Aims: The arctic front cryoballon (AF-CB) provides effective and durable pulmonary vein isolation (PVI) associated with encouraging clinical outcome data. The novel POLARx cryoballoon incorporates unique features and design changes which may translate into improved efficacy, safety and further simplified balloon based PVI procedures.

Methods: Twenty-five consecutive patients with paroxysmal or persistent atrial fibrillation (AF) were prospectively enrolled, underwent POLARx based PVI (POLARx group) and were compared to 25 consecutive patients treated with the fourth generation AF-CB (CB4, AF-CB4 group).

Results: A total of 100 (POLARx) and 97 (AF-CB4) pulmonary veins (PV) were identified and all PVs were successfully isolated utilizing the POLARx and AF-CB4, respectively. A significant difference regarding the mean minimal cryoballoon temperatures reached using the AF-CB4 and POLARx (-50±6°C versus -57±7°C, p=0.004) was observed. Real-time PVI was visualized in 81% of patients (POLARX) and 42% of patients (AF-CB4), respectively (p<0.001). Despite a certain learning curve utilizing the POLARx a trend towards shorter median procedure time (POLARx: 45 (39, 53) minutes vs AF-CB4: 55 (50, 60) minutes (p=0.062) was found. No differences were observed between AF-CB4 and POLARx concerning catheter maneuverability, catheter stability and periprocedural complications.

Conclusions: The novel POLARx showed similar safety and efficacy compared to the AF-CB4. A higher rate of real-time electrical PV recordings and significantly lower minimal balloon temperatures have been observed using the POLARx as compared to AF-CB4.