Feasibility, Accuracy, and Reproducibility of Real-Time Full-Volume 3D Transthoracic Echocardiography to Measure LV Volumes and Systolic Function : A Fully Automated Endocardial Contouring Algorithm in Sinus Rhythm and Atrial Fibrillation

ObjectivesTo assess the feasibility, accuracy, and reproducibility of real-time full-volume 3-dimensional transthoracic echocardiography (3D RT-VTTE) to measure left ventricular (LV) volumes and ejection fraction (EF) using a fully automated endocardial contouring algorithm and to identify and automatically correct the contours to obtain accurate LV volumes in sinus rhythm and atrial fibrillation (AF).Background3D transthoracic echocardiography is not used routinely to quantify LV volumes and EF. A fully automated workflow using RT-VTTE may improve clinical adoption.MethodsRT-VTTE was performed and 3D EF and volumes obtained using an automated trabecular endocardial contouring algorithm; an automated correction was applied to track the compacted myocardium. Cardiac magnetic resonance (CMR) and 2-dimensional biplane Simpson method were the reference standard.ResultsNinety-one patients (67 in normal sinus rhythm [NSR], 24 in AF) were included. Among all NSR patients, there was excellent correlation between RT-VTTE and CMR for end-diastolic volume (EDV), end-systolic volume (ESV), and EF (r = 0.90, 0.96, and 0.98, respectively; p < 0.001). In patients with EF ≥50% (n = 36), EDV and ESV were underestimated by 10.7 ± 17.5 ml (p = 0.001) and by 4.1 ± 6.1 ml (p < 0.001), respectively. In those with EF <50% (n = 31), EDV and ESV were underestimated by 25.7 ± 32.7 ml (p < 0.001) and by 16.2 ± 24.0 ml (p = 0.001). Automated contour correction to track the compacted myocardium eliminated mean volume differences between RT-VTTE and CMR. In patients with AF, LV volumes and EF were accurate by RT-VTTE (r = 0.94, 0.94, and 0.91 for EDV, ESV, and EF, respectively; p < 0.001). Automated 3D LV volumes and EF were highly reproducible.ConclusionsRapid, accurate, and reproducible EF can be obtained by RT-VTTE in NSR and AF patients by using an automated trabecular edge contouring algorithm. Furthermore, automated contour correction to detect the compacted myocardium yields accurate and reproducible 3D LV volumes.