obstructive and central sleep apnea with nocturnal atrial fibrillation. The findings included a 2 to 5 times higher odds of nocturnal atrial fibrillation, particularly in those with a moderate to severe degree of sleep-disordered breathing—even after adjusting for confounding influences (eg, obesity) and self-reported cardiac disease such as heart failure.

In MrOS Sleep, in an older male cohort, both obstructive and central sleep apnea were associated with nocturnal atrial fibrillation, though central sleep apnea and Cheyne-Stokes respirations had a stronger magnitude of association.¹⁸

Further insights can be drawn specifically from patients with heart failure. Sin et al,¹⁹ in a 1999 study, found that in 450 patients with systolic heart failure (85% men), the prevalence of sleep-disordered breathing was 25% to 33% (depending on the apnea-hypopnea index cutoff used) for central sleep apnea, and similarly 27% to 38% for obstructive sleep apnea. The prevalence of atrial fibrillation in this group was 10% in women and 15% in men. Atrial fibrillation was reported as a significant risk factor for central sleep apnea, but not for obstructive sleep apnea (for which only male sex and increasing body mass index were significant risk factors). Directionality was not clearly reported in this retrospective study in terms of timing of sleep studies and other assessments: ie, the report did not clearly state which came first, the atrial fibrillation or the sleep apnea. Therefore, the possibility that central sleep apnea is a predictor of atrial fibrillation cannot be excluded.  

Yumino et al,²⁰ in a study published in 2009, evaluated 218 patients with heart failure (with a left ventricular ejection fraction of ≤ 45%) and reported a prevalence of moderate to severe sleep apnea of 21% for central sleep apnea and 26% for obstructive sleep apnea. In multivariate analysis, atrial fibrillation was independently associated with central sleep apnea but not obstructive sleep apnea.

In recent cohort studies, central sleep apnea was associated with 2 to 3 times higher odds of developing atrial fibrillation, while obstructive sleep apnea was not a predictor of incident atrial fibrillation.^9,21

Although most available studies associate sleep apnea with atrial fibrillation, findings of a case-control study²² did not support a difference in the prevalence of sleep apnea syndrome (defined as apnea index ≥ 5 and apnea-hypopnea index ≥ 15, and the presence of sleep symptoms) in patients with lone atrial fibrillation (no evident cardiovascular disease) compared with controls matched for age, sex, and cardiovascular morbidity.

But observational studies are limited by the potential for residual unmeasured confounding factors and lack of objective cardiac structural data, such as left ventricular ejection fraction and atrial enlargement. Moreover, there can be significant differences in sleep apnea definitions among studies, thus limiting the ability to reach a definitive conclusion about the relationship between sleep apnea and atrial fibrillation.

SCREENING AND DIAGNOSIS

The 2014 joint guidelines of the American Heart Association, American College of Cardiology, and Heart Rhythm Society for the management of atrial fibrillation state that a sleep study may be useful if sleep apnea is suspected.²³ The 2019 focused update of the 2014 guidelines²⁴ state that for overweight and obese patients with atrial fibrillation, weight loss combined with risk-factor modification is recommended (class I recommendation, level of evidence B-R, ie, data derived from 1 or more randomized trials or meta-analysis of such studies). Risk-factor modification in this case includes assessment and treatment of underlying sleep apnea, hypertension, hyperlipidemia, glucose intolerance, and alcohol and tobacco use.

Laboratory polysomnography has long been considered the gold standard for sleep apnea diagnosis. In one study,¹³ obstructive sleep apnea was a greater predictor of atrial fibrillation when diagnosed by polysomnography (risk ratio 1.40, 95% CI 1.16–1.68) compared with identification by screening using the Berlin questionnaire (risk ratio 1.07, 95% CI 0.91–1.27). However, a laboratory sleep study is associated with increased patient burden and limited availability.

Home sleep apnea testing is being increasingly used in the diagnostic evaluation of obstructive sleep apnea and may be a less costly, more available alternative. However, since a home sleep apnea test is less sensitive than polysomnography in detecting obstructive sleep apnea, the American Academy of Sleep Medicine guidelines²⁸ state that if a single home sleep apnea test is negative or inconclusive, polysomnography should be done if there is clinical suspicion of sleep apnea. Moreover, current guidelines from this group recommend that patients with significant cardiorespiratory disease should be tested with polysomnography rather than home sleep apnea testing.²²

Further study is needed to determine the optimal screening method for sleep apnea in patients with atrial fibrillation and to clarify the role of home sleep apnea testing. While keeping in mind the limitations of a screening questionnaire in this population, as a general approach it is reasonable to use a screening questionnaire for sleep apnea. And if the screen is positive, further evaluation with a sleep study is merited, whether by laboratory polysomnography, a home sleep apnea test, or referral to a sleep specialist.

MULTIDISCIPLINARY CARE MAY BE IDEAL

Overall, given the high prevalence of sleep apnea in patients with atrial fibrillation, the deleterious effects of sleep apnea in general, the influence of sleep apnea on atrial fibrillation, and the cardiovascular and other beneficial effects of adequate treatment of sleep apnea, patients with atrial fibrillation should be assessed for sleep apnea.

While the optimal strategy in evaluating for sleep apnea in these patients needs to be further defined, a multidisciplinary approach to care involving a primary care provider, cardiologist, and sleep specialist may be ideal.

Yes. The prevalence of sleep apnea is exceedingly high in patients with atrial fibrillation—50% to 80% compared with 30% to 60% in respective control groups.^1–3 Conversely, atrial fibrillation is more prevalent in those with sleep-disordered breathing than in those without (4.8% vs 0.9%).⁴

Sleep-disordered breathing comprises obstructive sleep apnea and central sleep apnea. Obstructive sleep apnea, characterized by repetitive upper-airway obstruction during sleep, is accompanied by intermittent hypoxia, rises in carbon dioxide, autonomic nervous system fluctuations, and intrathoracic pressure alterations.⁵ Central sleep apnea may be neurally mediated and, in the setting of cardiac disease, is characterized by alterations in chemosensitivity and chemoresponsiveness, leading to a state of high loop gain—ie, a hypersensitive ventilatory control system leading to ventilatory drive oscillations.⁶

Both obstructive and central sleep apnea have been associated with atrial fibrillation. Experimental data implicate obstructive sleep apnea as a trigger of atrial arrhythmogenesis,^7,8 and epidemiologic studies support an association between central sleep apnea, Cheyne-Stokes respiration, and incident atrial fibrillation.⁹

HOW SLEEP APNEA COULD LEAD TO ATRIAL FIBRILLATION

In experiments in animals, intermittent upper-airway obstruction led to forced inspiration, substantial negative intrathoracic pressure, subsequent left atrial distention, and increased susceptibility to atrial fibrillation.¹⁰ The autonomic nervous system may be a mediator of apnea-induced atrial fibrillation, as apnea-induced atrial fibrillation is suppressed with autonomic blockade.¹⁰

Emerging data also support the hypothesis that intermittent hypoxia⁷ and resolution of hypercapnia,⁸ as observed in obstructive sleep apnea, exert atrial electrophysiologic changes that increase vulnerability to atrial arrhythmogenesis.

In a case-crossover study,¹¹ the odds of paroxysmal atrial fibrillation occurring after a respiratory disturbance were 17.9 times higher than after normal breathing (95% confidence interval [CI] 2.2–144.2), though the absolute rate of overall arrhythmia events (including both atrial fibrillation and nonsustained ventricular tachycardia) associated with respiratory disturbances was low (1 excess arrhythmia event per 40,000 respiratory disturbances).

EFFECT OF SLEEP APNEA ON ATRIAL FIBRILLATION MANAGEMENT

Sleep apnea also seems to affect the efficacy of a rhythm-control strategy for atrial fibrillation. For example, patients with obstructive sleep apnea have a higher risk of recurrent atrial fibrillation after cardioversion (82% vs 42% in controls)¹² and up to a 25% greater risk of recurrence after catheter ablation compared with those without obstructive sleep apnea (risk ratio 1.25, 95% CI 1.08–1.45).¹³

Several observational studies showed a higher rate of atrial fibrillation after pulmonary vein isolation in obstructive sleep apnea patients who do not use continuous positive airway pressure (CPAP) than in those who do.^14–17 CPAP therapy appears to exert beneficial effects on cardiac structural remodeling;  cardiac magnetic resonance imaging shows that patients with sleep apnea who received less than 4 hours of CPAP per night had larger left atrial dimensions and increased left ventricular mass compared with those who received more than 4 hours of CPAP at night.¹⁷ However, a need remains for high-quality, large randomized controlled trials to eliminate potential unmeasured biases due to differences that may exist between CPAP users and non-users, such as general adherence to medical therapy and healthcare interventions.

An additional consideration is that the overall utility and value of obtaining a diagnosis of obstructive sleep apnea strictly as it pertains to atrial fibrillation management is affected by whether a rhythm- or rate-control strategy is pursued. In other words, if a patient is deemed to be in permanent atrial fibrillation and a rhythm-control strategy is therefore not pursued, the potential effect of untreated obstructive sleep apnea on atrial fibrillation recurrence could be less important. In this case, however, the other beneficial cardiovascular and systemic effects of diagnosing and treating underlying obstructive sleep apnea would remain.

Epidemiologic and clinic-based studies have supported an association between sleep apnea (mostly central, but also obstructive) and atrial fibrillation.^4,18

Community-based studies such as the Sleep Heart Health Study⁴ and the Outcomes of Sleep Disorders in Older Men Study (MrOS Sleep),¹⁸ involving thousands of participants, have found the strongest cross-sectional associations of both obstructive and central sleep apnea with nocturnal atrial fibrillation. The findings included a 2 to 5 times higher odds of nocturnal atrial fibrillation, particularly in those with a moderate to severe degree of sleep-disordered breathing—even after adjusting for confounding influences (eg, obesity) and self-reported cardiac disease such as heart failure.

In MrOS Sleep, in an older male cohort, both obstructive and central sleep apnea were associated with nocturnal atrial fibrillation, though central sleep apnea and Cheyne-Stokes respirations had a stronger magnitude of association.¹⁸

Further insights can be drawn specifically from patients with heart failure. Sin et al,¹⁹ in a 1999 study, found that in 450 patients with systolic heart failure (85% men), the prevalence of sleep-disordered breathing was 25% to 33% (depending on the apnea-hypopnea index cutoff used) for central sleep apnea, and similarly 27% to 38% for obstructive sleep apnea. The prevalence of atrial fibrillation in this group was 10% in women and 15% in men. Atrial fibrillation was reported as a significant risk factor for central sleep apnea, but not for obstructive sleep apnea (for which only male sex and increasing body mass index were significant risk factors). Directionality was not clearly reported in this retrospective study in terms of timing of sleep studies and other assessments: ie, the report did not clearly state which came first, the atrial fibrillation or the sleep apnea. Therefore, the possibility that central sleep apnea is a predictor of atrial fibrillation cannot be excluded.  

Yumino et al,²⁰ in a study published in 2009, evaluated 218 patients with heart failure (with a left ventricular ejection fraction of ≤ 45%) and reported a prevalence of moderate to severe sleep apnea of 21% for central sleep apnea and 26% for obstructive sleep apnea. In multivariate analysis, atrial fibrillation was independently associated with central sleep apnea but not obstructive sleep apnea.

In recent cohort studies, central sleep apnea was associated with 2 to 3 times higher odds of developing atrial fibrillation, while obstructive sleep apnea was not a predictor of incident atrial fibrillation.^9,21

Although most available studies associate sleep apnea with atrial fibrillation, findings of a case-control study²² did not support a difference in the prevalence of sleep apnea syndrome (defined as apnea index ≥ 5 and apnea-hypopnea index ≥ 15, and the presence of sleep symptoms) in patients with lone atrial fibrillation (no evident cardiovascular disease) compared with controls matched for age, sex, and cardiovascular morbidity.

