Difference in tissue temperature change between two cryoballoons.

Background: Cryoballoon ablation, especially Arctic Front Advance Pro (AFA-Pro) (Medtronic, Minneapolis, Minnesota, USA), has been widely recognised as a standard approach to atrial fibrillation (AF). Recently, Boston Scientific has released a novel cryoballoon system (POLARx). Despite comparable acute clinical outcomes of these two cryoballoons, the recent study reported a higher complication rate, especially for phrenic nerve palsy, with POLARx. However, their impact on biological tissue remains unclear.

Objective: The purpose of our study is to evaluate temperature change of biological tissue during cryoablation of each cryoballoon using a porcine experimental model.

Method: A tissue-based pulmonary vein model was constructed from porcine myocardial tissue and placed on a stage designed to simulate pulmonary vein anatomy and venous flow. Controlled cryoablations of AFA-Pro and POLARx were performed in this model to evaluate the tissue temperature. A temperature sensor was set behind the muscle and cryoballoon ablation was performed after confirming the occlusion of pulmonary vein with cryoballoon.

Results: The mean tissue nadir temperature during cryoablation with AFA-Pro was -41.5°C±4.9°C, while the mean tissue nadir temperature during cryoablation with POLARx was -58.4°C±5.9°C (p<0.001). The mean balloon nadir temperature during cryoablation with AFA-Pro was -54.6°C±2.6°C and the mean balloon nadir temperature during cryoablation with POLARx was -64.7°C±3.8°C (p<0.001).

Conclusion: POLARx could freeze the biological tissue more strongly than AFA-Pro.