Women have been found to have significantly higher risk of operative mortality and postoperative complications after isolated coronary artery bypass (CABG) when compared with men. Results from a retrospective cohort study of over a million US patients were released today, revealing the “essentially unchanged” excess operative risk for women between 2011 and 2020.
Published online in JAMA Surgery, the investigators assert theirs is the first to provide “contemporary nationwide analysis” in operative mortality and morbidity trends for women undergoing CABG in the US. Women, the authors preface, are more commonly older and have a higher prevalence of cardiovascular risk factors when presenting for CABG. However, despite a national upward trend in CABG outcomes over the past decades, it is “unclear” why this improvement has remained static for women, the researchers state.
Led by Mario Gaudino (Weill Medical College, New York, USA) the authors reviewed data from the Society of Thoracic Surgeons Adult Cardiac Surgery Database (STS-ACSD), comparing outcomes between men (979, 488 [75.5%]) and women (317,716 [24.5%]). Spanning 110 participating centres, the STS-ACSD represents over 95% of the US cardiac surgical volume, and was evaluated by the authors using the primary analytic method to estimate the association of female sex with CABG operative outcomes over time.
Asserting their primary and secondary endpoints as operative mortality and combined mortality and morbidity respectively, Gaudino et al found their primary endpoint revealed significantly higher unadjusted mortality when compared with men (2.8% vs 1.7%; p<0.001). Their secondary endpoint also yielded significant results, showing the overall incidence of the composite of operative mortality and morbidity to be 22.9% for women (95% CI, 22.7–23.0) and 16.7% for men (95% CI, 16.6–16.8) (p<0.001).
Regarding trends over time, Gaudino and colleagues report that unadjusted mortality in women increased from 2.9% in 2011 to 3.3% in 2020, while adding the operative risk attributable to female sex varied from 1.28% in 2011 to 1.41% in 2020, showing no improvement over time.
“The reason for the lack of improvement in outcomes for women in the last decade is unclear,” the authors write. However, they recognise there are clear differences in baseline anatomical and clinical characteristics between men and women—such as the pattern of ischemic heart disease—alluding to revascularisation being less beneficial in some cases.
The authors point out, however, that current diagnostic and therapeutic protocols for coronary revascularisation, including studies comparing coronary artery bypass with percutaneous coronary intervention (PCI) are “all informed by data derived from studies performed prevalently in men”, and so provide “inadequate” generalisability to women.
Addressing the larger significance of their results, the authors believe a “multifactorial” approach is required to reduce mortality in women after CABG. They affirm that it is important that sex disparities are evaluated in basic science research and women enrolled in clinical trials, and Gaudino et al conclude that “further investigation in the determinants of operative outcomes in women is urgently needed”.