But observational studies are limited by the potential for residual unmeasured confounding factors and lack of objective cardiac structural data, such as left ventricular ejection fraction and atrial enlargement. Moreover, there can be significant differences in sleep apnea definitions among studies, thus limiting the ability to reach a definitive conclusion about the relationship between sleep apnea and atrial fibrillation.

SCREENING AND DIAGNOSIS

The 2014 joint guidelines of the American Heart Association, American College of Cardiology, and Heart Rhythm Society for the management of atrial fibrillation state that a sleep study may be useful if sleep apnea is suspected.²³ The 2019 focused update of the 2014 guidelines²⁴ state that for overweight and obese patients with atrial fibrillation, weight loss combined with risk-factor modification is recommended (class I recommendation, level of evidence B-R, ie, data derived from 1 or more randomized trials or meta-analysis of such studies). Risk-factor modification in this case includes assessment and treatment of underlying sleep apnea, hypertension, hyperlipidemia, glucose intolerance, and alcohol and tobacco use.

Laboratory polysomnography has long been considered the gold standard for sleep apnea diagnosis. In one study,¹³ obstructive sleep apnea was a greater predictor of atrial fibrillation when diagnosed by polysomnography (risk ratio 1.40, 95% CI 1.16–1.68) compared with identification by screening using the Berlin questionnaire (risk ratio 1.07, 95% CI 0.91–1.27). However, a laboratory sleep study is associated with increased patient burden and limited availability.

Home sleep apnea testing is being increasingly used in the diagnostic evaluation of obstructive sleep apnea and may be a less costly, more available alternative. However, since a home sleep apnea test is less sensitive than polysomnography in detecting obstructive sleep apnea, the American Academy of Sleep Medicine guidelines²⁸ state that if a single home sleep apnea test is negative or inconclusive, polysomnography should be done if there is clinical suspicion of sleep apnea. Moreover, current guidelines from this group recommend that patients with significant cardiorespiratory disease should be tested with polysomnography rather than home sleep apnea testing.²²

Further study is needed to determine the optimal screening method for sleep apnea in patients with atrial fibrillation and to clarify the role of home sleep apnea testing. While keeping in mind the limitations of a screening questionnaire in this population, as a general approach it is reasonable to use a screening questionnaire for sleep apnea. And if the screen is positive, further evaluation with a sleep study is merited, whether by laboratory polysomnography, a home sleep apnea test, or referral to a sleep specialist.

MULTIDISCIPLINARY CARE MAY BE IDEAL

Overall, given the high prevalence of sleep apnea in patients with atrial fibrillation, the deleterious effects of sleep apnea in general, the influence of sleep apnea on atrial fibrillation, and the cardiovascular and other beneficial effects of adequate treatment of sleep apnea, patients with atrial fibrillation should be assessed for sleep apnea.

While the optimal strategy in evaluating for sleep apnea in these patients needs to be further defined, a multidisciplinary approach to care involving a primary care provider, cardiologist, and sleep specialist may be ideal.

Despite guidelines recommending low-dose oral glucocorticoids over high-dose intravenous (IV) glucocorticoids for inpatient management of acute exacerbations of chronic obstructive pulmonary disease (COPD), we have observed that most patients still receive high-dose IV therapy before being transitioned to low-dose oral therapy at discharge. Clinical inertia undoubtedly plays a significant role in the slow adoption of new recommendations, but in this era of evidence-based practice, the unfortunate lack of data supporting low over high steroid doses for acute exacerbations of COPD also contributes to hesitancy of physicians.

A SIGNIFICANT AND GROWING BURDEN

COPD is one of the most common pulmonary conditions managed by hospitalists today, and by the year 2030, it is predicted to become the third leading cause of death worldwide.¹

COPD is also a significant economic burden, costing $50 billion to manage in the United States, most of that from the cost of lengthy hospital stays.² COPD patients have 1 to 2 exacerbations per year.³ Bacterial and viral infections are responsible for most exacerbations, and 15% to 20% are from air pollution and other environmental causes of airway inflammation.³

CHALLENGES TO CHANGING PRACTICE

Glucocorticoids are the gold standard for treatment of acute exacerbations of COPD. It is well-documented that compared with placebo, glucocorticoids reduce mortality risk, length of hospital stay, and exacerbation recurrence after 1 month.⁴ And while high-dose IV steroid therapy has been the standard approach, oral administration has been found to be noninferior to IV administration with regard to treatment and length of hospital stay.⁵

While adverse effects are more common at higher doses, the optimal dose and duration of systemic glucocorticoid therapy for acute exacerbations of COPD are still largely at the discretion of the physician. The 2019 report of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) recommends low doses (40 mg) for no more than 5 to 7 days for exacerbations, based on reports that showed no worse outcomes with low-dose oral than with high-dose IV therapy.^6,7 (In the 2010 study by Lindenauer et al,⁷ 92% of nearly 80,000 patients received high-dose IV steroids, reflecting standard practice at that time.) However, the GOLD guidelines do not address mortality rates, length of stay, or readmission rates for either approach, as they are devised to direct treatment in patients with stable mild to advanced COPD, not exacerbations.

Mortality rates

Aksoy et al⁸ established that, compared with placebo, low-dose steroids improved mortality rates in a subset of patients with acute exacerbations, specifically those with eosinophilic exacerbations. This study followed the 2013 Reduction in the Use of Corticosteroids in Exacerbated COPD (REDUCE) trial, which showed mortality rates were not lower with 14 days of low-dose prednisone treatment than with 5 days.9

Length of hospital stay

With regard to length of hospital stay, in 2011 Wang et al¹⁰ found no statistically significant difference between high- and low-dose steroid treatment.However, the REDUCE trial found that low-dose steroids shortened the median length of stay by 1 day compared with placebo.⁹

Hospital readmission rates

The REDUCE trial found no statistically significant difference in readmission rates when comparing 5 days of low-dose treatment vs 14 days.⁹ However, Aksoy et al⁸ found that readmission rates were significantly lower with low-dose treatment than with placebo.No study has yet examined readmission rates with high-dose vs low-dose steroid treatment.

What does the evidence tell us?

Low-dose oral glucocorticoid treatment shows definitive benefits in terms of lower mortality rates, shorter hospital length of stay, and lower readmission rates vs placebo in the treatment of acute exacerbations of COPD. Furthermore, a 14-day course is no better than 5 days in terms of mortality rates. And low-dose glucocorticoid treatment shows reduced mortality rates in addition to similar hospital length of stay when compared to high-dose glucocorticoid treatment.

Together, these findings lend credibility to the current GOLD recommendations. However, we have observed that in sharp contrast to the leading clinical guidelines, most patients hospitalized for acute exacerbations of COPD are still treated initially with high-dose IV corticosteroids. Why?

Obstacles that perpetuate the use of high-dose over low-dose treatment include lack of knowledge of glucocorticoid pharmacokinetics among clinicians, use of outdated order sets, and the reflex notion that more of a drug is more efficacious in its desired effect. In addition, administrative obstacles include using high-dose IV steroids to justify an inpatient stay or continued hospitalization.

COUNTERING THE OBSTACLES: THE HOSPITALIST’S ROLE

To counter these obstacles, we propose standardization of inpatient treatment of acute exacerbations of COPD to include initial low-dose steroid treatment in accordance with the most recent GOLD guidelines.⁶ This would benefit the patient by reducing undesirable effects of high-dose steroids, and at the same time reduce the economic burden of managing COPD exacerbations. Considering the large number of hospitalizations for COPD exacerbation each year, hospitalists can play a large role in this effort by routinely incorporating the low-dose steroid recommendation into their clinical practice.

Despite guidelines recommending low-dose oral glucocorticoids over high-dose intravenous (IV) glucocorticoids for inpatient management of acute exacerbations of chronic obstructive pulmonary disease (COPD), we have observed that most patients still receive high-dose IV therapy before being transitioned to low-dose oral therapy at discharge. Clinical inertia undoubtedly plays a significant role in the slow adoption of new recommendations, but in this era of evidence-based practice, the unfortunate lack of data supporting low over high steroid doses for acute exacerbations of COPD also contributes to hesitancy of physicians.

A SIGNIFICANT AND GROWING BURDEN

COPD is one of the most common pulmonary conditions managed by hospitalists today, and by the year 2030, it is predicted to become the third leading cause of death worldwide.¹

COPD is also a significant economic burden, costing $50 billion to manage in the United States, most of that from the cost of lengthy hospital stays.² COPD patients have 1 to 2 exacerbations per year.³ Bacterial and viral infections are responsible for most exacerbations, and 15% to 20% are from air pollution and other environmental causes of airway inflammation.³

CHALLENGES TO CHANGING PRACTICE

Glucocorticoids are the gold standard for treatment of acute exacerbations of COPD. It is well-documented that compared with placebo, glucocorticoids reduce mortality risk, length of hospital stay, and exacerbation recurrence after 1 month.⁴ And while high-dose IV steroid therapy has been the standard approach, oral administration has been found to be noninferior to IV administration with regard to treatment and length of hospital stay.⁵

While adverse effects are more common at higher doses, the optimal dose and duration of systemic glucocorticoid therapy for acute exacerbations of COPD are still largely at the discretion of the physician. The 2019 report of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) recommends low doses (40 mg) for no more than 5 to 7 days for exacerbations, based on reports that showed no worse outcomes with low-dose oral than with high-dose IV therapy.^6,7 (In the 2010 study by Lindenauer et al,⁷ 92% of nearly 80,000 patients received high-dose IV steroids, reflecting standard practice at that time.) However, the GOLD guidelines do not address mortality rates, length of stay, or readmission rates for either approach, as they are devised to direct treatment in patients with stable mild to advanced COPD, not exacerbations.

Mortality rates

Aksoy et al⁸ established that, compared with placebo, low-dose steroids improved mortality rates in a subset of patients with acute exacerbations, specifically those with eosinophilic exacerbations. This study followed the 2013 Reduction in the Use of Corticosteroids in Exacerbated COPD (REDUCE) trial, which showed mortality rates were not lower with 14 days of low-dose prednisone treatment than with 5 days.9

Length of hospital stay

With regard to length of hospital stay, in 2011 Wang et al¹⁰ found no statistically significant difference between high- and low-dose steroid treatment.However, the REDUCE trial found that low-dose steroids shortened the median length of stay by 1 day compared with placebo.⁹

Hospital readmission rates

The REDUCE trial found no statistically significant difference in readmission rates when comparing 5 days of low-dose treatment vs 14 days.⁹ However, Aksoy et al⁸ found that readmission rates were significantly lower with low-dose treatment than with placebo.No study has yet examined readmission rates with high-dose vs low-dose steroid treatment.

What does the evidence tell us?

Low-dose oral glucocorticoid treatment shows definitive benefits in terms of lower mortality rates, shorter hospital length of stay, and lower readmission rates vs placebo in the treatment of acute exacerbations of COPD. Furthermore, a 14-day course is no better than 5 days in terms of mortality rates. And low-dose glucocorticoid treatment shows reduced mortality rates in addition to similar hospital length of stay when compared to high-dose glucocorticoid treatment.

Together, these findings lend credibility to the current GOLD recommendations. However, we have observed that in sharp contrast to the leading clinical guidelines, most patients hospitalized for acute exacerbations of COPD are still treated initially with high-dose IV corticosteroids. Why?

Obstacles that perpetuate the use of high-dose over low-dose treatment include lack of knowledge of glucocorticoid pharmacokinetics among clinicians, use of outdated order sets, and the reflex notion that more of a drug is more efficacious in its desired effect. In addition, administrative obstacles include using high-dose IV steroids to justify an inpatient stay or continued hospitalization.

