Background: The novel fourth-generation cryoballoon (CB4) with a shortened tip allows for more frequent capture of pulmonary vein (PV) potentials which can be used to monitor real-time PV isolation.
Objective: This study evaluated feasibility and efficacy of time-to-isolation (TTI) guided ablation for PV isolation using CB4 with a shortened tip.
Methods: A total 100 patients with paroxysmal atrial fibrillation undergoing PV isolation were analyzed. Forty patients underwent TTI guided PV isolation (TTI + 120-second freeze) using the 28 mm CB4. Only in the left superior PV, 180-second cryoapplication was delivered despite TTI. Procedural data and acute success were compared to 60 patients who underwent single 180-second freeze PV isolation without PV potential monitoring using the 28 mm second-generation cryoballoon (CB2). Cryoballoon was positioned at the PV ostium without contrast medium. The balloon was pulled back to the left atrium after inflation (sealing-back) and pushed to PV ostium. When freezing temperature did not reach -30°C after 30 seconds, the balloon was pulled down. If PV isolation could not be achieved within 60 seconds, the cryoapplication was abandoned and cryoballoon was repositioned.
Results: The real-time PVI visualization rate in the CB4 group was 90%, 90%, 75% and 60% of left superior, right superior, right inferior and left inferior PVs, respectively. The mean TTI in the CB4 group was 37 ± 12, 37 ± 14, 24 ± 10 and 24 ± 14 seconds in right inferior, left superior, left inferior and right superior PVs, respectively. Touch-up application rate (6% in CB4 vs 4% in CB2, P=0.374) and the mean nadir balloon temperature (-47.0 ± 5.7°C in CB4 vs -47.0 ± 6.1°C in CB2, P=0.971) were not different between two groups. The mean freeze time (160 ± 24 vs 168 ± 26 seconds, P=0.024), procedure time (47 ± 8 vs 51 ± 9 minutes, P=0.028) and fluoroscopy time (11 ± 3 vs 14 ± 3 minutes, P=0.002) in the CB4 group were significantly shorter than those in the CB2 group.
Conclusion: TTI guided cryoablation using the CB4 with a shorter tip without contrast medium is feasible and effective, and can reduce the procedure and fluoroscopy times.