PO-04-121 PERSONALIZED VOLTAGE THRESHOLDS IN THE ERA OF HIGH-DENSITY MAPPING AND IMAGING

Abstract

Substrate-based ventricular tachycardia (VT) methods have been developed to identify ablation target sites during sinus rhythm, especially to guide ablation when VT is non-inducible or hemodynamic non tolerated. Voltage mapping has been one of the main strategies to define the abnormal arrhythmic substrate due to the potential capability of distinguish dense scar, border zone (BZ) and healthy tissue, delimiting the conducting channels potentially responsible for the clinical VT. Thresholds of 0.5-1.5mV using bipolar catheters were proposed initially for ischemic and later for non-ischemic patients being validated in a porcine model with transmural scar. Important limitations have been addressed, including a low correlation between these voltage channels and CMR channels or VT channels. To define new voltage thresholds for high density maps guided by CMR. All consecutive patients with scar-related VT undergoing ablation after CMR (October 2018-December 2020) were included. Voltage maps were compared side by side with CMR. First, the lower threshold was adjusted and after that, the upper threshold was set in order to get a voltage map the most resembling as possible to CMR. The characteristics of the tissue (dense scar, BZ or healthy tissue) of those areas identified as deceleration zones (DZ) in the isochronal late activation maps were recorded. Finally, if VT activation mapping was performed during the case, the concordance between the VT induced circuit and the voltage channels was analyzed. During the study period, 33 patients were included (medium age 66.5±11.1 years; 93.9% male; 78.8% ischemic heart disease, mean ejection fraction of 33.9±7.2). Adjusted cutoff voltages that better match with CMR images were 0.51±0.32 (0.14-1.68) and 1.81±0.71 (0.7-3.21). Overall, 53 DZs were observed, being 75.5% of them identified as BZ using personalized voltage thresholds vs. 44.2% with the standard cutoffs, p=0002. Of the 32 VT isthmus detected during the ablation procedures, 71.9% correlated with a voltage channel using adjusted thresholds vs. 24.4% with the standard ones, p=0.0006. No significant differences were observed between ischemic and non-ischemic patients. Personalized voltage thresholds based in CMR images enable a better identification of the substrate and a higher correlation between voltage channels and VT isthmus.