A Comparative Assessment of Echocardiographic Parameters for Determining Primary Mitral Regurgitation Severity Using Magnetic Resonance Imaging as a Reference Standard

Background: The American Society of Echocardiography (ASE) guidelines suggest the use of several echocardiographic methods to assess mitral regurgitation severity using an integrated approach, without guidance as to the weighting of each parameter. The purpose of this multicenter prospective study was to evaluate the recommended echocardiographic parameters against a reference modality and develop and validate a weighting for each echocardiographic measure of mitral regurgitation severity. Methods: This study included 112 patients who underwent evaluation with echocardiography and magnetic resonance imaging (MRI). Echocardiographic parameters recommended by the ASE were included and compared with MRI-derived regurgitant volume (MRI-RV). Results: Echocardiographic parameters that correlated best with MRI-RV were proximal isovelocity surface area (PISA) radius (r = 0.65, P <.0001), PISA-derived effective regurgitant orifice area (r = 0.65, P <.0001), left ventricular end-diastolic volume (r = 0.56, P <.0001), and PISA-derived regurgitant volume (r = 0.52, P <.0001). In the linear regression models PISA-derived effective regurgitant orifice area, PISA-derived regurgitant volume, left ventricular end-diastolic volume, and the presence of a flail leaflet independently predicted MRI-RV. Conclusion: Echocardiographic parameters of mitral regurgitation as recommended by the ASE had moderate correlations with MRI-RV. The best predictors of MRI-RV were PISA-derived effective regurgitant orifice area, PISA-derived regurgitant volume, left ventricular end-diastolic volume, and the presence of a flail leaflet, suggesting that these parameters should be weighted more heavily than other echocardiographic parameters in the application of the ASE-recommended integrated approach.