Clinical Implications of Three-Dimensional Real-Time Color Doppler Transthoracic Echocardiography in Quantifying Mitral Regurgitation: A Comparison with Conventional Two-Dimensional Methods

Background: Automatic quantification of real-time three-dimensional (3D) full-volume color Doppler transthoracic echocardiography (FVCD) has been proposed as a feasible and accurate method for quantifying MR. We aimed to explore the clinical implications of real-time 3D-FVCD for mitral regurgitation (MR) with various clinical manifestations, in comparison with the conventional two-dimensional (2D) proximal isovelocity surface area (PISA) and volumetric method and cardiac magnetic resonance imaging (CMR) methods. Methods: A total 186 patients with MR were enrolled prospectively. Based on exclusion criteria and image quality review, 152 patients were included in the final analysis for 3D-FVCD and 2D transthoracic echocardiography. Among them, 37 patients underwent subsequent CMR for the validation of 3D-FVCD. Results: MR volume from 3D-FVCD demonstrated a better agreement (r = 0.94) with CMR than 2D-PISA or the 2D volumetric method (VM; r = 0.87 vs 0.56). Overall, 2D methods underestimated MR when compared with 3D-FVCD (35.4 +/- 28.4 mL for 2D-VM vs 43.8 +/- 24.6 mL for 2D-PISA vs 64.6 +/- 35.1 mL for 3D-FVCD; P <.001). In subgroup analysis, multijet MR (odds ratio [OR], 6.30; 95% Cl, 2.52-15.72) and dilated left ventricular end-systolic diameter >= 40 mm (OR, 2.90; 95% Cl, 1.12-7.50) were predictors of significant difference in MR volume (> 30 mL for primary MR and > 15 mL for secondary MR) between 2D-PISA and 3D-FVCD. In identifying surgical candidates, patients with multijet MR (OR, 4.53, 95% Cl, 1.99-10.35) demonstrated a higher risk of discrepancy between 2D-PISA and 3D-FVCD, which were consistent in both primary and secondary MR, respectively. Conclusions: MR quantification with 3D-FVCD showed better correlation and agreement than conventional 2D methods. MR was underestimated by 2D methods, especially in multijet and dilated left ventricle. Multijet MR demonstrated higher risk of discrepancy for the identification of surgical candidate, regardless of MR etiology.