Defining the outcomes of risk stratification studies of ED patients with chest pain: the marginal value of adding revascularization to the composite end point.

OBJECTIVES: Cardiovascular risk stratification studies use various end points, sometimes including revascularization. We assessed whether adding revascularization to a strictly defined composite end point of death, acute myocardial infarction (AMI), and unstable angina (UA) impacts the likelihood of patients attaining the composite end point.
METHODS: We conducted a secondary analysis of a prospectively collected data set of emergency department patients who received an electrocardiogram for chest pain. Patients were followed daily; discharged patients had 30-day telephone follow-up. The main outcome was a 30-day composite end point of death, AMI, and UA compared with death, AMI, UA, and revascularization.
RESULTS: There were 4492 patients enrolled (mean age, 52 +/- 16 years; men, 41%; African American, 68%). One hundred seventy patients were revascularized (158 had AMI or UA). Overall, the incidence of death/AMI/UA was 20.1% (95% confidence interval, 18.9%-21.2%). With revascularization included, the incidence of the composite end point was 20.3% (95% confidence interval, 19.1%-21.5%).
CONCLUSION: When both AMI and UA are strictly defined, there appears to be a limited role for adding revascularization to a composite end point of death, AMI, and UA because most revascularized patients have a diagnosis of AMI or UA.