Quantitative Analysis of Mitral Valve Morphology in Mitral Valve Prolapse Using Real-Time Three-Dimensional Echocardiography: Importance of Annular Saddle-Shape in Pathogenesis of Mitral Regurgitation
Background—Few data exist regarding the relation of the 3-dimensional (3D) morphology of mitral valve and degree of mitral regurgitation (MR) in mitral valve prolapse (MVP).
Methods and Results—Real-time 3D transesophageal echocardiography of the mitral valve was acquired in 112 subjects including 36 patients with MVP and significant MR (≥3+; MR+ group), 32 patients with MVP but no or mild MR (≤2+; MR- group), 12 patients with significant MR due to non-prolapse pathologies (non-prolapse group), and 32 normal subjects. The 3D geometry of mitral valve apparatus was measured with dedicated quantification software. Compared to normal and MR- groups, MR+ group had more dilated mitral annulus (p<0.0001), reduced annular height-to-commissural width ratio (AHCWR) (p<0.0001) indicating flattening of annular saddle-shape, redundant leaflet surfaces (p<0.0001), greater leaflet billow volume (p<0.0001) and billow height (p<0.0001), longer lengths from papillary muscles to coaptation (p<0.0001), and more frequent chordal rupture (p<0.0001). Prevalence of chordal rupture increased progressively with annulus flattening (7% vs 24% vs 42% for AHCWR>20%, 15%~20%, and <15%, respectively; p=0.004). Leaflet billow volume increased exponentially with decreasing AHCWR in patients without chordal rupture (r2=0.66, p<0.0001). MR severity correlated strongly with leaflet billow volume (r2=0.74, p<0.0001) and inversely with AHCWR (r2=0.44, p<0.0001). In contrast, annulus dilatation but not flattening occurred in non-prolapse MR patients. An AHCWR<15% (odds ratio=7.1, p=0.0004) was strongly associated with significant MR in MVP.
Conclusions—Flattening of annular saddle-shape is associated with progressive leaflet billowing and increased frequencies of chordal rupture, and may be important in pathogenesis of MR in MVP.
- Received May 21, 2012.
- Accepted December 7, 2012.
- Copyright © 2012, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited