Coronary Artery Bypass Graft Failure in Women: Incidence and Clinical Implications

Background: Women have worse outcomes after coronary artery bypass surgery (CABG) than men. Objectives: This study aimed to determine the incidence of CABG graft failure in women, its association with cardiac events, and whether it contributes to sex-related differences in outcomes. Methods: A pooled analysis of individual patient data from randomized clinical trials with systematic imaging follow-up was performed. Multivariable logistic regression models were used to assess the association of graft failure with myocardial infarction and repeat revascularization between CABG and imaging (primary outcome) and death after imaging (secondary outcome). Mediation analysis was performed to evaluate the effect of graft failure on the association between female sex and risk of death. Results: Seven randomized clinical trials (N = 4,413, 777 women) were included. At a median imaging follow-up of 1.03 years, graft failure was significantly more frequent among women than men (37.3% vs 32.9% at the patient-level and 20.5% vs 15.8% at the graft level; P = 0.02 and P < 0.001, respectively). In women, graft failure was associated with an increased risk of myocardial infarction and repeat revascularization (OR: 3.94; 95% CI: 1.79-8.67) and death (OR: 3.18; 95% CI: 1.73-5.85). Female sex was independently associated with the risk of death (direct effect, HR: 1.84; 95% CI: 1.35-2.50) but the association was not mediated by graft failure (indirect effect, HR: 1.04; 95% CI: 0.86-1.26). Conclusions: Graft failure is more frequent in women and is associated with adverse cardiac events. The excess mortality risk associated with female sex among CABG patients is not mediated by graft failure.