The influence of gender on the outcome of coronary artery bypass surgery

Background. To assess the impact of gender as an independent risk factor for early and late morbidity and mortality following coronary artery bypass surgery. Methods. Perioperative and long-term data on all 4,823 patients undergoing isolated coronary bypass operations from November 1989 to July 1998 were analyzed. Of these patients, 932 (19.3%) were females. Results. During the years 1989 to 1998 there was a progressive increase in the percentage of women undergoing coronary artery bypass surgery. The following preoperative risk factors were more prevalent among women than men: age above 70, angina class 3 or 4, urgent operation, preoperative intraaortic balloon pump usage, congestive heart failure, previous percutaneous transluminal coronary angioplasty, diabetes, hypertension, and peripheral vascular disease (all p< 0.05). Men were more likely to have an ejection fraction less than 35%, three-vessel disease, repeat operations, and a recent history of smoking. Women had a statistically significant smaller mean body surface area than men (1.72 ± 0.18 versus 1.96% ± 0.26% m2). On average, women had fewer bypass grafts constructed than men (2.9% ± 0.8% versus 3.2% ± 0.9%) and were less likely to have internal mammary artery grafting (76.2% versus 86.1%), multiple arterial conduits (10.1% versus 19.8%), or coronary endarterectomy performed (4.9% versus 8.6%). The early mortality rate in women was 2.7% versus 1.8% in men (p = 0.09). Women were more prone to perioperative myocardial infarction (4.5% versus 3.1% p< 0.05). After adjustment for other risk variables, female gender was not an independent predictor of early mortality but was a weak independent predictor for the prespecified composite endpoint of death, perioperative myocardial infarction, intraaortic balloon counterpulsation pump insertion, or stroke (8.55 versus 5.9%; odds ratio, 1.30; 95% confidence interval, 0.99 to 1.68; p = 0.05) Recurrent angina class 3 or 4 was more frequent in female patients (15.2% ± 4.0% versus 8.5% ± 2.0% at 60 months, p = 0.001) but not repeat revascularization procedures (percutaneous transluminal coronary angioplasty, redo) (0.6% ± 0.3% versus 4.1% ± 0.8% at 60 months). Actuarial survival at 60 months was greater in women then men (93.1% ± 1.7% versus 90.0% ± 1.0%), and after adjustment for other risk variables, female gender was protective for late survival (risk ratio, 0.40; 95% confidence interval, 0.16–0.74; p< 0.005). Conclusions. Perioperative complications were increased and recurrent angina more frequent in women. Despite this, late survival was increased in women compared with men after adjustment for other risk variables