First-time catheter ablation for atrial fibrillation in hypertrophic cardiomyopathy: comparison between radiofrequency and cryoballoon ablation

Background/Introduction Atrial fibrillation (AF) is a frequent arrhythmic complication in patients with hypertrophic cardiomyopathy (HCM) and is associated with increased morbidity and mortality. Catheter ablation (CA) has emerged as an important rhythm control strategy; however, the optimal ablation modality and its long-term efficacy in HCM remain uncertain, particularly among Japanese patients. Purpose This study aimed to evaluate the procedural and clinical outcomes of first-time CA for AF in HCM patients, comparing radiofrequency (RF) ablation with cryoballoon (CB) ablation. Methods We retrospectively analyzed 43 consecutive HCM patients who underwent first-time CA for AF between 2016 and 2024 at a single tertiary center. HCM was diagnosed according to the JCS 2018 Guideline on Diagnosis and Treatment of Cardiomyopathies. Patients were divided into two groups according to the energy source: RF (n=26) and CB (n=17). Pulmonary vein isolation (PVI) was the primary lesion set, and additional ablation beyond PVI was performed at the operator’s discretion. AF recurrence was defined as any atrial tachyarrhythmia lasting ≥30 seconds beyond a 3-month blanking period. Procedural outcomes, recurrence mechanisms, and PV reconnection findings at redo ablation were compared between the two groups. Results The mean age was 63±10 years, and 70% were male. Paroxysmal AF was present in 67% and persistent AF in 33%. Baseline clinical characteristics were comparable between groups. Acute PVI success was achieved in all patients. During a median follow-up of 24 months, AF/AT recurrence occurred in 14 patients (RF 53.8% vs. CB 35.3%, p=0.349). Redo ablation was performed in 11 patients (RF 8, CB 3). PV reconnection was identified in 12/32 (37.5%) PVs in the RF group and 2/12 (16.7%) in the CB group (p=0.282). Non-PV mechanisms, including the left atrial posterior wall or mitral isthmus conduction, accounted for 6 of 11 recurrence cases. No major periprocedural complications, including stroke or cardiac tamponade, were observed. Conclusion In Japanese patients with HCM undergoing first-time AF ablation, recurrence tended to be more frequent after RF ablation than after CB ablation, although the difference was not statistically significant. Non-PV mechanisms contributed to more than half of recurrence cases, suggesting that tailored substrate modification beyond standard PVI may be necessary to achieve durable rhythm control in this population.