Missed Diagnoses of Acute Cardiac Ischemia in the Emergency Department

Background: Discharging patients with acute myocardial infarction or unstable angina from the emergency department because of missed diagnoses can have dire consequences. We studied the incidence of, factors related to, and clinical outcomes of failure to hospitalize patients with acute cardiac ischemia.

Methods: We analyzed clinical data from a multicenter, prospective clinical trial of all patients with chest pain or other symptoms suggesting acute cardiac ischemia who presented to the emergency departments of 10 U.S. hospitals.

Results: Of 10,689 patients, 17 percent ultimately met the criteria for acute cardiac ischemia (8 percent had acute myocardial infarction and 9 percent had unstable angina), 6 percent had stable angina, 21 percent had other cardiac problems, and 55 percent had noncardiac problems. Among the 889 patients with acute myocardial infarction, 19 (2.1 percent) were mistakenly discharged from the emergency department (95 percent confidence interval, 1.1 to 3.1 percent); among the 966 patients with unstable angina, 22 (2.3 percent) were mistakenly discharged (95 percent confidence interval, 1.3 to 3.2 percent). Multivariable analysis showed that patients who presented to the emergency department with acute cardiac ischemia were more likely not to be hospitalized if they were women less than 55 years old (odds ratio for discharge, 6.7; 95 percent confidence interval, 1.4 to 32.5), were nonwhite (odds ratio, 2.2; 1.1 to 4.3), reported shortness of breath as their chief symptom (odds ratio, 2.7; 1.1 to 6.5), or had a normal or nondiagnostic electrocardiogram (odds ratio, 3.3; 1.7 to 6.3). Patients with acute infarction were more likely not to be hospitalized if they were nonwhite (odds ratio for discharge, 4.5; 95 percent confidence interval, 1.8 to 11.8) or had a normal or nondiagnostic electrocardiogram (odds ratio, 7.7; 95 percent confidence interval, 2.9 to 20.2). For the patients with acute infarction, the risk-adjusted mortality ratio for those who were not hospitalized, as compared with those who were, was 1.9 (95 percent confidence interval, 0.7 to 5.2), and for the patients with unstable angina, it was 1.7 (95 percent confidence interval, 0.2 to 17.0).

Conclusions: The percentage of patients who present to the emergency department with acute myocardial infarction or unstable angina who are not hospitalized is low, but the discharge of such patients is associated with increased mortality. Failure to hospitalize is related to race, sex, and the absence of typical features of cardiac ischemia. Continued efforts to reduce the number of missed diagnoses are warranted.