Impact of Proportionality of Secondary Mitral Regurgitation on Outcome After Transcatheter Mitral Valve Repair

Objectives: The purpose of this paper was to evaluate the impact of proportionality of secondary mitral regurgitation (SMR) in a large real-world registry of transcatheter edge-to-edge mitral valve repair (TMVr) BACKGROUND: Differences in the outcomes of recent randomized trials of TMVr for SMR may be explained by the proportionality of SMR severity to left ventricular (LV) volume.

Methods: The ratio of pre-procedural effective regurgitant orifice area (EROA) to LV end-diastolic volume (LVEDV) was retrospectively assessed in patients undergoing TMVr for severe SMR between 2008 and 2019 from the EuroSMR registry. A recently proposed SMR proportionality scheme was adapted to stratify patients according to EROA/LVEDV ratio in 3 groups: MR-dominant (MD), MR-LV-co-dominant (MLCD), and LV-dominant (LD). All-cause mortality was assessed as a primary outcome, secondary heart failure (HF) outcomes included hospitalization for HF (HHF), New York Heart Association (NYHA) functional class, N-terminal pro-B-type natriuretic peptide (NT-proBNP), 6-min-walk distance, quality of life and MR grade.

Results: A total of 1,016 patients with an EROA/LVEDV ratio were followed for 22 months after TMVr. MR was reduced to grade ≤2+ in 92%, 96%, and 94% of patients (for MD, MLCD, and LD, respectively; p = 0.18). After adjustment for covariates including age, sex, diabetes, kidney function, body surface area, LV ejection fraction, and procedural MR reduction (grade ≤2+), adjusted rates of 2-year mortality in MD patients did not differ from those for MLCD patients (17% vs. 18%, respectively), whereas it was higher in LD patients (23%; p = 0.02 for comparison vs. MD+MLCD). The adjusted first HHF rate differed between groups (44% in MD, 56% in MLCD, 29% in LD; p = 0.01) as did the adjusted time for first death or HHF rate (66% in MD, 82% in MLCD, 68% in LD; p = 0.02). Improvement of NYHA functional class was seen in all groups (p < 0.001). Values for 6-min-walk distances, quality of life and NT-proBNP improved in most patients.

Conclusions: MD and MLCD patients had a comparable, adjusted 2-year mortality rate after TMVr which was slightly better than that of LD patients. Patients treated with TMVr had symptomatic improvement regardless of EROA/LVEDV ratio.