B-PO03-130 COMPARISON BETWEEN TIME AND ABLATION INDEX-BASED RADIOFREQUENCY ENERGY DOSING DURING ABLATION IN LEFT VENTRICULAR PORCINE MODEL

Abstract

Ablation Index (AI) is a quality marker combining contact force (CF), time, and power to assess durability of radiofrequency (RF) lesions. However, the risk-benefit of AI for ablation of ventricular arrhythmias is currently unknown. We compared AI and time-based RF dosing strategies in left ventricles of freshly harvested porcine hearts. Ablation was performed in vitro using an open-irrigated ablation catheter (Thermocool ST/SF), power of 40 Watts and CF of 10-15 grams. After ablation, tissue samples were cross-sectioned and stained in triphenyltetrazolium chloride for measurement of lesion dimensions. In total, 560 lesions were performed. Using NS (n=280), growth in lesion depth slowed substantially after 30 seconds and after reaching an AI of 550, although size of impedance drops continued to increase with longer ablation time and higher AI cut offs. Risk of steam pop (SP) was higher after 30 seconds of ablation (RF < 30 sec: 1 SP (2.5%) vs. RF > 30 sec: 15 SP (25%);p=0.002) and AI >550 (AI 350-550: 2 SP (2%) vs AI 600-750: 15 SP (19%);p=0.001). Using HNS (n=280), impedance drops were larger but growth in lesion depth slowed after reaching AI of 500. Risk of SPs was higher above AI 550 (AI 350-550: 7 (7%) SPs vs. AI 600-750: 28 (35%)SP; p<0.00001). While co-dependent variables, correlation between AI and time was modest despite similar power and CF parameters. Long durations of RF may result in excessive tissue heating and risk of SPs without necessarily achieving substantial increase in lesion depth desired. An AI-guided protocol including variables beyond time, may improve procedure time, safety and efficacy during ventricular ablation.