Distinct Automaticity and Excitability Between Radiofrequency and Cryoballoon Ablation in Paroxysmal Atrial Fibrillation

BACKGROUND: Cryoballoon ablation (CBA) has been shown as an effective alternative strategy to radiofrequency ablation (RFA) for the treatment of paroxysmal atrial fibrillation (PAF), with comparable efficacy and safety. However, the electrophysiological properties in pulmonary veins (PVs) after CBA and RFA are not well understood. This study compares these characteristics in PAF patients. METHODS: Consecutive patients with PAF undergoing initial catheter ablation were prospectively randomized to CBA (N = 50) or RFA (N = 50) for PV isolation (PVI). Each PV's automaticity and excitability were assessed. Follow-up for atrial tachyarrhythmia recurrence at 3, 6, and 12 months was monitored via electrocardiogram/Holter. RESULTS: A total of 100 patients were randomized (mean age of 62 ± 10 years). After initial PVI, 33 (66%) patients in the RFA group retained PV automaticity, compared to 17 (34%) patients in the CBA group (p = 0.027). The number of PVs exhibiting stable automaticity was significantly higher in the RFA group compared with the CBA group (51/198 vs. 19/197, p < 0.0001). Ipsilateral PV crosstalk was more common in the RFA group (7/17 vs. 0/2, p = 0.5088). Moreover, low-frequency pacing revealed local capture in 46% of the RFA group versus 2% of the CBA group (p < 0.0001). Fluoroscopy time was shorter with RFA (p = 0.0003), but ablation time was longer (p < 0.0001). Over an average of 13-month follow-up, atrial tachyarrhythmia recurrence rates were similar between groups. CONCLUSIONS: Automaticity and excitability within PVs were more prevalent in the RFA group than the CBA group after AF ablation.