Background: Transcutaneous mitral valve repair (TMVR) using the edge-to-edge technique has become a treatment option for selected patients with severe mitral regurgitation. Clip devices with different sizes (XTR and NT or NTR device) have been developed for TMVR. 

 

Purpose: This study sought to compare the effect on procedural reduction of mitral regurgitation, decrease of mitral valve opening area (MVA) and changes of annulus geometry of the larger XTR and the smaller NT or NTR devices by 3-dimensional (3D) echocardiography analysis. 

 

Methods: 55 consecutive patients (age 76±7 years) with severe secondary mitral valve regurgitation undergoing TMVR with only one clip were included. In 30 of these 55 patients (55%) the smaller NT or NTR and in 25 patients (45%) the larger XTR MitraClip device (Abbott Vascular Structural Heart, Menlo Park, CA, USA) was implanted. Periprocedural 3D transesophageal echocardiography (TEE) was performed without and with color Doppler. Vena contracta area (VCA) was measured by 3D color Doppler TEE direct planimetry to define mitral regurgitation severity before and after TMVR. Mean pressure gradient was calculated by continuous-wave Doppler. MVA was assessed by 3D TEE direct planimetry to determine postprocedural stenosis. Finally, 3D TEE datasets were used to assess mitral annulus area, anterior-to-posterior diameter and posteromedial-to-anterolateral diameter for analysis of changes of mitral annulus geometry.

 

Results: In all patients, VCA by 3D color Doppler TEE was reduced from 0.53±0.29 cm² to 0.17±0.12 cm2 (p<0.0001) (Figure 1) and MVA from 5.9±2.1 cm² to 2.8±1.2 cm2 (p<0.0001) after TMVR (Figure 2, A-E). Relative reduction of mitral regurgitation severity was greater by the XTR compared to the NT/NTR device (Δ-VCA 71.9±17.1% vs. 61.5±16.1%; p=0.0252). There was no difference in postprocedural mean pressure gradient (2.9±1.2 mmHg vs. 3.4±2.0 mmHg; p=0.2658) and relative reduction of MVA (Δ-MVA 54.0±18.5% vs. 49.8±13.5%; p=0.3317) between the XTR and NT/NTR device. 

Mitral annulus area decreased after the procedure with the XTR device (from 11.4±2.4 cm² to 10.3±2.3 cm²; p=0.0006) and the NT/NTR device (from 9.9±2.9 cm² to 9.5±2.8 cm²; p<0.0001). The decrease of mitral annulus area was greater by the XTR compared with the NT/NTR device (1.1±1.4 cm² vs. 0.4±0.5 cm²; p=0.0194). Concordantly, there was greater decrease of the mitral annulus anterior-to-posterior diameter using the XTR compared with the NT/NTR device (-0.8±0.4 cm vs. -0.6±0.3 cm; p=0.0222) while there was no difference in change of the posteromedial-to-anterolateral diameter between the devices (0.2±0.3 cm vs. 0.3±0.3 cm; p=0.5261) (Figure 2, F-G). 

 

Conclusions: TMVR using the XTR device resulted in a greater reduction of mitral regurgitation severity compared with the NT or NTR device without increase of valve stenosis. There was a considerably greater change of mitral annulus geometry using the XTR device with a greater decrease of mitral annulus area and annulus anterior-to-posterior diameter using the XTR device compared with the NT or NTR device.