Two-year clinical outcome after a single cryoballoon ablation procedure: A comparison of first- and second-generation cryoballoons.

Background: The ablation of paroxysmal atrial fibrillation (PAF) by cryoballoon has increased dramatically in recent years. However, there are few data comparing first- and second-generation cryoballoons.

Aim: To compare safety and mid-term (2-year) efficacy of first- and second-generation cryoballoons in PAF ablation, using cryoballoon size tailored to pulmonary vein anatomy.

Methods: In this single-centre study, we included the last 50 consecutive PAF patients who underwent cryoballoon-based pulmonary vein isolation using the first-generation cryoballoon (CB-1) and the first 50 patients using the second-generation cryoballoon (CB-2). The choice of 23 or 28mm cryoballoon was driven by patient anatomy. After discharge, follow-up was with systematic outpatient visits at 3, 6, 9, 12 and 24 months, including 12-lead electrocardiogram, Holter monitoring and telephone interviews, plus additional electrocardiograms, as required, in case of symptoms. Arrhythmia recurrence was defined as a documented atrial tachycardia or fibrillation episode>30seconds after a 3-month blanking period.

Results: At 24 months, freedom from arrhythmia after a single procedure was similar for both generations of cryoballoon (72.0% and 72.0% for CB-1 and CB-2, respectively; P=0.95). Mean procedure and fluoroscopy times were longer in the CB-1 group than in the CB-2 group: 139±37.8 vs 95.2±21.3minutes and 10.2±7.2 vs 5.1±2.4minutes, respectively (P<0.02 for both). Transient right phrenic nerve palsy occurred only in the CB-1 group (five patients, 9.8%).

Conclusions: CB-1 and CB-2 showed similar efficacy for PAF ablation, with similar arrhythmia recurrence 24 months after a single ablation procedure. However, our findings suggest that CB-2 may have more effective cooling capabilities, enabling shorter procedure and fluoroscopy times.