Relationship Between Mitral Leaflet Size and Coaptation and Their Associated Factors in Patients with Normal Left Ventricular Size and Systolic Function

Enlargement of the mitral valve (MV) has gained attention as a compensatory mechanism for functional mitral regurgitation (FMR). We aimed to determine if MV leaflet area is associated with MV coaptation-zone area and identify the clinical factors associated with MV leaflet size and coaptation-zone area in patients with normal left ventricle (LV) systolic function and size using real-time 3D echocardiography (RT3DE).We performed RT3DE in 135 patients with normal LV size and ejection fraction. MV leaflet and coaptation-zone areas were measured using custom 3D software. The clinical factors associated with MV leaflet and coaptation-zone areas were evaluated using univariate and multivariate linear regression analyses.There was a significant relationship between MV leaflet and coaptation-zone areas (r = 0.499, P < 0.001). MV leaflet area was strongly associated with body surface area (BSA) (r = 0.905, P < 0.001) rather than LV size and age. MV leaflet area/BSA was independently associated with male gender (P = 0.002), lower diastolic blood pressure (P = 0.042), and LV end-diastolic volume (LVEDV) index (P = 0.048); MV coaptation-zone area/BSA was independently associated with lower LVEDV index (P = 0.01).In patients with normal LV systolic function and size, MV leaflet size has a significant impact on competent MV coaptation. MV leaflet area might be intrinsically determined by body size rather than age and LV size, and the MV leaflet area/BSA is relatively constant. On the other hand, some clinical factors might also influence MV leaflet and coaptation-zone area.