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

B. Köll (Hamburg)¹, L. Stolz (München)², J. Weimann (Hamburg)¹, M. Kassar (Bern)³, M. Neuß (Bernau bei Berlin)⁴, A. Petrescu (Mainz)⁵, C. Iliadis (Köln)⁶, M. Unterhuber (Leipzig)⁷, M. Adamo (Brescia)⁸, C. Giannini (Pisa)⁹, B. Melica (Porto)¹⁰, M. Spieker (Düsseldorf)¹¹, M. Joner (München)¹², E. Xhepa (München)¹², S. Ludwig (Hamburg)¹, S. Massberg (München)², F. Praz (Bern)³, R. Pfister (Köln)⁶, H. Thiele (Leipzig)⁷, R. S. von Bardeleben (Mainz)¹³, S. Baldus (Köln)¹⁴, C. Butter (Bernau bei Berlin)⁴, P. Lurz (Mainz)¹⁵, S. Windecker (Bern)³, M. Metra (Brescia)⁸, A. S. Petronio (Pisa)¹⁶, J. Hausleiter (München)², D. Kalbacher (Hamburg)^17
1Universitäres Herz- und Gefäßzentrum Hamburg Klinik für Kardiologie Hamburg, Deutschland; ²LMU Klinikum der Universität München Medizinische Klinik und Poliklinik I München, Deutschland; ³Inselspital - Universitätsspital Bern Universitätsklinik für Kardiologie Bern, Schweiz; ⁴Immanuel Klinikum Bernau Herzzentrum Brandenburg / Kardiologie Bernau bei Berlin, Deutschland; ⁵Universitätsmedizin der Johannes Gutenberg-Universität Mainz Zentrum für Kardiologie Mainz, Deutschland; ⁶Herzzentrum der Universität zu Köln Klinik III für Innere Medizin Köln, Deutschland; ⁷Herzzentrum Leipzig - Universität Leipzig Klinik für Innere Medizin/Kardiologie Leipzig, Deutschland; ⁸University of Brescia Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health Brescia, Italien; ⁹AOUP - Azienda Ospedaliero Universitaria Pisana S.D. Emodinamica Pisa, Italien; ¹⁰Centro Hospitalar Vila Nova de Gaia/Espinho Porto, Portugal; ¹¹Universitätsklinikum Düsseldorf Klinik für Kardiologie, Pneumologie und Angiologie Düsseldorf, Deutschland; ¹²Deutsches Herzzentrum München Klinik für Herz- und Kreislauferkrankungen München, Deutschland; ¹³Universitätsmedizin der Johannes Gutenberg-Universität Mainz Zentrum für Kardiologie im Herz- und Gefäßzentrum Mainz, Deutschland; ¹⁴Herzzentrum der Universität zu Köln Klinik für Kardiologie, Angiologie, Pneumologie und Internistische Intensivmedizin Köln, Deutschland; ¹⁵Universitätsmedizin der Johannes Gutenberg-Universität Mainz Kardiologie 1, Zentrum für Kardiologie Mainz, Deutschland; ¹⁶University of Pisa Pisa, Italien; ¹⁷Universitäres Herz- und Gefäßzentrum Hamburg Allgemeine und Interventionelle Kardiologie Hamburg, Deutschland

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) <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 >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<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<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<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 and Kaplan Meier analyses for all-cause mortality after 5 years according to SMR etiology.