COUNTERING THE OBSTACLES: THE HOSPITALIST’S ROLE

To counter these obstacles, we propose standardization of inpatient treatment of acute exacerbations of COPD to include initial low-dose steroid treatment in accordance with the most recent GOLD guidelines.⁶ This would benefit the patient by reducing undesirable effects of high-dose steroids, and at the same time reduce the economic burden of managing COPD exacerbations. Considering the large number of hospitalizations for COPD exacerbation each year, hospitalists can play a large role in this effort by routinely incorporating the low-dose steroid recommendation into their clinical practice.

Despite guidelines recommending low-dose oral glucocorticoids over high-dose intravenous (IV) glucocorticoids for inpatient management of acute exacerbations of chronic obstructive pulmonary disease (COPD), we have observed that most patients still receive high-dose IV therapy before being transitioned to low-dose oral therapy at discharge. Clinical inertia undoubtedly plays a significant role in the slow adoption of new recommendations, but in this era of evidence-based practice, the unfortunate lack of data supporting low over high steroid doses for acute exacerbations of COPD also contributes to hesitancy of physicians.

A SIGNIFICANT AND GROWING BURDEN

COPD is one of the most common pulmonary conditions managed by hospitalists today, and by the year 2030, it is predicted to become the third leading cause of death worldwide.¹

COPD is also a significant economic burden, costing $50 billion to manage in the United States, most of that from the cost of lengthy hospital stays.² COPD patients have 1 to 2 exacerbations per year.³ Bacterial and viral infections are responsible for most exacerbations, and 15% to 20% are from air pollution and other environmental causes of airway inflammation.³

CHALLENGES TO CHANGING PRACTICE

Glucocorticoids are the gold standard for treatment of acute exacerbations of COPD. It is well-documented that compared with placebo, glucocorticoids reduce mortality risk, length of hospital stay, and exacerbation recurrence after 1 month.⁴ And while high-dose IV steroid therapy has been the standard approach, oral administration has been found to be noninferior to IV administration with regard to treatment and length of hospital stay.⁵

While adverse effects are more common at higher doses, the optimal dose and duration of systemic glucocorticoid therapy for acute exacerbations of COPD are still largely at the discretion of the physician. The 2019 report of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) recommends low doses (40 mg) for no more than 5 to 7 days for exacerbations, based on reports that showed no worse outcomes with low-dose oral than with high-dose IV therapy.^6,7 (In the 2010 study by Lindenauer et al,⁷ 92% of nearly 80,000 patients received high-dose IV steroids, reflecting standard practice at that time.) However, the GOLD guidelines do not address mortality rates, length of stay, or readmission rates for either approach, as they are devised to direct treatment in patients with stable mild to advanced COPD, not exacerbations.

Mortality rates

Aksoy et al⁸ established that, compared with placebo, low-dose steroids improved mortality rates in a subset of patients with acute exacerbations, specifically those with eosinophilic exacerbations. This study followed the 2013 Reduction in the Use of Corticosteroids in Exacerbated COPD (REDUCE) trial, which showed mortality rates were not lower with 14 days of low-dose prednisone treatment than with 5 days.9

Length of hospital stay

With regard to length of hospital stay, in 2011 Wang et al¹⁰ found no statistically significant difference between high- and low-dose steroid treatment.However, the REDUCE trial found that low-dose steroids shortened the median length of stay by 1 day compared with placebo.⁹

Hospital readmission rates

The REDUCE trial found no statistically significant difference in readmission rates when comparing 5 days of low-dose treatment vs 14 days.⁹ However, Aksoy et al⁸ found that readmission rates were significantly lower with low-dose treatment than with placebo.No study has yet examined readmission rates with high-dose vs low-dose steroid treatment.

What does the evidence tell us?

Low-dose oral glucocorticoid treatment shows definitive benefits in terms of lower mortality rates, shorter hospital length of stay, and lower readmission rates vs placebo in the treatment of acute exacerbations of COPD. Furthermore, a 14-day course is no better than 5 days in terms of mortality rates. And low-dose glucocorticoid treatment shows reduced mortality rates in addition to similar hospital length of stay when compared to high-dose glucocorticoid treatment.

Together, these findings lend credibility to the current GOLD recommendations. However, we have observed that in sharp contrast to the leading clinical guidelines, most patients hospitalized for acute exacerbations of COPD are still treated initially with high-dose IV corticosteroids. Why?

Obstacles that perpetuate the use of high-dose over low-dose treatment include lack of knowledge of glucocorticoid pharmacokinetics among clinicians, use of outdated order sets, and the reflex notion that more of a drug is more efficacious in its desired effect. In addition, administrative obstacles include using high-dose IV steroids to justify an inpatient stay or continued hospitalization.

COUNTERING THE OBSTACLES: THE HOSPITALIST’S ROLE

To counter these obstacles, we propose standardization of inpatient treatment of acute exacerbations of COPD to include initial low-dose steroid treatment in accordance with the most recent GOLD guidelines.⁶ This would benefit the patient by reducing undesirable effects of high-dose steroids, and at the same time reduce the economic burden of managing COPD exacerbations. Considering the large number of hospitalizations for COPD exacerbation each year, hospitalists can play a large role in this effort by routinely incorporating the low-dose steroid recommendation into their clinical practice.

Portopulmonary hypertension (POPH) is a form of group 1 pulmonary arterial hypertension. When treating patients with POPH, baseline assessment is necessary so that response to therapy can be measured as the change from baseline. Patients should undergo echocardiography and right heart catheterization, and their exercise capacity and NYHA functional class should be determined. Patients with POPH should be considered for treatment if they are NYHA functional class II or above and/or their mean pulmonary artery pressure (MPAP) is greater than 35 mm Hg in transplant candidates. The goal in the treatment and management of POPH is to improve pulmonary hemodynamics by reducing the obstruction to pulmonary arterial flow and to preserve right ventricular function (Table). This article, the second in a 2-part review of POPH in patients with liver disease, reviews the role of medical therapy and liver transplantation in treatment. Evaluation and diagnosis of POPH are discussed in a separate article.

Medical Therapy

Prostanoids

Although prostacyclin and prostaglandin analogs entered routine clinical practice for POPH in the 1990s, reports of investigational use date back to the 1980s. Prostanoids are potent vasodilators with antiplatelet aggregation and antiproliferative properties. Prostacyclin synthase is reduced in patients with PAH, resulting in decreased concentration of prostacyclin with vasoconstriction and proliferative changes in the pulmonary vasculature.¹

Epoprostenol

Epoprostenol is also known as synthetic prostaglandin I₂ or prostacyclin. It was the first therapy approved for the treatment of PAH in 1995 by the US Food and Drug Administration (FDA) as a continuous intravenous infusion.^2,3 It also inhibits platelet aggregation and may help modulate pulmonary vascular remodeling.^4,5 Epoprostenol is derived from the metabolism of arachidonic acid and is a potent pulmonary and systemic vasodilator. One study reported an immediate 11.8% decrease in MPAP, 24% decrease in pulmonary vascular resistance (PVR) and 28% drop in systemic vascular resistance (SVR) during an epoprostenol infusion.⁶ The authors reported that epoprostenol was a more potent vasodilator than nitric oxide and may have a role in predicting the reversibility of POPH. In a case series of 33 patients with secondary pulmonary hypertension (including 7 patients with POPH) treated with continuous intravenous prostacyclin for approximately 1 year, exercise tolerance, NYHA functional class, and pulmonary hemodynamics improved in each patient compared to baseline.⁷ Krowka et al studied 14 patients with moderate to severe POPH treated with intravenous epoprostenol.⁸ No significant side effects were noted and treatment resulted in significant improvements in PVR, MPAP, and cardiac output. In 2007, Fix et al published a large retrospective cohort of patients with moderate to severe POPH.⁹ Nineteen patients treated with epoprostenol were compared to 17 patients with no treatment. After a median treatment period of 15.4 months, the epoprostenol group showed significant improvement in MPAP, PVR and cardiac output, but survival did not differ between the 2 groups.

Epoprostenol has often been considered a bridge to transplant in patients with POPH. Sussman et al described 8 consecutive patients with POPH who were treated with intravenous epoprostenol (2 to 8 ng/kg/min dose).¹⁰ Liver transplant was considered in 7 of the 8 patients when MPAP decreased to less than 35 mm Hg. Six patients were eventually listed for liver transplant, but 2 died waiting on the list. Long-term outcomes in the group of transplanted recipients were excellent. They remained alive and well at least 9 to 18 months post-transplant, and half did not require long-term vasodilator therapy post-orthotopic liver transplant. Similarly, Ashfaq et al published their data on 16 patients with moderate-to-severe POPH who were treated with vasodilator therapy.¹¹ MPAP decreased to acceptable levels in 75% of the treated patients, and 11 went on to liver transplantation. Rates of 1- and 5-year survival in the transplanted patients were 91% and 67% respectively. None of the patients who failed vasodilator therapy survived.

Epoprostenol has a short half-life (3 to 5 minutes) and requires continuous infusion through central access via an infusion pump. Aseptic technique must be maintained to avoid blood stream infections. Pump failure or loss of vascular access can result in rebound pulmonary vasoconstriction that can be life-threatening and requires immediate attention. Side effects associated with epoprostenol include flushing, headache, nausea/vomiting, bradycardia, chest pain, jaw pain, diarrhea, and musculoskeletal pain.

Patients on epoprostenol should be monitored for prostanoid overdose. In the case of patients with chronic liver disease, epoprostenol increases systemic vasodilation in patients with already low systemic vascular tone. As a result, cardiac output may increase to the point of high cardiac output failure. MPAP will remain elevated secondary to high cardiac output rather than high PVR. In these patients, right heart catheterization will show an elevated MPAP in the setting of normal to low PVR/transpulmonary gradient (TPG) values. Lowering the epoprostenol dose will successfully reduce both cardiac output and MPAP.

Treprostinil

Treprostinil is a prostacyclin analog that is available in intravenous, inhalational, and subcutaneous form, although subcutaneous dosing may be limited by pain. Sakai et al published a small case series of 3 patients with PAH and end-stage liver disease treated with intravenous treprostinil.¹² Pulmonary hemodynamics improved in all patients, and 2 patients went on to an uneventful liver transplantation. More than 10 years later, data were published on 255 patients with PAH on therapy with bosentan or sildenafil randomized to additional inhaled treprostinil.¹³ Treprostinil proved to be safe and well tolerated, with improvement in quality of life measures but no improvement in other secondary endpoints.

Iloprost

Inhaled iloprost is another prostacyclin that has a short therapeutic half-life of 20 to 30 minutes and requires frequent administration (6 to 9 times daily). In study in which patients with severe POPH were treated for up to 3 years with inhaled iloprost,¹⁴ survival rates at 1, 2, and 3 years were 77%, 62%, and 46%, respectively. A second study published in 2010 was designed to assess the acute effects of inhaled iloprost on pulmonary hemodynamics and evaluate the clinical outcome after 12 months of treatment.¹⁵ Iloprost was found to rapidly reduce pulmonary arterial pressure and PVR. In the long-term evaluation, inhaled iloprost increased the 6-minute walk distance (6MWD) and functional class, but no change was noted in the systolic pulmonary artery pressure. The authors concluded that iloprost might provide symptomatic improvement and improvement in exercise capacity.

Selexipag

Selexipag is an oral selective IP prostacyclin receptor agonist that is structurally distinct from other prostacyclins.¹⁶ In a phase 3 randomized double blind clinical trial, PAH patients treated with selexipag had lower composite of death or complication of PAH to the end of the study period.¹⁷ This effect was consistent across all dose ranges, but POPH patients were excluded from this study. Safety and efficacy of selexipag has not been evaluated in POPH patients.

