Abstract P186: Extent of Myocardium at Risk in Women, but Not in Men, is Associated With Major Adverse Cardiac Events Following Coronary Artery Bypass Grafting

Objective: Many studies have reported higher rates of adverse outcomes in women than men following CABG surgery. To date, the mechanism has not been elucidated. We studied a large group of CABG patients for whom detailed angiographic data were available and investigated the impact of myocardium at risk (MAR) on major adverse cardiac events (MACE) in men and women post-CABG. Methods: For patients undergoing isolated primary CABG, a Duke Index score was calculated from angiographic data. Duke Index is a validated score that quantifies MAR using distribution and severity of coronary artery disease. Categories of MAR were defined as Low, Moderate and High based on number of diseased vessels as well as location of disease, with proximal lesions conferring a higher weight than distal stenoses. The post-CABG outcome was in-hospital MACE (1 or more of mortality, low cardiac output, stroke, MI, sepsis, deep sternal wound infection, ventilation >48 hrs or return to ICU). Logistic regression was used to examine the impact of MAR as a predictor of MACE in women and in men, after adjusting for clinical comorbidities. Results: Of 3744 CABG patients, 70% (2614) had complete angiographic data and were included in the analysis; 23% (607 of 2614) were women. Compared with men, women undergoing CABG had similar Duke Index scores but were older and more likely to have diabetes, hypertension, vascular disease, disabling angina, and require urgent surgery. Completeness of revascularization did not differ between men and women. Prevalence of MACE was higher in women than in men: 19.9% (121 of 607) versus 13.0% (262 of 2007), p=0.0001. In a logistic regression model fully adjusted for comorbidities, there was a significant interaction between female sex and increased MAR as predictors of MACE. In separate logistic regression models for each sex, increasing MAR was an independent predictor of MACE for women (High MAR: OR 3.2, 95% CI 1.4-7.6, Moderate MAR: OR 2.5, 95% CI 1.0-6.2), but not for men (High MAR: OR 1.0, 95% CI 0.6-1.7, Moderate MAR: OR 1.1, 95% CI 0.6-1.8). Conclusions: Myocardium at risk impacts post-CABG outcome differently for women than for men. This novel finding suggests that CABG surgery may not provide the same potential for recovery of ischemic myocardium for women compared with men.