Outcomes of mitral valve surgery for nonischemic ventricular functional mitral regurgitation.

OBJECTIVE: This study aimed to assess the outcomes of mitral valve surgery for nonischemic ventricular functional mitral regurgitation (left ventricular ejection fraction ≤ 40%). METHODS: Study subjects were identified from the Japan Cardiovascular Surgery Database. Early and late mortality were assessed relative to established risk models. The extent of postoperative left ventricular reverse remodeling was also investigated. RESULTS: A total of 131 patients were categorized into four groups: mitral valve repair alone (n = 25), mitral valve repair with subvalvular procedures (n = 18), mitral valve replacement alone (n = 81), and mitral valve replacement with subvalvular procedures (n = 7). Estimated operative mortality was 5.9%, 5.5%, 12.8%, and 11.6% for each group, while observed mortality was 8.0%, 16.7%, 11.1%, and 0% (corresponding to observed-to-estimated ratio of 1.36, 3.03, 0.87, and 0.00, respectively). Observed 2-year mortality rates were 19.5%, 25.6%, 24.5%, and 16.7% for each group, and were lower than the corresponding estimated mortality across all groups. Subvalvular procedures were associated with greater postoperative left ventricular reverse remodeling. Furthermore, papillary muscle suspension was associated with lower operative mortality (observed-to-estimated ratio = 0.77 vs. 4.03 without suspension), whereas papillary muscle approximation was not. CONCLUSIONS: Given the favorable risk-adjusted outcomes and postoperative reverse remodeling, mitral valve surgery, particularly when combined with a subvalvular procedure, remains a feasible option for patients with nonischemic VFMR even in the era of catheter-based treatment.