The applications for coronary angioplasty have greatly expanded and the procedure is now increasingly used in complex and potentially high risk conditions. This report describes the short- and long-term effects of coronary angioplasty in 61 patients with severely depressed left ventricular function (ejection fraction less than or equal to 35%) with unstable or refractory anginal symptoms, or both, in whom revascularization was necessary despite increased risk. In a retrospective analysis of 1,260 patients undergoing angioplasty between January 1985 through December 1987, 61 had an ejection fraction less than or equal to 35%. The common clinical presentation was unstable angina (70%) with or without recent myocardial infarction. Mean left ventricular ejection fraction was 27 +/- 6%. Forty-five patients (74%) had multivessel disease. Clinical success after angioplasty was achieved in 55 patients (90%). Major complications (death, infarction and emergency bypass surgery) occurred in five patients (8.2%), with death in two (3.2%). During long-term (mean 21 +/- 11 months) follow-up study of the 55 patients with successful angioplasty, 13 (23%) died, including 3 of noncardiac causes, and 11 (20%) had clinically symptomatic recurrence. Continued clinical success was present in 39 patients (71%), of whom 28 (51%) were event-free patients and 11 (20%) had clinical recurrence; a successful second angioplasty procedure was performed in 9 because of restenosis. Thus, in patients with depressed left ventricular function, coronary angioplasty can be performed with a short-term success rate comparable to that of routine angioplasty or surgical procedures. However, acute complications are more frequent and the late mortality rate is higher than in patients with less depressed function.