Randomized, single-center. A total of 198 patients were randomized to the PTCA group and 194 to the CABG group. As initial treatment, one patient in the CABG group underwent angioplasty and two patients in the PTCA group underwent surgery, but the groups were followed according to an intention-to-treat analysis. Randomization was performed on the basis of four angiographic strata. Data were collected at baseline, and the patients were contacted every six months for follow-up information. Coronary arteriography and thallium stress scanning were performed at one and three years. All patients were followed for the duration of the trial. Repeat angiographic studies were performed in 87 percent of the eligible patients at one year and in 76 percent at three years. Thallium scans were obtained in 88 percent of the patients at one year and in 77 percent at three years. The primary endpoint was a composite of death, Q-wave myocardial infarction within the previous three years, and detection of a large ischemic defect on thallium scanning at three years. Secondary endpoints involved the degree of revascularization at one and three years, ventricular function, exercise performance, the need for subsequent revascularization procedures, the quality of life, and costs. All patients admitted to Emory University Hospital and Crawford Long Memorial Hospital for cardiac catheterization, whether entered into the study or not, were entered into a study registry as were patients who were referred for a revascularization procedure but who had their initial catheterization performed elsewhere. Recruitment ended in April 1990. The trial has been extended through August 1997 to allow a minimum of eight years and a maximum of ten years of followup for the registry patients as well as for the main cohort of randomized patients. Telephone contact is established annually with study participants in order to determine rates of survival, rehospitalization, repeat revascularization procedures, and functional status. The justification for the long-term followup is the evidence that CABG begins to increase its failure rates between five and ten years.