Occlusion of the infarct-related artery has recently been associated with an increased risk of sudden death, particularly in patients with poor left ventricular function. Depressed heart rate variability (HRV) also identifies postinfarction patients at an increased risk of sudden death. The correlation between infarct artery patency, left ventricular function, and HRV was therefore examined in 186 survivors of a first myocardial infarction. Predischarge coronary angiography and Holter monitoring were carried out in 186 patients with a first acute myocardial infarction. Coronary angiography was performed because of abnormal predischarge exercise test findings. Mean age (56 +/- 9 years) and the proportions of type and site of infarction did not differ between patients with occluded or patent arteries or between patients who did or did not undergo coronary angiography. The mean left ventricular ejection fraction (EF) was 55 +/- 15% in patients with patent and 49 +/- 14% in those with occluded infarct arteries (p < 0.001), and the EF was < 40% in 17% and 28% of the respective groups (p < 0.05). HRV was < 20 U in 7 (18%) of the 39 patients with an EF < 40% but in only 7 (5%) of the 147 patients with an EF > 40% (p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)