Endothelin Receptor Antagonists

Endothelin receptor antagonists block the production of endothelin-1 (ET-1), a potent vasoconstrictor and smooth muscle mitogen that may contribute to the development of PAH. Three different receptors have been described: endothelin A, endothelin B, and endothelin B2. Elevated ET-1 levels have been reported in patients with chronic liver disease and may originate from hepatosplanchnic circulation.¹⁸

Bosentan

Bosentan is an oral, nonspecific, ET-1A and ET-1B receptor antagonist. Initial use of bosentan in patients with POPH was limited because of concern for hepatotoxicity. Approximately 10% of patients on bosentan were reported to have mild hepatic side effects in the form of elevated aminotransferases, but severe injury has been reported.¹⁹ One of the first clinical experiences of bosentan in patients with POPH was published in 2005. Hoeper et al followed 11 patients with Child A cirrhosis and severe POPH.²⁰ All patients included were in NYHA functional class III or IV and were treated with bosentan for over 1 year. Exercise capacity and symptoms improved in all treated patients. The medication was tolerated well and there was no evidence of drug-induced liver injury. A single case report showed the effectiveness of bosentan in a 43-year-old man with alcohol-related liver disease (Child-Pugh A) and right ventricular enlargement and dysfunction secondary to POPH.²¹ Pulmonary arterial pressure decreased, exercise capacity increased, and improvement was maintained over 2 years.

In a group of 31 patients with Child A or B cirrhosis and severe POPH, bosentan had significantly better effects than inhaled iloprost on exercise capacity, hemodynamics, and survival.¹⁴ One, 2, and 3-year survival rates in the bosentan group were 94%, 89%, and 89% (compared to 77%, 62%, and 46% in the iloprost group). Both drugs were considered safe with no reported hepatotoxicity. In 2013, Savale et al published data on 34 patients with POPH, Child-Pugh A and/or B who were treated with bosentan for a median of 43 months.²² The authors reported significant improvements in hemodynamics, NYHA functional class, and 6WMD. Event-free survival rates at 1, 2, and 3 years were 82%, 63%, and 47%, respectively.

Ambrisentan

Ambrisentan is a highly selective ET-1A receptor antagonist with once daily dosing and a lower risk of hepatotoxicity compared to bosentan. Fourteen patients with moderate to severe POPH treated with ambrisentan in 4 German hospitals were retrospectively analyzed.²³ Median follow-up was 16 months, and the study demonstrated significant improvement in exercise capacity and clinical symptoms without significant change in liver function tests. Cartin-Ceba et al published their experience of 13 patients with moderate to severe POPH treated with ambrisentan monotherapy.²⁴ Patients were followed for a median of 613 days and on treatment for a median time of 390 days. Significant improvements were shown in pulmonary arterial pressure and PVR without adverse effect on hepatic function. Over 270 patients with PAH (6% with POPH) received ambrisentan from March 2009 through June 2013 at a large United Kingdom portal hypertension referral center.²⁵ Discontinuation due to side effects was higher than previously reported. Discontinuation due to abnormal transaminases was uncommon.

Macitentan

Macitentan is a dual endothelin-receptor antagonist developed by modifying the structure of bosentan to increase efficacy and safety. The SERAPHIN trial compared oral macitentan to placebo in 250 patients with moderate to severe PAH, some of whom were also on a stable dose of oral or inhaled therapy for PAH.²⁶ Over a 2-year period, patients treated with macitentan were less likely to have progression of their disease or die on therapy (38% and 31% versus 46%), regardless of if they were receiving additional oral therapy and more likely to have improvement of their exercise capacity and WHO functional class. Nasopharyngitis and significant anemia were more common in the macitentan group, but there was no difference in the rate of liver function test abnormalities compared to placebo. Trials with macitentan are currently ongoing in patients with POPH.

Phosphodiesterase-5 Inhibitors

Cyclic guanosine monophosphate (cGMP) is the mediator of nitric oxide–induced vasodilation. Phosphodiesterase-5 (PDE-5) inhibitors prolong the vasodilatory effects of cyclic guanosine monophosphate by preventing its hydrolysis, thereby reducing the pulmonary arterial pressure.

Sildenafil

Sildenafil is the most widely accepted PDE-5 inhibitor for POPH. Fourteen patients with moderate to severe POPH were treated with sildenafil (50 mg 3 times per day) in an observational study published by Reichenberger et al in 2006.²⁷ Eight patients were newly started on sildenafil, whereas sildenafil was added to inhaled prostanoids in the remaining 6x patients. Sildenafil significantly decreased 66MWD, MPAP, PVR, and cardiac index alone or in combination with inhaled prostanoids.

Sildenafil has also been used as a bridge to transplant in liver transplant candidates with POPH. Ten patients with POPH treated with sildenafil monotherapy were followed for a 21±16 months.²⁸ Patients improved symptomatically and increased their 6MWD at 1 year by 30 meters or more. Three patients became transplant eligible and another 3 patients were stable, without progression of their liver disease or POPH. Four patients were not considered transplant candidates, 2 because of refractory POPH and 2 for other comorbidities. The authors concluded that sildenafil monotherapy could stabilize or improve pulmonary hemodynamics in patients with POPH and eventually lead to liver transplantation. Gough et al took a similar look at 9 patients with POPH treated with sildenafil.²⁹ All patients had initial and follow-up right heart catheterizations within a period of 3 years. Mean PVR improved in all patients, decreasing from 575 to 375 dynes/s/cm^–5. MPAP decreased to ≤ 35 mmHg in 4 patients, 1 of whom went on to receive a liver transplant. Overall sildenafil improved pulmonary hemodynamics in this small cohort of POPH patients.

Tadalafil

Tadalafil is another oral PDE-5 inhibitor but with a longer half-life than sildenafil. Unlike sildenafil, which requires 3 times daily dosing, tadalafil requires once daily administration. A few case reports have demonstrated tadalafil’s effectiveness for POPH in combination with other medical therapy (eg, sildenafil, ambrisentan).^30,31

Guanylate Cyclase Stimulator

Riociguat

Riociguat is a first-in-class activator of soluble form of guanylate cyclase that increases levels of cyclic GMP. Two randomized clinical trials, PATENT, a study in PAH patients, and CHEST, a study in patients with chronic thromboembolic pulmonary hypertension showed improvement in 6MWD at 12 weeks (PATENT) or 16 weeks (CHEST), with improvement in secondary endpoints such as PVR, N-terminal pro b-type natriuretic peptide and WHO functional class.^32,33 Riociguat may have potential advantages in patients with POPH given that it has a favorable liver safety profile. A subgroup analysis of patients enrolled in the PATENT study showed that 13 had POPH and 11 were randomized to receive riociguat 2.5 mg 3 times daily dose and 2 received placebo.³⁴ Riociguat was well tolerated and improved 6MWD that was maintained over 2 years in the open label extension.

Medications to Avoid

Nonselective beta-blockers are commonly recommended in patients with portal hypertension to help prevent variceal hemorrhage. However, in patients with POPH, beta-blockers have been shown to decrease exercise capacity and worsen pulmonary hemodynamics. A study of 10 patients with moderate to severe POPH who were receiving beta-blockers for variceal bleeding prophylaxis showed that 6MWD improved in almost all of the patients, cardiac output increased by 28%, and PVR decreased by 19% when beta-blockers were discontinued.³⁵ The authors concluded that the use of beta-blockers should be avoided in this patient population.

Calcium channel blockers should not be used in patients with POPH because they can cause significant hypotension due to systemic vasodilatation and decreased right ventricular filling. Patients with portal hypertension and chronic liver disease commonly have low systemic vascular resistance and are particularly susceptible to the deleterious effects of calcium channel blockers.

Transplantation

Liver transplantation is a potential cure for POPH and its role in POPH has evolved over the past 2 decades. In 1997, Ramsay et al published their review of 1205 consecutive liver transplants at Baylor University Medical Center (BUMC) in Texas.³⁶ The incidence of POPH in this group was 8.5%, with the majority of patients having mild POPH. Liver transplant outcomes were not affected by mild and moderate pulmonary hypertension. However, patients with severe POPH (n = 7, systolic pulmonary artery pressure > 60 mm Hg) had a mortality rate of 42% at 9 months post-transplantation and 71% at 36 months post-transplant. The surviving patients continued to deteriorate with progressive right heart failure and no improvement in POPH.

To understand the effect of liver transplantation on POPH, one must understand the hemodynamic changes that occur with POPH and during liver transplant. The right ventricle is able to manage the same volume as the left ventricle under normal circumstances, but is unable to pump against a significant pressure gradient.³⁷ In the setting of POPH, right ventricular hypertrophy occurs and RV output remains stable for some time. With time, pulmonary artery pressure increases secondary to pulmonary arteriolar vasoconstriction, intimal thickening, and progressive occlusion of the pulmonary vascular bed. Right ventricular failure may occur as a result. Cardiac output increases significantly at the time of reperfusion during liver transplant (up to 3-fold in 15 minutes),³⁸ and in the setting of a noncompliant vascular bed, the patient is at risk for right heart failure. This is the likely explanation to such high perioperative mortality rates in patients with uncontrolled POPH. Failure to decrease MPAP to less than 50 mm Hg is considered a complete contraindication to liver transplant at most institutions. Many transplant centers will list patients for liver transplant if MPAP can be decreased to less than 35 mm Hg and PVR < 400 dynes/s/cm^–5. These parameters are thought to represent an adequate right ventricular reserve and a compliant pulmonary vascular bed.³⁷ However, even with good pressure control, the anesthesiology and critical care teams must be prepared to deal with acute right heart failure peri-operatively. Intraoperative transesophageal echocardiography has been recommended to closely follow right ventricular function.³⁸ Inhaled or intravenous dilators are the most effective agents in the event of a pulmonary hypertensive crisis.

Review of Outcomes

A retrospective review evaluated 43 patients with untreated POPH who underwent attempted liver transplantation.³⁹ Data were collected from 18 peer-reviewed studies and 7 patients at the authors’ institution. Overall mortality was 35% (15 patients), with almost all of the deaths secondary to cardiac dysfunction. Two deaths occurred intraoperatively and 8 deaths occurred during the transplant hospitalization. The transplant could not be successfully completed in 4 of the patients. MPAP > 50 mm Hg was associated with 100% mortality, whereas patients with MPAP between 35 mm Hg and 50 mm Hg had a 50% mortality. No mortality was noted in patients with MPAP < 35 mm Hg.

Liver transplantation has been shown to be successful in patients with controlled POPH. Sussman et al published their data on 8 patients with severe POPH in 2006. In this prospective study, all patients were treated with sequential epoprostenol infusions and 7 of the 8 patients experienced a significant reduction in MPAP and PVR. Six patients were listed for liver transplant, 4 of who were transplanted successfully and alive up to 5 years later.

The Baylor University Medical Center published their data on POPH patients who received liver transplants in 2007.¹¹ POPH was confirmed by right heart catheterization in 30 patients evaluated for liver transplant. Sixteen patients were considered to be suitable candidates for transplant and MPAP was decreased to less than 35 mmHg in 12 patients with vasodilator therapy. Eleven patients eventually underwent liver transplant and 1- and 5-year survival rates were 91% and 67%.

Compared to medical therapy or liver transplant alone, patients who receive medical therapy followed by liver transplantation have the best survival. The Mayo Clinic retrospectively reviewed 74 POPH patients identified between 1994 and 2007.⁴⁰ Patients were categorized in 1 of 3 categories: no medical therapy, medical therapy alone for POPH, or medical therapy for POPH followed by liver transplantation. Patients who received no medical therapy for POPH and no liver transplant had the worst outcomes, with a dismal 5-year survival of only 14% with over 50% deceased at 1 year of diagnosis. Five-year survival was 45% in patients who received medical therapy only. Patients who received medical therapy with prostacyclin followed by liver transplantation had the best outcomes, with a 5-year survival of 67% versus 25% in those who were transplanted without prior prostacyclin therapy.

