The Prognostic Importance of the Electrocardiogram After Myocardial Infarction

Findings in the resting electrocardiograms of 2035 men, survivors of myocardial infarction in the placebo-treated group of the Coronary Drug Project, were related to the subsequent risk of death over a 3-year follow-up period. Ambulant postinfarct patients with a normal ECG had one third the mortality risk of those with residual ECG findings. Electrocardiographic manifestations of myocardial hypoxia, necrosis, conduction defects, and superexcitability were importantly related to the risk of dying. An ST-segment depression of the "ischemic" type was the most important independent risk predictor of all clinical and ECG findings studied. Both simple and multivariate analyses showed independent prognostic importance for classes of ST-segment depression, Q waves, ventricular conduction defects, atrial fibrillation, ventricular premature beats, and several detailed amplitude measurements, providing information additional to the clinical status. The ECG findings in infarct survivors effectively discriminate between men with vastly different risk and contribute to prediction of the probability of dying in a given period.