BACKGROUND:

Angina pectoris is a symptomatic condition of attacks of chest pain, often debilitating. It is caused by a decreased supply of blood to the heart, such as that which might occur in coronary artery disease. The usual treatment of angina pectoris is designed to relieve the symptoms. It includes avoidance of activities that produce the discomfort and the use of nitroglycerin and beta blocking drugs. Soon after the introduction of coronary bypass surgery, many doctors enthusiastically adopted this approach in treating patients with unstable angina.

In 1972, emphasizing that there was no definitive evidence showing the superiority of intensive medical management or coronary bypass surgery in determining mortality and morbidity in patients hospitalized with unstable angina, some of the participating groups in the NHLBI Myocardial Infarction Research Units developed a cooperative clinical trial to compare these medical and surgical approaches to therapy.

From 1972 through 1976, 288 patients were entered into this randomized clinical trial. One hundred forty-seven patients received intensive pharmacological medical therapy, and 141 comparable patients underwent coronary artery bypass surgery. Careful follow-up studies were performed on patients in both groups, in-hospital and during the post-hospital phase. These studies included, apart from routine physical examinations, resting electrocardiograms, chest x-ray films, and grade exercise tolerance tests at six months and twelve months.

DESIGN NARRATIVE:

Randomized, non-blind, sequential design with a control group and an experimental group. The patients in the experimental group were treated with coronary bypass surgery. Patients in the control group received intensive medical management. Endpoints were mortality and morbidity measures, such as incidence of myocardial infarction and persistence of angina.