Abstract 11107: Impact of Annular Septal-Lateral Diameter on Mitral Leaflet Adaptation and Severity of Functional Mitral Regurgitation: Three-Dimensional Analysis with Computed Tomography
Background: It has been reported that chronic leaflet tethering causes the mitral leaflet area to adapt in patients with functional mitral regurgitation (FMR). However, little is known about the relationship between annular dimension and mitral leaflet adaptation. We sought to investigate the impact of annular septal-lateral (SL) diameter on the mitral leaflet adaptation and the severity of FMR using multislice computed tomography (MSCT).
Methods: We obtained volumetric MSCT images of mitral apparatus in 38 patients with prior myocardial infarction or dilated cardiomyopathy with moderate or severe FMR. 3D reconstruction was performed using the original software. After cropping the 3D data into 12 to 18 planes and marking the mitral annulus, leaflets, and papillary muscles, we measured annular SL diameter, commissure-commissure (CC) diameter, tenting volume, and closure area (the closed leaflet surface) in end-systole. We also assessed total leaflet area in end-diastole. The ratio of total leaflet area to closure area (TLA/ClosA) was calculated to evaluate the surplus of leaflet area. Patients were divided into two groups according to TML/ClosA: poor adaptation group (TLA/ClosA <1.1, n=19), good adaptation group (TLA/ClosA ≥1.1, n=19).
Results: Annular SL diameter was significantly increased in poor adaptation group compared with good adaptation group (3.1±0.5 cm versus 2.7±0.3 cm, P=0.004). However, there was no significant difference of annular CC diameter between the two groups (4.1±0.4 cm versus 3.8±0.5, P=NS). Annular SL diameter showed better correlation with TLA/ClosA (r=0.57, P<0.001) in all patients, compared with CC diameter (r=0.42, P<0.01). Annular SL diameter showed good correlation with tenting volume and vena contracta width (r=0.66, P<0.001, and r=0.50, P=0.001, respectively).
Conclusions: Increase of annular SL diameter has more impact on mitral leaflet adaptation compared with annular CC diameter, leading to excessive leaflet tethering and exacerbation of FMR. Our results suggest that shortening of SL diameter may improve loss of leaflet adaptation in patients with FMR.
- © 2011 by American Heart Association, Inc.