Abstract 20063: Mitral Valve Alterations in Hypertrophic Cardiomyopathy Sarcomere Mutation Carriers Without Left Ventricular Hypertrophy
Introduction: Anatomic and imaging studies have shown that abnormal mitral valve (MV) morphology is present in patients with overt hypertrophic cardiomyopathy (HCM) compared to healthy controls. There is much less experience in evaluating the MV in HCM sarcomere mutation carriers without left ventricular hypertrophy (G+/LVH-).
Hypothesis: Structural abnormalities of the MV are an early phenotypic expression of HCM sarcomere mutations.
Methods: MV parameters were compared using transthoracic echocardiography in 80 G+/LVH- subjects and 66 healthy controls.
Results: Anterior leaflet length (ALL) and posterior leaflet length (PLL) were significantly longer in G+/LVH- subjects compared to controls when corrected for body surface area (BSA) or LV size (Table). However, absolute leaflet lengths were not significantly different between the cohorts. MV annular diameter at end-diastole and LV internal diameter at the level of the papillary muscles (LVIDd) were smaller among G+/LVH- subjects. A sarcomere mutation was associated with 0.04 ± 0.02 (p=0.02) and 0.05 ± 0.02 (p=0.001) respective increases in ALL:MV annulus and ALL:LVIDd ratios, after adjusting for age, gender, and BSA. Adjusted analyses did not demonstrate an association between mutation status and similar PLL-based ratios or leaflet thickness. Systolic anterior motion (SAM) of MV apparatus was more frequent among G+/LVH- subjects (15 versus 3%, p=0.02) but no subjects had obstruction.
Conclusion: MV leaflets are elongated relative to body size and LV cavity size in sarcomere mutation carriers without LVH. ALL is longer relative to MV annular and LV internal dimensions suggesting an intrinsic mismatch in leaflet length to cavity size in G+/LVH- subjects. SAM is also more prevalent compared to controls. These findings provide further support that structural abnormalities of the MV may precede LVH as part of the early phenotypic expression of HCM sarcomere mutations.
Author Disclosures: J.D. Groarke: None. N. Lakdawala: None. J.J. Thune: None. H. Bundgaard: None. R.A. Levine: None. C.Y. Ho: None.
- © 2014 by American Heart Association, Inc.