Seventy-two patients with stable or unstable angina treated since 1983 by multivessel-PTCA(MVP) were retrospectively compared with 44 similar patients that were suitable for MVP, but who had undergone bilateral mammary artery (BIMA) surgery (and additional vein grafts in 60.5% of the patients) since 1986. Both groups were comparable (P = not significant [NS]) for gender, age, most risk factors, objective ischaemia and left ventricular function; however, in the BIMA group there were more previous infarctions (P = 0.02), hypertension (P = 0.03), three-vessel disease (P = 0.0001), and less severe angina (P = 0.007). In the BIMA group, a mean of 3.1 (range 2-5) vessels were treated and in the MVP group 2.0 (range 2-3) vessels (P = 0.0001). Both groups were almost completely revascularized (NS). In 39.5% of the BIMA group, no veins were used and in 20.9% the BIMAs were used as sequential grafts. In-hospital mortality was comparable: 2.3% for BIMA and 1.4% for MVP, so were periprocedural infarctions (13.6% vs 8.3%), rethoracotomies (9.1% vs 0%), emergency procedures (0% vs 5.7%), low cardiac output (2.3% vs 5.6%) and other complications (18.2% vs 9.2%). The mean stay (days) on the ICU/CCU for BIMA was 2.3 and for MVP 1.6 (P = 0.005) and the mean hospital stay for BIMA 12.3 and for MVP 6.6 (P = 0.0001). The maximum and mean follow-up (months) of 43 BIMA and 71 MVP hospital survivors was 35 vs 72 and 9.5 vs 22.3 (P = 0.0001) with a late mortality of 0% and 4.2% (NS). MVP patients, including 12 with re-procedures, had more recurrent angina (17.7% vs 4.7%, P less than 0.05) and more often used anti-anginal medications (62.0% vs 18.6%, P less than 0.0001). Late complications (excluding re-procedures) were comparable for MVP and BIMA (20% vs 9.3%, 4.4% vs 0%, 9.2% vs 14%). MVP patients had more re-hospitalizations (34 vs 5, P less than 0.0001), re-catheterizations (33% vs 2.3%, P less than 0.0001) and cardiac re-procedures (16 vs 0, P = 0.0006) than BIMA patients. Recurrent-angina-free survival at 1 year was 96% after BIMA and 64% after MVP (P less than 0.01). Event-free survival at 1 year was 86% after BIMA and 58% after MVP (P less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)