The relations of hemodynamic factors, plasma fibrinogen concentration, serum lipoprotein levels, and clinical risk indicators to coronary atherosclerosis were studied in 56 men who had survived a first myocardial infarction before the age of 45 years and who subsequently underwent two coronary angiographies with an intervening time interval of 4 to 7 years. Presence, severity, and rate of progression of both diffuse lesions and distinct stenoses were determined by means of separate classification systems in 15 proximal coronary arterial segments. High minimum heart rate measured during a 24-hour period in connection with the reangiography was associated with progression of both diffuse lesions and distinct stenoses. High minimum heart rate also correlated positively with angiographic scores of global severity of diffuse atherosclerosis and stenoses. Progression of disease was predicted independently by minimum heart rate and low-density lipoprotein/high-density lipoprotein ratio, whereas lipoprotein A, fibrinogen levels, hypertension, smoking, and beta-adrenergic receptor blockade treatment did not discriminate between patients with and without progression.