3D Echo Characterization of Proportionate and Disproportionate Functional Mitral Regurgitation before and after Percutaneous Mitral Valve Repair

Abstract

Background: The impact of percutaneous mitral valve repair (PMVr) on long-term prognosis in patients with functional mitral regurgitation (FMR) is still unclear. Recently, a new conceptual framework classifying FMR as proportionate (P-MR) and disproportionate (D-MR) was proposed, according to the effective regurgitant orifice area/left ventricular end-diastolic volume (EROA/LVEDV) ratio. The aim was to assess its possible influence on PMVr efficacy.

Methods: A total of 56 patients were enrolled. MV annulus, LV volumes and function were assessed. Global longitudinal strain (GLS) was also calculated. Patients were divided into two groups, according to the EROA/LVEDV ratio. Echocardiographic follow-up was performed after 6 months, and adverse events were collected after 12 months.

Results: D-MR patients (n = 28, 50%) had a significantly more elliptical MV annulus (p = 0.048), lower tenting volume (p = 0.01), higher LV ejection fraction (LVEF: 32 ± 7 vs. 26 ± 5%, p = 0.003), lower LVEDV, LV end-systolic volume (LVESV) and mass (LVEDV/i: 80 ± 20 vs. 126 ± 27 mL, p = 0.001; LVESV/i: 60 ± 20 vs. 94 ± 23 mL, p < 0.001; LV mass: 249 ± 63 vs. 301 ± 69 gr, p = 0.035). GLS was more impaired in P-MR (p = 0.048). After 6 months, P-MR patients showed a higher rate of MR recurrence. After 12 months, the rate of CV death and rehospitalization due to HF was significantly higher in P-MR patients (46% vs. 7%, p < 0.001). P-MR status was strongly associated with CV death/rehospitalization (HR = 3.4, CI 95% = 1.3-8.6, p = 0.009).

Conclusions: Patients with P-MR seem to have worse outcomes after PVMr than D-MR patients. Our study confirms the importance of the EROA/LVEDV ratio in defining different subsets of FMR based on the anatomical characteristic of MV and LV.

Keywords: EROA/LVEDV ratio; MitraClip; PMVr; disproportionate MR; functional mitral regurgitation.

Figure 1

(A) Mitral valve quantification analysis: an example of MVQ analysis showing bi-commissural view (upper-left box), left ventricular outflow tract view (upper-right box), MV annulus in short axis (lower-left box) and 3D reconstruction of the MV annulus and leaflets (lower-right box). (B1) Three-dimensional (3D) reconstruction of the MV annulus and leaflets in D-MR patients, where the green area represents the tenting volume; (B2). Three-dimensional (3D) reconstruction of the MV annulus and leaflets in P-MR patients, where the green area represents the tenting volume, which is higher if compared with D-MR and labeled by a big white arrow.

Figure 2

(A) Dynamic heart model analysis in D-MR patients, with LVEF of 35% and LVEDV of 205 mL. (B) Dynamic heart model analysis in P-MR patient with a severely dilated LV, LVEF of 27% and LVEDV of 480 mL.

Figure 3

(A) Differences in mean LVEDV and LVESV between D-MR and P-MR patients, where p < 0.001 in both cases. (B) Differences in mean tenting height and tenting volume between D-MR and P-MR patients, where p = 0.01 in both cases. Box plots represent median, quartiles and extremes, and while circles represent the outliers.

Figure 4

Survival analysis (Kaplan–Meier curves) for cardiovascular (CV) death and rehospitalization for HF. All curves show the 1-year event probability (expressed as 1—cumulative survival). (A) Factor: P-MR and D-MR status. (B) Factor: median value of LVEDV/I (mL/m²). (C) Factor: median value of PASp (mmHg) (D) Factor: median value of tenting volume (mL).