Transcatheter mitral valve implantation (TMVI) has emerged as an alternative to surgery in high risk patients with failing mitral bioprosthesis or annuloplasties.

The presence of an elevated mean gradient>5mmHg after the procedure has been defined as an unsuccessful procedure but the impact and outcomes of an elevated mean gradient after TMVI have not been studied.

In all, 175 patients undergoing TMVI from 2010 to 2024 were included. Patients were classified in three groups according to mean gradient after the procedure: group 1<5mmHg, group 2 between 5 and 10mmHg and group 3≥10mmHg.

The median age was 69 (52.5–80) years. Indications for TMVI were bioprosthesis failure in 131 patients (74.9%) and ring annuloplasty failure in 44 patients (25.1%). 155 (88.6%) patients were in NYHA class III or IV. Fifty patients were in group 1, 111 in group 2 and 14 in group 3, without any difference in baseline characteristics (except for age [P=0.02]) or procedural findings. At 30 days, the rates of all-cause mortality (respectively 2.6%, 0% and 0%, P=0.3), rehospitalization for heart failure (respectively 7,7%, 7.4% and 20%, P=0.62), paravalvular leak (4.6%, 16.8%, 20%, P=0.41), LVOT obstruction (respectively 0%, 2.1% and 10%, P=0.48) or valve thrombosis (respectively 11.6%, 4.2% and 0%, P=0.48) were similar in the three groups. At a median follow-up of 3 years, 43 patients have died (35 for cardiovascular reasons) with a cumulative rate of all-cause mortality at 1, 2 and 3 years of 18.7%, 19.2% and 25.4% respectively. An elevated mean gradient was associated with increased risk of cardiovascular mortality with a HR of 1.16 (1.03–1.31, P=0.02, Fig. 1). An improvement of NYHA class was observed in the two groups with mean gradient<10mmHg at one month and one year (P<0.01) compared to baseline without any difference for the group 3. At one year, median systolic pulmonary arterial pressure also significantly improved in group 1 (from 50mmHg (43–65) in baseline to respectively 45mmHg (36–55), P<0.01), in group 2 (from 55mmHg [45–70] in baseline to 41mmHg [35–55], P<0.01]) without improvement in group 3 (from 55mmHg (50–62) to 51mmHg (35–58), P=1).

An elevated mean gradient post-TMVI≥10mmHg was associated with cardiovascular mortality up to 3 years and without significant functional improvement. Further studies with longer follow up are necessary.