Primary myocardial revascularization. Trends in surgical mortality.

From 1970 to 1982, 24,672 patients underwent primary isolated myocardial revascularization: Group I, 4,517 patients operated upon from 1970 to 1973; Group II, 6,181 patients from 1974 to 1976; Group III, 6,869 patients from 1977 to 1979; and Group IV, 7,105 patients from 1980 to 1982. Operative mortality was 1.2% for the entire experience and 1.2%, 1.4%, 1.6%, and 0.8% for Groups I to IV, respectively. Mortality for Group IV was significantly lower (p less than 0.001). In decreasing order of significance, the risk factors were emergency operation, congestive heart failure, left main disease, female gender, history of congestive heart failure, advancing age, normothermic arrest, number of grafts, poor ventricular function, and incomplete revascularization. The same analysis of Groups I to IV demonstrated that advanced age, emergency operation, female gender, and congestive heart failure persisted as risk factors while incomplete revascularization and abnormal electrocardiogram emerged as new risk factors. Cardiac causes accounted for 203 (66.2%) patient deaths. This gradually decreased from 75.3% in Group II to 58.5% in Group IV. Neurological deficit was the second most frequent cause of death, 29 (9.6%), reaching a high in Group IV (18.9%). We conclude that (1) morbidity and mortality have decreased significantly despite increasing risk factors; (2) congestive heart failure has replaced emergency operation as the principal risk factor; (3) left main disease, number of grafts, and poor ventricular function have been neutralized as risk factors; and (4) cardiac causes of death are decreasing and being replaced by other system failure.