In patients after myocardial infarction, survival is influenced by the presence or absence of anterograde flow in the infarct artery, and late potentials on signal-averaged electrocardiography identify those at risk for tachyarrhythmias and sudden death. To assess the frequency of late potentials in survivors of first infarction, coronary arteriography and signal-averaged electrocardiography were performed in 109 subjects (64 men, 45 women, aged 30 to 77 years), 49 with (group I) and 60 without (group II) anterograde flow in the infarct artery. The groups were similar in age, sex, infarct artery, severity of coronary artery disease and left ventricular function. However, only 4 (8%) of group I had late potentials, whereas 24 (40%) of group II had late potentials (p less than 0.001). Thus, anterograde flow in the infarct artery after myocardial infarction is associated with a low incidence of late potentials on signal-averaged electrocardiography, whereas the absence of anterograde flow is more often associated with late potentials.