Letters To The Editor

In Reply: We appreciate the response of Drs. Maharaj, Chang, and Shaikh. Antiphospholipid antibody testing and the diagnosis of antiphospholipid antibody syndrome are quite complex. We recognize that there is controversy with regard to the role of antiphosphatidylserine (aPS) antibodies, antiprothrombin antibodies, (aPT-A), and antibodies to the antiphosphatidylserine-prothrombin complex (aPS/PT).

In the systematic review cited, the authors concluded that measurement of aPS/PT may be helpful in determining the thrombotic risk in a subset of patients with prior thrombosis and systemic lupus erythematosus (SLE).¹ However, the majority of the studies included in the systematic review enrolled patients with antiphospholipid antibody syndrome and SLE. Our patient did not have SLE. Additionally, most of the studies were small. Therefore, the independent association between aPS/PT and thrombosis in patients without known SLE or previously known antiphospholipid antibody syndrome is challenging to infer on the basis of available data.¹

At our institution, we do not routinely test for these “non-criteria” antibodies as part of our evaluation of suspected antiphospholipid antibody syndrome. However, we agree that this is an area that warrants further investigation. There is a need for prospective trials or, more likely, longitudinal observational studies to further delineate the association of aPT-A, aPS, or aPS/PT with clinical features of antiphospholipid antibody syndrome.²

In Reply: We appreciate the response of Drs. Maharaj, Chang, and Shaikh. Antiphospholipid antibody testing and the diagnosis of antiphospholipid antibody syndrome are quite complex. We recognize that there is controversy with regard to the role of antiphosphatidylserine (aPS) antibodies, antiprothrombin antibodies, (aPT-A), and antibodies to the antiphosphatidylserine-prothrombin complex (aPS/PT).

In the systematic review cited, the authors concluded that measurement of aPS/PT may be helpful in determining the thrombotic risk in a subset of patients with prior thrombosis and systemic lupus erythematosus (SLE).¹ However, the majority of the studies included in the systematic review enrolled patients with antiphospholipid antibody syndrome and SLE. Our patient did not have SLE. Additionally, most of the studies were small. Therefore, the independent association between aPS/PT and thrombosis in patients without known SLE or previously known antiphospholipid antibody syndrome is challenging to infer on the basis of available data.¹

At our institution, we do not routinely test for these “non-criteria” antibodies as part of our evaluation of suspected antiphospholipid antibody syndrome. However, we agree that this is an area that warrants further investigation. There is a need for prospective trials or, more likely, longitudinal observational studies to further delineate the association of aPT-A, aPS, or aPS/PT with clinical features of antiphospholipid antibody syndrome.²

In Reply: We appreciate the response of Drs. Maharaj, Chang, and Shaikh. Antiphospholipid antibody testing and the diagnosis of antiphospholipid antibody syndrome are quite complex. We recognize that there is controversy with regard to the role of antiphosphatidylserine (aPS) antibodies, antiprothrombin antibodies, (aPT-A), and antibodies to the antiphosphatidylserine-prothrombin complex (aPS/PT).

In the systematic review cited, the authors concluded that measurement of aPS/PT may be helpful in determining the thrombotic risk in a subset of patients with prior thrombosis and systemic lupus erythematosus (SLE).¹ However, the majority of the studies included in the systematic review enrolled patients with antiphospholipid antibody syndrome and SLE. Our patient did not have SLE. Additionally, most of the studies were small. Therefore, the independent association between aPS/PT and thrombosis in patients without known SLE or previously known antiphospholipid antibody syndrome is challenging to infer on the basis of available data.¹

At our institution, we do not routinely test for these “non-criteria” antibodies as part of our evaluation of suspected antiphospholipid antibody syndrome. However, we agree that this is an area that warrants further investigation. There is a need for prospective trials or, more likely, longitudinal observational studies to further delineate the association of aPT-A, aPS, or aPS/PT with clinical features of antiphospholipid antibody syndrome.²

To the Editor: I read with interest the thoughtful review of cardiorenal syndrome by Drs. Thind, Loehrke, and Wilt¹ and the accompanying editorial by Dr. Grodin.² These articles certainly add to our growing knowledge of the syndrome and the importance of treating volume overload in these complex patients.

