Abstract 9177: Mitral Valve Adaptation in Chronic Aortic Regurgitation with Preserved Systolic Function: A Three-Dimensional Echocardiographic Study
Introduction: Chronic aortic regurgitation (AR) causes left ventricular (LV) remodeling and ultimately heart failure. This creates the potential for functional mitral regurgitation (MR) caused by papillary muscle displacement and mitral valve tethering. However, MR is typically absent during the compensated stage of AR despite substantial LV dilatation. Increased mitral leaflet area has been identified in ischemic and non-ischemic heart failure. It is unknown whether increased mitral valve size could represent a compensatory mechanism capable of preventing MR in patients with LV dilatation due to chronic AR.
Hypothesis: Chronic AR is associated with mitral valve enlargement and this can prevent functional MR in patients with LV dilatation. Our objective is to compare mitral valve leaflet area in patients with chronic AR and preserved systolic function to that of normal patients using 3D-echocardiography.
Methods: From January to April 2011, we prospectively enrolled 44 patients (22 with at least moderate aortic regurgitation and 22 controls). 3D echocardiograms were performed to assess mitral valve geometry including total diastolic leaflet area measured by a previously validated method.
Results: Both groups had normal ejection fraction (60 ± 7 % in AR vs 63 ± 7 % in normals, p=0.17). Only 1 AR patient had significant (more than mild) functional MR. LV volume by 3D echocardiography was significantly larger in the AR group (LV end-diastolic volume index: 80 ± 23 cm3/m2 vs 49 ± 12 cm3/m2, p<0.01). The mitral valve leaflet area indexed for body surface area was significantly increased in the AR group (8.9 ± 1.7 cm2/m2 vs 7.4 ± 1.2 cm2/m2, p<0.01). Patients with AR also had increased mitral leaflet thickness (2.3 ± 0.3 mm vs 2.0 ± 0.3 mm, p<0.01) regardless of AR jet impact on the valve. Mitral valve leaflet area significantly correlated with LV end-diastolic LV volume (p<0.01).
Conclusion: Mitral valve leaflet area and thickness are significantly increased in patients with chronic AR and preserved ejection fraction. Area enlargement is proportional to LV volume, and can potentially explain why functional MR is uncommon in this population. Understanding the mechanisms underlying this adaptation could lead to new therapeutic interventions for functional MR.
- © 2011 by American Heart Association, Inc.