Ablation Targets of Scar-Related Ventricular Tachycardia Identified by Dynamic Functional Substrate Mapping

Abstract Background Dynamic functional substrate mapping of scar-related ventricular tachycardia offers better identification of ablation targets with limited number of ablation lesions. Several functional substrate mapping approaches have been proposed, including Decrement-evoked potential (DEEP) mapping. The aim of our study was to compare the short and long term efficacy of a DEEP-guided strategy versus that of a fixed-substrate strategy for the ablation of scar-related ventricular tachycardia (VT). Methods In this single-blind randomized trial, forty consecutive patients presenting for ablation of scar-related VT were randomized to either a DEEP-guided or a substrate-guided ablation strategy. Late potentials were tagged and ablated in the non-DEEP group, while those in the DEEP group were subjected to RV extrastimulus pacing after a drive train. Only potentials showing significant delay were ablated. Patients in both groups were followed for a median duration of 12 months. Results Twenty patients were allocated to the DEEP group while the other 20 were allocated to the non-DEEP group. Twelve patients (60%) in the DEEP group had ischemic cardiomyopathy versus 10 patients (50%) in the non-DEEP group (P- value 0.525). Intraoperatively, the median percentage of points with LPs was 19% in the DEEP group and 20.6% in the non-DEEP group (P-value 1). The median percentage of LPs demonstrating DEEP was 5.8% for the DEEP group which is much higher than the total number of LPs in the same group (P value 0.00). VT non-inducibility was successfully accomplished in 16 patients (80%) in the DEEP group versus 17 patients (85%) in the non-DEEP group (P value 0.597). After a median follow up duration of 12 months, the VT recurrence rate was 65% in both groups (P value 0.311) with a dropout rate of 10% in the DEEP group. As for the secondary endpoints, all-cause mortality rates were 20% and 25% in the DEEP and non-DEEP groups respectively (P-value 0.342). Conclusion DEEP-assisted mapping and ablation of scar-related ventricular tachycardia is a feasible strategy with comparable short and long term outcomes to a fixed- substrate-based strategy with more specific ablation targets. Further large-scale randomized trials that integrate recent mapping technologies with novel functional substrate mapping protocols are recommended to improve ablation outcomes.