Simultaneous Comparison of Electrocardiographic Imaging and Epicardial Contact Mapping in Structural Heart Disease

BACKGROUND:The accuracy of ECG imaging (ECGI) in structural heart disease remains uncertain. This study aimed to provide a detailed comparison of ECGI and contact-mapping system (CARTO) electrograms. METHODS:Simultaneous epicardial mapping using CARTO (Biosense-Webster, CA) and ECGI (CardioInsight) in 8 patients was performed to compare electrogram morphology, activation time (AT), and repolarization time (RT). Agreement between AT and RT from CARTO and ECGI was assessed using Pearson correlation coefficient, ρAT and ρRT, root mean square error, EAT and ERT, and Bland-Altman plots. RESULTS:After geometric coregistration, 711 (439–905; median, first-third quartiles) ECGI and CARTO points were paired per patient. AT maps showed ρAT=0.66 (0.53–0.73) and EAT=24 (21–32) ms, RT maps showed ρRT=0.55 (0.41–0.71) and ERT=51 (38–70) ms. The median correlation coefficient measuring the morphological similarity between the unipolar electrograms was equal to 0.71 (0.65–0.74) for the entire signal, 0.67 (0.59–0.76) for QRS complexes, and 0.57 (0.35–0.76) for T waves. Local activation map correlation, ρAT, was lower when default filters were used (0.60 (0.30–0.71), P=0.053). Small misalignment of the ECGI and CARTO geometries (below ±4 mm and ±4°) could introduce variations in the median ρAT up to ±25%. Minimum distance between epicardial pacing sites and the region of earliest activation in ECGI was 13.2 (0.0–28.3) mm from 25 pacing sites with stimulation to QRS interval