Effects of Mitral Annulus Remodeling Following MitraClip Procedure on Reduction of Functional Mitral Regurgitation

Changes in mitral valve geometry after percutaneous valve repair with the MitraClip® System

The aim of our study was to assess the anatomical changes of the mitral valve apparatus after percutaneous repair with the MitraClip® system. We included consecutive patients who underwent MitraClip® implantation in our center. Patients were assessed by 2- and 3-dimensional transesophageal echocardiography, acquired before and immediately after MitraClip® implantation. Off-line images analysis was performed to assess mitral annular diameters (antero-posterior and inter-commisural), area and circumference. Mitral tenting distance, area and volume were evaluated for functional mitral regurgitation. Patients had a 2-dimensional transthoracic echocardiography at follow-up (8 months). 38 patients with successful results (residual mitral regurgitation grade ≤ II) were included. The anteroposterior annulus diameter (ADP) decreased (from 35 ± 5 to 28 ± 5 mm, p < 0.001) with smaller decreases in the annular area and circumference and in the inter-commissural diameter. Annular ellipticity improved. The reduction in APD and tenting distance was sustained at follow-up. Successful percutaneous mitral valve repair with the MitraClip® system induces a stable change in mitral valve geometry mainly at the ADP, suggesting a significant annuloplasty that contributes to the reduction of mitral regurgitation.

Functional mitral regurgitation: structural modifications with percutaneous valve repair with MitraClip

Background

Mitral regurgitation (MR) is one of the most prevalent valvular diseases in our society. Transcatheter mitral valve repair (TMVR) with the MitraClip^® system is increasingly used for treating this condition. The aim of our study is to analyse morphological mitral valve changes related to the procedure and its correlation with the degree of regurgitation at mid-term follow-up and with the combined endpoint of heart failure and all-cause mortality.

Methods

A single-centre, prospective and observational study including consecutive patients admitted between October 2015 and October 2019 for TMVR was designed. The mitral valve annulus (MVA) was analyzed using the three-dimensional MVQ QLAB mitral valve quantification software (Philips; Amsterdam, The Netherlands). Clinical data was collected retrospectively.

Results

Eighty-two MitraClip^® were implanted. Control echocardiograms showed a significant decrease in the three measures: annular diameters, perimeter and area. Patients with functional MR had greater left ventricular and mitral annular dimensions and experienced greater reductions in anteroposterior diameter and mitral valve area compared with organic MR patients. The anteroposterior diameter reduction (OR 0.90; 95% CI: 0.82–0.99), as well as posterior leaflet grasping (OR 0.94; 95% CI: 0.89–0.99) were associated with the probability of significant MR recurrence. Posterior leaflet grasping and left ventricle ejection fraction were associated with the combined endpoint of heart failure and any cause death.

Conclusions

MitraClip^® implantation results in secondary changes in the mitral annular morphology. The magnitude of these morphological changes varies depending on the etiology of the mitral valve regurgitation. Posterior leaflet grasping and anteroposterior diameter reduction after clip are factors associated with relevant clinical and echocardiographic endpoints.

Mechanical effects of MitraClip on leaflet stress and myocardial strain in functional mitral regurgitation - A finite element modeling study

Purpose

MitraClip is the sole percutaneous device approved for functional mitral regurgitation (MR; FMR) but MR recurs in over one third of patients. As device-induced mechanical effects are a potential cause for MR recurrence, we tested the hypothesis that MitraClip increases leaflet stress and procedure-related strain in sub-valvular left ventricular (LV) myocardium in FMR associated with coronary disease (FMR-CAD).

Methods

Simulations were performed using finite element models of the LV + mitral valve based on MRI of 5 sheep with FMR-CAD. Models were modified to have a 20% increase in LV volume (↑LV_VOLUME) and MitraClip was simulated with contracting beam elements (virtual sutures) placed between nodes in the center edge of the anterior (AL) and posterior (PL) mitral leaflets. Effects of MitraClip on leaflet stress in the peri-MitraClip region of AL and PL, septo-lateral annular diameter (SLAD), and procedure-related radial strain (E_rr) in the sub-valvular myocardium were calculated.

Results

MitraClip increased peri-MitraClip leaflet stress at end-diastole (ED) by 22.3±7.1 kPa (p<0.0001) in AL and 14.8±1.2 kPa (p<0.0001) in PL. MitraClip decreased SLAD by 6.1±2.2 mm (p<0.0001) and increased E_rr in the sub-valvular lateral LV myocardium at ED by 0.09±0.04 (p<0.0001)). Furthermore, MitraClip in ↑LV_VOLUME was associated with persistent effects at ED but also at end-systole where peri-MitraClip leaflet stress was increased in AL by 31.9±14.4 kPa (p = 0.0268) and in PL by 22.5±23.7 kPa (p = 0.0101).

Conclusions

MitraClip for FMR-CAD increases mitral leaflet stress and radial strain in LV sub-valvular myocardium. Mechanical effects of MitraClip are augmented by LV enlargement.