The early and late outcome of patients who underwent multivessel percutaneous transluminal coronary angioplasty (PTCA) in a 1-stage procedure are described, and the predictors for clinical event and new revascularization procedure are identified. Of 1,937 patients treated by PTCA between 1981 and 1986, 203 (10.4%) had multivessel PTCA in a 1-step procedure. A follow-up extending to 71 +/- 23 months was obtained in 195 patients (96%). Primary success was achieved in 91% of 494 attempted sites, and complete revascularization in 65% of 203 patients. There were no in-hospital deaths. Acute complications occurred in 13 patients (6.4%), including non-Q-wave (n = 8) and Q-wave (n = 5) infarction, and urgent coronary artery bypass surgery (n = 3). Before PTCA, 126 patients (62%) were in class III or IV of the Canadian Cardiovascular Society classification; at follow-up, 84% were angina-free or in class I. Death occurred in 14 patients and nonfatal myocardial infarction in 18. Angiographic restenosis was diagnosed in 37.2% of dilated lesions in 96 patients (60% of 159 restudied). A repeat revascularization procedure for restenosis or progression of disease, or both, was needed in 92 symptomatic patients (47%). The survival rate at 7 years without the need for surgery or PTCA was 53%, and cardiac survival without myocardial infarction was 85.5%. The only independent predictor of cardiac death was ejection fraction (p < 0.001). The rate of restenosis per patient was primarily determined by the number of segments dilated, whereas progression of disease was related to the number of nonsignificant coronary artery stenoses (< 50%) at baseline (p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)