Sex-based Analysis of In-hospital and Long-term Outcomes in Mitral Valve Repair for Degenerative Mitral Regurgitation

M. I. Malik¹, R. Nedadur¹, A. Hage², F. Hage³, N. Tzemos¹, M. Chu^4
1London Health Science Centre, London, Ontario ²London Health Sciences Centre, Western University, London, Ontario ³London Health Sciences Centre, London, Ontario ⁴Western University, London Health Sciences Centre, London, Ontario

Purpose: Mitral valve repair is the gold-standard treatment of severe degenerative mitral regurgitation (MR). Guideline-directed treatment has been largely based on evidence in predominantly male patients, without accounting for diagnostic and physiologic differences in MR pathology between sexes. (1,2) This study aims to compare outcomes of mitral valve repair by sex.

Methods: A single-centre retrospective analysis of patients undergoing mitral repairs was conducted, from May 2008 – February 2023. Baseline characteristics, preoperative clinical and echocardiographic data, intraoperative data and postoperative in-hospital and follow-up data was collected for all patients. Major adverse cardiovascular event (MACE) was defined as death, surgical reintervention, stroke, myocardial infarction, and permanent-pacemaker insertion. Univariate analysis was conducted comparing sex across all baseline datapoints and presented as p-value and standardized mean difference (SMD). Adjusted outcome analysis was performed using inverse-probability treatment weighting (IPTW), with covariates selected for adjustment based on likely influence on the outcomes and a p-value < 0.10. IPTW-adjusted hazard ratios are presented for 30-day outcomes. Unadjusted and IPTW-adjusted Kaplan-Meier curves and hazard-ratios were plotted for long-term survival and freedom from mitral valve reintervention based on sex.

Results: A total of 490 patients underwent mitral valve repair between May 2008 and February 2023, including 343 males and 147 females. Median follow-up time was 3.6 years [IQR 1.4-6.5 years]. After IPTW-adjustment of baseline variables, there was good group balance, with SMD less than 0.10 for all included covariates. Females were significantly more likely to be older (68.8 vs 63.7), had a lower BMI (25.5 vs 26.3), were more symptomatic (NYHA≥3: 53.7% vs 36.7%), had better baseline kidney function (eGFR: 76.3 vs 84), higher preoperative left ventricular ejection fraction (65% vs 60%), more annuloplasty-only repairs (6.8% vs 0.9%), more concomitant tricuspid valve repair (21.8% vs 8.7%) and atrial septal defect repair (32.7% vs 19.5%), with shorter median cardiopulmonary bypass (131 min vs 142 min) and cross-clamp time (93 min vs 102 min). IPTW-adjusted 30-day outcomes, including death and MACE, were not significantly different between males and females. Unadjusted Kaplan-Meier curves for survival was significant, with a hazard-ratio of 0.41 (95% CI 0.20-0.84), favoring males. However, on IPTW-adjustment, hazard-ratio was not significant at 0.52 (95% CI 0.19-1.44). Both unadjusted and IPTW-adjusted Kaplan-Meier curves for freedom from mitral reintervention demonstrated no significant difference at follow-up between males or females.

Conclusion: Baseline preoperative and intraoperative differences were present between males and females prior to mitral valve repair, which could affect outcomes. In this cohort analysis, while there was a trend towards worse survival for women, after IPTW-adjusted analysis, there were no significant differences in 30-day or long-term outcomes based on sex.

Identify the source of the funding for this research project: N/A