Left main coronary angioplasty may be a therapeutic revascularization procedure for a subset of patients with symptomatic coronary artery disease. The purpose of this study is to report procedural outcomes and long-term clinical follow-up of 15 patients who underwent either protected or unprotected left main angioplasty for rest angina, These patients represent a cohort of unstable angina patients who were considered high risk for coronary artery bypass surgery, Ten of 15 patients had Canadian Heart Class IV angina, and three patients were hemodynamically unstable, Balloon angioplasty was successful in 14 patients, and one patient was treated with directional atherectomy. Initial angiographic success was achieved in 14 of 15 patients (93%), Major complications (myocardial infarction, emergent coronary artery bypass graft, death) occurred in one patient (6%); 73% of the patients were asymptomatic or had stable exertional angina at 6 months follow-up, One year survival was 87% (13 of 15), During the follow-up period six patients had repeat catheterization for recurrent angina. Four of these patients had left main restenosis and underwent successful repeat left main angioplasty, No patient had coronary bypass surgery during follow-up, This report suggests that left main angioplasty can be a safe and effective revascularization procedure for critically ill patients with unstable angina who are at high risk for coronary bypass surgery. (C) 1994 Wiley-Liss, Inc.