text: Quantification of mitral valve regurgitation by 2D and 3D echocardiography compared with cardiac magnetic resonance a systematic review and meta-analysis.
  By means of systematic literature review and meta-analysis, we compared results of studies examining different echocardiographic methods assessing severity of mitral valve regurgitation volume (MVR) with cardiac magnetic resonance imaging (CMR) as standard reference. A systematic search of electronic databases revealed twenty studies eligible for meta-analysis. Results of 2D- and 3D-trans-thoracic (TTE) and trans-esophageal echocardiographic (TEE) proximal isovelocity surface area (PISA) and volumetric methods were compared with CMR. Mean differences (ml) with 95% limits of agreement (LoA) derived from Bland-Altman tests and correlations coefficients [(R) 95% confidence interval (CI)] were pooled together. Overall 1187 patients [mean age = 59 ± 13 years and 678(57%) males] with primary or secondary mild to severe MVR were included. Comparing all echocardiographic methods with CMR showed an overestimation and moderate agreement with difference and 95% LoA of 8.05(- 3.40, 19.49) ml, R = 0.73(95% CI 0.71-0.76) p < 0.001. 3D-PISA followed by 3D-volumetric methods showed the better agreement with an underestimation of - 3.20(- 12.33, 5.92) ml, R = 0.84(95% CI 0.78-0.89) p < 0.001 and overestimation of 3.73(- 9.17, 16.61) ml, R = 0.90(95% CI 0.87, 0.94) p < 0.001, respectively. 2D-volumetric method showed the poorest agreement with difference and 95% LoA of 23.56(- 4.19, 51.31) ml, R = 0.64(95% CI 0.54-0.73) p < 0.001. In patients (n = 280) with severe MVR, 2D technique incorrectly estimated regurgitation volume severity in 106 (38%) compared to 4(14%) patients using 3D technique. Among echocardiographic methods 3D-PISA agreed best with CMR as reference, making 3D-PISA the most reliable method to quantify MVR. CMR can be considered in severe MVR where uncertainties arise and a decision-making prior valve surgery is required. Further powerful studies are needed to assess the accuracy of different echocardiographic methods.