Accuracy of non-invasive electrocardiographic imaging in scar-dependent ventricular tachycardia: Relationship to arrhythmogenic substrate and imaging defined scar

Figure 1. View Into Ventricular Onset (VIVO) ECGi mapping system integration protocol. (A) MSCT or CMR scan performed with full thoracic coverage prior to procedure. (B) Cross-sectional imaging is imported and segmented, creating a patient-specific cardiac model in preparation for the procedure. (C) A 3D image of the patient torso with ECG lead positions is taken on the day of the procedure. (D) The 12-lead ECG of the VT is imported into the proprietary VIVO software and the ECGi map are constructed. CMR, cardiovascular magnetic resonance; MSCT, multislice cardiovascular computed tomography; VT, ventricular tachycardia.

Figure 2. Study workflow to generate EAM and ECGi maps for post hoc blinded analysis. (A) Representative case 1: VT activation map with surface ECG and intracardiac electrograms highlighting the entrance, middle, and exit of the critical diastolic isthmus at the inferolateral LV. Late diastolic exit potentials define the VT-ESR (dashed white oval). (B) VIVO ECGi map highlights the VT-ESR at the inferolateral LV. (C) Substrate map identifies extensive scar in the basal segments of the inferolateral LV. (D) Substrate map highlighting ablation lesion sites (dark red spheres). (E) Representative case 2: VT activation map with surface ECG and intracardiac electrograms highlighting the entrance, middle, and exit of the critical diastolic isthmus at the apex. Late diastolic exit potentials define the VT-ESR (dashed white oval). (F) VIVO ECGi map highlights the VT-ESR at the apex. (G) Substrate map identifies extensive scar at the apex, extending to the anterior wall. (H) Substrate map highlighting ablation lesion sites (red circles). EAM, electroanatomical mapping; ECGi, electrocardiographic imaging; RV, right ventricle; RVOT, right ventricular outflow tract; LV, left ventricle; VT, ventricular…

Figure 3. Heat maps based on the AHA segment model displaying the spatial distribution of the VT exit sites defined by EAM and ECGi maps. Location heat map of VT-ESR, (A) localized using EAM (n = 48) within the left ventricle (LV) and right ventricle (RV); (B) accurate co-localization (defined as a complete or partial match) using VIVO ECGi mapping (n = 42). EAM, electroanatomical mapping; ECGi, electrocardiographic imaging; VIVO, view into ventricular onset; VT-ESR, ventricular tachycardia exit site region.

Figure 4. QRS onset and offset calliper adjustment to improve accuracy of ECGi maps. The representative case highlights the change in VIVO-ECGi defined VT-ESR with QRS onset (red line) and QRS offset (blue line) calliper adjustments (white arrows). (A) VIVO ECGi map highlights VT-ESR which co-localizes to (B) the VT-ESR identified with the VT activation map. The VIVO ECGi map shows an epicardial exit compared to the VT activation map which shows an endocardial exit. (C) Shows the VIVO ECGi map with QRS onset (red line) moved by −10 ms. (D) VIVO ECGi map with QRS offset (blue line) moved by 10 ms. (E) VIVO map with QRS onset (red line) moved by −20 ms. (F) VIVO ECGi map with QRS offset (blue line) moved by 20 ms showing the VT-ESR has moved to the right ventricular outflow tract. With adjustments C and D, the accuracy of the VIVO ECGi map improved moving the VT-ESR from the epicardial to the endocardial LV surface. Calliper adjustment E resulted in the VT-ESR shifting more inferiorly in the endocardial LV. EAM, electroanatomical map; VT-ESR, ventricular tachycardia exit site region; VIVO, view into ventricular onset; LV, left ventricle.