Assessment of Left Ventricular Volumes with Echocardiography and Cardiac Magnetic Resonance Imaging: Real-Life Evaluation of Standard versus New Semiautomatic Methods

Background: Routine quantitative assessment of left ventricular (LV) volumes with echocardiography is hindered by time-consuming methods requiring a manual trace of the LV cavity from two apical two-dimensional planes. Thus, the aim of this study was to evaluate faster new semiautomatic echocardiographic methods that could represent a feasible alternative for the assessment of LV volumes and ejection fraction (EF) in clinical practice. Methods: Two semiautomatic methods, the automated EF (Auto-EF) for two-dimensional echocardiography and the 4D Auto LVQ tool for three-dimensional echocardiography (3DE), were compared with the biplane modified Simpson's method and cardiac magnetic resonance (CMR) imaging in 47 patients. To evaluate the accuracy of volumetry, additional in vitro measurements using water-filled latex balloons were performed with both modalities. Results: Results of balloon volumetry by echocardiography and CMR measurements were in good agreement with real balloon volumes. The mean LV EF was 45 +/- 11% by Auto-EF, 45 +/- 11% by 3DE, 48 +/- 11% by Simpson's method, and 54 +/- 12% by CMR. Linear regression and Bland-Altman analyses showed good associations for semiautomatic methods with Simpson's method (Auto-EF, r = 0.85, bias = 3%, limits of agreement [LOA] = 12%; 3DE, r = 0.79, bias = 3%, LOA = 14%), as well as with CMR (Auto-EF, r = 0.74, bias = 9%, LOA = 17%; 3DE, r = 0.73, bias = 9%, LOA = 17%). Intra-and interobserver variability were 6% and 12% with Auto-EF and 8% and 11% with 3DE, respectively. Conclusions: Good correlations between semiautomatic echocardiographic parameters for assessment of LV volumes and EF could be observed when compared with Simpson's method or CMR. However, intertechnique agreement analysis of absolute LV volumes revealed considerable differences, with significant underestimation of volumes and EF with respect to CMR.