Indeed, we and others have stressed the primary importance of renal dysfunction in patients with volume overload and acute decompensated heart failure.^3,4 We have learned that even small rises in serum creatinine predict poor outcomes in these patients. And even if the serum creatinine level comes back down during hospitalization, acute kidney injury (AKI) is still associated with risk.⁵

Nevertheless, clinicians remain frustrated with the practical management of patients with volume overload and worsening AKI. When faced with a rising serum creatinine level in a patient being treated for decompensated heart failure with signs or symptoms of volume overload, I suggest the following:

Perform careful bedside and chart review searching for evidence of AKI related to causes other than cardiorenal syndrome. Ask whether the rise in serum creatinine could be caused by new obstruction (eg, urinary retention, upper urinary tract obstruction), a nephrotoxin (eg, nonsteroidal anti-inflammatory drugs), a primary tubulointerstitial or glomerular process (eg, drug-induced acute interstitial nephritis, acute glomerulonephritis), acute tubular necrosis, or a new hemodynamic event threatening renal perfusion (eg, hypotension, a new arrhythmia). It is often best to arrive at a diagnosis of AKI due to cardiorenal dysfunction by exclusion, much like the working definitions of hepatorenal syndrome.⁶ This requires review of the urine sediment (looking for evidence of granular casts of acute tubular necrosis, or evidence of glomerulonephritis or interstitial nephritis), electronic medical record, vital signs, telemetry, and perhaps renal ultrasonography.

In the absence of frank evidence of “overdiuresis” such as worsening hypernatremia, with dropping blood pressure, clinical hypoperfusion, and contraction alkalosis, avoid the temptation to suspend diuretics. Alternatively, an increase in diuretic dose, or addition of a distal diuretic (ie, metolazone) may be needed to address persistent renal venous congestion as the cause of the AKI.³ In this situation, be sure to monitor electrolytes, volume status, and renal function closely while diuretic treatment is augmented. In many such cases, the serum creatinine may actually start to decrease after a more robust diuresis is generated. In these patients, it may also be prudent to temporarily suspend antagonists of the renin-angiotensin-aldosterone system, although this remains controversial.

Management of such patients should be done collaboratively with cardiologists well versed in the treatment of cardiorenal syndrome. It may be possible that the worsening renal function in these patients represents important changes in cardiac rhythm or function (eg, low cardiac output state, new or worsening valvular disease, ongoing myocardial ischemia, cardiac tamponade, uncontrolled bradycardia or tachyarrythmia). Interventions aimed at reversing such perturbations could be the most important steps in improving cardiorenal function and reversing AKI.

To the Editor: I read with interest the thoughtful review of cardiorenal syndrome by Drs. Thind, Loehrke, and Wilt¹ and the accompanying editorial by Dr. Grodin.² These articles certainly add to our growing knowledge of the syndrome and the importance of treating volume overload in these complex patients.

Indeed, we and others have stressed the primary importance of renal dysfunction in patients with volume overload and acute decompensated heart failure.^3,4 We have learned that even small rises in serum creatinine predict poor outcomes in these patients. And even if the serum creatinine level comes back down during hospitalization, acute kidney injury (AKI) is still associated with risk.⁵

Nevertheless, clinicians remain frustrated with the practical management of patients with volume overload and worsening AKI. When faced with a rising serum creatinine level in a patient being treated for decompensated heart failure with signs or symptoms of volume overload, I suggest the following:

