Two-year outcome after pulmonary vein isolation using the second-generation 28-mm cryoballoon: lessons from the bonus freeze protocol

Background: Pulmonary vein isolation (PVI) using the second-generation cryoballoon (CB2) in patients with paroxysmal and persistent atrial fibrillation (AF) has demonstrated encouraging acute and mid-term results. Follow-up data on outcome beyond 1-year is lacking. The purpose of this analysis was to investigate the 2-year clinical outcome after CB2-based PVI. Methods: Sixty patients (age 62 ± 11 years) with paroxysmal [45/60 (75 %) patients] or short-standing persistent AF [15/60 (25 %) patients] underwent 28-mm CB2-based PVI. Freeze-cycle duration was 240 s. After successful PVI, a bonus freeze-cycle of the same duration was applied. Follow-up was based on outpatient clinic visits at 3, 6, 12, 18, and 24 months including 24 h Holter-ECGs and telephone interviews. Recurrence was defined as any symptomatic and/or documented atrial tachyarrhythmia (ATA) episode >30 s following a 3-month blanking period. Results: A total of 231 pulmonary veins (PV) were identified and 230/231 (99.6 %) PVs were successfully isolated. Phrenic nerve palsy occurred in 2/60 (3.3 %) patients. No other periprocedural complications occurred. Follow-up was available for 59/60 (98 %) patients with a mean duration of 838 ± 67 days. A total of 43/59 (73 %) patients remained in stable sinus rhythm. In 10/16 (63 %) patients with ATA recurrence, a repeat procedure was performed using radiofrequency energy. The overall success rate after a maximum of two ablation procedures and a follow-up period of 838 ± 67 days was 88 % (52/59) patients. Conclusions: Patients with paroxysmal or short-persistent AF undergoing PVI using the 28-mm CB2 demonstrated a 73 % 2-year single-procedure clinical success rate.