Sex Differences in Long-Term Survival After Major Cardiac Surgery: A Population-Based Cohort Study

Background Little attention has been paid to the importance of sex in the long-term prognosis of patients undergoing cardiac surgery. Methods and Results We conducted a retrospective cohort study of Ontario residents, aged ≥40 years, who underwent coronary artery bypass grafting (CABG) and/or aortic, mitral, or tricuspid valve surgery between October 1, 2008, and December 31, 2016. The primary outcome was all-cause mortality. The mortality rate in each surgical group was calculated using the Kaplan-Meier method. The risk of death was assessed using multivariable Cox proportional hazard models. Sex-specific mortality risk factors were identified using multiplicative interaction terms. A total of 72 824 patients were included in the study (25% women). The median follow-up period was 5 (interquartile range, 3-7) years. The long-term age-standardized mortality rate was lowest in patients who underwent isolated CABG and highest among those who underwent combined CABG/multiple valve surgery. Women had significantly higher age-standardized mortality rate than men after CABG and combined CABG/mitral valve surgery. Men had lower rates of long-term mortality than women after isolated mitral valve repair, whereas women had lower rates of long-term mortality than men after isolated mitral valve replacement. We observed a statistically significant association between female sex and long-term mortality after adjustment for key risk factors. Conclusions Female sex was associated with long-term mortality after cardiac surgery. Perioperative optimization and long-term follow-up should be tailored to younger women with a history of myocardial infarction and percutaneous coronary intervention and older men with a history of chronic obstructive pulmonary disease and depression.