Background: In symptomatic atrial fibrillation (AF) patients cryoballoon pulmonary vein isolation (PVI) is a well-established and highly efficient treatment strategy. Recently, a novel cryoballoon system has been released which provides several enhancements. The sheath allows a deflection angle of 155°, and the balloon diameter (28 mm) remains stable during the inflation and ablation phases.

Methods: A prospective, single-center feasibility study was conducted to evaluate the novel cryoballoon ablation system (POLARx™) regarding its safety, efficacy and advantages in symptomatic paroxysmal AF patients undergoing PVI.

Results: Eighteen patients with paroxysmal AF, mean age 65.8±15 years, and median AF history of 10 (IQR 34) months were enrolled. Study population comprised 11 (61.1) male and 7 (38.9) female patients. Total procedure time was 96.4±21.3 minutes. A median dose area product of 861.5 (IQR 588) cGy x cm2 and a mean fluoroscopy time of 17.9±6.8 minutes were observed. Acute PVI could be achieved in 73 (100%) veins with a mean time to isolation (TTI) of 38 (IQR 28) seconds. TTI was attained in 67 (92%) pulmonary veins (PV). Minimal balloon temperature was −58 (IQR 6) °C. A total of 125 (100%) freeze applications were performed with a median number of 2 (IQR 1) per vein to achieve PVI. Of all 73 veins, 62 (84.9%) were isolated with a single-shot application. Three (2.4%) freeze attempts were ineffective and one PV (1.3%) showed intraprocedural reconnection, which required repositioning and additional cryoapplications. Optimal balloon positioning was achieved over the spiral mapping catheter placed at the ostium of the PV without the need to apply strong force on balloon or sheath. There was no severe procedural- or device-related adverse event until hospital discharge. One patient experienced an aseptic inflammation treated by ibuprofen.

Conclusion: The novel cryoballoon system had an overall very high efficacy and safety. Particularly noticeable is its high rate of attaining TTI, the low balloon temperature and the high single shot success. Long-term outcome has to be evaluated in the future.