Prognosis of patients with unstable angina and low-risk exercise test: significance of ST-segment depression on the admission ECG.

The presence of ST-segment depression on the admission electrocardiogram (ECG) is an important predictor of poor outcome in patients with unstable angina. On the other hand, patients with unstable angina who undergo a low-risk exercise test are supposed to have a favorable prognosis. The objective of the study was to determine the prognostic significance of ST-segment depression on the admission ECG in patients with unstable angina who undergo an exercise test that indicates a low risk of events. An interpretable exercise test was performed in 257 patients with primary unstable angina. A low-risk exercise test was completed by 156 (60%) patients and medical therapy was planned for all these patients. A multivariate analysis was performed in order to determine the independent predictors of events (cardiac death, nonfatal acute myocardial infarction, or admission for unstable angina) during a 12-month follow-up. Among patients with a low-risk exercise test, there were no significant differences between patients with and without ST-segment depression on the presenting ECG with regard to event rate (34 vs. 29%, P=NS). In multivariate analysis, ST-segment depression was not related to a higher incidence of events. Our findings appear to indicate that the presence of ST-segment depression on the admission ECG loses its prognostic significance in patients with primary unstable angina if they complete a low-risk exercise test.