Rules Identify Which Chest Pain Patients Can Be Sent Home

BOSTON – Two newly derived and validated clinical prediction rules have the potential for identifying a low-risk cohort of chest pain patients who could safely be discharged from the emergency department without extensive diagnostic evaluation.

The two different rules were both derived from prospective cohort studies of emergency department populations. One, presented at the annual meeting of the Society for Academic Emergency Medicine by Dr. Erik P. Hess of the Mayo Clinic, Rochester, Minn., enrolled 2,718 patients. The other, presented by Dr. Frank Scheuermeyer of the University of British Columbia, Vancouver, included 1,669 patients.

Dr. Hess’ study enrolled patients from two academic emergency departments in Canada and one in the United States. To be eligible, patients had to be aged 25 years or older with chest pain syndrome and cardiac troponin ordered to evaluate for acute coronary syndrome (ACS). Exclusion criteria included ST-segment elevation myocardial infarction (STEMI), hemodynamic instability, cocaine use, and unreliable clinical history. Investigators were blinded to predictor variables and patient outcomes.

The 2,718 patients had a mean age of 60 years, and 53% were men. Of this cohort, 23% had a history of MI and 33% had known coronary artery disease (CAD). A third (33%) had cardiac stress testing, 32% were admitted to the hospital, and 19% went on to have coronary angiography. At the Mayo Clinic, which has an observation unit in the ED, 48% of 1,205 patients were admitted through that unit.

The proportion with the primary adjudicated outcome – acute MI, revascularization, or death within 30 days – was 12%; 6% had acute MI, 10% underwent revascularization, and 0.2% (6 patients) died (some patients had more than one primary outcome).

On univariate analysis, factors significantly associated with 30-day cardiac events included mean age (66 years in those with events vs. 59 years for those without events), male gender (69% vs. 44%), acute MI (37% vs. 21%), known CAD (57% vs. 29%), and stroke or transient ischemic attack (8% vs. 4%). Significant univariate predictors pertaining to chest pain history included pleuritic pain (7% vs. 19%), pain similar to prior ischemia (47% vs. 21%), and pain "atypical for ACS" based on physician opinion (24% vs. 64%).

Of a total of 38 variables associated with the primary outcome and another 15 from the clinical history, a rule was derived on the basis of 5 predictive variables: age 50 years or less, known CAD, pain typical of ACS, absence of acute ischemic changes on ECG, and any cardiac troponin value greater than the 99th percentile. This rule was 100% sensitive (none of the 336 patients who went on to have events were missed; 95% confidence interval, 97.2-100) and 20.9% specific (the test was positive in 79% of the 2,382 patients who did not have an event; 95% CI, 16.9-24.9).

On the basis of these findings, the "North American Chest Pain Rule" states that patients who meet the four cardiac criteria and who are less than 40 years old can be safely discharged from the ED without urgent cardiac stress testing. Those aged 41-50 years can be dismissed if a repeat troponin test performed 6 hours from symptom onset is negative, Dr. Hess said.

In all, the prediction rule found that 18% of patients could be safely discharged: those younger than 41 years with no acute ischemia on ECG and a single negative troponin test (7%) and those aged 41-50 years with no acute ischemia and two negative troponin tests (11%). Further prospective validation is required, he said.

The other prediction rule was based on data from a single Canadian center. In a derivation cohort of 763 patients, the 30-day ACS rate (MI and unstoppable angina) was 22%, and in the validation cohort of 906 patients, 13% had ACS. The derived "Vancouver Chest Pain Rule" states that patients have a very low risk of ACS if initial ECG is nonischemic, both arrival and 2-hour troponin levels are normal, the patient has no prior ACS or nitrate use, the patient is younger than 50 years, and the patient experiences the same pain with palpation. This rule was 100% sensitive and 18% specific, Dr. Scheuermeyer reported. The validation cohort identified 118 of 119 patients with ACS, for a sensitivity of 99.2% (95% CI, 95.4-100), and 184 out of 787 patients who could be discharged, for a specificity of 23.4% (95% CI, 20.6-26.5).

Prior studies that have tried to develop ACS prediction rules have been hampered by selection bias, suboptimal methodology, and low sensitivity, he said. The Vancouver rule uses reliable clinical criteria and widely available minimally invasive tests, he added. "It preserves ED and hospital resources by rapidly discharging one-fifth of patients and does not jeopardize patient outcomes."

