A new cryoenergy for ventricular tachycardia ablation: A proof-of-concept study

Abstract

Introduction Lack of transmural lesion formation during radiofrequency (RF) ablation for ventricular tachycardia (VT) is an important determinant of arrhythmia recurrence. The aim of this proof-of-concept study was to evaluate safety and efficacy of a new and more powerful cryoablation system for ventricular ablation. Methods and results Five healthy female sheep (59 ± 6 kg) underwent a surgical sternotomy for epicardial and endocardial access [endocardial access via right atrial appendage and left ventricular (LV) apex]. A cryoablation system with liquid nitrogen (IceCure) was used to create 3 min freezes at the right ventricle (RV). Left ventricular cryoablation was performed with either a 6 min or 2 × 4 min freezes. To assess safety, ablation was also performed on the mid left anterior descending artery and the proximal coronary sinus. A total of 45 lesions were created (RV epicardial, n = 12; LV epicardial, n = 18; RV endocardial, n = 7; LV endocardial, n = 8; LAD, n = 4; and CS, n = 4). The mean lesion volume was 5055 ± 92 mm3 (length: 32 ± 4.6 mm, width: 16.0 ± 6.4 mm, and depth: 11.2 ± 4.4 mm). Lesions were transmural in 28/45 (62%) and >10 mm in depth in 35/45 (78%). Of the endocardial lesions, 12/15 were transmural (80%). There was no benefit of the bonus freeze in LV lesions (6 vs. 2 × 4 min: 6790 ± 44 vs. 5595 ± 63 mm3; P = 0.44). All ablated vascular structures appeared macroscopically normal without acute stenosis. One animal died due to incessant Ventricular fibrillation (VF). Conclusion Our results indicate that a more powerful cryoablation system is able to create large, transmural ventricular lesions from both the endocardium and the epicardium. The technology may hold potential for both surgical and catheterbased VT ablation in humans.