Newer versus Early Generation of the MitraClip for Primary Mitral Regurgitation: A Japanese Single-Center Experience

Abstract

Background: The MitraClip G4 system is the latest version of the transcatheter edge-to-edge repair (TEER) system for mitral regurgitation (MR). We aimed to investigate the impact of the new system on routine clinical practice and patient outcomes in the treatment of primary MR. Methods: Consecutive patients with primary MR who underwent TEER with either the MitraClip G2 or G4 between 2018 and 2021 were enrolled from a single center registry. Baseline clinical and echocardiographic characteristics as well as procedural and clinical outcomes up to 1 year were compared between groups. Technical and device success were defined in accordance with the Mitral Valve Academic Research Consortium criteria. Results: Among 71 patients with primary MR, 34 were treated with G2 and 37 were treated with G4. Patients treated with G4 had lower surgical risk (7.74 [5.04, 14.97] vs. 5.26 [3.98, 6.40]; p < 0.01) than those with G2. There were no significant differences in other baseline clinical variables between groups. On baseline echocardiography, MR volume and flail gap were significantly greater in the G4 group than in the G2 group (regurgitant volume: 63 [41–76] mL vs. 68 [62–84] mL; p = 0.04, flail gap: 4.5 [3.5–5.5] mm vs. 5.4 [4.5–7.1] mm; p = 0.04). Technical success was achieved in over 95% of both groups with no significant difference (p > 0.99). Device success was achieved in 61.8% of the G2 group, while in 70.3% of the G4 group (p = 0.47). Post-procedural MR severity was comparable (p = 0.42) and there was no significant difference in the occurrence of mitral stenosis (p = 0.61) between groups. Among patients who reached 1-year follow-up (n = 54), there was no significant difference between groups in a composite endpoint of death or heart failure rehospitalization (10.5% vs. 20.2%; HR 0.61; 95% CI 0.17–2.22; p = 0.45). Residual heart failure symptoms (NYHA ≥3) at 1 year were observed in 3.7% of the G2 group, while no patient in the G4 group (p > 0.99). Conclusions: The MitraClip G4 system achieved comparable device outcomes to the early-generation device (G2), despite treating more severe primary MR with a larger flail gap.