Introduction: Cryoballoon (CB) ablation for pulmonary vein isolation (PVI) is an established rhythm control therapy for atrial fibrillation (AF). The recent published Circa Dose trial demonstrated that a freezing protocol with 2x120 seconds freeze was as effective as a 2x240 seconds freeze protocol. Since the involvement of extracardiac structures is “freezing-time” dependent, we hypothesized that a freeze duration reduction to 120 seconds could also result in an increased procedural safety

Methods: 80 consecutive patients with symptomatic AF treated with a double 120 seconds freeze protocol (Group “CB120”) were enrolled. The  control group consisted in 80 consecutive patients previously treated with a single 240 seconds freeze application (Group CB240). In both groups a further bonus application was mandatory in case of late time to isolation (TTI>75”): 120 seconds freeze in the CB120, 180 seconds freeze in the CB240. All procedures were performed under luminal esophageal temperature (LET) control, during ablation at septal PV the phrenic was monitored via pacing, palpation and recording of the compound motor action potential (CMAP).

Results: The single CB PVI procedure was successfully performed in all patients (n=160; 631 PVs) without the need for focal touch-up ablation. Single shot PVI was obtained in 87% (546 of 631) of all PVs. In the CB120 group a non sustained block isolation was recorded in 7/316 (2,2%) PVs (LSPV 4, RIPV 3) vs no patients in the 240” Group (p=0,015). Procedure time (CB120 59,7±16,7, CB240 56,7±15,4 minutes, p=0,24), fluoroscopy time (CB120 9,2±4,1, CB240 8,1±3,7 minutes, p=0,08) and fluoroscopy dose (CB120 859,7±757,7; CB240 845,8±702,8 mGy, p=0,90) didn ́t differ between the two groups. 4/80 patients (5%) of the CB120 group experienced a PN injury, exclusively in the transient form, with intraprocedural recovery; 11/80 patients (14%) of the CB240 group experienced a PN injury, 3 in a persistent form (p= 0,10). A LET <15°C was recorded in 3/80 patients (4%) in the CB120 group and in 16/80 patients (20%) in the CB240 group (p=0,001).  Taken altogether, CB120 was associated to a lower rate of PN-Injury or LET<15°C  (8,7% vs 33%, p=0,002).

Conclusions: Safety of second generation CB PVI can be increased using a double 120 seconds TTI-guided freeze protocol. However, more acute PV reconnections are observed if a shorter freeze duration is applied.