Transcatheter mitral valve repair in proportionate and disproportionate functional mitral regurgitation—insights from a small cohort study

Background Functional mitral regurgitation (FMR) can be subclassified based on its proportionality relative to left ventricular function and end-diastolic volume. FMR proportionality could help identify responders to transcatheter edge-to-edge mitral valve repair (MitraClip) in terms of residual FMR and/or clinical improvement. Methods This single-centre retrospective cohort study evaluated the feasibility of determining FMR proportionality in symptomatic heart failure patients with reduced left ventricular function who were treated with MitraClip for ≥ moderate-to-severe FMR. Baseline proportionate (pFMR) and disproportionate FMR (dFMR) were distinguished. Patient characteristics and MitraClip procedural outcomes were described. Results From an overall cohort of 81 eligible FMR patients, 23/81 (28%) had to be excluded due to missing transthoracic echocardiogram parameters, 22/81 were excluded based on FMR severity. The remaining cohort, of 36/81 patients (44%), could be classified into dFMR ( n = 26) or pFMR ( n = 10). Conduction disorders were numerically increased in dFMR. All cases requiring > 2 clips were in the dFMR group and absence of FMR reduction occurred more frequently with dFMR. Point of view/Conclusion Important limitations in terms of imaging acquisition affect the translation of the FMR proportionality concept to a real-world data set. We did observe different demographic and FMR response patterns in patients with proportionate and disproportionate FMR that warrant further investigation.