Predictors of Left Ventricular Outflow Tract Obstruction After Transcatheter Mitral Valve Replacement

Abstract

Objectives: The aim of this study was to evaluate the predictors of left ventricular outflow tract (LVOT) obstruction after transcatheter mitral valve replacement (TMVR).

Background: LVOT obstruction is a major concern with TMVR, but limited data exist regarding its predictors and impact on outcomes.

Methods: Patients with pre-procedural multidetector row computed tomography (MDCT) undergoing TMVR for failed mitral bioprosthetic valves (valve-in-valve), annuloplasty rings (valve-in-ring), and mitral annular calcification (valve-in-MAC) were included in this study. Echocardiographic and procedural characteristics were recorded, and comprehensive assessment with MDCT was performed to identify the predictors of LVOT obstruction (defined as an increment of mean LVOT gradient ≥10 mm Hg from baseline). The new LVOT (neo-LVOT) area left after TMVR was estimated by embedding a virtual valve into the mitral annulus on MDCT, simulating the procedure.

Results: Among 194 patients with pre-procedural MDCT undergoing TMVR (valve-in-valve, 107 patients; valve-in-ring, 50 patients; valve-in-MAC, 37 patients), LVOT obstruction was observed in 26 patients (13.4%), with a higher rate after valve-in-MAC than valve-in-ring and valve-in-valve (54.1% vs. 8.0% vs. 1.9%; p < 0.001). Patients with LVOT obstruction had significantly higher procedural mortality compared with those without LVOT obstruction (34.6% vs. 2.4%; p < 0.001). Receiver-operating characteristic curve analysis showed that an estimated neo-LVOT area ≤1.7 cm² predicted LVOT obstruction with sensitivity of 96.2% and specificity of 92.3%.

Conclusions: LVOT obstruction after TMVR was associated with higher procedural mortality. A small estimated neo-LVOT area was significantly associated with LVOT obstruction after TMVR and may help identify patients at high risk for LVOT obstruction.

Keywords: annuloplasty ring; degenerated bioprosthesis; left ventricular outflow tract obstruction; mitral annular calcification; mitral valve; transcatheter valve implantation.