We reported the longest follow-up study for patients undergoing liver transplantation with POPH in 2014.⁴¹ Seven patients with moderate to severe POPH received a liver transplant at our institution between June 2004 and January 2011. Mean pulmonary artery pressure was reduced to < 35 mm Hg, with appropriate POPH therapy in all of the patients. Both the graft and patient survival rates were 85.7% after a median follow-up of 7.8 years. The 1 patient who did not survive died from complications related to recurrent hepatitis C and cirrhosis, not from POPH-related issues. Four of the remaining 6 patients continue to require oral vasodilator therapy post-transplant, suggesting irreversible remodeling of the pulmonary vasculature. Two patients (4.4 and 8.5 years post-transplant) have no evidence of pulmonary hypertension post-transplant and therefore do not require medical treatment for pulmonary hypertension. We concluded that POPH responsive to vasodilator therapy is an appropriate indication for liver transplant, with excellent long-term survival.

Hollatz et al published their data on 11 patients with moderate to severe POPH who were successfully treated (mostly with oral sildenafil and subcutaneous treprostinil) as a bridge to liver transplant.⁴² The mortality rate was 0, with a follow-up duration of 7 to 60 months. Interestingly, 7 of the 11 patients (64%) were off all pulmonary vasodilators post-transplant. Ashfaq et al reported similar results.¹¹ Nine of 11 patients with treated moderate to severe POPH who received liver transplants stopped vasodilator therapy at a median period of 9.2 months post-transplant. Raevens et al described a group of 3 patients with POPH who went on to liver transplant after their pulmonary pressures were decreased with combined oral vasodilator therapy: 1 required continued long-term vasodilator therapy, another was weaned off medications after transplant, and the third patient died during the liver transplant from perioperative complications that induced uncontrolled pulmonary hypertension.⁴³

Patient Selection

In 2006, the United Network for Organ Sharing (UNOS) initiated a policy whereby a higher priority for liver transplantation was granted for highly selected patients in the United States.⁴⁴ UNOS policy 3.6.4.5.6 upgraded POPH patients to a MELD score of 22, with an increase in MELD every 3 months as long as MPAP remained < 35 mm Hg and PVR remained < 400 dynes/s/cm^–5. One hundred fifty-five patients were granted MELD exception points for POPH between 2002 and 2010 and went on to receive liver transplants.⁴⁵ Goldberg et al collected data from the Organ Procurement and Transplantation Network (OPTN) and compared outcomes of patients with approved POPH MELD exception points versus waitlist candidates with no exception points.⁴⁶ One hundred fifty-five waitlisted patients received POPH MELD exception points, with only 43.1% meeting OPTN exception requirements. One-third did not fulfill hemodynamic criteria consistent with POPH or had missing data, and 80% went on to receive a liver transplant. Waitlist candidates receiving POPH MELD exception points also had increased waitlist mortality and several early post-transplant deaths. The authors felt these data highlighted the need for OPTN/UNOS to revise their policy for POPH MELD exceptions points, revise how points are rewarded, and continue research to help risk stratify these patients to minimize perioperative complications.

Conclusion

Several effective medical treatment regimens are available, including prostanoids, endothelin receptor antagonists, and PDE-5 inhibitors. Liver transplantation is a potential cure but is only recommended if MPAP can be decreased to ≤ 35 mmHg. Long-term follow-up studies have shown these patients do well several years post-transplant but may continue to require oral therapy for their POPH.

Portopulmonary hypertension (POPH) is a form of group 1 pulmonary arterial hypertension. When treating patients with POPH, baseline assessment is necessary so that response to therapy can be measured as the change from baseline. Patients should undergo echocardiography and right heart catheterization, and their exercise capacity and NYHA functional class should be determined. Patients with POPH should be considered for treatment if they are NYHA functional class II or above and/or their mean pulmonary artery pressure (MPAP) is greater than 35 mm Hg in transplant candidates. The goal in the treatment and management of POPH is to improve pulmonary hemodynamics by reducing the obstruction to pulmonary arterial flow and to preserve right ventricular function (Table). This article, the second in a 2-part review of POPH in patients with liver disease, reviews the role of medical therapy and liver transplantation in treatment. Evaluation and diagnosis of POPH are discussed in a separate article.

Medical Therapy

Prostanoids

Although prostacyclin and prostaglandin analogs entered routine clinical practice for POPH in the 1990s, reports of investigational use date back to the 1980s. Prostanoids are potent vasodilators with antiplatelet aggregation and antiproliferative properties. Prostacyclin synthase is reduced in patients with PAH, resulting in decreased concentration of prostacyclin with vasoconstriction and proliferative changes in the pulmonary vasculature.¹

Epoprostenol

Epoprostenol is also known as synthetic prostaglandin I₂ or prostacyclin. It was the first therapy approved for the treatment of PAH in 1995 by the US Food and Drug Administration (FDA) as a continuous intravenous infusion.^2,3 It also inhibits platelet aggregation and may help modulate pulmonary vascular remodeling.^4,5 Epoprostenol is derived from the metabolism of arachidonic acid and is a potent pulmonary and systemic vasodilator. One study reported an immediate 11.8% decrease in MPAP, 24% decrease in pulmonary vascular resistance (PVR) and 28% drop in systemic vascular resistance (SVR) during an epoprostenol infusion.⁶ The authors reported that epoprostenol was a more potent vasodilator than nitric oxide and may have a role in predicting the reversibility of POPH. In a case series of 33 patients with secondary pulmonary hypertension (including 7 patients with POPH) treated with continuous intravenous prostacyclin for approximately 1 year, exercise tolerance, NYHA functional class, and pulmonary hemodynamics improved in each patient compared to baseline.⁷ Krowka et al studied 14 patients with moderate to severe POPH treated with intravenous epoprostenol.⁸ No significant side effects were noted and treatment resulted in significant improvements in PVR, MPAP, and cardiac output. In 2007, Fix et al published a large retrospective cohort of patients with moderate to severe POPH.⁹ Nineteen patients treated with epoprostenol were compared to 17 patients with no treatment. After a median treatment period of 15.4 months, the epoprostenol group showed significant improvement in MPAP, PVR and cardiac output, but survival did not differ between the 2 groups.

Epoprostenol has often been considered a bridge to transplant in patients with POPH. Sussman et al described 8 consecutive patients with POPH who were treated with intravenous epoprostenol (2 to 8 ng/kg/min dose).¹⁰ Liver transplant was considered in 7 of the 8 patients when MPAP decreased to less than 35 mm Hg. Six patients were eventually listed for liver transplant, but 2 died waiting on the list. Long-term outcomes in the group of transplanted recipients were excellent. They remained alive and well at least 9 to 18 months post-transplant, and half did not require long-term vasodilator therapy post-orthotopic liver transplant. Similarly, Ashfaq et al published their data on 16 patients with moderate-to-severe POPH who were treated with vasodilator therapy.¹¹ MPAP decreased to acceptable levels in 75% of the treated patients, and 11 went on to liver transplantation. Rates of 1- and 5-year survival in the transplanted patients were 91% and 67% respectively. None of the patients who failed vasodilator therapy survived.

Epoprostenol has a short half-life (3 to 5 minutes) and requires continuous infusion through central access via an infusion pump. Aseptic technique must be maintained to avoid blood stream infections. Pump failure or loss of vascular access can result in rebound pulmonary vasoconstriction that can be life-threatening and requires immediate attention. Side effects associated with epoprostenol include flushing, headache, nausea/vomiting, bradycardia, chest pain, jaw pain, diarrhea, and musculoskeletal pain.

Patients on epoprostenol should be monitored for prostanoid overdose. In the case of patients with chronic liver disease, epoprostenol increases systemic vasodilation in patients with already low systemic vascular tone. As a result, cardiac output may increase to the point of high cardiac output failure. MPAP will remain elevated secondary to high cardiac output rather than high PVR. In these patients, right heart catheterization will show an elevated MPAP in the setting of normal to low PVR/transpulmonary gradient (TPG) values. Lowering the epoprostenol dose will successfully reduce both cardiac output and MPAP.

Treprostinil

Treprostinil is a prostacyclin analog that is available in intravenous, inhalational, and subcutaneous form, although subcutaneous dosing may be limited by pain. Sakai et al published a small case series of 3 patients with PAH and end-stage liver disease treated with intravenous treprostinil.¹² Pulmonary hemodynamics improved in all patients, and 2 patients went on to an uneventful liver transplantation. More than 10 years later, data were published on 255 patients with PAH on therapy with bosentan or sildenafil randomized to additional inhaled treprostinil.¹³ Treprostinil proved to be safe and well tolerated, with improvement in quality of life measures but no improvement in other secondary endpoints.

Iloprost

Inhaled iloprost is another prostacyclin that has a short therapeutic half-life of 20 to 30 minutes and requires frequent administration (6 to 9 times daily). In study in which patients with severe POPH were treated for up to 3 years with inhaled iloprost,¹⁴ survival rates at 1, 2, and 3 years were 77%, 62%, and 46%, respectively. A second study published in 2010 was designed to assess the acute effects of inhaled iloprost on pulmonary hemodynamics and evaluate the clinical outcome after 12 months of treatment.¹⁵ Iloprost was found to rapidly reduce pulmonary arterial pressure and PVR. In the long-term evaluation, inhaled iloprost increased the 6-minute walk distance (6MWD) and functional class, but no change was noted in the systolic pulmonary artery pressure. The authors concluded that iloprost might provide symptomatic improvement and improvement in exercise capacity.

Selexipag

Selexipag is an oral selective IP prostacyclin receptor agonist that is structurally distinct from other prostacyclins.¹⁶ In a phase 3 randomized double blind clinical trial, PAH patients treated with selexipag had lower composite of death or complication of PAH to the end of the study period.¹⁷ This effect was consistent across all dose ranges, but POPH patients were excluded from this study. Safety and efficacy of selexipag has not been evaluated in POPH patients.

Endothelin Receptor Antagonists

Endothelin receptor antagonists block the production of endothelin-1 (ET-1), a potent vasoconstrictor and smooth muscle mitogen that may contribute to the development of PAH. Three different receptors have been described: endothelin A, endothelin B, and endothelin B2. Elevated ET-1 levels have been reported in patients with chronic liver disease and may originate from hepatosplanchnic circulation.¹⁸

Bosentan

Bosentan is an oral, nonspecific, ET-1A and ET-1B receptor antagonist. Initial use of bosentan in patients with POPH was limited because of concern for hepatotoxicity. Approximately 10% of patients on bosentan were reported to have mild hepatic side effects in the form of elevated aminotransferases, but severe injury has been reported.¹⁹ One of the first clinical experiences of bosentan in patients with POPH was published in 2005. Hoeper et al followed 11 patients with Child A cirrhosis and severe POPH.²⁰ All patients included were in NYHA functional class III or IV and were treated with bosentan for over 1 year. Exercise capacity and symptoms improved in all treated patients. The medication was tolerated well and there was no evidence of drug-induced liver injury. A single case report showed the effectiveness of bosentan in a 43-year-old man with alcohol-related liver disease (Child-Pugh A) and right ventricular enlargement and dysfunction secondary to POPH.²¹ Pulmonary arterial pressure decreased, exercise capacity increased, and improvement was maintained over 2 years.

In a group of 31 patients with Child A or B cirrhosis and severe POPH, bosentan had significantly better effects than inhaled iloprost on exercise capacity, hemodynamics, and survival.¹⁴ One, 2, and 3-year survival rates in the bosentan group were 94%, 89%, and 89% (compared to 77%, 62%, and 46% in the iloprost group). Both drugs were considered safe with no reported hepatotoxicity. In 2013, Savale et al published data on 34 patients with POPH, Child-Pugh A and/or B who were treated with bosentan for a median of 43 months.²² The authors reported significant improvements in hemodynamics, NYHA functional class, and 6WMD. Event-free survival rates at 1, 2, and 3 years were 82%, 63%, and 47%, respectively.

