Cryoballoon ablation for persistent atrial fibrillation in Japan: 12-month results from the Cryo Global Registry

Abstract Background/Introduction Atrial fibrillation (AF) prevalence has risen in Japan in the increasing elderly population. Despite this, data on clinical outcomes following treatment with cryoballoon ablation (CBA) for persistent AF (PsAF) are limited as Japanese patients continue to be largely underrepresented in clinical studies. Purpose To report real-world outcomes in Japanese patients with PsAF undergoing CBA within the Cryo Global Registry (NCT02752737); an ongoing, prospective, global, multi-center, observational, post-market registry. Methods This analysis included a total of 1226 PsAF (AF episode ≥ 7 days and ≤12 months) patients from 60 Japanese centers that underwent a CBA procedure between January 2021 and June 2022 and were followed for 12 months. The effect of PsAF diagnosis-to-ablation time and ablation strategy on atrial arrhythmia (AA) recurrence (defined ≥30 sec after 90-day blanking period) was evaluated. Diagnosis-to-ablation time was assessed in 4 subgroups based on quartiles of the time between PsAF diagnosis and ablation. Ablation strategy was defined as pulmonary vein isolation (PVI) only vs. PVI+, defined as PVI and ablation targets beyond PVI, including cavotricuspid isthmus (CTI) and linear lesions. Serious device- or procedure related adverse events (SAE) were evaluated through 12 months post-ablation. Results Patients were 68±10 years old; 29.0% were female and all had a history of symptomatic AF, with 29.6% not reporting symptoms at their baseline visit. The majority of patients were treated early after PsAF diagnosis: the median (Q1-Q3) time from diagnosis of PsAF to treatment was 0.2 [0.1 - 0.4] years. PsAF diagnosis-to-ablation between 0-1.6 months resulted in highest freedom from atrial arrhythmias (86.6% (95% CI: 81.8%-90.3%)) compared to "delayed" treatment of >5 months (83.7% (95% CI: 78.7%-87.7%) (P=0.72). All patients received standard PVI. In addition, 33.0% of patients received a CTI line, and 34.6% of patients received non-PVI, non-CTI, mainly left atrial roofline ablation (27.2%). At 12 months, freedom from atrial arrhythmia recurrence was 82.0% (CI: 78.6%-84.9%) in patients receiving PVI-only ablation vs. 86.6% (CI: 83.6%-89.1%) in patients receiving PVI+ ablations (p=0.03). Forty device- or procedure-related SAEs were reported in 38 patients (3.1%), with the most common being phrenic nerve injury (19, 1.5%). However, no deaths or atrioesophageal fistula were reported as related to the device or the procedure. Conclusion In Japanese patients undergoing CBA for PsAF, early treatment in addition to a PVI+ approach is safe and effective with low procedure-related adverse events and low recurrence of atrial arrhythmias through 12 months post-ablation.