Transcatheter mitral valve replacement (TMVR) has emerged as a promising technique for the treatment of these patients with severe mitral valve disease and high or prohibitive surgical risk. Early experience with TMVR has shown a high rate of technical success and promising reductions in the severity of mitral regurgitation sustained out to 1 year post procedure. Despite this, procedural complications remain high, with the most common and significant of these being valve embolization, left ventricualr outflow tract (LVOT) obstruction and paravalvular leakage (PVL). It is this currently unanswered question that Morris et al. start to address in this issue of the Journal. They use the same annular segmentation and valve simulation as already proposed to predict LVOT obstruction, but use it to focus instead on examining the residual gap left between the base of the simulated transcatheter valve and the mitral leaflets or surgical prosthesis.