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<0.05) than the comparable medical group and less unstable angina requiring operation (P<0.02). All unstable angina was less frequent in the surgical group (15 vs. six, P<0.01). Functional classification improved more in surgical patients at six months (P<0.01) and at late follow-up examination (P<0.05). After six months, surgical patients achieved significantly higher exercise work loads (P<0.01), exercise heart rates (P<0.05), maximum paced heart rates (P<0.01) and myocardial lactate extraction (P<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. (N Engl J Med 300:149–157, 1979) THIS study was initiated in late 1971 when saphenous-vein bypass for coronary heart disease was becoming widely accepted and used. Prospective, randomized studies are generally considered the most discriminating technic for evaluating new modes of therapy, and it seemed appropriate to apply this approach to assess the influence of bypass operations on the symptoms and objective findings of myocardial ischemia, left ventricular function, mortality and morbidity.^{1 2 3} Now, more than six years later, there is some agreement regarding the results of bypass in relieving angina and reversing myocardial ischemia.^{4 5 6 7 8 9 10} The effects on survival, myocardial infarction or other major cardiac events^{7 8 9 10 11 12 13 14 15} and.