Sex differences in outcomes of patients undergoing on-pump coronary artery bypass grafting surgery

There are controversies regarding the impact of sex on mortality and postoperative complications in patients undergoing on-pump coronary artery bypass grafting (CABG), although some studies demonstrate comparable outcomes. This study sought to evaluate sex differences regarding risk factors associated with hospital mortality and postoperative clinical outcomes among patients undergoing isolated on-pump CABG. We conducted a retrospective observational cohort study of patients who underwent isolated on-pump CABG from January 1996 to January 2020. Patients were divided into two groups (male and female) and compared regarding preoperative characteristics, surgical technical variables, and in-hospital outcomes. All-cause mortality between groups was compared using logistic regression. Risk factors for mortality, along with their respective odds ratios (OR), were separately assessed using a logistic regression model with p-values for interaction. We analyzed 4,882 patients, of whom 31.6% were female. Women exhibited a higher prevalence of age >75 years (12.2% vs 8.3%, p<0.001), obesity (22.6% vs 11.5%, p<0.001), diabetes (41.6% vs 32.2%, p<0.001), hypertension (85.2% vs 73.5%, p<0.001), and NYHA functional classes 3 and 4 (16.2% vs 11.2%, p<0.001) compared to men. Use of the mammary artery for revascularization was less frequent among women (73.8% vs 79.9%, p<0.001), who also received fewer saphenous vein grafts (2.17 vs 2.27, p = 0.002). A history of previous or recent myocardial infarction (MI) had an impact on women's mortality, unlike in men (OR 1.61 vs 0.94, p = 0.014; OR 1.86 vs 0.99, p = 0.015, respectively). After adjusting for several risk factors, mortality was found to be comparable between men and women, with an OR of 1.20 (95% CI 0.94-1.53, p = 0.129). In conclusion, female patients undergoing isolated on-pump CABG presented with a higher number of comorbidities. Previous and recent MI were associated with higher mortality only in women. In this cohort analysis, female gender was not identified as an independent risk factor for outcome after CABG.