1-Year Outcomes of Fourth-Generation Mitral Transcatheter Edge-to-Edge Repair in Japan From the EXPAND G4 Study.

Background: The MitraClip (Abbott), a percutaneous edge-to-edge mitral valve (MV) repair device, is the only approved device in Japan for mitral transcatheter edge-to-edge repair (M-TEER) therapy to treat primary and secondary mitral regurgitation (MR). Outcomes of the fourth-generation M-TEER system, featuring independent grasping, improved clip deployment, and 4 clip sizes with wider and longer clip arms, have not been reported in Japan.

Objectives: This study evaluates the 1-year safety and effectiveness of the fourth-generation M-TEER system in Japan to treat MR in a contemporary, real-world setting.

Methods: EXPAND G4 is a prospective, single-arm, international, postmarket study. One-year outcomes from subjects treated in Japan include MR severity (assessed by an echocardiography core laboratory), all-cause mortality, heart failure hospitalization, NYHA functional class, and quality of life.

Results: A total of 95 subjects were treated with the fourth-generation M-TEER system at 7 centers in Japan. Subjects in Japan had a higher surgical risk with smaller cardiac dimensions and MV areas. A 100% implant rate was achieved with a large proportion of standard clips (NT/XT). At 1 year, there was significant and sustained MR reduction (99%, 77/78 MR ≤1+), with low MV mean gradients (2.9 ± 1.8 mm Hg) and improved functional capacity (96.2%, 75/78 NYHA functional class I/II). The 1-year rates of all-cause mortality and heart failure hospitalizations were 9.5% and 18.9%, respectively, with low major and device-related adverse event rates.

Conclusions: This first report of echocardiography core laboratory-assessed outcomes with the fourth-generation M-TEER system in Japan shows that excellent and durable technical and clinical outcomes can be achieved with M-TEER in Japan. (MitraClip EXPAND G4 Study; NCT04177394).