Transcatheter Edge-to-Edge Repair in Proportionate Versus Disproportionate Functional Mitral Regurgitation.

Background: Functional mitral regurgitation (FMR) can be subclassified on the basis of its proportionality relative to left ventricular (LV) volume and function, indicating potential differences in underlying etiology. The aim of this study was to evaluate the association of FMR proportionality with FMR reduction, heart failure hospitalization and mortality after transcatheter edge-to-edge mitral valve repair (TEER).
Methods: This multicenter registry included 241 patients with symptomatic heart failure with reduced LV ejection fraction treated with TEER for moderate to severe or greater FMR. FMR proportionality was graded on preprocedural transthoracic echocardiography using the ratio of the effective regurgitant orifice area to LV end-diastolic volume. Baseline characteristics, follow-up transthoracic echocardiography, and 2-year clinical outcomes were compared between groups.
Results: Median LV ejection fraction, effective regurgitant orifice area and LV end-diastolic volume index were 30% (interquartile range [IQR], 25%-35%), 27 mm ² , and 107 mL/m ² (IQR, 90-135 mL/m ² ), respectively. Median effective regurgitant orifice area/LV end-diastolic volume ratio was 0.13 (IQR, 0.10-0.18). Proportionate FMR (pFMR) and disproportionate FMR (dFMR) was present in 123 and 118 patients, respectively. Compared with patients with pFMR, those with dFMR had higher baseline LV ejection fractions (median, 32% [IQR, 27%-39%] vs 26% [IQR, 22%-33%]; P < .01). Early FMR reduction with TEER was more pronounced in patients with dFMR (odds ratio, 0.45; 95% CI, 0.28-0.74; P < .01) than those with pFMR, but not at 12 months (odds ratio, 0.93; 95% CI, 0.53-1.63; P = .80). Overall, in 35% of patients with initial FMR reduction after TEER, FMR deteriorated again at 1-year follow-up. Rates of 2-year all-cause mortality and heart failure hospitalization were 30% (n = 66) and 37% (n = 76), with no differences between dFMR and pFMR.
Conclusions: TEER resulted in more pronounced early FMR reduction in patients with dFMR compared with those with pFMR. Yet after initial improvement, FMR deteriorated in a substantial number of patients, calling into question durable mitral regurgitation reductions with TEER in selected patients. The proportionality framework may not identify durable TEER responders.
(Copyright © 2021 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.)