Sex Differences in Preoperative Risk Profiles and 1-Year Mortality Following Elective Cardiac Surgery: A Retrospective Single-Centre Cohort Study

<b>Background:</b> Sex-related differences in outcomes following cardiac surgery are well documented, with females generally experiencing higher postoperative mortality rates than males. However, the underlying factors driving this disparity remain incompletely understood. This study aimed to compare the preoperative risk characteristics of female and male patients who died within one year after elective cardiac surgery with those who survived, in order to identify sex-specific risk profiles associated with postoperative mortality. <b>Methods:</b> In this retrospective single-centre cohort study, data were derived from a prospective quality assurance database at Amsterdam University Medical Centres (Amsterdam UMC), The Netherlands, covering January 2001 to December 2020. All adult patients (≥18 years) undergoing elective cardiac surgery were included. Descriptive and comparative analyses were performed to characterise sex-specific preoperative differences between survivors and non-survivors. <b>Results:</b> The study cohort comprised 10,614 patients, including 2804 females (26%; median age 72 years [IQR 65-77]) and 7810 males (74%; median age 67 years [IQR 59-73]). In both sexes, non-survivors more frequently had major comorbidities, including atrial fibrillation, history of reoperation, pulmonary hypertension, chronic obstructive pulmonary disease, cerebrovascular disease, and kidney dysfunction. Within one year post-surgery, 143 (5.1%) females and 299 (3.8%) males had died. Among females, non-survivors within one year of surgery more frequently had several preoperative risk factors compared with survivors, including moderately impaired left ventricular function (16% vs. 11%), pulmonary hypertension (12% vs. 3%), extracardiac arteriopathy (25% vs. 9%), and kidney dysfunction (46% vs. 21%) dependent on the type of surgery (combined valve + coronary artery bypass grafting (CABG) (29% vs. 15%) or aortic surgery (14% vs. 4%)). In male patients, however, different risk factors such as higher age (median 73 years [IQR 66-77] vs. 67 [59-73]), lower Body Surface Area (mean 1.96 m² (SD ± 0.19) vs. 2.02 ± 0.18), hypercholesterolaemia (35% vs. 44%), severely impaired left ventricular function (14% vs. 6%), myocardial infarction (31% vs. 22%), and type of surgery (aortic surgery (9% vs. 3%), or combined valve + CABG (22% vs. 12%)) were preoperative predictors of mortality compared to non-survivors. <b>Conclusions:</b> Our study demonstrates that one-year mortality following elective cardiac surgery is driven by distinct preoperative risk profiles in females and males. Recognising that mortality in females is associated with systemic disease and males by direct cardiac damage is a critical step toward developing more equitable, precise, and effective perioperative management strategies.