Sex Disparities in Outcomes After Minimally Invasive Direct CABG for Single-Vessel Disease: A Propensity...

Background: Female sex is widely regarded as an independent risk factor for adverse outcomes after conventional coronary artery bypass grafting (CABG) and is incorporated as a risk variable in EuroSCORE II. Whether this disadvantage persists in the setting of minimally invasive direct coronary artery bypass (MIDCAB), in which sternotomy and cardiopulmonary bypass are avoided, remains insufficiently characterised. We assessed sex-specific short- and long-term outcomes after MIDCAB in a single-centre cohort with extended follow-up. Methods: We retrospectively analysed 350 consecutive patients who underwent MIDCAB at Hannover Medical School between July 1999 and April 2025 (follow-up to April 2025). Eligibility criteria and heart team-applied exclusion criteria (prior left thoracotomy, unfavourable LAD anatomy, prohibitive respiratory reserve, hostile chest wall, active endocarditis, or haemodynamic instability requiring on-pump revascularization) are detailed in the Methods. Females (n = 102) and males (n = 248) were compared before and after 1:1 propensity score matching using greedy nearest-neighbour matching with a caliper of 0.2 × SD of the logit propensity score. The primary endpoint was all-cause long-term mortality; secondary endpoints included perioperative complications and in-hospital outcomes. Long-term survival was assessed by Kaplan-Meier analysis and multivariable Cox proportional hazards regression performed in the full unmatched cohort. A pre-specified subgroup analysis of long-term survival by coronary disease pattern (single-vessel vs. multivessel disease) was also performed. Results: Matching produced 100 female-male pairs with excellent covariate balance (all standardized mean differences < 0.20). MIDCAB was completed without intraoperative conversion in all patients. Thirty-day mortality was 0% in both sexes; no postoperative stroke or new requirement for dialysis occurred. New-onset atrial fibrillation (3.0% vs. 1.0%, p = 0.621), length of intensive care unit stay (median 1 day in both groups), and hospital length of stay (median 8 days in both groups) were comparable between females and males. Re-exploration for bleeding was numerically more frequent in women (5.0% vs. 0.0%; Newcombe 95% CI for the risk difference +0.3 to +11.2%; Fisher's exact p = 0.059). At a median follow-up of 19.0 years (IQR 11.8-23.9), all-cause mortality was identical (12.0% vs. 12.0%, p = 1.000; log-rank p = 0.703). In multivariable Cox regression in the full unmatched cohort, female sex was not associated with long-term mortality (adjusted HR 0.80, 95% CI 0.38-1.70, p = 0.560); only advancing age emerged as a strong independent predictor (HR 1.10 per year, 95% CI 1.05-1.15, p < 0.001), with EuroSCORE II approaching significance (HR 1.67 per unit, 95% CI 1.00-2.82, p = 0.052). Long-term survival in patients with multivessel disease (20-year Kaplan-Meier 90.9%) was equivalent to that in single-vessel disease (92.3%; log-rank p = 0.94). Conclusions: In this propensity-matched analysis with two decades of follow-up, MIDCAB conferred equivalent perioperative safety and long-term survival in women and men. Female sex was not an independent predictor of adverse outcome. These findings support MIDCAB as a sex-neutral revascularization strategy for single-vessel and LAD-predominant coronary artery disease in the very low-risk, appropriately selected population studied, and are consistent with the most recent published MIDCAB literature.