During the discussion period, an audience member mentioned another chest pain decision rule that was published earlier this year, based on observational data from 3,582 consecutive patients in 14 EDs in nine countries in the Asia-Pacific region. This rule uses a structured pretest probability scoring method involving the Thrombolysis in Myocardial Infarction score, electrocardiography, and a point-of-care biomarker panel of troponin, creatine kinase MB, and myoglobin (Lancet 2011;377:1077-84).

"It will be interesting to compare all these rules at some point," Dr. Scheuermeyer said.

The two SAEM conference papers were presented at a session titled "Defining the Low-Risk Cardiac Patients." In an interview, session moderator Dr. Alexander T. Limkakeng Jr. said that finding a reliable decision rule on low-risk chest pain has been called the Holy Grail of acute coronary research.

"It was exciting to see two high-quality studies done at different centers at the same session. It was especially so because both studies not merely derived but also validated rules," said Dr. Limkakeng, director of acute care research in the emergency medicine division at Duke University, Durham, N.C.

"It felt like the beginning of a paradigm shift. I sensed that for the first time, many researchers who were present now feel it really is possible to identify some chest pain patients in the ED who could be safely discharged using only history, ECG, and troponin data. Of course, further external validation is necessary, but it is exciting to see."

Dr. Hess’ study was jointly funded by an Emergency Medicine Fellow award from the American Heart Association and the Society for Academic and Emergency Medicine, the Ontario Innovation Fund, and the University of Ottawa. He had no other disclosures. Dr. Scheuermeyer had no disclosures. Dr. Limkakeng disclosed receiving financial support from Roche for a cardiac biomarker study and from the National Institutes of Health for the ProCESS trial.

BOSTON – Two newly derived and validated clinical prediction rules have the potential for identifying a low-risk cohort of chest pain patients who could safely be discharged from the emergency department without extensive diagnostic evaluation.

The two different rules were both derived from prospective cohort studies of emergency department populations. One, presented at the annual meeting of the Society for Academic Emergency Medicine by Dr. Erik P. Hess of the Mayo Clinic, Rochester, Minn., enrolled 2,718 patients. The other, presented by Dr. Frank Scheuermeyer of the University of British Columbia, Vancouver, included 1,669 patients.

Dr. Hess’ study enrolled patients from two academic emergency departments in Canada and one in the United States. To be eligible, patients had to be aged 25 years or older with chest pain syndrome and cardiac troponin ordered to evaluate for acute coronary syndrome (ACS). Exclusion criteria included ST-segment elevation myocardial infarction (STEMI), hemodynamic instability, cocaine use, and unreliable clinical history. Investigators were blinded to predictor variables and patient outcomes.

The 2,718 patients had a mean age of 60 years, and 53% were men. Of this cohort, 23% had a history of MI and 33% had known coronary artery disease (CAD). A third (33%) had cardiac stress testing, 32% were admitted to the hospital, and 19% went on to have coronary angiography. At the Mayo Clinic, which has an observation unit in the ED, 48% of 1,205 patients were admitted through that unit.

The proportion with the primary adjudicated outcome – acute MI, revascularization, or death within 30 days – was 12%; 6% had acute MI, 10% underwent revascularization, and 0.2% (6 patients) died (some patients had more than one primary outcome).

On univariate analysis, factors significantly associated with 30-day cardiac events included mean age (66 years in those with events vs. 59 years for those without events), male gender (69% vs. 44%), acute MI (37% vs. 21%), known CAD (57% vs. 29%), and stroke or transient ischemic attack (8% vs. 4%). Significant univariate predictors pertaining to chest pain history included pleuritic pain (7% vs. 19%), pain similar to prior ischemia (47% vs. 21%), and pain "atypical for ACS" based on physician opinion (24% vs. 64%).

Of a total of 38 variables associated with the primary outcome and another 15 from the clinical history, a rule was derived on the basis of 5 predictive variables: age 50 years or less, known CAD, pain typical of ACS, absence of acute ischemic changes on ECG, and any cardiac troponin value greater than the 99th percentile. This rule was 100% sensitive (none of the 336 patients who went on to have events were missed; 95% confidence interval, 97.2-100) and 20.9% specific (the test was positive in 79% of the 2,382 patients who did not have an event; 95% CI, 16.9-24.9).

On the basis of these findings, the "North American Chest Pain Rule" states that patients who meet the four cardiac criteria and who are less than 40 years old can be safely discharged from the ED without urgent cardiac stress testing. Those aged 41-50 years can be dismissed if a repeat troponin test performed 6 hours from symptom onset is negative, Dr. Hess said.

