Importance  It has been reported that women undergoing coronary artery bypass have higher mortality and morbidity compared with men but it is unclear if the difference has decreased over the last decade.

Objective  To evaluate trends in outcomes of women undergoing coronary artery bypass in the US from 2011 to 2020.

Design, Setting, and Participants  This retrospective cohort study at hospitals contributing to the Adult Cardiac Surgery Database of the Society of Thoracic Surgeons included 1 297 204 patients who underwent primary isolated coronary artery bypass from 2011 to 2020.

Exposure  Coronary artery bypass.

Main Outcomes and Measures  The primary outcome was operative mortality. The secondary outcome was the composite of operative mortality and morbidity (including operative mortality, stroke, kidney failure, reoperation, deep sternal wound infection, prolonged mechanical ventilation, and prolonged hospital stay). The attributable risk (the association of female sex with coronary artery bypass grafting outcomes) for the primary and secondary outcomes was calculated.

Results  Between 2011 and 2020, 1 297 204 patients underwent primary isolated coronary artery bypass grafting with a mean age of 66.0 years, 317 716 of which were women (24.5%). Women had a higher unadjusted operative mortality (2.8%; 95% CI, 2.8-2.9 vs 1.7%; 95% CI, 1.7-1.7; P < .001) and overall unadjusted incidence of the composite of operative mortality and morbidity compared with men (22.9%; 95% CI, 22.7-23.0 vs 16.7%; 95% CI, 16.6-16.8; P < .001). The attributable risk of female sex for operative mortality varied from 1.28 in 2011 to 1.41 in 2020, with no significant change over the study period (P for trend = 0.38). The attributable risk for the composite of operative mortality and morbidity was 1.08 in both 2011 and 2020 with no significant change over the study period (P for trend = 0.71).

Conclusions and Relevance  Women remain at significantly higher risk for adverse outcomes following coronary artery bypass grafting and no significant improvement has been seen over the course of the last decade. Further investigation into the determinants of operative outcomes in women is urgently needed.