Coronary bypass surgery in women is associated with lower survival than in men. We need to know whether this is because of patient-related factors and whether the lower survival is present in all subgroups of patients and for all time periods during which the surgery was performed.Methods and Results
Using actuarial techniques, we determined the outcome of coronary bypass surgery performed for chronic stable and unstable angina in 1979 women and 6927 men. The operative mortality was 2.7% for women and 1.9%o for men (P=.02). The higher operative mortality in women was seen in those with three-vessel disease or greater and abnormal left ventricular function (5.4% versus 2.8%, P=.009) and those with stable angina (2.6% versus 1.5%, P=.006). The 5-, 10-, 15-, and 18-year survival for women was 86+0.9'%'Y, 70+1.5%, 50±2.5%, and 37+6.4%, respectively, and for men, 88±0.4%, 73 +0.7%, 54±1.2%, and 42±1.9%o, respectively (P=.03). The lower survival in women compared with men was seen in those with three-vessel disease or greater and abnormal left ventricular function (at 10 years, 53±3.7% versus 65±1.6%, P=.0006) and in those with stable angina (at 10 years, 69±1.8% versus 73+0.8%, P=.005). At 15 years, the incidence of reoperation was 26±2.4% versus 28±1.2% and of myocardial infarction, 30±2.8% versus 32+1.3%, P=NS for either. The incidence of no angina or mild angina was 70%o in women and 78% in men, P<.0001. The operative mortality and late survival of those operated on in different time periods for either women or men was not significantly different. Women were older (64_9.4 versus 61±9.9 years, P<.0001) and smaller (body surface area, 2.0±0.2 versus 1.7±0.2 in2, P<.0001), had a higher incidence of diabetes, systemic hypertension, and unstable angina, and had a smaller lumen of the left anterior descending coronary artery (1.7±0.4 versus 1.9±0.4 mm, P<.0001), right coronary artery, and diagonal arteries. More men were smokers, and men had a higher incidence of prior myocardial infarction, previous coronary bypass surgery, and extent of coronary disease and of abnormal left ventricular function. The Cox regression model of survival showed that independent risk factors for lower survival were older age, previous coronary bypass surgery, previous myocardial infarction, and diabetes. Sex was not an independent risk factor for poorer survival.Conclusions
Women have a higher operative mortality and lower long-term survival than men after coronary bypass surgery for angina. However, the differences are small, even if statistically significant. Importantly, patient-related factors and not sex are independent predictors of poorer survival. Therefore, coronary bypass surgery should not be delayed or denied to women who have the usual indications for surgery.