Submaximal exercise testing after stabilization of unstable angina pectoris

To determine the prognostic value of exercise testing in patients with unstable angina pectoris, 125 hospitalized patients were prospectively evaluated soon after stabilization of their pain. Exercise testing was performed after exclusion of acute myocardial infarction and a pain-free period of at least 3 days (mean +/- SD 3.9 +/- 1.4). No complications were noted during or immediately after exercise testing. A positive test (angina or greater than or equal to 1 mm ST segment depression, or both) was noted in 60 patients (48%). During a 1 year follow-up period, 52 (87%) of these 60 patients had an unfavorable outcome (American Heart Association class III or IV angina, recurrent unstable angina, coronary artery bypass surgery, acute myocardial infarction or cardiac death) compared with 19 (29%) of the 65 patients with a negative test (p less than 0.001). The sensitivity and specificity of exercise testing in predicting outcome were 73 and 85%, respectively. The predictive value of a positive test was 87% and that of a negative test was 71%. Angina by itself during the exercise test was a reliable predictor of severe angina (class III or IV angina) at follow-up (sensitivity 92%, specificity 89%, positive predictive value 83% and negative predictive value 95%; p less than 0.001). The findings were not significantly affected by beta-adrenergic blocking agents or digitalis in the study sample. Thus, in patients with unstable angina which has been stabilized, the results of early submaximal exercise testing may be useful in predicting outcome in the first year after hospital discharge. Patients with a positive test result should be considered for further diagnostic studies.