Prognostic value of exercise electrocardiogram in men at high risk of future coronary heart disease: Multiple Risk Factor Intervention Trial experience

Abstract

The prognostic value of the exercise electrocardiogram was examined in the 6,438 usual care men of the Multiple Risk Factor Intervention Trial in relation to fatal and nonfatal coronary heart disease events, rest electrocardiographic abnormalities and coronary heart disease risk factors. An abnormal response to exercise, defined as an ST depression integral of 16 microV-s or more, was observed in 12.2% of the men. There was a nearly fourfold increase in 7 year coronary mortality among men with an abnormal response to exercise compared with men with a normal ST segment in exercise (risk ratio 3.8, 95% confidence limits 2.5 to 5.5). The risk ratio for coronary death, adjusted for age, diastolic blood pressure, serum cholesterol and smoking status at baseline was 3.5, and the corresponding adjusted risk ratio for death from all causes was 1.6. A similar trend toward excess coronary events was seen for angina pectoris (risk ratio of 1.6). The trend was not significant for nonfatal myocardial infarction. Multivariate analyses indicated that the ST depression integral was a strong independent predictor of future coronary death (p less than 0.001). Men with an abnormal electrocardiogram at rest (mainly high amplitude R waves) and with an abnormal ST response to exercise had an over sixfold relative risk for coronary death compared with men with an abnormal electrocardiogram at rest and a normal ST response to exercise. These results suggest that exercise testing may be indicated for improved risk assessment and the assessment of the significance of minor rest electrocardiographic abnormalities in middle-aged men with elevated levels of coronary heart disease risk factors.