In all, the prediction rule found that 18% of patients could be safely discharged: those younger than 41 years with no acute ischemia on ECG and a single negative troponin test (7%) and those aged 41-50 years with no acute ischemia and two negative troponin tests (11%). Further prospective validation is required, he said.

The other prediction rule was based on data from a single Canadian center. In a derivation cohort of 763 patients, the 30-day ACS rate (MI and unstoppable angina) was 22%, and in the validation cohort of 906 patients, 13% had ACS. The derived "Vancouver Chest Pain Rule" states that patients have a very low risk of ACS if initial ECG is nonischemic, both arrival and 2-hour troponin levels are normal, the patient has no prior ACS or nitrate use, the patient is younger than 50 years, and the patient experiences the same pain with palpation. This rule was 100% sensitive and 18% specific, Dr. Scheuermeyer reported. The validation cohort identified 118 of 119 patients with ACS, for a sensitivity of 99.2% (95% CI, 95.4-100), and 184 out of 787 patients who could be discharged, for a specificity of 23.4% (95% CI, 20.6-26.5).

Prior studies that have tried to develop ACS prediction rules have been hampered by selection bias, suboptimal methodology, and low sensitivity, he said. The Vancouver rule uses reliable clinical criteria and widely available minimally invasive tests, he added. "It preserves ED and hospital resources by rapidly discharging one-fifth of patients and does not jeopardize patient outcomes."

During the discussion period, an audience member mentioned another chest pain decision rule that was published earlier this year, based on observational data from 3,582 consecutive patients in 14 EDs in nine countries in the Asia-Pacific region. This rule uses a structured pretest probability scoring method involving the Thrombolysis in Myocardial Infarction score, electrocardiography, and a point-of-care biomarker panel of troponin, creatine kinase MB, and myoglobin (Lancet 2011;377:1077-84).

"It will be interesting to compare all these rules at some point," Dr. Scheuermeyer said.

The two SAEM conference papers were presented at a session titled "Defining the Low-Risk Cardiac Patients." In an interview, session moderator Dr. Alexander T. Limkakeng Jr. said that finding a reliable decision rule on low-risk chest pain has been called the Holy Grail of acute coronary research.

"It was exciting to see two high-quality studies done at different centers at the same session. It was especially so because both studies not merely derived but also validated rules," said Dr. Limkakeng, director of acute care research in the emergency medicine division at Duke University, Durham, N.C.

"It felt like the beginning of a paradigm shift. I sensed that for the first time, many researchers who were present now feel it really is possible to identify some chest pain patients in the ED who could be safely discharged using only history, ECG, and troponin data. Of course, further external validation is necessary, but it is exciting to see."

Dr. Hess’ study was jointly funded by an Emergency Medicine Fellow award from the American Heart Association and the Society for Academic and Emergency Medicine, the Ontario Innovation Fund, and the University of Ottawa. He had no other disclosures. Dr. Scheuermeyer had no disclosures. Dr. Limkakeng disclosed receiving financial support from Roche for a cardiac biomarker study and from the National Institutes of Health for the ProCESS trial.

BOSTON – Two newly derived and validated clinical prediction rules have the potential for identifying a low-risk cohort of chest pain patients who could safely be discharged from the emergency department without extensive diagnostic evaluation.

The two different rules were both derived from prospective cohort studies of emergency department populations. One, presented at the annual meeting of the Society for Academic Emergency Medicine by Dr. Erik P. Hess of the Mayo Clinic, Rochester, Minn., enrolled 2,718 patients. The other, presented by Dr. Frank Scheuermeyer of the University of British Columbia, Vancouver, included 1,669 patients.

Dr. Hess’ study enrolled patients from two academic emergency departments in Canada and one in the United States. To be eligible, patients had to be aged 25 years or older with chest pain syndrome and cardiac troponin ordered to evaluate for acute coronary syndrome (ACS). Exclusion criteria included ST-segment elevation myocardial infarction (STEMI), hemodynamic instability, cocaine use, and unreliable clinical history. Investigators were blinded to predictor variables and patient outcomes.

The 2,718 patients had a mean age of 60 years, and 53% were men. Of this cohort, 23% had a history of MI and 33% had known coronary artery disease (CAD). A third (33%) had cardiac stress testing, 32% were admitted to the hospital, and 19% went on to have coronary angiography. At the Mayo Clinic, which has an observation unit in the ED, 48% of 1,205 patients were admitted through that unit.

The proportion with the primary adjudicated outcome – acute MI, revascularization, or death within 30 days – was 12%; 6% had acute MI, 10% underwent revascularization, and 0.2% (6 patients) died (some patients had more than one primary outcome).

