Relation of mitral valve morphology and motion to mitral regurgitation severity in patients with mitral valve prolapse

BACKGROUND Mitral valve thickness is used as a criterion to distinguish the classical from the non-classical form of mitral valve prolapse (MVP). Classical form of MVP has been associated with higher risk of mitral regurgitation (MR) and concomitant complications. We sought to determine the relation of mitral valve morphology and motion to mitral regurgitation severity in patients with MVP. METHODS We prospectively analyzed transthoracic echocardiograms of 38 consecutive patients with MVP and various degrees of MR. In the parasternal long-axis view, leaflets length, diastolic leaflet thickness, prolapsing depth, billowing area and non-coaptation distance between both leaflets were measured. RESULTS Twenty patients (53%) and 18 patients (47%) were identified as having moderate to severe and mild MR respectively (ERO = 45 ± 27 mm² vs. 5 ± 7 mm², p < 0.001). Diastolic leaflet thickness was similar in both groups (5.5 ± 0.9 mm vs. 5.3 ± 1 mm, p = 0.57). On multivariate analysis, the non-coaptation distance (OR 7.9 per 1 mm increase; 95% CI 1.72-37.2) was associated with significant MR. Thick mitral valve leaflet as traditionally reported (≥ 5 mm) was not associated with significant MR (OR 0.9; 95% CI 0.2-3.4). CONCLUSIONS In patients with MVP, thick mitral leaflet is not associated with significant MR. Leaflet thickness is probably not as important in risk stratification as previously reported in patients with MVP. Other anatomical and geometrical features of the mitral valve apparatus area appear to be much more closely related to MR severity.