EN-452414-1 IMPACT OF MULTI-DIRECTIONAL PACING ON LATE SIGNAL ACTIVATION, ACTIVATION SLOWING AND REPOLARIZATION GRADIENTS TO LOCALIZE RE-ENTRANT VENTRICULAR TACHYCARDIA CIRCUITS IN A PORCINE INFARCT MODEL.

Abstract

Optimal signal parameters and substrate mapping strategies for identifying key arrhythmogenic sites in ventricular tachycardia (VT) ablation are not established. To evaluate multi-directional pacing on the distribution of late signal activation, activation slowing and repolarization gradients in relation to critical sites of re-entrant VT, in a porcine infarct model. Electrophysiology studies were performed 4 weeks post-infarction in 13 pigs using the EnSite Precision system (Abbott, IL, USA), and the Advisor HD Grid (Abbott) multi-electrode catheter. Substrate maps were created during right ventricular (RV), left ventricular (LV), and biventricular pacing (BIV), and sinus rhythm (SR). Sites of early, mid-, and late-diastolic signals of induced VT’s were delineated. Off-line analysis compared these critical VT sites to algorithmically identified 20 most vulnerable sites of latest activation timing within and post-QRS, and the largest activation (GradAT) and activation recovery interval gradients (GradARI). 34 VTs were mapped with at least one diastolic recorded component, with a mean tachycardia cycle length of 236.5 ± 32.4 ms. 48 sinus rhythm and pacing maps were obtained, 10 using BIV pacing (mean points 375 ± 263), 13 using LV pacing (mean points 610 ± 334), 13 from RV pacing (mean points 603 ± 263) and 12 in sinus rhythm (mean points 1078 ± 654). Late potential (LP) mapping in sinus rhythm was taken as the established clinical standard for statistical comparison with all other protocols, displayed in Figure 1. GradARI using RV pacing provided the closest localization for VT exit and entrance, with a median distance of 10.6mm (IQR 5.0mm, p <0.05) and median 9.4mm (IQR 8.0mm, p <0.05) compared to LP in sinus rhythm, respectively. LAT with BIV pacing provided closest VT isthmus localization for VT isthmus, with a median of 5.5mm (IQR 7.15mm, p <0.05) compared to LP in sinus rhythm (Figure 1). A global sensitivity and specificity analysis was performed on all points. GradARI mapping in SR reported the highest AUC (area – under curve) for early diastolic VT signals (AUC 0.96, sensitivity 93%, specificity 91%), mid-diastolic signals (AUC 0.92, sensitivity 84%, specificity 88%) and late diastolic signals (AUC 0.92, sensitivity 88%, specificity 84%). Sites with the largest ARI gradients in sinus rhythm best predict critical sites of VT in this model, with the most effective protocol being RV pacing examining ARI gradients.