Ultra-Low Temperature Cryoablation Combined With Pulsed Field Ablation in a Swine Ventricular Infarct Model.

Abstract

BACKGROUND: Treatment of ventricular arrhythmias with radiofrequency catheter ablation can be challenging due to insufficient ablation efficacy in scar. The performance of ultra-low temperature cryoablation (ULTC) and combined ULTC + pulsed field ablation (PFA) has not been studied in ventricular tissue. OBJECTIVES: This study sought to compare ventricular lesion size between ULTC alone and combined ULTC+PFA. METHODS: A total of 5 swine underwent chronic infarction via 120-minute balloon occlusion of the left anterior descending coronary artery. Three ablation approaches were tested: single 2-minute freeze (ULTC-1), 2 sequential 2-minute freezes delivered in a freeze-thaw-freeze cycle (ULTC-2), and a single 2-minute freeze with 8 PFA trains (ULTC-1+PFA). RESULTS: A total of 36 lesions (7 ULTC-1, 14 ULTC-2, 15 ULTC-1+PFA lesions) were applied to the left ventricular endocardium in 5 swine. Median (Q1-Q3) width was 9 (7-13) mm in healthy tissue and 11 (9-14) mm in scar (P = 0.18). In both healthy and scar tissue, lesion width was larger with ULTC-2 and with ULTC-1+PFA when compared with ULTC-1 alone. Lesion depth was 11 (9-15) mm in healthy tissue and 11 (8-13) mm in scar (P = 0.57). Lesion depth trended deeper with ULTC-2 and with ULTC-1+PFA. Within scar, zero of the ULTC-1, 13% of the ULTC-2 lesions, and 67% of the ULTC-1+PFA lesions were transmural. CONCLUSIONS: ULTC resulted in clinically substantial lesions in healthy and infarcted ventricular myocardium. The addition of PFA to ULTC allowed for larger and more transmural lesions compared with a single ULTC ablation alone while avoiding the longer ablation times associated with 2 successive freezes.