Perform careful bedside and chart review searching for evidence of AKI related to causes other than cardiorenal syndrome. Ask whether the rise in serum creatinine could be caused by new obstruction (eg, urinary retention, upper urinary tract obstruction), a nephrotoxin (eg, nonsteroidal anti-inflammatory drugs), a primary tubulointerstitial or glomerular process (eg, drug-induced acute interstitial nephritis, acute glomerulonephritis), acute tubular necrosis, or a new hemodynamic event threatening renal perfusion (eg, hypotension, a new arrhythmia). It is often best to arrive at a diagnosis of AKI due to cardiorenal dysfunction by exclusion, much like the working definitions of hepatorenal syndrome.⁶ This requires review of the urine sediment (looking for evidence of granular casts of acute tubular necrosis, or evidence of glomerulonephritis or interstitial nephritis), electronic medical record, vital signs, telemetry, and perhaps renal ultrasonography.

In the absence of frank evidence of “overdiuresis” such as worsening hypernatremia, with dropping blood pressure, clinical hypoperfusion, and contraction alkalosis, avoid the temptation to suspend diuretics. Alternatively, an increase in diuretic dose, or addition of a distal diuretic (ie, metolazone) may be needed to address persistent renal venous congestion as the cause of the AKI.³ In this situation, be sure to monitor electrolytes, volume status, and renal function closely while diuretic treatment is augmented. In many such cases, the serum creatinine may actually start to decrease after a more robust diuresis is generated. In these patients, it may also be prudent to temporarily suspend antagonists of the renin-angiotensin-aldosterone system, although this remains controversial.

Management of such patients should be done collaboratively with cardiologists well versed in the treatment of cardiorenal syndrome. It may be possible that the worsening renal function in these patients represents important changes in cardiac rhythm or function (eg, low cardiac output state, new or worsening valvular disease, ongoing myocardial ischemia, cardiac tamponade, uncontrolled bradycardia or tachyarrythmia). Interventions aimed at reversing such perturbations could be the most important steps in improving cardiorenal function and reversing AKI.

To the Editor: I read with interest the thoughtful review of cardiorenal syndrome by Drs. Thind, Loehrke, and Wilt¹ and the accompanying editorial by Dr. Grodin.² These articles certainly add to our growing knowledge of the syndrome and the importance of treating volume overload in these complex patients.

Indeed, we and others have stressed the primary importance of renal dysfunction in patients with volume overload and acute decompensated heart failure.^3,4 We have learned that even small rises in serum creatinine predict poor outcomes in these patients. And even if the serum creatinine level comes back down during hospitalization, acute kidney injury (AKI) is still associated with risk.⁵

Nevertheless, clinicians remain frustrated with the practical management of patients with volume overload and worsening AKI. When faced with a rising serum creatinine level in a patient being treated for decompensated heart failure with signs or symptoms of volume overload, I suggest the following:

Perform careful bedside and chart review searching for evidence of AKI related to causes other than cardiorenal syndrome. Ask whether the rise in serum creatinine could be caused by new obstruction (eg, urinary retention, upper urinary tract obstruction), a nephrotoxin (eg, nonsteroidal anti-inflammatory drugs), a primary tubulointerstitial or glomerular process (eg, drug-induced acute interstitial nephritis, acute glomerulonephritis), acute tubular necrosis, or a new hemodynamic event threatening renal perfusion (eg, hypotension, a new arrhythmia). It is often best to arrive at a diagnosis of AKI due to cardiorenal dysfunction by exclusion, much like the working definitions of hepatorenal syndrome.⁶ This requires review of the urine sediment (looking for evidence of granular casts of acute tubular necrosis, or evidence of glomerulonephritis or interstitial nephritis), electronic medical record, vital signs, telemetry, and perhaps renal ultrasonography.