Ambrisentan

Ambrisentan is a highly selective ET-1A receptor antagonist with once daily dosing and a lower risk of hepatotoxicity compared to bosentan. Fourteen patients with moderate to severe POPH treated with ambrisentan in 4 German hospitals were retrospectively analyzed.²³ Median follow-up was 16 months, and the study demonstrated significant improvement in exercise capacity and clinical symptoms without significant change in liver function tests. Cartin-Ceba et al published their experience of 13 patients with moderate to severe POPH treated with ambrisentan monotherapy.²⁴ Patients were followed for a median of 613 days and on treatment for a median time of 390 days. Significant improvements were shown in pulmonary arterial pressure and PVR without adverse effect on hepatic function. Over 270 patients with PAH (6% with POPH) received ambrisentan from March 2009 through June 2013 at a large United Kingdom portal hypertension referral center.²⁵ Discontinuation due to side effects was higher than previously reported. Discontinuation due to abnormal transaminases was uncommon.

Macitentan

Macitentan is a dual endothelin-receptor antagonist developed by modifying the structure of bosentan to increase efficacy and safety. The SERAPHIN trial compared oral macitentan to placebo in 250 patients with moderate to severe PAH, some of whom were also on a stable dose of oral or inhaled therapy for PAH.²⁶ Over a 2-year period, patients treated with macitentan were less likely to have progression of their disease or die on therapy (38% and 31% versus 46%), regardless of if they were receiving additional oral therapy and more likely to have improvement of their exercise capacity and WHO functional class. Nasopharyngitis and significant anemia were more common in the macitentan group, but there was no difference in the rate of liver function test abnormalities compared to placebo. Trials with macitentan are currently ongoing in patients with POPH.

Phosphodiesterase-5 Inhibitors

Cyclic guanosine monophosphate (cGMP) is the mediator of nitric oxide–induced vasodilation. Phosphodiesterase-5 (PDE-5) inhibitors prolong the vasodilatory effects of cyclic guanosine monophosphate by preventing its hydrolysis, thereby reducing the pulmonary arterial pressure.

Sildenafil

Sildenafil is the most widely accepted PDE-5 inhibitor for POPH. Fourteen patients with moderate to severe POPH were treated with sildenafil (50 mg 3 times per day) in an observational study published by Reichenberger et al in 2006.²⁷ Eight patients were newly started on sildenafil, whereas sildenafil was added to inhaled prostanoids in the remaining 6x patients. Sildenafil significantly decreased 66MWD, MPAP, PVR, and cardiac index alone or in combination with inhaled prostanoids.

Sildenafil has also been used as a bridge to transplant in liver transplant candidates with POPH. Ten patients with POPH treated with sildenafil monotherapy were followed for a 21±16 months.²⁸ Patients improved symptomatically and increased their 6MWD at 1 year by 30 meters or more. Three patients became transplant eligible and another 3 patients were stable, without progression of their liver disease or POPH. Four patients were not considered transplant candidates, 2 because of refractory POPH and 2 for other comorbidities. The authors concluded that sildenafil monotherapy could stabilize or improve pulmonary hemodynamics in patients with POPH and eventually lead to liver transplantation. Gough et al took a similar look at 9 patients with POPH treated with sildenafil.²⁹ All patients had initial and follow-up right heart catheterizations within a period of 3 years. Mean PVR improved in all patients, decreasing from 575 to 375 dynes/s/cm^–5. MPAP decreased to ≤ 35 mmHg in 4 patients, 1 of whom went on to receive a liver transplant. Overall sildenafil improved pulmonary hemodynamics in this small cohort of POPH patients.

Tadalafil

Tadalafil is another oral PDE-5 inhibitor but with a longer half-life than sildenafil. Unlike sildenafil, which requires 3 times daily dosing, tadalafil requires once daily administration. A few case reports have demonstrated tadalafil’s effectiveness for POPH in combination with other medical therapy (eg, sildenafil, ambrisentan).^30,31

Guanylate Cyclase Stimulator

Riociguat

Riociguat is a first-in-class activator of soluble form of guanylate cyclase that increases levels of cyclic GMP. Two randomized clinical trials, PATENT, a study in PAH patients, and CHEST, a study in patients with chronic thromboembolic pulmonary hypertension showed improvement in 6MWD at 12 weeks (PATENT) or 16 weeks (CHEST), with improvement in secondary endpoints such as PVR, N-terminal pro b-type natriuretic peptide and WHO functional class.^32,33 Riociguat may have potential advantages in patients with POPH given that it has a favorable liver safety profile. A subgroup analysis of patients enrolled in the PATENT study showed that 13 had POPH and 11 were randomized to receive riociguat 2.5 mg 3 times daily dose and 2 received placebo.³⁴ Riociguat was well tolerated and improved 6MWD that was maintained over 2 years in the open label extension.

Medications to Avoid

Nonselective beta-blockers are commonly recommended in patients with portal hypertension to help prevent variceal hemorrhage. However, in patients with POPH, beta-blockers have been shown to decrease exercise capacity and worsen pulmonary hemodynamics. A study of 10 patients with moderate to severe POPH who were receiving beta-blockers for variceal bleeding prophylaxis showed that 6MWD improved in almost all of the patients, cardiac output increased by 28%, and PVR decreased by 19% when beta-blockers were discontinued.³⁵ The authors concluded that the use of beta-blockers should be avoided in this patient population.

Calcium channel blockers should not be used in patients with POPH because they can cause significant hypotension due to systemic vasodilatation and decreased right ventricular filling. Patients with portal hypertension and chronic liver disease commonly have low systemic vascular resistance and are particularly susceptible to the deleterious effects of calcium channel blockers.

Transplantation

Liver transplantation is a potential cure for POPH and its role in POPH has evolved over the past 2 decades. In 1997, Ramsay et al published their review of 1205 consecutive liver transplants at Baylor University Medical Center (BUMC) in Texas.³⁶ The incidence of POPH in this group was 8.5%, with the majority of patients having mild POPH. Liver transplant outcomes were not affected by mild and moderate pulmonary hypertension. However, patients with severe POPH (n = 7, systolic pulmonary artery pressure > 60 mm Hg) had a mortality rate of 42% at 9 months post-transplantation and 71% at 36 months post-transplant. The surviving patients continued to deteriorate with progressive right heart failure and no improvement in POPH.

To understand the effect of liver transplantation on POPH, one must understand the hemodynamic changes that occur with POPH and during liver transplant. The right ventricle is able to manage the same volume as the left ventricle under normal circumstances, but is unable to pump against a significant pressure gradient.³⁷ In the setting of POPH, right ventricular hypertrophy occurs and RV output remains stable for some time. With time, pulmonary artery pressure increases secondary to pulmonary arteriolar vasoconstriction, intimal thickening, and progressive occlusion of the pulmonary vascular bed. Right ventricular failure may occur as a result. Cardiac output increases significantly at the time of reperfusion during liver transplant (up to 3-fold in 15 minutes),³⁸ and in the setting of a noncompliant vascular bed, the patient is at risk for right heart failure. This is the likely explanation to such high perioperative mortality rates in patients with uncontrolled POPH. Failure to decrease MPAP to less than 50 mm Hg is considered a complete contraindication to liver transplant at most institutions. Many transplant centers will list patients for liver transplant if MPAP can be decreased to less than 35 mm Hg and PVR < 400 dynes/s/cm^–5. These parameters are thought to represent an adequate right ventricular reserve and a compliant pulmonary vascular bed.³⁷ However, even with good pressure control, the anesthesiology and critical care teams must be prepared to deal with acute right heart failure peri-operatively. Intraoperative transesophageal echocardiography has been recommended to closely follow right ventricular function.³⁸ Inhaled or intravenous dilators are the most effective agents in the event of a pulmonary hypertensive crisis.

Review of Outcomes

A retrospective review evaluated 43 patients with untreated POPH who underwent attempted liver transplantation.³⁹ Data were collected from 18 peer-reviewed studies and 7 patients at the authors’ institution. Overall mortality was 35% (15 patients), with almost all of the deaths secondary to cardiac dysfunction. Two deaths occurred intraoperatively and 8 deaths occurred during the transplant hospitalization. The transplant could not be successfully completed in 4 of the patients. MPAP > 50 mm Hg was associated with 100% mortality, whereas patients with MPAP between 35 mm Hg and 50 mm Hg had a 50% mortality. No mortality was noted in patients with MPAP < 35 mm Hg.

Liver transplantation has been shown to be successful in patients with controlled POPH. Sussman et al published their data on 8 patients with severe POPH in 2006. In this prospective study, all patients were treated with sequential epoprostenol infusions and 7 of the 8 patients experienced a significant reduction in MPAP and PVR. Six patients were listed for liver transplant, 4 of who were transplanted successfully and alive up to 5 years later.

The Baylor University Medical Center published their data on POPH patients who received liver transplants in 2007.¹¹ POPH was confirmed by right heart catheterization in 30 patients evaluated for liver transplant. Sixteen patients were considered to be suitable candidates for transplant and MPAP was decreased to less than 35 mmHg in 12 patients with vasodilator therapy. Eleven patients eventually underwent liver transplant and 1- and 5-year survival rates were 91% and 67%.

Compared to medical therapy or liver transplant alone, patients who receive medical therapy followed by liver transplantation have the best survival. The Mayo Clinic retrospectively reviewed 74 POPH patients identified between 1994 and 2007.⁴⁰ Patients were categorized in 1 of 3 categories: no medical therapy, medical therapy alone for POPH, or medical therapy for POPH followed by liver transplantation. Patients who received no medical therapy for POPH and no liver transplant had the worst outcomes, with a dismal 5-year survival of only 14% with over 50% deceased at 1 year of diagnosis. Five-year survival was 45% in patients who received medical therapy only. Patients who received medical therapy with prostacyclin followed by liver transplantation had the best outcomes, with a 5-year survival of 67% versus 25% in those who were transplanted without prior prostacyclin therapy.

We reported the longest follow-up study for patients undergoing liver transplantation with POPH in 2014.⁴¹ Seven patients with moderate to severe POPH received a liver transplant at our institution between June 2004 and January 2011. Mean pulmonary artery pressure was reduced to < 35 mm Hg, with appropriate POPH therapy in all of the patients. Both the graft and patient survival rates were 85.7% after a median follow-up of 7.8 years. The 1 patient who did not survive died from complications related to recurrent hepatitis C and cirrhosis, not from POPH-related issues. Four of the remaining 6 patients continue to require oral vasodilator therapy post-transplant, suggesting irreversible remodeling of the pulmonary vasculature. Two patients (4.4 and 8.5 years post-transplant) have no evidence of pulmonary hypertension post-transplant and therefore do not require medical treatment for pulmonary hypertension. We concluded that POPH responsive to vasodilator therapy is an appropriate indication for liver transplant, with excellent long-term survival.

