Leaflet remodelling in functional mitral valve regurgitation: characteristics, determinants, and relation to regurgitation severity.

BACKGROUND Recently, it has been hypothesized that mitral leaflet remodelling may play a role in the pathophysiology of functional mitral regurgitation (FMR). We investigated the characteristics, determinants, and relation of mitral leaflet remodelling to FMR severity. METHODS AND RESULTS Three-dimensional transoesophageal echocardiographic data of the mitral valve (MV) were studied in 30 patients with FMR ≥ grade 3 (≥3), 24 patients with FMR < grade 3 (<3), and 22 controls with normal MV. FMR <3 and ≥3 patients showed leaflet remodelling compared with control subjects with larger overall MV leaflet areas (11.47 ± 3.16 and 9.58 ± 1.99 vs. 7.30 ± 1.57 cm(2)/m(2), respectively; all P < 0.01). Tenting volume (r(2) = 0.55), left ventricular (LV) ejection fraction (r(2) = 0.20), annulus area (r(2) = 0.87), and LV sphericity index (r(2) = 0.25) were correlated with overall MV leaflet area (all P < 0.001). Although these correlates were similar between FMR <3 and ≥3 patients (all P > 0.05), the overall MV leaflet area was smaller in FMR ≥3 compared with FMR <3 patients (P = 0.01), indicating less remodelling despite similar tethering degree. Particularly, coaptation/overall MV leaflet area ratio ≤0.24, reflecting insufficient leaflet remodelling, was associated with FMR ≥3 [area under receiver operating characteristic (ROC) curve = 0.93, sensitivity 90%, and specificity 91%]. This ratio was independently associated with FMR ≥3 (odds ratio 70.0, 95% confidence interval 11.7-419.9, P < 0.001) and showed significant correlation with effective regurgitant orifice area (r(2) = 0.38, P < 0.001). CONCLUSION MV leaflet remodelling in FMR is common and relates to LV function, LV sphericity, MV tenting volume, and annulus dilatation. Insufficient leaflet remodelling relative to the mitral annular and LV changes is independently associated with FMR severity.