In the absence of frank evidence of “overdiuresis” such as worsening hypernatremia, with dropping blood pressure, clinical hypoperfusion, and contraction alkalosis, avoid the temptation to suspend diuretics. Alternatively, an increase in diuretic dose, or addition of a distal diuretic (ie, metolazone) may be needed to address persistent renal venous congestion as the cause of the AKI.³ In this situation, be sure to monitor electrolytes, volume status, and renal function closely while diuretic treatment is augmented. In many such cases, the serum creatinine may actually start to decrease after a more robust diuresis is generated. In these patients, it may also be prudent to temporarily suspend antagonists of the renin-angiotensin-aldosterone system, although this remains controversial.

Management of such patients should be done collaboratively with cardiologists well versed in the treatment of cardiorenal syndrome. It may be possible that the worsening renal function in these patients represents important changes in cardiac rhythm or function (eg, low cardiac output state, new or worsening valvular disease, ongoing myocardial ischemia, cardiac tamponade, uncontrolled bradycardia or tachyarrythmia). Interventions aimed at reversing such perturbations could be the most important steps in improving cardiorenal function and reversing AKI.

In Reply: We thank Dr. Freda for his remarks and observations. Certainly, the clinical importance of this entity and the challenge it poses to clinicians cannot be overemphasized. We concur with the overall message and reply to his specific comments:

We completely agree that clinical data-gathering is of paramount importance. This includes careful history-taking, physical examination, electronic medical record review, laboratory data review, and imaging. As discussed in our article, renal electrolytes will reveal a prerenal state in acute cardiorenal syndrome, and other causes of prerenal acute kidney injury (AKI) should be ruled out. The role of point-of-care ultrasonography (eg, to measure the size and respirophasic variation of the inferior vena cava) as a vital diagnostic tool has been well described, and we endorse it.¹ Moreover, apart from snapshot values, trends are also very important. This is especially pertinent when the patient care is being transferred to a new service (eg, from hospitalist service to the critical care service). In this case, careful review of diuretic dosage, renal function trend, intake and output, and weight trend would help in the diagnosis.

Inadequate diuretic therapy is perhaps one of the most common errors made in the management of patients with acute cardiorenal syndrome. As mentioned in our article, diuretics should be correctly dosed based on the patient’s renal function. It is a common misconception that diuretics are nephrotoxic: in reality, there is no direct renal toxicity from the drug itself. Certainly, overdiuresis may lead to AKI, but this is not a valid concern in patients with acute cardiorenal syndrome, who are fluid-overloaded by definition.

Another challenging clinical scenario is when a patient is diagnosed with acute cardiorenal syndrome but renal function worsens with diuretic therapy. In our experience, this is a paradoxical situation and often stems from misinterpretation of clinical data. The most common example is diuretic underdosage leading to inadequate diuretic response. Renal function will continue to decline in these patients, as renal congestion has not yet been relieved. This reiterates the importance of paying close attention to urine output and intake-output data. When the diuretic regimen is strengthened and a robust diuretic response is achieved, renal function should improve as systemic congestion diminishes.

Acute cardiorenal syndrome stems from hemodynamic derangements, and a multidisciplinary approach may certainly lead to better outcomes. Although we described the general theme of hemodynamic disturbances, patients with acute cardiorenal syndrome may have certain unique and complex hemodynamic “phenotypes” that we did not discuss due to the limited scope of the paper. One such phenotype worth mentioning is decompensated right heart failure, as seen in patients with severe pulmonary hypertension. Acute cardiorenal syndrome due to renal congestion is often seen in these patients, but they also have certain other unique characteristics such as ventricular interdependence.² Giving intravenous fluids to these patients not only will worsen renal function but can also cause catastrophic reduction in cardiac output and blood pressure due to worsening interventricular septal bowing. Certain treatments (eg, pulmonary vasodilators) are unique to this patient population, and these patients should hence be managed by experienced clinicians.

