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 < .001). There was a significant positive correlation between MLSI2D and MVA3D (r = .93, P < .001) irrespective of concurrent mitral regurgitation (r = .94, P < .001) and/or atrial fibrillation (r = .92, P < .001). By receiver operating characteristic (ROC) curves, MLSI2D  ≤ 8.6 mm showed 100% sensitivity and 76% specificity for very severe MS. MLSI2D  ≥ 11.2 mm determined progressive MS with 100% sensitivity and 82% specificity. The study population was then divided into a derivation group and a validation group. A regression equation for MVA by MLSI2D was derived in first group. Then, the MVA was calculated by this equation in validation group and was not significantly different from MVA3D . CONCLUSION:MLSI2D showed an excellent ability to assess MS severity and correlates well with planimetered MVA measured by 3DTEE.