Comparison of three-dimensional echocardiographic findings to those of magnetic resonance imaging for determination of left ventricular mass in patients with ischemic and non-ischemic cardiomyopathy
The standard echocardiographic evaluation of left ventricular (LV) mass, particularly in ischemic cardiomyopathy (IC) is challenging because it is based on geometric assumptions. The aim of this study was to assess the accuracy of LV mass calculation using echocardiographic modalities compared with cardiac magnetic resonance (CMR) in IC and in nonischemic cardiomyopathy (non-IC). Echocardiography was performed in 104 patients (mean age 55 ± 15 years) referred for CMR: 63 with IC and 41 with non-IC. CMR, M-mode echocardiography, 2-dimensional echocardiography, and 3-dimensional echocardiography (3DE) were analyzed using standard commercial tools to obtain LV mass. LV mass on 3DE showed a higher correlation with CMR than 2-dimensional echocardiography (r = 0.87 vs r = 0.70, p <0.001). M-mode echocardiography overestimated LV mass (bias +30%) and 2-dimensional echocardiography underestimated LV mass (bias -11%), whereas measurements on 3DE showed only minimal bias (-2%). LV mass on 3DE in non-IC showed a significantly higher correlation with CMR than in IC (r = 0.92 vs r = 0.84, z = 2.3, p <0.05). In non-IC, the mean difference was -2 g (-1% of the mean), with 95% limits of agreement of ±33 g (±19% of the mean). In IC, the mean difference was -7 g (-4% of the mean), with limits of agreement of ±56 g (±31% of the mean). There was a correlation between the absolute LV mass differences (3DE derived and CMR derived) and scar percentage (infarcted mass/total LV mass) using delayed-hyperenhancement images (r = 0.40, p <0.05). The net reclassification index with 3DE was +16% for concentric LV hypertrophy. In conclusion, the most accurate and reliable echocardiographic measurement of LV mass is 3DE, but underestimation and variability remain challenges in IC.