LAUSR

Abstract Funding Acknowledgements Type of funding sources: None. Background A new functional mapping strategy based on targeting deceleration zones (DZs) has become one of the most commonly used strategies within the armamentarium of substrate-based ablation methods for ventricular tachycardia (VT) in patients with structural heart disease. The classic conduction channels detected by voltage mapping can be accurately determined by cardiac magnetic resonance (CMR). Objectives To analyze the evolution of DZs during ablation and their correlation with CMR. Methods Forty-two consecutive patients with scar-related VT undergoing ablation after CMR (October 2018-December 2020) were included (medium age 65.3±11.8 years; 94.7% male; 73.7% ischemic heart disease). Baseline DZs and their evolution in isochronal late activation remaps were analyzed. A comparison between DZs and CMR conducting channels (CMR-CCs) was realized. Patients were prospectively followed for VT recurrence for one year. Results Overall, 95 DZs were analyzed, 93.68% of which were correlated with CMR-CCs: 44.8% located in the middle segment and 55.2% located in the entrance/exit of the channel. Remapping was performed in 91.7% of patients (1remap: 33.3%, 2remaps: 55.6% and 3remaps: 2.8%). Regarding the evolution of DZs, 72.2% disappeared after the first ablation set, with 14.13% not ablated at the end of the procedure. A total of 32.5% of DZs in remaps correlated with a CMR-CCs already detected, and 17.5% were associated with an unmasked CMR-CCs. One-year VT recurrence was 22.9%. Conclusions DZs are highly correlated with CMR-CCs. In addition, remapping can lead to the identification of hidden substrate initially not identified by electroanatomic mapping but detected by CMR. Evolution of DZs during ablation