Targeted Ablation of Ventricular Tachycardia Guided by Wavefront Discontinuities During Sinus Rhythm

Abstract

Background: Accurate and expedited identification of scar regions most prone to reentry is needed to guide ventricular tachycardia (VT) ablation. We aimed to prospectively assess outcomes of VT ablation guided primarily by the targeting of deceleration zones (DZ) identified by propagational analysis of ventricular activation during sinus rhythm. Methods: Patients with scar-related VT were prospectively enrolled in the UChicago VT Ablation Registry between 2016-2018. Isochronal late activation maps annotated to the latest local electrogram deflection were created with high-density multielectrode mapping catheters. Targeted ablation of DZ (>3 isochrones within 1 cm radius) was performed, prioritizing later activated regions with maximal isochronal crowding. When possible, activation mapping of VT was performed and successful ablation sites were compared with DZ locations for mechanistic correlation. Patients were prospectively followed for VT recurrence and mortality. Results: 120 patients (median age 65 years (59-71), 15% female, 50% nonischemic, median EF 31%) underwent 144 ablation procedures for scar-related VT. 57% of patients had previous ablation and epicardial access was employed in 59% of cases. High-density mapping during baseline rhythm was performed (2,518 points (1615-3752) endo, 5049 ± 2580 points epi) and identified an average of 2±1 DZ, which co-localized to successful termination sites in 95% of cases. The median total RF application duration was 29 min (21-38 min) to target DZ, representing ablation of 18% of the low voltage area. At 12±10 months, 70% freedom from VT recurrence (80% in ICM and 63% in NICM) was achieved. The overall survival rate was 87%. Conclusions: A novel voltage-independent high-density mapping display can identify the functional substrate for VT during sinus rhythm and guide targeted ablation, obviating the need for extensive radiofrequency delivery. Regions with isochronal crowding during the baseline rhythm were predictive of VT termination sites, providing mechanistic evidence that deceleration zones are highly arrhythmogenic, functioning as niduses for reentry.