Left ventricular outflow tract area after percutaneous transseptal transcatheter mitral valve implantation: A three‐dimensional transesophageal echocardiography study

Abstract

Left ventricular (LV) outflow tract (LVOT) obstruction increases mortality in patients undergoing transcatheter mitral valve implantation (TMVI) in degenerated bioprostheses, annuloplasty rings, and native mitral valves. We aimed to evaluate the LVOT area after TMVI using 3-dimensional (3D) transesophageal echocardiography (TEE) and to investigate the preprocedural cardiac geometry that affects the LVOT area after TMVI. We retrospectively reviewed echocardiography data in 43 patients who had TMVI. A change in pressure gradient across LVOT from before to after TMVI (∆PG) and postprocedure 3D LVOT cross-sectional area at the level of the most distal portion of the mitral valve stent that was closest to the LV apex were assessed as evidence of LVOT narrowing. Transcatheter mitral valve implantation with the use of balloon-expandable valve system was performed for 24 bioprostheses, 7 annuloplasty rings, and 12 native valves. Compared to patients without increase in LVOT gradient (∆PG <10mm Hg; n=33), patients with increase in LVOT gradient (∆PG ≥10mm Hg; n=10) had smaller LV end-systolic volume (LVESV), greater LV ejection fraction (LVEF), and smaller aorto-mitral (AM) angle. The LVOT area at the valve stent distal edge showed strong association with ∆PG (r=-.68, P<.0001). Only a small AM angle was associated with a small LVOT area at the valve stent distal edge on multivariable analysis, independent of LVESV and LVEF. Small LV size, preserved LVEF, and small AM angle were associated with LVOT narrowing. 3D-derived AM angle might be independently associated with LVOT narrowing in patients undergoing transcatheter mitral valve-in-valve, valve-in-ring, and valve-in-native valve implantation, independent of LVESV and LVEF.