Electrocardiographic imaging after myocardial infarction identifies repolarization patterns near ventricular tachycardia exit sites

Alessandra Fiorenza1, Job Stoks1, Jana Reventós Presmanes2, Andreu M. Climent3, Paul Volders1, Matthijs Cluitmans1
1Maastricht University, 2Arrhythmias Department, Hospital Clínic de Barcelona, 3Universitat Politècnica de València


Abstract

In post-myocardial infarction (MI) patients with ventricular tachycardia (VT), identification of the VT exit site is essential for substrate-guided ablation. A non-invasive approach could reduce procedural time, risk, and complexity. In this study, we investigated whether electrocardiographic imaging (ECGI) can identify electrophysiological characteristics during sinus rhythm (SR) associated with the VT exit site. Body-surface potentials were recorded in eight post-MI patients and combined with CT-derived torso and cardiac geometry to reconstruct epicardial unipolar electrograms (UEGs). The VT exit site was defined as the region of earliest epicardial activation during reconstructed VT beats. Activation and repolarization times (ATs and RTs) were then computed during SR and analyzed relative to this site across three radial zones (<20 mm, 20–40 mm, >40 mm). In free-wall VT patients (n=5), ATs and RTs were highest at the VT exit site and decreased with increasing distance from it. In septal VT patients (n=3), AT decreased with distance while RT showed no consistent pattern. These findings suggest that the VT exit site is characterized by electrophysiological properties and that SR ECGI mapping may support non-invasive pre-procedural substrate characterization.