In Reply: We thank Dr. Freda for his remarks and observations. Certainly, the clinical importance of this entity and the challenge it poses to clinicians cannot be overemphasized. We concur with the overall message and reply to his specific comments:

We completely agree that clinical data-gathering is of paramount importance. This includes careful history-taking, physical examination, electronic medical record review, laboratory data review, and imaging. As discussed in our article, renal electrolytes will reveal a prerenal state in acute cardiorenal syndrome, and other causes of prerenal acute kidney injury (AKI) should be ruled out. The role of point-of-care ultrasonography (eg, to measure the size and respirophasic variation of the inferior vena cava) as a vital diagnostic tool has been well described, and we endorse it.¹ Moreover, apart from snapshot values, trends are also very important. This is especially pertinent when the patient care is being transferred to a new service (eg, from hospitalist service to the critical care service). In this case, careful review of diuretic dosage, renal function trend, intake and output, and weight trend would help in the diagnosis.

Inadequate diuretic therapy is perhaps one of the most common errors made in the management of patients with acute cardiorenal syndrome. As mentioned in our article, diuretics should be correctly dosed based on the patient’s renal function. It is a common misconception that diuretics are nephrotoxic: in reality, there is no direct renal toxicity from the drug itself. Certainly, overdiuresis may lead to AKI, but this is not a valid concern in patients with acute cardiorenal syndrome, who are fluid-overloaded by definition.

Another challenging clinical scenario is when a patient is diagnosed with acute cardiorenal syndrome but renal function worsens with diuretic therapy. In our experience, this is a paradoxical situation and often stems from misinterpretation of clinical data. The most common example is diuretic underdosage leading to inadequate diuretic response. Renal function will continue to decline in these patients, as renal congestion has not yet been relieved. This reiterates the importance of paying close attention to urine output and intake-output data. When the diuretic regimen is strengthened and a robust diuretic response is achieved, renal function should improve as systemic congestion diminishes.

Acute cardiorenal syndrome stems from hemodynamic derangements, and a multidisciplinary approach may certainly lead to better outcomes. Although we described the general theme of hemodynamic disturbances, patients with acute cardiorenal syndrome may have certain unique and complex hemodynamic “phenotypes” that we did not discuss due to the limited scope of the paper. One such phenotype worth mentioning is decompensated right heart failure, as seen in patients with severe pulmonary hypertension. Acute cardiorenal syndrome due to renal congestion is often seen in these patients, but they also have certain other unique characteristics such as ventricular interdependence.² Giving intravenous fluids to these patients not only will worsen renal function but can also cause catastrophic reduction in cardiac output and blood pressure due to worsening interventricular septal bowing. Certain treatments (eg, pulmonary vasodilators) are unique to this patient population, and these patients should hence be managed by experienced clinicians.

In Reply: We thank Dr. Freda for his remarks and observations. Certainly, the clinical importance of this entity and the challenge it poses to clinicians cannot be overemphasized. We concur with the overall message and reply to his specific comments:

We completely agree that clinical data-gathering is of paramount importance. This includes careful history-taking, physical examination, electronic medical record review, laboratory data review, and imaging. As discussed in our article, renal electrolytes will reveal a prerenal state in acute cardiorenal syndrome, and other causes of prerenal acute kidney injury (AKI) should be ruled out. The role of point-of-care ultrasonography (eg, to measure the size and respirophasic variation of the inferior vena cava) as a vital diagnostic tool has been well described, and we endorse it.¹ Moreover, apart from snapshot values, trends are also very important. This is especially pertinent when the patient care is being transferred to a new service (eg, from hospitalist service to the critical care service). In this case, careful review of diuretic dosage, renal function trend, intake and output, and weight trend would help in the diagnosis.

Inadequate diuretic therapy is perhaps one of the most common errors made in the management of patients with acute cardiorenal syndrome. As mentioned in our article, diuretics should be correctly dosed based on the patient’s renal function. It is a common misconception that diuretics are nephrotoxic: in reality, there is no direct renal toxicity from the drug itself. Certainly, overdiuresis may lead to AKI, but this is not a valid concern in patients with acute cardiorenal syndrome, who are fluid-overloaded by definition.

