Electro-Anatomic (CARTO) Mapping for Measurement of Left Atrial Volume: Validation Against Real-Time 3D Echocardiography

Background: Left atrial size is a determinant of atrial fibrillation ablation efficacy and embolic risk. The recent advent of real-time full-volume 3DE allows now rapid measurement of chamber volume more accurately than with standard two-dimensional echocardiography as volume is reconstructed from endocardial contours of the entire chamber without making geometric assumptions. Electro-anatomic (CARTO) mapping allows measurement of chamber volume during the ablation procedure of atrial arrhythmias, but has never been validated for measuring left atrial size against three-dimensional echocardiography (3DE). Our aim was to compare left atrial volume measured using CARTO with that measured by real-time 3D echocardiography. Methods: 37 patients undergoing CARTO-guided radiofrequency ablation for atrial fibrillation or atypical left atrial flutter were studied and left atrial volume measured by mapping 73±17 points. Full-volume transthoracic real-time 3-D echocardiography was performed within 24 hours in each patient, and end-systolic left atrial volume measured offline. Results: Left atrial volume measured using CARTO correlated well with that using 3D echocardiography (r = 0.78, p<0.001), but electro-anatomic mapping consistently yielded greater values (mean difference of 33±19cc). Conclusion: Left atrial volume measured by CARTO correlates well with that obtained by real-time 3D echocardiography, although the former technique consistently yields larger values.