The basal electrocardiogram and the exercise stress test in assessing prognosis in patients with unstable angina.

Abstract

The purpose of this study was to evaluate the prognostic usefulness of basal electrocardiogram and exercise stress test in 374 patients with unstable angina submitted to coronary angiography during the same hospitalization period. After stabilization of symptoms by medical therapy, patients were subdivided into four groups according to the ECG and stress test: Group 1 (54 patients with normal ECG and exercise stress test negative for ischaemia); Group 2 (86 patients with normal ECG and exercise stress test positive for ischaemia); Group 3 (59 patients with abnormal ECG and exercise stress test negative for ischaemia); Group 4 (175 patients with abnormal ECG and exercise stress test positive for ischaemia). The severity of coronary atherosclerosis and impairment of left ventricular function increased progressively from Group 1 to 4, although differences in ventricular function were not significant between Groups 2 and 3. When discharged, patients were treated with verapamil and nitrates and followed for a period ranging from 1 to 8 years; during follow-up, only one patient of Group 1 underwent coronary bypass surgery, compared to 22, 7 and 46 patients in Groups 2, 3 and 4, respectively. The eight-year survival rate in the four groups (1-4) was 100%, 97%, 88% and 70%, respectively. Statistically significant differences were observed between Groups 1 and 3, 1 and 4, 2 and 4, and 3 and 4. Thus, the ECG and exercise stress test allow a population of patients with unstable angina to be selected (Group 1), having excellent long-term prognosis. These patients could avoid angiography, thereby reducing hospital costs, without compromising their health.