Moderate Ischemic Mitral Regurgitation with Ejection Fraction <40% Undergoing Concomitant Mitral Valve Repair during Revascularization: A Single-Center Observational Study

Background: Numerous studies have examined the therapeutic effects of mitral valve repair during revascularization on moderate ischemic mitral regurgitation (IMR), as well as the incremental benefit of subvalvular repair alongside an annuloplasty ring. However, the impact of depressed left ventricular (LV) function on the surgical outcome of patients with moderate IMR has been rarely investigated. The aims of this single-center, retrospective, observational study were firstly to evaluate short-and medium-term outcomes in this patient group after undergoing mitral valve repair during revascularization, and secondly to assess the impact of depressed LV function on surgical outcomes. Methods: A total of 272 eligible patients who had moderate IMR and underwent concomitant mitral valve repair and revascularization from January 2010 to December 2017 were included in the study. These patients were categorized into different groups based on their ejection fraction (EF) levels: an EF <40% group (n = 90) and an EF >= 40% group (n = 182). The median time course of follow-up was 42 months and the shortest follow-up time was 30 months. This study compared in-hospital outcomes (major postoperative morbidity and surgical mortality) as well as midterm outcomes (moderate or more mitral regurgitation, all-cause mortality, and reoperation) of the two groups before and after propensity score (PS) matching (1:1). Results: No significant difference was observed in surgical mortality between groups (8.9% vs. 3.3%, p = 0.076). More patients in the EF <40% group developed low cardiac output (8.9% vs. 2.7%, p = 0.034) and prolonged ventilation (13.3% vs. 5.5%, p = 0.026) compared to the EF >= 40% group. Propensity score (PS) matching successfully established 82 patient pairs in a 1:1 ratio. No significance was discovered between the matched cohorts in terms of major postoperative morbidity and surgical mortality, except for prolonged ventilation. Conditional mixed-effects logistic regression analysis revealed that EF <40% had an independent impact on prolonged ventilation (odds ratio (OR) = 2.814, 95% CI 1.321- 6.151, p = 0.031), but was not an independent risk factor for surgical mortality (OR = 2.967, 95% CI 0.712-7.245, p = 0.138) or other major postoperative morbidity. Furthermore, the two groups showed similar cumulative survival before (log-rank p = 0.278) and after (stratified log-rank p = 0.832) PS matching. Cox regression analysis suggested that EF <40% was not related to mortality compared with EF >= 40% (PS-adjusted hazard ratio (HR) =1.151, 95% CI 0.763-1.952, p = 0.281). Conclusions: Patients with moderate IMR and EF <40% shared similar midterm outcomes and surgical mortality to patients with moderate IMR and EF >= 40%, but received prolonged ventilation more often. Depressed LV function may be not associated with surgical or midterm mortality.