Mitral leaflet separation to evaluate the severity of mitral stenosis: Validation of the index by transesophageal three‐dimensional echocardiography

Background Determining severity of mitral stenosis (MS) by planimetry of mitral valve orifice area (MVA) has been a challenging issue in clinical practice, especially for less experienced cardiologists. Mitral leaflet separation (MLS) has shown a good correlation with MVA measurements. However, it has never been validated against multiplane 3DTEE planimetry (MVA3D). We aimed to evaluate the accuracy of MLS index (MLSI2D) in predicting MS severity. Methods We prospectively enrolled 144 patients with MS who underwent clinically indicated 2DTTE and 3DTEE. MLSI2D was yield by averaging the maximal leaflet tip distance in diastole, in parasternal long‐axis and apical four‐chamber views. MVA3D was used as the reference method. Results MLSI2D showed an excellent discriminatory ability between different grades of MS (P