Assessment of Left Atrial Volume in Dogs: Comparisons of Two-Dimensional and Real-Time Three-Dimensional Echocardiography with ECG-gated Multidetector Computed Tomography Angiography

Introduction: We hypothesized that real-time three-dimensional echo cardiography (RT-3DE) was superior to two-dimensional echocardiography for the estimation of left atrial volume (LAV), using electrocardiographic (ECG)-gated multidetector computed tomography angiography (MDCTA) as a volumetric gold standard. The aim was to compare maximum LAV (LAV(max)) and minimum LAV (LAV(min)) measured by biplane area-length method (ALM), biplane method of disk (MOD) and RT-3DE with 64-slice ECG-gated MDCTA in dogs Animals: The study included twenty dogs, anaesthetized for various diagnostic purposes and without evidence of cardiovascular disease. Methods: Left atrial volume was estimated by ALM, MOD and RT-3DE following ECG gated MDCTA. The results were compared with LAV from MDCTA and correlations were performed. The limits of agreement (LoA) between methods were evaluated using Bland-Altman analysis and intraclass correlations. Coefficients of variation were calculated. Results: Area-length method (r = 0.79 and 0.72), MOD (r = 0.81 and 0.70) and RT-3DE (r = 0.94 and 0.82) correlated with MDCTA for LAV(max) and LAV(min), respectively (all p < 0.05). Biases for LAV(max) (-0.96 mL, 95% LoA: -5.6 to 3.7) and LAV(min) (-0.67 mL, 95% LoA:-5.4 -4.1) were minimal with RT-3DE, reflecting a slight underestimation. Conversely, MOD (LAV(max)bias = 3.19 mL, 95% LoA: -5.7 -12.1; LAV(min)bias = 1.96 mL, 95% LoA: -4.6 -8.5) and ALM (LAV(max)bias = 4.05, 95% LoA: -5.7 -13.8; LAV(min)bias = 2.80 mL, 95% LoA: -3.9 -9.5) suggested LAV overestimation. Intraobserver and interobserver variability were adequate. Conclusions: Real-time three-dimensional echocardiography is a non-invasive, accurate and feasible method with superior accuracy to two-dimensional methods. (C) 2019 Elsevier B.V. All rights reserved.