Between 1 September, 1980 and 1 January, 1989, 4142 patients underwent percutaneous transluminal coronary angioplasty (PTCA). We retrospectively studied the 155 [3.7%; 119 males, mean age 53.4 years, (range 33-78 years) and 36 females, mean age 59.6 years (range 40-74 years)] who required urgent coronary artery bypass grafting (CABG) (Group I) and a select control group of 155 patients, in whom PTCA was performed without complications (Group II). Before PTCA, 14 Group I and 42 Group II patients had angina Class II, and 78 Group I and 49 Group II patients had angina class IV (chi 2-test, P less than 0.05). There were 445 complications in the 155 group I patients: 303 (68%) early (during PTCA) and 141 (32%) late (within 24 h). On arrival in the operating room 126 patients were stable; five were in cardiac arrest and 19 in cardiogenic shock (AS-group; 24 patients). In the AS-group and control group, respectively, angina Class II occurred in 2/24 (8.3%) and 42/155 (27.1%) patients, angina Class IV in 14/24 (58.3%) and 49/155 (31.6%) (P less than 0.05), single-vessel disease in 8/24 (33.3%) and 85/155 (54.8%), triple-vessel disease in 7/24 (29.2%) and 23/155 (14.9%) (P less than 0.05); elective PTCA in 11/24 (45.8%) and 92/155 (59.4%), urgent PTCA in 12/24 (50%) and 48/155 (30.9%) (P less than 0.05), PTCA of the left anterior descending artery (LAD) in 18/24 (75%) and 86/166 (51.8%), PTCA of the right coronary artery in 2/24 (8.3%) and 47/166 (28.3%) (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)