Another challenging clinical scenario is when a patient is diagnosed with acute cardiorenal syndrome but renal function worsens with diuretic therapy. In our experience, this is a paradoxical situation and often stems from misinterpretation of clinical data. The most common example is diuretic underdosage leading to inadequate diuretic response. Renal function will continue to decline in these patients, as renal congestion has not yet been relieved. This reiterates the importance of paying close attention to urine output and intake-output data. When the diuretic regimen is strengthened and a robust diuretic response is achieved, renal function should improve as systemic congestion diminishes.

Acute cardiorenal syndrome stems from hemodynamic derangements, and a multidisciplinary approach may certainly lead to better outcomes. Although we described the general theme of hemodynamic disturbances, patients with acute cardiorenal syndrome may have certain unique and complex hemodynamic “phenotypes” that we did not discuss due to the limited scope of the paper. One such phenotype worth mentioning is decompensated right heart failure, as seen in patients with severe pulmonary hypertension. Acute cardiorenal syndrome due to renal congestion is often seen in these patients, but they also have certain other unique characteristics such as ventricular interdependence.² Giving intravenous fluids to these patients not only will worsen renal function but can also cause catastrophic reduction in cardiac output and blood pressure due to worsening interventricular septal bowing. Certain treatments (eg, pulmonary vasodilators) are unique to this patient population, and these patients should hence be managed by experienced clinicians.

To the Editor: We read with great interest the article by Munyon et al¹ addressing recent developments in perioperative medicine. We would like to comment on the perioperative interruption of dual antiplatelet therapy, a common clinical problem.

Several registry analyses have shown that, with second-generation drug-eluting stents, interruption of 1 antiplatelet agent after the first month is safe.^2,3 These registries included a substantial proportion of patients whose index stenting procedure was performed for acute coronary syndrome (up to 60%).² On average, antiplatelet therapy interruption was brief (about 6 to 7 days).

Additional registry analyses have shown that surgery may be safely performed beyond the first month after drug-eluting stent placement.^4,5 Specifically, a large Danish analysis of patients with a drug-eluting stent who underwent noncardiac surgery, matched to control patients without ischemic heart disease, showed that the risk of perioperative myocardial infarction and death was not increased beyond the first month after drug-eluting stent implantation. Specifically, the risk was not increased at the 1- to 2-month and 2- to 12-month postimplantation intervals. Acute coronary syndrome was the indication for stenting in 56% of the patients.

Therefore, while surgery is preferably delayed 6 months after drug-eluting stent implantation (class I recommendation in the European Society of Cardiology guidelines), surgery may be selectively performed 1 to 6 months after drug-eluting stent implantation with an acceptable risk. This is particularly so if the index stenting was performed in the setting of stable coronary arterial disease (class IIa recommendation if stenting was performed in the setting of stable coronary arterial disease without complex procedural features; class IIb recommendation if stenting was performed in the setting of acute coronary syndrome or complex procedural features).⁶ After drug-eluting stent implantation, the earliest cutpoint for considering surgery is 1 month rather than 3 months.

When surgery is performed within this 1- to 6-month interval, thienopyridine interruption should be kept brief and dual antiplatelet therapy reinitiated as soon as possible postoperatively. In fact, when thienopyridine therapy is interrupted 1 to 6 months after drug-eluting stent implantation, stent thrombosis typically occurs more than 6 or 7 days after interruption.⁷

To the Editor: We read with great interest the article by Munyon et al¹ addressing recent developments in perioperative medicine. We would like to comment on the perioperative interruption of dual antiplatelet therapy, a common clinical problem.

Several registry analyses have shown that, with second-generation drug-eluting stents, interruption of 1 antiplatelet agent after the first month is safe.^2,3 These registries included a substantial proportion of patients whose index stenting procedure was performed for acute coronary syndrome (up to 60%).² On average, antiplatelet therapy interruption was brief (about 6 to 7 days).