On univariate analysis, factors significantly associated with 30-day cardiac events included mean age (66 years in those with events vs. 59 years for those without events), male gender (69% vs. 44%), acute MI (37% vs. 21%), known CAD (57% vs. 29%), and stroke or transient ischemic attack (8% vs. 4%). Significant univariate predictors pertaining to chest pain history included pleuritic pain (7% vs. 19%), pain similar to prior ischemia (47% vs. 21%), and pain "atypical for ACS" based on physician opinion (24% vs. 64%).

Of a total of 38 variables associated with the primary outcome and another 15 from the clinical history, a rule was derived on the basis of 5 predictive variables: age 50 years or less, known CAD, pain typical of ACS, absence of acute ischemic changes on ECG, and any cardiac troponin value greater than the 99th percentile. This rule was 100% sensitive (none of the 336 patients who went on to have events were missed; 95% confidence interval, 97.2-100) and 20.9% specific (the test was positive in 79% of the 2,382 patients who did not have an event; 95% CI, 16.9-24.9).

On the basis of these findings, the "North American Chest Pain Rule" states that patients who meet the four cardiac criteria and who are less than 40 years old can be safely discharged from the ED without urgent cardiac stress testing. Those aged 41-50 years can be dismissed if a repeat troponin test performed 6 hours from symptom onset is negative, Dr. Hess said.

In all, the prediction rule found that 18% of patients could be safely discharged: those younger than 41 years with no acute ischemia on ECG and a single negative troponin test (7%) and those aged 41-50 years with no acute ischemia and two negative troponin tests (11%). Further prospective validation is required, he said.

The other prediction rule was based on data from a single Canadian center. In a derivation cohort of 763 patients, the 30-day ACS rate (MI and unstoppable angina) was 22%, and in the validation cohort of 906 patients, 13% had ACS. The derived "Vancouver Chest Pain Rule" states that patients have a very low risk of ACS if initial ECG is nonischemic, both arrival and 2-hour troponin levels are normal, the patient has no prior ACS or nitrate use, the patient is younger than 50 years, and the patient experiences the same pain with palpation. This rule was 100% sensitive and 18% specific, Dr. Scheuermeyer reported. The validation cohort identified 118 of 119 patients with ACS, for a sensitivity of 99.2% (95% CI, 95.4-100), and 184 out of 787 patients who could be discharged, for a specificity of 23.4% (95% CI, 20.6-26.5).

Prior studies that have tried to develop ACS prediction rules have been hampered by selection bias, suboptimal methodology, and low sensitivity, he said. The Vancouver rule uses reliable clinical criteria and widely available minimally invasive tests, he added. "It preserves ED and hospital resources by rapidly discharging one-fifth of patients and does not jeopardize patient outcomes."

During the discussion period, an audience member mentioned another chest pain decision rule that was published earlier this year, based on observational data from 3,582 consecutive patients in 14 EDs in nine countries in the Asia-Pacific region. This rule uses a structured pretest probability scoring method involving the Thrombolysis in Myocardial Infarction score, electrocardiography, and a point-of-care biomarker panel of troponin, creatine kinase MB, and myoglobin (Lancet 2011;377:1077-84).

"It will be interesting to compare all these rules at some point," Dr. Scheuermeyer said.

The two SAEM conference papers were presented at a session titled "Defining the Low-Risk Cardiac Patients." In an interview, session moderator Dr. Alexander T. Limkakeng Jr. said that finding a reliable decision rule on low-risk chest pain has been called the Holy Grail of acute coronary research.

"It was exciting to see two high-quality studies done at different centers at the same session. It was especially so because both studies not merely derived but also validated rules," said Dr. Limkakeng, director of acute care research in the emergency medicine division at Duke University, Durham, N.C.

"It felt like the beginning of a paradigm shift. I sensed that for the first time, many researchers who were present now feel it really is possible to identify some chest pain patients in the ED who could be safely discharged using only history, ECG, and troponin data. Of course, further external validation is necessary, but it is exciting to see."

Dr. Hess’ study was jointly funded by an Emergency Medicine Fellow award from the American Heart Association and the Society for Academic and Emergency Medicine, the Ontario Innovation Fund, and the University of Ottawa. He had no other disclosures. Dr. Scheuermeyer had no disclosures. Dr. Limkakeng disclosed receiving financial support from Roche for a cardiac biomarker study and from the National Institutes of Health for the ProCESS trial.