Introduction: Pulmonary vein isolation (PVI) with cryoablation was shown to be comparable to radiofrequency ablation (RF) in terms of safety and outcome for patients with atrial fibrillation (AF), so that both techniques are recommended equally by the current guidelines. A new cryoablation system PolarX® (Boston Scientific) was introduced in 2020. We analysed the first patients, who underwent ablation with the new system with respect to procedural and safety outcome and evaluated the freedom from arrhythmia occurrence in the first 6 months compared to patients treated with the established Arctic Front Advance® cryoablation system.  

Methods: We included the consecutive 44 patients who underwent cryoablation with the new PolarX® cryoablation system (28mm) (PolarX group) and 24 patients who underwent cryoablation with the established Arctic Front Advance® cryoablation system (28mm) (ArcticFront group) for paroxysmal AF. We retrospectively analysed baseline characteristics, procedural- and safety data. In 5 patients of each group an additional high-density 3D-mapping was performed, evaluating the scar-area after cryoablation in both groups (figure 1A+B). After 6 months the freedom of AF (by 7d-Holter-ECG) was evaluated in both groups.

Results: Baseline, procedural characteristics and results are listed in table 1. Mean total procedure duration (‘door-to-door-time’) was significantly shorter in the PolarX group compared to the Arctic-Front group (136±34min vs. 163±43min; p<0.05). Number of freezes required to achieve isolation of all pulmonary veins (PVs) and cumulative freezing time was comparable in both groups. Minimal achieved temperatures were significantly lower in the PolarX group vs. ArcticFront group (-53.6±6.8°C vs. -45.0±5.5°C; p<0.001). The scar-area analyzed by 3D-mapping post ablation did not differ in the two groups. Complication rates as well as clinical outcome (freedom from AF) were low and did not differ in the Kaplan-Meier analysis (table 1; figure 1C).

Conclusion: Based on these initial results, cryoablation with the PolarX cryoballoon seems to be comparably effective and safe, with a significantly shorter procedure time and significantly lower achieved temperatures. Nevertheless, future controlled trials with a longer follow-up period will be necessary to evaluate long-term effectiveness.