Update on surgical repair in functional mitral valve regurgitation.

Background: Functional mitral regurgitation (FMR) is common in patients with myocardial infarction or dilated cardiomyopathies, and portends a poor prognosis despite guideline-directed medical therapy. Surgical or transcatheter mitral repair for FMR from recent randomized clinical trials showed disappointing or conflicting results. Aims: To provide an update on the role of surgical repair in the management of FMR. Materials & Methods: A literature search was conducted utilizing PubMed, Ovid, Web of Science, Embase and Cochrane Library. The search terms included secondary/functional mitral regurgitation, ischemic mitral regurgitation, mitral repair, mitral replacement, mitral annuloplasty, transcatheter mitral repair, and percutaneous mitral repair. Randomized clinical trials over the past decade were the particular focus of this current review. Results: Recent data underlined the complexity and poor prognosis of FMR. Guideline-directed medical therapy and cardiac resynchronization, when indicated, should always be applied. Accurate assessment of the interplay between ventricular geometry and mitral valve function is essential to differentiate proportionate FMR from the disproportionate subgroup, which could be helpful in selecting appropriate transcatheter intervention strategies. Surgical repair, most commonly performed with an undersized ring annuloplasty, remains controversial. Adjunctive valvular or subvalvular repair techniques are evolving and may produce improved results in selected FMR patients. Conclusion: FMR resulted from complex valve-ventricular interaction and remodeling. Distinguishing proportionate FMR from disproportionate FMR is important in exploring their underlying mechanisms and to guide medical treatment with surgical or transcatheter interventions. Further studies are warranted to confirm the clinical benefit of appropriate surgical repair in selected FMR patients.