Preoperative left ventricular function variables were evaluated as potential risk factors for peroperative and postoperative complications in 183 consecutive patients undergoing coronary bypass surgery. Fifty-six patients had no abnormal criteria and 127 had at least one criterion (AN). The incidence of history of infarction was significantly greater in the AN (71.6 percent) than in the N (39.6 percent) group (p less than 0.04). During the early postoperative course, N and AN differentiated significantly in (1) the need for inotropic therapy (II vs 30 percent, p less than 0.05); (2) intra-aortic balloon pump (0 vs 13 percent); (3) arrhythmias (20 and 40 percent, p less than 0.002); and (4) stay in the Intensive Care Unit (2.3 +/- 0.8 and 3.9 +/- 2 days, p less than 0.01). Perioperative necrosis and mortality were not different. During a follow-up period of two years, N and AN did not show any difference in mortality and recurrence of angina.