Additional registry analyses have shown that surgery may be safely performed beyond the first month after drug-eluting stent placement.^4,5 Specifically, a large Danish analysis of patients with a drug-eluting stent who underwent noncardiac surgery, matched to control patients without ischemic heart disease, showed that the risk of perioperative myocardial infarction and death was not increased beyond the first month after drug-eluting stent implantation. Specifically, the risk was not increased at the 1- to 2-month and 2- to 12-month postimplantation intervals. Acute coronary syndrome was the indication for stenting in 56% of the patients.

Therefore, while surgery is preferably delayed 6 months after drug-eluting stent implantation (class I recommendation in the European Society of Cardiology guidelines), surgery may be selectively performed 1 to 6 months after drug-eluting stent implantation with an acceptable risk. This is particularly so if the index stenting was performed in the setting of stable coronary arterial disease (class IIa recommendation if stenting was performed in the setting of stable coronary arterial disease without complex procedural features; class IIb recommendation if stenting was performed in the setting of acute coronary syndrome or complex procedural features).⁶ After drug-eluting stent implantation, the earliest cutpoint for considering surgery is 1 month rather than 3 months.

When surgery is performed within this 1- to 6-month interval, thienopyridine interruption should be kept brief and dual antiplatelet therapy reinitiated as soon as possible postoperatively. In fact, when thienopyridine therapy is interrupted 1 to 6 months after drug-eluting stent implantation, stent thrombosis typically occurs more than 6 or 7 days after interruption.⁷

To the Editor: We read with great interest the article by Munyon et al¹ addressing recent developments in perioperative medicine. We would like to comment on the perioperative interruption of dual antiplatelet therapy, a common clinical problem.

Several registry analyses have shown that, with second-generation drug-eluting stents, interruption of 1 antiplatelet agent after the first month is safe.^2,3 These registries included a substantial proportion of patients whose index stenting procedure was performed for acute coronary syndrome (up to 60%).² On average, antiplatelet therapy interruption was brief (about 6 to 7 days).

Additional registry analyses have shown that surgery may be safely performed beyond the first month after drug-eluting stent placement.^4,5 Specifically, a large Danish analysis of patients with a drug-eluting stent who underwent noncardiac surgery, matched to control patients without ischemic heart disease, showed that the risk of perioperative myocardial infarction and death was not increased beyond the first month after drug-eluting stent implantation. Specifically, the risk was not increased at the 1- to 2-month and 2- to 12-month postimplantation intervals. Acute coronary syndrome was the indication for stenting in 56% of the patients.

Therefore, while surgery is preferably delayed 6 months after drug-eluting stent implantation (class I recommendation in the European Society of Cardiology guidelines), surgery may be selectively performed 1 to 6 months after drug-eluting stent implantation with an acceptable risk. This is particularly so if the index stenting was performed in the setting of stable coronary arterial disease (class IIa recommendation if stenting was performed in the setting of stable coronary arterial disease without complex procedural features; class IIb recommendation if stenting was performed in the setting of acute coronary syndrome or complex procedural features).⁶ After drug-eluting stent implantation, the earliest cutpoint for considering surgery is 1 month rather than 3 months.

When surgery is performed within this 1- to 6-month interval, thienopyridine interruption should be kept brief and dual antiplatelet therapy reinitiated as soon as possible postoperatively. In fact, when thienopyridine therapy is interrupted 1 to 6 months after drug-eluting stent implantation, stent thrombosis typically occurs more than 6 or 7 days after interruption.⁷

In Reply: We reported on publications from 2016–2017 and, unfortunately, at the time we were writing our paper, the European Society of Cardiology (ESC) update on dual antiplatelet therapy¹ had not yet been published. We presented the recommendations from the American College of Cardiology (ACC) and American Heart Association (AHA),² which differ from the recently published ESC guidelines. The ESC suggests that the minimum waiting period after drug-eluting stent placement before noncardiac surgery should be 1 month rather than 3 months but acknowledges that in the setting of complex stenting or recent acute coronary syndrome, 6 months is preferred. The recommendation in this latter scenario is a class IIb C recommendation—essentially expert consensus opinion.

