AB-452672-2 ULTRA-LOW TEMPERATURE CRYOABLATION VERSUS ULTRA-LOW TEMPERATURE CRYOABLATION COMBINED WITH PULSED FIELD ABLATION IN A SWINE VENTRICULAR INFARCT MODEL

Abstract

Treatment of ventricular arrhythmias with radiofrequency (RF) catheter ablation can be limited by insufficient lesion size and depth, especially within diseased myocardium. A recent investigation using a force-sensing RF catheter (30 watts / 30 seconds) described average lesion depths of 5.1 mm within healthy tissue and 2.0 mm within scar. To compare catheter ablation lesion size measurements using ultra-low temperature cryoablation (ULTC) versus pulsed field cryoablation (ULTC combined with pulsed field ablation, PFCA) in both healthy and infarcted myocardium in an in-vivo swine model. An anterior infarct was created in three swine using 120 minute left anterior descending balloon occlusion. After one month, endocardial lesions were placed in the left ventricle using a linear, deflectable ablation catheter (Figure, Panel A) capable of delivering ULTC or PFCA lesions (Adagio Medical, Irvine, CA). The ULTC system utilizes pressurized nitrogen at -196 degrees C to deliver lesions. Electroanatomic mapping was used to differentiate healthy from infarcted tissue and to ensure non-overlapping lesions. One animal received ULTC only (freeze-thaw-freeze lesions at each ablation site, both freezes two minutes) and two animals received PFCA (single two-minute freeze with 4kV biphasic, bipolar PFA pulses delivered during the freeze). Animals were euthanized after lesion delivery and gross measurements of lesion size were performed. A total of 8 ULTC and 15 PFCA lesions were delivered. Lesion size was slightly larger in healthy compared to infarcted tissue, although all lesions were clinically substantial (Figure, Panel B). While there was no significant difference in median lesion size between ULTC and PFCA (Figure, Panels C and D), PFCA resulted in significantly more transmural lesions within ventricular scar compared to ULTC alone (67% versus 0%, p = 0.02). In total, 35% of all lesions were transmural. Maximal single lesion depth was 17 and 20.5 mm with ULTC and PFCA, respectively. Maximal single lesion width was 22 mm for both ULTC and PFCA. Ultra-low temperature cryoablation resulted in clinically substantial lesions in both healthy and infarcted ventricular myocardium. Addition of pulsed field ablation to ultra-low temperature cryoablation allowed ablation time per lesion to be halved without significant change in lesion size.