2.1 Study population
We reviewed 48 patients who had TMVI with balloon-expandable transcatheter valve systems using Sapien family valves (Sapien XT or Sapien 3; Edwards Lifesciences, Irvine, California) under real-time 3D TEE guidance between March 2014 and October 2018 at Cedars-Sinai Smidt Heart Institute (Los Angeles, California, U.S.A.). Among them, 4 patients with concomitant transcatheter aortic valve replacement (3 for aortic stenosis and 1 for aortic regurgitation) were excluded because it was difficult to assess the change in LVOT gradient from before to after the TMVI procedure using continuous wave Doppler, and 1 with suboptimal image quality were also excluded. A total of 43 patients were included in this study. This study was approved by the Cedars-Sinai institutional review board.