Association of Baseline Mitral Valve Area With Procedural and Clinical Outcomes of Mitral Transcatheter Edge-to-Edge Repair: Insights From the OCEAN-Mitral Registry

BACKGROUND: A small mitral valve area (MVA) is one of the challenging anatomies for transcatheter edge-to-edge repair (TEER) for mitral regurgitation, but the relationship between baseline MVA and clinical outcomes remains unknown. This study aimed to evaluate the association of baseline MVA with procedural and clinical outcomes in patients undergoing TEER with MitraClip from the OCEAN-Mitral registry (Optimized Catheter Valvular Intervention-Mitral). METHODS: A total of 1768 patients undergoing TEER were divided into 3 groups according to baseline MVA: group 1: <4.0 cm 2 , n=358; group 2: 4.0–5.0 cm 2 , n=493; and group 3: ≥5.0 cm 2 , n=917. The primary end point was a composite of all-cause death and heart failure hospitalization within 2 years of TEER and compared between the 3 groups. RESULTS: Patients with smaller MVA had significantly fewer clips implanted and higher postprocedural transmitral mean pressure gradient. There was no significant difference in the acute procedural success rate and postprocedural mitral regurgitation severity between the 3 groups. The incidence of the primary end point was similar in group 1 compared with groups 2 and 3 (35.2% versus 34.5% versus 34.0%; P =0.96) and was also similar in patients with MVA <3.5 cm 2 and those with MVA 3.5 to 4.0 cm 2 . The adjusted risk of MVA <4.0 cm 2 relative to MVA of 4.0 to 5.0 cm 2 and MVA ≥5 cm 2 for the primary end point remained insignificant (hazard ratio, 1.06 [95% CI, 0.79–1.41]; P =0.68; hazard ratio, 0.99 [95% CI, 0.75–1.31]; P =0.96, respectively). At 1 year, no significant difference in the proportion of residual mitral regurgitation 3+/4+ was observed between the 3 groups (7.2% versus 4.4% versus 6.5%; P =0.49). CONCLUSIONS: In patients undergoing TEER, a small MVA <4.0 cm 2 may limit the number of clips implanted and increase the transmitral pressure gradient after TEER, but baseline MVA was not associated with mitral regurgitation reduction and clinical outcomes. REGISTRATION: URL: https://center6.umin.ac.jp/cgiope n-bin/ctr/ctr_view.cgi?recptno=R000027188 ; Unique identifier: UMIN000023653.