Coronary bypass for stable angina: a prospective randomized study.

To evaluate the effects of coronary-artery bypass, 100 patients with stable, disabling angina were randomized to medical (49) or surgical (51) therapy. There was no statistical difference in major cardiac events after three years (death in five medical vs. four surgical, infarction in eight vs. 10, and unstable angina requiring operation or reoperation in eight vs. three cases). Surgical patients with three-vessel disease had fewer major events (P less than 0.05) than the comparable medical group and less unstable angina requiring operation (P less than 0.02). All unstable angina was less frequent in the surgical group (15 vs. six, P less than 0.01). Functional classification improved more in surgical patients at six months (P less than 0.01) and at late followup examination (P less than 0.05). After six months, surgical patients achieved significantly higher exercise work loads (P less than 0.01), exercise heart rates (P less than 0.05), maximum paced heart rates (P less than 0.01) and myocardial lactate extraction (P less than 0.01). On the basis of this interim report of a relatively small group of patients, we conclude that bypass results in greater functional improvement and less unstable angina than medical therapy. The likelihood of death and myocardial infarction is unchanged by operation.