MORTALITY AND MORBIDITY AFTER CORONARY-ARTERY BYPASS-SURGERY RELATED TO PREOPERATIVE LEFT-VENTRICULAR EJECTION FRACTION - A FOLLOW-UP-STUDY

Objective To study the pre-operative level of left ventricular ejectio n fraction that may be indicative of an increased risk of early and la te mortality and of recurrent angina pectoris and late non-fatal myoca rdial infarction. Material and methods A total of 934 patients with kn own left ventricular ejection fraction, 80 women and 854 men, were sub mitted to coronary artery bypass grafting at the Cardiovascular Unit o f Rikshospitalet. Oslo, between August 1982 and December 1986. The clo sing date was the 1st of January 1993, with a mean follow-up of time o f 7.4 years. The patients were divided in to four subgroups according to their level of left ventricular ejection fraction: less than or equ al to 40%:, 41-60%, 61-80%. The left ventricular ejection fraction var ied from 13-98%. A chi-square test of linear trend was used to calcula te the relative risk between the different subgrouys. Cumulative survi val was determined rising survival curves. Results Early mortality. Tw enty-five patients (2.7%) died d within 30 days of operation. Patients with left ventricular ejection fraction less than or equal to 40%, ha d a relative risk of 10.2 (1.9-17.2), for left ventricular ejection fr action 41-60% the relative risk was 0.9 (0.1-8.9) and for left ventric ular ejection fraction 61-80% the relative risk was 2.8 (0.6-17.2). Le ft ventricular ejection fraction > 80% was defined as relative risk = 1. Late mortality. Altogether, 174 patients died in the late phase (18 .6%). For patients with left ventricular ejection fraction less than o r equal to 40% the relative risk was 3.6 (2.8-10.9), for left ventricu lar ejection ejection fraction 41-60% the relative risk was 1.8 (1.1-3 .6), and for left ventricular ejection fraction 61-80% the relative ri sk was 1.5 (0.9-2.8). Recurrent angina pectoris. A total of 138 patien ts developed recurrent angina pectoris during the follow-up period, gi ving an incidence of 14.8%. Here, for left ventricular ejection fracti on less than or equal to 40% the relative risk was 0.5 (0.2-13), for l eft ventricular ejection fraction 41-60% the relative risk was 1.0 (0. 5-1.8) and for left ventricular ejection fraction 61-80% the relative risk was 1.2 (0.7-2.0). Late non-fatal myocardial infarction. Altogeth er, 90 patients (9.6%) experienced non-fatal myocardial infarction in the late phase. For left ventricular ejection fraction less than or eq ual to 40% the relative risk was 0.6 (1.2-1.8), for left ventricular e jection fraction 41-60% the relative risk was 1.0 (0.5-2.0) and for le ft ventricular ejection fraction 61-80% the relative risk was 0.7 (0.4 1-1.3). Cumulative survival. When pooled together, the cumulative surv ival for patients with left ventricular ejection fraction > 40% was 95 .9, 91.9 and 79% after 1, 5 and 10 years, respectively. For the patien ts with left ventricular ejection fraction less than or equal to 40% c umulative survival was 87.5, 73.1 and 55.2%, respectively. Conclusion When the left ventricular ejection fraction was 40% or lower, there wa s a substantial increase in the risk of early mortality in patients su bmitted to coronary artery bypass grafting. As for the risk of late mo rtality, there was a practically linear increase in risk with falling values of left ventricular ejection fraction. We found no difference i n risk of developing recurrent angina pectoris or of late non-fatal my ocardial infarction related to values of left ventricular ejection fra ction.