Dynamic Spatial Dispersion Of Repolarization Is Present In Regions Critical For Ischemic Ventricular Tachycardia Ablation

Abstract Background The presence of dynamic substrate changes may facilitate functional block and reentry in ventricular tachycardia (VT). Objective We aimed to study dynamic ventricular repolarization changes in critical regions of the VT circuit during sensed single extrastimulus pacing known as the Sense Protocol (SP). Methods Twenty patients (age 67 +/- years, 17Male) underwent VT ablation. A bipolar voltage map was obtained during sinus rhythm (SR) and right ventricular SP pacing at 20msec above ventricular effective refractory period. Ventricular repolarization maps were constructed. Ventricular repolarization time (RT) was calculated from unipolar electrogram T-waves using the Wyatt method, as the dV/dtmax of the unipolar T-wave. Entrainment or pace mapping confirmed critical sites for ablation. Results The median global repolarization range (max-min RT per patient) was 166ms (IQR 143-181ms) during SR mapping vs 208ms (IQR 182-234) during SP mapping (p= 0.0003 vs intrinsic rhythm). Regions of late potentials (LP) had a longer RT during SP mapping compared to regions without LP (mean 394ms±40 vs 342ms±25, p Conclusion "Ventricular repolarization is prolonged in regions of LP and increases dynamically resulting in dynamic spatial dispersion of repolarization in critical areas of the VT circuit. These dynamic substrate changes may be an important factor that facilitates VT circuits.