SEX-RELATED DIFFERENCES AND SYSTEMIC INFLAMMATORY RESPONSE IN CARDIAC SURGERY AND CARDIOPULMONARY BYPASS

Background: Women experience worse outcome after cardiac surgery, possibly linked to distinct inflammatory patterns. We ascertained how sex affects systemic inflammatory reaction syndrome (SIRS) and outcome in heart surgery patients. Methods: A retrospective evaluation of prospectively collected data from patients who had undergone cardiac surgery from 2018 to 2020 in a single hospital was performed. SIRS was defined as per the American College of Chest Physicians/Society of Critical Care Medicine. Multivariate logistic models were used to identify predictors of SIRS and of a composite outcome including death, transient ischemic attack/stroke, renal replacement therapy, bleeding, postcardiotomy extracorporeal membrane oxygenation or intra-aortic balloon pump, and a ICU stay >96 hours. A structural equation modeling was applied to separate the direct influence of SIRS predictors on the composite outcome from the SIRS-mediated effects. Results: A total of 1,005 consecutive patients were included, 299 (29.8%) were female. SIRS incidence was 28.1%, 128 (12.7%) patients experienced the composite outcome. Female sex was associated with SIRS (OR 1.56; 95% CI 1.12-2.18, p=0.009) and the composite endpoint (OR 1.72; 95% CI 1.10-2.69, p=0.017). Other common predictors were baseline left ventricular impairment and intraoperative hyperlactatemia. SIRS mediated 50.8% of the effect of sex on the outcome, 17.0% of that due to left ventricular dysfunction, and 30.9% of the effect caused by intraoperative hyperlactatemia. Conclusions: Female sex independently predicts postoperative SIRS and poorer outcome. Systemic inflammation, preoperative anemia and procedural hyperlactatemia are key factors in the complex mechanisms through which female sex appears to worsen outcome after cardiac surgery.