Transcatheter mitral-valve repair for functional mitral regurgitation data from the real-life in comparison with landmark randomized trials
Authors: Kaddoura R , Al-Badriyeh D B , Abushanab D A , Al-Hijji M A 
Published: October 2022

Abstract

Background
Publication of COAPT and MITRA-FR trials on the use of transcatheter mitral-valve repair (TMVR) for functional mitral regurgitation (MR) in 2018, has raised many questions due to their divergent results despite having similar objectives.

Purpose
To investigate the characteristics and outcomes of patients from real-life data who underwent TMVR for functional MR, in comparison with the two landmark trials.

Methods
A meta-analysis was performed according to Cochrane Handbook for Systematic Reviews and the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. A comprehensive systematic literature search was conducted to identify observational studies that enrolled patients with functional MR, published in 2020 and 2021. No further restrictions were implemented. Independent reviewers performed study selection, data extraction, risk-of-bias and quality-of-evidence assessments. Variables of interest were related to patient demographics, medications, echocardiogram parameters, and outcomes. Patient variables from observational studies were compared with those reported in randomized trials, using a random-effects model for each variable. Mean difference (MD) and odds ratio (OR), with 95% confidence intervals (95% CI), were used to compare continuous and categorical data, respectively. Variables that were not reported in both COAPT and MITRA-FR trials were not presented. R software was used for non-comparative pooling of variables, and RevMan software was used for comparative meta-analysis.

Results
Thirty-two studies, enrolling 9497 patients, were included. Patients were found to be older in real-life than in landmark trials ([MD −2.73; 95% CI: −4.06, −1.40] for COAPT; [MD −4.33; 95% CI: −5.94, −2.72] for MITRA-FR), while more males were recruited in MITRA-FR trial (OR 1.71; 95% CI: 1.15–2.52). Moreover, patients in MITRA-FR trial were less likely to have atrial fibrillation or renal insufficiency. Patients from real-life were more likely to be more symptomatic (i.e., New York Heart Association (NYHA) class III/IV) and less likely to have implanted cardiac devices than those in randomized trials. MITRA-FR trial patients had better compliance with guideline-directed therapies for heart failure with reduced ejection fraction. Ejection fraction ranged from 31.3% to 33.9% between three study arms. More patients in randomized trials presented with moderate-to-severe MR (grade 3+), whereas severe MR (grade 4+) was more common among patients from real-life. Procedure success, defined as MR grade ≤2+, was more frequent in randomized trials, with better symptoms' relief in COAPT trial (NYHA class I/II). There was no difference in number of devices implanted between real-life and landmark trials data. [Tables 1 and 2]

Conclusion
Real-life data on TMVR in functional MR, as presented by low-quality and heterogenous observational studies, showed substantial differences from the results of the main randomized trials.

Funding Acknowledgement
Type of funding sources: None.