Hollatz et al published their data on 11 patients with moderate to severe POPH who were successfully treated (mostly with oral sildenafil and subcutaneous treprostinil) as a bridge to liver transplant.⁴² The mortality rate was 0, with a follow-up duration of 7 to 60 months. Interestingly, 7 of the 11 patients (64%) were off all pulmonary vasodilators post-transplant. Ashfaq et al reported similar results.¹¹ Nine of 11 patients with treated moderate to severe POPH who received liver transplants stopped vasodilator therapy at a median period of 9.2 months post-transplant. Raevens et al described a group of 3 patients with POPH who went on to liver transplant after their pulmonary pressures were decreased with combined oral vasodilator therapy: 1 required continued long-term vasodilator therapy, another was weaned off medications after transplant, and the third patient died during the liver transplant from perioperative complications that induced uncontrolled pulmonary hypertension.⁴³

Patient Selection

In 2006, the United Network for Organ Sharing (UNOS) initiated a policy whereby a higher priority for liver transplantation was granted for highly selected patients in the United States.⁴⁴ UNOS policy 3.6.4.5.6 upgraded POPH patients to a MELD score of 22, with an increase in MELD every 3 months as long as MPAP remained < 35 mm Hg and PVR remained < 400 dynes/s/cm^–5. One hundred fifty-five patients were granted MELD exception points for POPH between 2002 and 2010 and went on to receive liver transplants.⁴⁵ Goldberg et al collected data from the Organ Procurement and Transplantation Network (OPTN) and compared outcomes of patients with approved POPH MELD exception points versus waitlist candidates with no exception points.⁴⁶ One hundred fifty-five waitlisted patients received POPH MELD exception points, with only 43.1% meeting OPTN exception requirements. One-third did not fulfill hemodynamic criteria consistent with POPH or had missing data, and 80% went on to receive a liver transplant. Waitlist candidates receiving POPH MELD exception points also had increased waitlist mortality and several early post-transplant deaths. The authors felt these data highlighted the need for OPTN/UNOS to revise their policy for POPH MELD exceptions points, revise how points are rewarded, and continue research to help risk stratify these patients to minimize perioperative complications.

Conclusion

Several effective medical treatment regimens are available, including prostanoids, endothelin receptor antagonists, and PDE-5 inhibitors. Liver transplantation is a potential cure but is only recommended if MPAP can be decreased to ≤ 35 mmHg. Long-term follow-up studies have shown these patients do well several years post-transplant but may continue to require oral therapy for their POPH.

Portopulmonary hypertension (POPH) is a form of group 1 pulmonary arterial hypertension. When treating patients with POPH, baseline assessment is necessary so that response to therapy can be measured as the change from baseline. Patients should undergo echocardiography and right heart catheterization, and their exercise capacity and NYHA functional class should be determined. Patients with POPH should be considered for treatment if they are NYHA functional class II or above and/or their mean pulmonary artery pressure (MPAP) is greater than 35 mm Hg in transplant candidates. The goal in the treatment and management of POPH is to improve pulmonary hemodynamics by reducing the obstruction to pulmonary arterial flow and to preserve right ventricular function (Table). This article, the second in a 2-part review of POPH in patients with liver disease, reviews the role of medical therapy and liver transplantation in treatment. Evaluation and diagnosis of POPH are discussed in a separate article.

Medical Therapy

Prostanoids

Although prostacyclin and prostaglandin analogs entered routine clinical practice for POPH in the 1990s, reports of investigational use date back to the 1980s. Prostanoids are potent vasodilators with antiplatelet aggregation and antiproliferative properties. Prostacyclin synthase is reduced in patients with PAH, resulting in decreased concentration of prostacyclin with vasoconstriction and proliferative changes in the pulmonary vasculature.¹

Epoprostenol

Epoprostenol is also known as synthetic prostaglandin I₂ or prostacyclin. It was the first therapy approved for the treatment of PAH in 1995 by the US Food and Drug Administration (FDA) as a continuous intravenous infusion.^2,3 It also inhibits platelet aggregation and may help modulate pulmonary vascular remodeling.^4,5 Epoprostenol is derived from the metabolism of arachidonic acid and is a potent pulmonary and systemic vasodilator. One study reported an immediate 11.8% decrease in MPAP, 24% decrease in pulmonary vascular resistance (PVR) and 28% drop in systemic vascular resistance (SVR) during an epoprostenol infusion.⁶ The authors reported that epoprostenol was a more potent vasodilator than nitric oxide and may have a role in predicting the reversibility of POPH. In a case series of 33 patients with secondary pulmonary hypertension (including 7 patients with POPH) treated with continuous intravenous prostacyclin for approximately 1 year, exercise tolerance, NYHA functional class, and pulmonary hemodynamics improved in each patient compared to baseline.⁷ Krowka et al studied 14 patients with moderate to severe POPH treated with intravenous epoprostenol.⁸ No significant side effects were noted and treatment resulted in significant improvements in PVR, MPAP, and cardiac output. In 2007, Fix et al published a large retrospective cohort of patients with moderate to severe POPH.⁹ Nineteen patients treated with epoprostenol were compared to 17 patients with no treatment. After a median treatment period of 15.4 months, the epoprostenol group showed significant improvement in MPAP, PVR and cardiac output, but survival did not differ between the 2 groups.

Epoprostenol has often been considered a bridge to transplant in patients with POPH. Sussman et al described 8 consecutive patients with POPH who were treated with intravenous epoprostenol (2 to 8 ng/kg/min dose).¹⁰ Liver transplant was considered in 7 of the 8 patients when MPAP decreased to less than 35 mm Hg. Six patients were eventually listed for liver transplant, but 2 died waiting on the list. Long-term outcomes in the group of transplanted recipients were excellent. They remained alive and well at least 9 to 18 months post-transplant, and half did not require long-term vasodilator therapy post-orthotopic liver transplant. Similarly, Ashfaq et al published their data on 16 patients with moderate-to-severe POPH who were treated with vasodilator therapy.¹¹ MPAP decreased to acceptable levels in 75% of the treated patients, and 11 went on to liver transplantation. Rates of 1- and 5-year survival in the transplanted patients were 91% and 67% respectively. None of the patients who failed vasodilator therapy survived.

Epoprostenol has a short half-life (3 to 5 minutes) and requires continuous infusion through central access via an infusion pump. Aseptic technique must be maintained to avoid blood stream infections. Pump failure or loss of vascular access can result in rebound pulmonary vasoconstriction that can be life-threatening and requires immediate attention. Side effects associated with epoprostenol include flushing, headache, nausea/vomiting, bradycardia, chest pain, jaw pain, diarrhea, and musculoskeletal pain.

Patients on epoprostenol should be monitored for prostanoid overdose. In the case of patients with chronic liver disease, epoprostenol increases systemic vasodilation in patients with already low systemic vascular tone. As a result, cardiac output may increase to the point of high cardiac output failure. MPAP will remain elevated secondary to high cardiac output rather than high PVR. In these patients, right heart catheterization will show an elevated MPAP in the setting of normal to low PVR/transpulmonary gradient (TPG) values. Lowering the epoprostenol dose will successfully reduce both cardiac output and MPAP.

Treprostinil

Treprostinil is a prostacyclin analog that is available in intravenous, inhalational, and subcutaneous form, although subcutaneous dosing may be limited by pain. Sakai et al published a small case series of 3 patients with PAH and end-stage liver disease treated with intravenous treprostinil.¹² Pulmonary hemodynamics improved in all patients, and 2 patients went on to an uneventful liver transplantation. More than 10 years later, data were published on 255 patients with PAH on therapy with bosentan or sildenafil randomized to additional inhaled treprostinil.¹³ Treprostinil proved to be safe and well tolerated, with improvement in quality of life measures but no improvement in other secondary endpoints.

Iloprost

Inhaled iloprost is another prostacyclin that has a short therapeutic half-life of 20 to 30 minutes and requires frequent administration (6 to 9 times daily). In study in which patients with severe POPH were treated for up to 3 years with inhaled iloprost,¹⁴ survival rates at 1, 2, and 3 years were 77%, 62%, and 46%, respectively. A second study published in 2010 was designed to assess the acute effects of inhaled iloprost on pulmonary hemodynamics and evaluate the clinical outcome after 12 months of treatment.¹⁵ Iloprost was found to rapidly reduce pulmonary arterial pressure and PVR. In the long-term evaluation, inhaled iloprost increased the 6-minute walk distance (6MWD) and functional class, but no change was noted in the systolic pulmonary artery pressure. The authors concluded that iloprost might provide symptomatic improvement and improvement in exercise capacity.

Selexipag

Selexipag is an oral selective IP prostacyclin receptor agonist that is structurally distinct from other prostacyclins.¹⁶ In a phase 3 randomized double blind clinical trial, PAH patients treated with selexipag had lower composite of death or complication of PAH to the end of the study period.¹⁷ This effect was consistent across all dose ranges, but POPH patients were excluded from this study. Safety and efficacy of selexipag has not been evaluated in POPH patients.

Endothelin Receptor Antagonists

Endothelin receptor antagonists block the production of endothelin-1 (ET-1), a potent vasoconstrictor and smooth muscle mitogen that may contribute to the development of PAH. Three different receptors have been described: endothelin A, endothelin B, and endothelin B2. Elevated ET-1 levels have been reported in patients with chronic liver disease and may originate from hepatosplanchnic circulation.¹⁸

Bosentan

Bosentan is an oral, nonspecific, ET-1A and ET-1B receptor antagonist. Initial use of bosentan in patients with POPH was limited because of concern for hepatotoxicity. Approximately 10% of patients on bosentan were reported to have mild hepatic side effects in the form of elevated aminotransferases, but severe injury has been reported.¹⁹ One of the first clinical experiences of bosentan in patients with POPH was published in 2005. Hoeper et al followed 11 patients with Child A cirrhosis and severe POPH.²⁰ All patients included were in NYHA functional class III or IV and were treated with bosentan for over 1 year. Exercise capacity and symptoms improved in all treated patients. The medication was tolerated well and there was no evidence of drug-induced liver injury. A single case report showed the effectiveness of bosentan in a 43-year-old man with alcohol-related liver disease (Child-Pugh A) and right ventricular enlargement and dysfunction secondary to POPH.²¹ Pulmonary arterial pressure decreased, exercise capacity increased, and improvement was maintained over 2 years.

In a group of 31 patients with Child A or B cirrhosis and severe POPH, bosentan had significantly better effects than inhaled iloprost on exercise capacity, hemodynamics, and survival.¹⁴ One, 2, and 3-year survival rates in the bosentan group were 94%, 89%, and 89% (compared to 77%, 62%, and 46% in the iloprost group). Both drugs were considered safe with no reported hepatotoxicity. In 2013, Savale et al published data on 34 patients with POPH, Child-Pugh A and/or B who were treated with bosentan for a median of 43 months.²² The authors reported significant improvements in hemodynamics, NYHA functional class, and 6WMD. Event-free survival rates at 1, 2, and 3 years were 82%, 63%, and 47%, respectively.

Ambrisentan

Ambrisentan is a highly selective ET-1A receptor antagonist with once daily dosing and a lower risk of hepatotoxicity compared to bosentan. Fourteen patients with moderate to severe POPH treated with ambrisentan in 4 German hospitals were retrospectively analyzed.²³ Median follow-up was 16 months, and the study demonstrated significant improvement in exercise capacity and clinical symptoms without significant change in liver function tests. Cartin-Ceba et al published their experience of 13 patients with moderate to severe POPH treated with ambrisentan monotherapy.²⁴ Patients were followed for a median of 613 days and on treatment for a median time of 390 days. Significant improvements were shown in pulmonary arterial pressure and PVR without adverse effect on hepatic function. Over 270 patients with PAH (6% with POPH) received ambrisentan from March 2009 through June 2013 at a large United Kingdom portal hypertension referral center.²⁵ Discontinuation due to side effects was higher than previously reported. Discontinuation due to abnormal transaminases was uncommon.

Macitentan

Macitentan is a dual endothelin-receptor antagonist developed by modifying the structure of bosentan to increase efficacy and safety. The SERAPHIN trial compared oral macitentan to placebo in 250 patients with moderate to severe PAH, some of whom were also on a stable dose of oral or inhaled therapy for PAH.²⁶ Over a 2-year period, patients treated with macitentan were less likely to have progression of their disease or die on therapy (38% and 31% versus 46%), regardless of if they were receiving additional oral therapy and more likely to have improvement of their exercise capacity and WHO functional class. Nasopharyngitis and significant anemia were more common in the macitentan group, but there was no difference in the rate of liver function test abnormalities compared to placebo. Trials with macitentan are currently ongoing in patients with POPH.

