Unstable angina: Relationship of clinical presentation,coronary artery pathology,and clinical outcome

Patients with unstable angina are heterogeneous with respect to presentation, coronary artery morphology, and clinical outcome. Subclassification of these patients based on clinical history has been proposed as a means of identifying individuals at increased cardiac risk. We applied such a classification system to 129 patients discharged from a coronary care unit with a diagnosis of acute myocardial ischemia. Patients were then assessed for cardiac events (recurrent angina requiring revascularization, myocardial infarction, death) 12 months following hospital discharge. Patients were classified as recent onset unstable angina preinfarction (n = 42), crescendo unstable angina preinfarction (n = 48), and unstable angina postinfarction (n = 39). Within each of these groups, the patients were further subclassified based on the occurrence of angina on effort, at rest, or both. No attempt was made to subset patients taking antiischemic drugs at the time of clinical presentation to the physician. Coronary angiographic pathology (morphology and number of vessels involved) was similar in the subgroups, but coronary artery thrombus was statistically more likely to be found in patients with crescendo rest angina preinfarction or with frequent anginal episodes at rest postinfarction. Mortality was significantly higher for patients with unstable angina postinfarction (7.7%) than preinfarction (1.1%). No statistical differences were noted between the subgroups with respect to the occurrence of myocardial infarction or recurrent unstable angina requiring revascularization. These data suggest that subclassification of unstable angina patients based on clinical characteristics at presentation is not useful to predict subsequent myocardial infarction or recurrent angina requiring revascularization. However, as one might expect, patients with recurrent angina postinfarction have a higher mortality rate than patients with unstable angina preinfarction, and patients with recurrent rest angina, either pre- or postinfarction, are more likely to have intracoronary thrombus than patients with new onset angina or crescendo effort angina; however, the presence of thrombus did not predict a poor clinical outcome.