Mechanisms of Mitral Valve Repair Failure in a Redo Cohort: Association with Patient Characteristics and Initial Repair Features

Objective: Mitral valve repair failure encompasses heterogeneous anatomical patterns requiring redo surgery, yet the factors determining why repaired valves fail through different mechanisms remain poorly understood. We investigated the association of patient characteristics and index repair features with the anatomical mechanisms of failure among patients requiring redo surgery after degenerative mitral valve repair. Methods: We retrospectively reviewed all consecutive patients undergoing redo mitral valve surgery after previous degenerative mitral valve repair between January 2010 and June 2026. To minimize misclassification bias, only patients with complete operative documentation of the index repair and detailed intraoperative information regarding the mechanism of repair failure were included. Operative reports were reviewed to identify the reconstructive techniques used during the initial repair and the anatomical mechanism of failure at reoperation. To account for mutually exclusive clinical outcomes (prolapse recurrence and mitral stenosis), a competing-risks framework was employed. Results: A total of 121 patients constituted the study cohort. Recurrent leaflet prolapse was the most frequent mechanism of repair failure (71.6%) among patients with mitral regurgitation; mitral stenosis was present in 27.3% overall. Leaflet preservation versus resection, implantation of expanded polytetrafluoroethylene (ePTFE) neochordae, edge-to-edge repair, and annuloplasty ring size were not significantly associated with the anatomical mechanism of repair failure. In multivariable analysis, older age at the index operation was independently associated with recurrent prolapse, whereas younger age and female sex independently predicted the development of mitral stenosis. Within this redo cohort, no statistically significant association was observed between the recorded index repair features and the predominant anatomical mechanisms of failure after adjustment for patient characteristics. Conclusions: Among patients requiring redo surgery after degenerative mitral valve repair, the anatomical mechanisms of failure were associated with selected patient characteristics, whereas no significant association was observed with the recorded index repair features. These findings should be interpreted within the context of a selected redo population and do not support conclusions regarding the comparative durability of different repair strategies.