Elevated mitral valve pressure gradient following transcatheter edge-to-edge repair is independently associated with inferior outcomes in atrial, but not in ventricular secondary mitral regurgitation
Authors: Koell B , Stolz L , Weimann J , Xhepa E , Melica B , Iliadis C , Karam N , Neuss M , Petronio A S , Praz F , Metra M , Thiele H , Von Bardeleben R S , Hausleiter J , Kalbacher D 
Published: October 2024

Abstract

Background
In transcatheter mitral valve edge-to-edge repair (M-TEER), the goal of optimizing post-procedural residual mitral regurgitation inadvertently carries the risk of generating relevant mitral stenosis, resulting in an elevated mean mitral valve pressure gradient (MPG). In patients with primary mitral regurgitation, an elevated post-procedural MPG has been found to independently predict impaired outcomes. However, the effect of elevated post-procedural MPG on outcome after M-TEER in patients with secondary mitral regurgitation (SMR) has yet to be fully elucidated. This study investigated the impact of elevated MPG on outcome in the EuroSMR registry, a large, multi-center real-world cohort of patients with SMR.

Methods
This retrospective study included patients who underwent M-TEER for SMR between 2009 and 2021 in 12 centers. Patients were stratified into two groups based on SMR etiology: (1) ventricular SMR (vSMR), and (2) atrial SMR (aSMR). The etiology was considered as vSMR in patients with a left ventricular ejection fraction (LV-EF) &lt;50% and aSMR in subjects with preserved left ventricular function (LV-EF ≥50%) and a markedly dilated left atrium (Left Atrial Volume Index [LAVi] ≥40ml/m2). According to the proposed M-VARC threshold, post-procedural MPG was assessed by discharge transthoracic echocardiography and was considered elevated if &gt;5 mmHg. The primary endpoint was all-cause mortality after 5 years, with statistical analysis conducted using Kaplan-Meier and uni- and multivariable Cox Regression analysis.

Results
Among the 1703 patients in the study (vSMR: n=1420; aSMR: n=283), elevated post-procedural MPG was observed in 9.4% (n=133) of vSMR and 19.1% (n=54) of aSMR patients. Atrial fibrillation was significantly more prevalent in aSMR (78.4% vs. 57.1%, p&lt;0.001). Patients with vSMR had a higher median surgical risk assessed by the EuroScore II (aSMR vs. vSMR: 7.0% [IQR 4.0, 13.1] vs. 4.9% [IQR 2.9, 8.5], p&lt;0.001). Kaplan-Meier analyses for all-cause mortality after 5 years demonstrated significant differences in aSMR patients (low vs. elevated MPG: 48.9% vs. 69.8%, log-rank p&lt;0.01), while there was no difference in vSMR patients (55.7% vs. 60.8%, log-rank p=0.66) (Figure 1). This observed effect remained significant even after accounting for common confounding factors: elevated MPG was an independent predictor for all-cause mortality in aSMR patients (HR=1.86; 95%-CI: 1.14-3.02, p=0.013) but not in vSMR patients (HR=1.00; 95%-CI: 0.74-1.35, p=0.99).

Conclusion
Our findings suggest that elevated post-procedural MPG is an independent predictor of adverse outcomes in patients with aSMR, but not in those with vSMR. This effect may partially be explained by a reduced left atrial function and higher rates of atrial fibrillation.Figure 1.Study flowchart