Dynamic annular geometry and function in patients with mitral regurgitation: Insight from three-dimensional annular tracking

Background: Real-time three-dimensional (3D) echocardiography and unique software permit mitral annular (MA) tracking throughout systole to assess MA remodeling and function. Whether MA structure and function are altered differently depending on the etiology of mitral regurgitation (MR) is currently not known. Methods: We evaluated dynamic MA characteristics in patients with significant MR secondary to mitral valve prolapse and functional MR and compared them with normal controls. Novel 3D tracking software (based on 3D optical flow combined with block matching) was used to identify 16 circumferential equidistant MA points and to track changes in MA area and apical descent from end-diastole to end-systole. Twenty-eight patients with at least moderate MR and 15 normal controls underwent complete transthoracic two-dimensional and quantitative Doppler studies with 3D full-volume MA imaging from the apical 4-chamber view. Results: For each group studied, left ventricular size, systolic function, and dynamic MA characteristics were characterized. Patients with functional MR demonstrated end-diastolic MA area enlargement with reduced systolic area change and reduced apical descent (11.1 ± 2.7 cm ², 13 ± 5%, and 6 ± 2 mm, respectively) compared with normal controls (9 ± 2 cm², 26 ± 8%, 11 ± 2 mm, respectively) (P < .05). In comparison, patients with prolapse MR demonstrated the largest end-diastolic MA areas with preserved annular area change and only mild reduction of apical descent (16.1 ± 3.5 cm ², 21 ± 6%, and 9 ± 3 mm; P < .05 for area change and apical descent compared with normal). This finding suggests that the pathophysiology of mitral leaflet prolapse may involve significant MA remodeling without deterioration of dynamic MA function. Conclusion: Patients with MR have significant MA enlargement, irrespective of MR etiology. In contrast to functional MR, patients with MR secondary to leaflet prolapse have the largest annular remodeling - almost 80% increase in area - and yet have preserved annular function and dynamicity. These findings may influence surgical repair technique.