Further, in the study by Egholm et al,³ the event rates in patients undergoing noncardiac surgery in the 1- to 2-month period were numerically higher than in the control group, and no adjusted odds ratios were given. The numbers of events were very low, and a change of only 1 or 2 events in the other direction in the groups would likely make it statistically significant.

All of these recommendations are based on observational studies and registry data, as there are no randomized controlled trials to address this issue. There are many complexities to be accounted for including the type of stent, timing, circumstances surrounding stenting, anatomy, number of stents, patient comorbidities (particularly age, diabetes mellitus, cardiac disease), type of surgery and anesthesia, and perioperative management of antiplatelet therapy. While we acknowledge the ESC recommendation, we would urge caution in the recommendation to wait only 1 month, and in the United States most would prefer to wait 3 months if possible.

In Reply: We reported on publications from 2016–2017 and, unfortunately, at the time we were writing our paper, the European Society of Cardiology (ESC) update on dual antiplatelet therapy¹ had not yet been published. We presented the recommendations from the American College of Cardiology (ACC) and American Heart Association (AHA),² which differ from the recently published ESC guidelines. The ESC suggests that the minimum waiting period after drug-eluting stent placement before noncardiac surgery should be 1 month rather than 3 months but acknowledges that in the setting of complex stenting or recent acute coronary syndrome, 6 months is preferred. The recommendation in this latter scenario is a class IIb C recommendation—essentially expert consensus opinion.

Further, in the study by Egholm et al,³ the event rates in patients undergoing noncardiac surgery in the 1- to 2-month period were numerically higher than in the control group, and no adjusted odds ratios were given. The numbers of events were very low, and a change of only 1 or 2 events in the other direction in the groups would likely make it statistically significant.

All of these recommendations are based on observational studies and registry data, as there are no randomized controlled trials to address this issue. There are many complexities to be accounted for including the type of stent, timing, circumstances surrounding stenting, anatomy, number of stents, patient comorbidities (particularly age, diabetes mellitus, cardiac disease), type of surgery and anesthesia, and perioperative management of antiplatelet therapy. While we acknowledge the ESC recommendation, we would urge caution in the recommendation to wait only 1 month, and in the United States most would prefer to wait 3 months if possible.

In Reply: We reported on publications from 2016–2017 and, unfortunately, at the time we were writing our paper, the European Society of Cardiology (ESC) update on dual antiplatelet therapy¹ had not yet been published. We presented the recommendations from the American College of Cardiology (ACC) and American Heart Association (AHA),² which differ from the recently published ESC guidelines. The ESC suggests that the minimum waiting period after drug-eluting stent placement before noncardiac surgery should be 1 month rather than 3 months but acknowledges that in the setting of complex stenting or recent acute coronary syndrome, 6 months is preferred. The recommendation in this latter scenario is a class IIb C recommendation—essentially expert consensus opinion.

Further, in the study by Egholm et al,³ the event rates in patients undergoing noncardiac surgery in the 1- to 2-month period were numerically higher than in the control group, and no adjusted odds ratios were given. The numbers of events were very low, and a change of only 1 or 2 events in the other direction in the groups would likely make it statistically significant.

All of these recommendations are based on observational studies and registry data, as there are no randomized controlled trials to address this issue. There are many complexities to be accounted for including the type of stent, timing, circumstances surrounding stenting, anatomy, number of stents, patient comorbidities (particularly age, diabetes mellitus, cardiac disease), type of surgery and anesthesia, and perioperative management of antiplatelet therapy. While we acknowledge the ESC recommendation, we would urge caution in the recommendation to wait only 1 month, and in the United States most would prefer to wait 3 months if possible.