Phosphodiesterase-5 Inhibitors

Cyclic guanosine monophosphate (cGMP) is the mediator of nitric oxide–induced vasodilation. Phosphodiesterase-5 (PDE-5) inhibitors prolong the vasodilatory effects of cyclic guanosine monophosphate by preventing its hydrolysis, thereby reducing the pulmonary arterial pressure.

Sildenafil

Sildenafil is the most widely accepted PDE-5 inhibitor for POPH. Fourteen patients with moderate to severe POPH were treated with sildenafil (50 mg 3 times per day) in an observational study published by Reichenberger et al in 2006.²⁷ Eight patients were newly started on sildenafil, whereas sildenafil was added to inhaled prostanoids in the remaining 6x patients. Sildenafil significantly decreased 66MWD, MPAP, PVR, and cardiac index alone or in combination with inhaled prostanoids.

Sildenafil has also been used as a bridge to transplant in liver transplant candidates with POPH. Ten patients with POPH treated with sildenafil monotherapy were followed for a 21±16 months.²⁸ Patients improved symptomatically and increased their 6MWD at 1 year by 30 meters or more. Three patients became transplant eligible and another 3 patients were stable, without progression of their liver disease or POPH. Four patients were not considered transplant candidates, 2 because of refractory POPH and 2 for other comorbidities. The authors concluded that sildenafil monotherapy could stabilize or improve pulmonary hemodynamics in patients with POPH and eventually lead to liver transplantation. Gough et al took a similar look at 9 patients with POPH treated with sildenafil.²⁹ All patients had initial and follow-up right heart catheterizations within a period of 3 years. Mean PVR improved in all patients, decreasing from 575 to 375 dynes/s/cm^–5. MPAP decreased to ≤ 35 mmHg in 4 patients, 1 of whom went on to receive a liver transplant. Overall sildenafil improved pulmonary hemodynamics in this small cohort of POPH patients.

Tadalafil

Tadalafil is another oral PDE-5 inhibitor but with a longer half-life than sildenafil. Unlike sildenafil, which requires 3 times daily dosing, tadalafil requires once daily administration. A few case reports have demonstrated tadalafil’s effectiveness for POPH in combination with other medical therapy (eg, sildenafil, ambrisentan).^30,31

Guanylate Cyclase Stimulator

Riociguat

Riociguat is a first-in-class activator of soluble form of guanylate cyclase that increases levels of cyclic GMP. Two randomized clinical trials, PATENT, a study in PAH patients, and CHEST, a study in patients with chronic thromboembolic pulmonary hypertension showed improvement in 6MWD at 12 weeks (PATENT) or 16 weeks (CHEST), with improvement in secondary endpoints such as PVR, N-terminal pro b-type natriuretic peptide and WHO functional class.^32,33 Riociguat may have potential advantages in patients with POPH given that it has a favorable liver safety profile. A subgroup analysis of patients enrolled in the PATENT study showed that 13 had POPH and 11 were randomized to receive riociguat 2.5 mg 3 times daily dose and 2 received placebo.³⁴ Riociguat was well tolerated and improved 6MWD that was maintained over 2 years in the open label extension.

Medications to Avoid

Nonselective beta-blockers are commonly recommended in patients with portal hypertension to help prevent variceal hemorrhage. However, in patients with POPH, beta-blockers have been shown to decrease exercise capacity and worsen pulmonary hemodynamics. A study of 10 patients with moderate to severe POPH who were receiving beta-blockers for variceal bleeding prophylaxis showed that 6MWD improved in almost all of the patients, cardiac output increased by 28%, and PVR decreased by 19% when beta-blockers were discontinued.³⁵ The authors concluded that the use of beta-blockers should be avoided in this patient population.

Calcium channel blockers should not be used in patients with POPH because they can cause significant hypotension due to systemic vasodilatation and decreased right ventricular filling. Patients with portal hypertension and chronic liver disease commonly have low systemic vascular resistance and are particularly susceptible to the deleterious effects of calcium channel blockers.

Transplantation

Liver transplantation is a potential cure for POPH and its role in POPH has evolved over the past 2 decades. In 1997, Ramsay et al published their review of 1205 consecutive liver transplants at Baylor University Medical Center (BUMC) in Texas.³⁶ The incidence of POPH in this group was 8.5%, with the majority of patients having mild POPH. Liver transplant outcomes were not affected by mild and moderate pulmonary hypertension. However, patients with severe POPH (n = 7, systolic pulmonary artery pressure > 60 mm Hg) had a mortality rate of 42% at 9 months post-transplantation and 71% at 36 months post-transplant. The surviving patients continued to deteriorate with progressive right heart failure and no improvement in POPH.

To understand the effect of liver transplantation on POPH, one must understand the hemodynamic changes that occur with POPH and during liver transplant. The right ventricle is able to manage the same volume as the left ventricle under normal circumstances, but is unable to pump against a significant pressure gradient.³⁷ In the setting of POPH, right ventricular hypertrophy occurs and RV output remains stable for some time. With time, pulmonary artery pressure increases secondary to pulmonary arteriolar vasoconstriction, intimal thickening, and progressive occlusion of the pulmonary vascular bed. Right ventricular failure may occur as a result. Cardiac output increases significantly at the time of reperfusion during liver transplant (up to 3-fold in 15 minutes),³⁸ and in the setting of a noncompliant vascular bed, the patient is at risk for right heart failure. This is the likely explanation to such high perioperative mortality rates in patients with uncontrolled POPH. Failure to decrease MPAP to less than 50 mm Hg is considered a complete contraindication to liver transplant at most institutions. Many transplant centers will list patients for liver transplant if MPAP can be decreased to less than 35 mm Hg and PVR < 400 dynes/s/cm^–5. These parameters are thought to represent an adequate right ventricular reserve and a compliant pulmonary vascular bed.³⁷ However, even with good pressure control, the anesthesiology and critical care teams must be prepared to deal with acute right heart failure peri-operatively. Intraoperative transesophageal echocardiography has been recommended to closely follow right ventricular function.³⁸ Inhaled or intravenous dilators are the most effective agents in the event of a pulmonary hypertensive crisis.

Review of Outcomes

A retrospective review evaluated 43 patients with untreated POPH who underwent attempted liver transplantation.³⁹ Data were collected from 18 peer-reviewed studies and 7 patients at the authors’ institution. Overall mortality was 35% (15 patients), with almost all of the deaths secondary to cardiac dysfunction. Two deaths occurred intraoperatively and 8 deaths occurred during the transplant hospitalization. The transplant could not be successfully completed in 4 of the patients. MPAP > 50 mm Hg was associated with 100% mortality, whereas patients with MPAP between 35 mm Hg and 50 mm Hg had a 50% mortality. No mortality was noted in patients with MPAP < 35 mm Hg.

Liver transplantation has been shown to be successful in patients with controlled POPH. Sussman et al published their data on 8 patients with severe POPH in 2006. In this prospective study, all patients were treated with sequential epoprostenol infusions and 7 of the 8 patients experienced a significant reduction in MPAP and PVR. Six patients were listed for liver transplant, 4 of who were transplanted successfully and alive up to 5 years later.

The Baylor University Medical Center published their data on POPH patients who received liver transplants in 2007.¹¹ POPH was confirmed by right heart catheterization in 30 patients evaluated for liver transplant. Sixteen patients were considered to be suitable candidates for transplant and MPAP was decreased to less than 35 mmHg in 12 patients with vasodilator therapy. Eleven patients eventually underwent liver transplant and 1- and 5-year survival rates were 91% and 67%.

Compared to medical therapy or liver transplant alone, patients who receive medical therapy followed by liver transplantation have the best survival. The Mayo Clinic retrospectively reviewed 74 POPH patients identified between 1994 and 2007.⁴⁰ Patients were categorized in 1 of 3 categories: no medical therapy, medical therapy alone for POPH, or medical therapy for POPH followed by liver transplantation. Patients who received no medical therapy for POPH and no liver transplant had the worst outcomes, with a dismal 5-year survival of only 14% with over 50% deceased at 1 year of diagnosis. Five-year survival was 45% in patients who received medical therapy only. Patients who received medical therapy with prostacyclin followed by liver transplantation had the best outcomes, with a 5-year survival of 67% versus 25% in those who were transplanted without prior prostacyclin therapy.

We reported the longest follow-up study for patients undergoing liver transplantation with POPH in 2014.⁴¹ Seven patients with moderate to severe POPH received a liver transplant at our institution between June 2004 and January 2011. Mean pulmonary artery pressure was reduced to < 35 mm Hg, with appropriate POPH therapy in all of the patients. Both the graft and patient survival rates were 85.7% after a median follow-up of 7.8 years. The 1 patient who did not survive died from complications related to recurrent hepatitis C and cirrhosis, not from POPH-related issues. Four of the remaining 6 patients continue to require oral vasodilator therapy post-transplant, suggesting irreversible remodeling of the pulmonary vasculature. Two patients (4.4 and 8.5 years post-transplant) have no evidence of pulmonary hypertension post-transplant and therefore do not require medical treatment for pulmonary hypertension. We concluded that POPH responsive to vasodilator therapy is an appropriate indication for liver transplant, with excellent long-term survival.

Hollatz et al published their data on 11 patients with moderate to severe POPH who were successfully treated (mostly with oral sildenafil and subcutaneous treprostinil) as a bridge to liver transplant.⁴² The mortality rate was 0, with a follow-up duration of 7 to 60 months. Interestingly, 7 of the 11 patients (64%) were off all pulmonary vasodilators post-transplant. Ashfaq et al reported similar results.¹¹ Nine of 11 patients with treated moderate to severe POPH who received liver transplants stopped vasodilator therapy at a median period of 9.2 months post-transplant. Raevens et al described a group of 3 patients with POPH who went on to liver transplant after their pulmonary pressures were decreased with combined oral vasodilator therapy: 1 required continued long-term vasodilator therapy, another was weaned off medications after transplant, and the third patient died during the liver transplant from perioperative complications that induced uncontrolled pulmonary hypertension.⁴³

Patient Selection

In 2006, the United Network for Organ Sharing (UNOS) initiated a policy whereby a higher priority for liver transplantation was granted for highly selected patients in the United States.⁴⁴ UNOS policy 3.6.4.5.6 upgraded POPH patients to a MELD score of 22, with an increase in MELD every 3 months as long as MPAP remained < 35 mm Hg and PVR remained < 400 dynes/s/cm^–5. One hundred fifty-five patients were granted MELD exception points for POPH between 2002 and 2010 and went on to receive liver transplants.⁴⁵ Goldberg et al collected data from the Organ Procurement and Transplantation Network (OPTN) and compared outcomes of patients with approved POPH MELD exception points versus waitlist candidates with no exception points.⁴⁶ One hundred fifty-five waitlisted patients received POPH MELD exception points, with only 43.1% meeting OPTN exception requirements. One-third did not fulfill hemodynamic criteria consistent with POPH or had missing data, and 80% went on to receive a liver transplant. Waitlist candidates receiving POPH MELD exception points also had increased waitlist mortality and several early post-transplant deaths. The authors felt these data highlighted the need for OPTN/UNOS to revise their policy for POPH MELD exceptions points, revise how points are rewarded, and continue research to help risk stratify these patients to minimize perioperative complications.

Conclusion

Several effective medical treatment regimens are available, including prostanoids, endothelin receptor antagonists, and PDE-5 inhibitors. Liver transplantation is a potential cure but is only recommended if MPAP can be decreased to ≤ 35 mmHg. Long-term follow-up studies have shown these patients do well several years post-transplant but may continue to require oral therapy for their POPH.