Unstable angina pectoris: comparison with the National Cooperative Study.

Seventy-eight patients having prolonged pain (greater than 20 minutes) with transient S-T segment and T-wave changes and coronary artery bypass were compared to 288 patients previously reported in the National Cooperative Study on the treatment of unstable angina pectoris. Clinical characteristics observed in the present study that differed from those of the National Cooperative Study included a more chronic anginal pattern, slightly older age, greater number of women, and higher incidence of prior myocardial infarction. The severity of vessel disease was the same for both groups. Left ventricular function was slightly better in the present series. The incidence of perioperative infarction in the present series (3.8%) was significantly less than that for surgical patients reported in the National Cooperative Study (17%). Hospital mortality was also less: 1.2% versus 2.0 and 3.0% for the medical and surgical patients, respectively, in the National Cooperative Study. Late myocardial infarction was 11% and 13% at 30 months for medical and surgical patients in the National Cooperative Study, and only 3% at 43 months in the present surgical series. Actuarial survival for the entire patient population was 95% at 42 months. The reduced hospital mortality and perioperative infarction rates were attributed to immediate operation once acute myocardial infarction has been ruled out, advances in surgical and anesthetic technique, selection of patients with preserved left ventricular function, and a trend toward complete revascularization.