Abstract 16985: Spatial Accuracy of Non-Invasive Activation Mapping Modalities for Complex Ventricular Arrhythmias: A Direct Comparison of Electromechanical Wave Imaging (EWI) Using High Frame Rate Transthoracic Echocardiography and Electrocardiographic Imaging (ECGi) With Cardiac CT

Abstract

Background: Non-invasive identification of the site of origin (SOO) of ventricular arrhythmias is vital in informing ablation strategy. ECGi is an established method to generate 3D activation maps with a multielectrode vest combined with cardiac CT. EWI is an emerging echocardiography based modality that provides a low cost & non-ionizing mapping alternative. Hypothesis: EWI more precisely localises SOO of Complex Ventricular Ectopy (VEs) & intramural location than commercial ECGi. Aim: Compare spatial accuracy of EWI and ECGi to estimate SOO and validate against contact mapping. Methods: VE-ablation patients underwent preprocedural EWI & ECGi to estimate SOO on the AHA segment-model. A commercial ECGi system with cardiac CT was used for reconstruction of epicardial VE activation maps. EWI was performed using a research ultrasound acquiring B-mode and high frame rate (2000fps) images with simultaneous ECG. Local electromechanical activation was defined as time-point of the downward zero-crossing on the incremental axial strain curve (250 strain curves/view) and displayed on 3D rendered maps. The site of earliest activation & successful VE ablation was defined as ground truth for VE SOO. Results: 10 patients were enrolled: 50% male, age 40.8 +/- 18.1 years, LV EF 41+/-15%, 50% with scar on MRI. CT ECGi correctly identified the VE AHA segment in 8/10 (80%) cases (misclassified 2 papillary muscle (PM) VEs) but did not afford transmural localization. After excluding 1 patient with insufficient VE’s for EWI, EWI correctly identified the VE-SOO segment in 8/9 (88%) cases locating 2 subepicardial, 2 septal intramural & 3 VEs at the base or intramural segment adjacent to a PM. It misclassified 1 PM VE. Conclusion Both EWI & ECGI identified the VE-SOO segment in at least 80% of cases irrespective of presence of scar. EWI also correctly determined the transmural VE origin which cannot be located using commercial ECGI. This has important implications in planning ablation procedures.