Comparative analysis of resizable and standard cryoballoons in atrial fibrillation ablation: preliminary results from a two-center randomized trial

Abstract Introduction Pulmonary vein isolation (PVI) is the gold-standard treatment for rhythm control in atrial fibrillation (AF). Cryoballoon (CB) technology is a single-shot technology with established superiority over drug therapy for paroxysmal AF (PAF)¹. By providing two different balloon dimensions (28 and 31 mm), novel resizable CB may improve the effectiveness of pulmonary vein isolation². This study compares a new resizable CB with the fixed-size 28 mm CB. Purpose To evaluate the non-inferiority of the resizable POLARx FIT cryoballoon compared to fixed-size Arctic Front Advance Pro cryoballoon. Methods This two-center randomized controlled trial so far enrolled 155 PAF patients with indication for PVI, assigning them in a 1:1 ratio to either the Medtronic 4th generation fixed-size CB (Arctic Front Advance Pro) or the Boston Scientific resizable CB (POLARx FIT). Follow-ups include clinic visits and 24-hour ECG recordings at 3, 6, and 12 months, with additional visits every six months. Results Among the 155 recruited patients (75 in the Polar group, 80 in the Arctic group), 64 (41.3%) were female, with an average age of 60.4 ± 12.1 years. Groups were similar regarding sex and age. Procedure duration in the Polar group was 67.0 ± 20.2 min compared to 63.5 ± 20.2 min in the Arctic group (p=0.27). Fluoroscopy times and dose area products were comparable as well, with 8.3 ± 7.0 min and 742 ± 753 mcGym² in the Polar group and 7.9 ± 7.1 min and 617 ± 1016 mcGym² in the Arctic group (respectively p = 0.69 and p = 0.39). Complete PVI was achieved in 98.7% of Polar cases and 96.3% of Arctic cases (p=0.36). The Polar group exhibited somewhat higher incidence of impending or transient phrenic nerve palsy (5 cases) compared to the Arctic group (2 cases, p = 0.22). There was one Polar patient who developed effusive pericarditis. Vascular complications were detected in 3 Polar patients (arteriovenous fistula ± pseudoaneurysm) and one Arctic patient (arteriovenous fistula with pseudoaneurysm). No other complications were noted. The differences between the groups were not statistically significant. Conclusion In our study, the new resizable POLARx FIT cryoballoon was equivalent to the Arctic Front Advance Pro CB regarding procedure duration, fluoroscopy time, radiation dose, and acute PVI success. Only complications related to venous access were reported. Ongoing follow-up is essential to establish non-inferiority in terms of long-term outcomes.