It is generally thought that coronary artery disease (CAD) in octogenarians would involve multiple vessels. The purpose of the current study was to determine the relative importance of single vessel disease in octogenarians with acute myocardial infarction (AMI) and unstable angina and its outcome from a revascularization procedure such as percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG). Our study included 70 patients (25 men, 45 women) aged 80 or older (mean, 84.5 +/- 0.5) admitted for the first time to the St. Agnes Hospital coronary care unit during 1994 for AMI or unstable angina. Patients admitted primarily for congestive heart failure, cardiogenic shock, hypertensive heart disease, or cardiomyopathy were excluded. Fifty patients (71.4%) had AMI and 20 (28.6%) had unstable angina. Of the 19 patients who had cardiac catheterization done, 10 had single vessel disease, 8 had flow-limiting disease in 2 or more coronary arteries, and 1 had no flow-limiting disease. The mean ejection fraction was 56.5 +/- 6.9 in patients with single vessel disease, 48.0 +/- 3.3 in those with multiple vessel disease, and 38.7 +/- 1.7 in those who did not have cardiac catheterization done. Fourteen PTCA (20%) and 3 CABG (4.3%) were performed without inhospital mortality from the procedures. There were 9 deaths (12.9%) overall: none among 10 patients with single vessel disease, 1 (12.5%) among 8 patients with widespread CAD, and 8 (15.7%) among 51 patients who did not have cardiac catheterization. Study results emphasize the need for recognition and treatment of single vessel disease by revascularization procedures to reduce mortality from CAD in octogenarians.