Autonomic Effects of Pulsed Field vs Thermal Ablation for Treating Atrial Fibrillation

BACKGROUND Autonomic denervation is an ancillary phenomenon during thermal ablation of atrial fibrillation (AF), that may have synergistic effects on symptomatic improvement and long-term freedom from AF. Pulsed field ablation (PFA), a non-thermal ablation modality, was non-inferior to thermal ablation in treating AF; however, PFA's relative myocardial selectivity may minimize autonomic effects. OBJECTIVES Compare heart rate (HR) and heart rate variability (HRV) metrics as markers of autonomic function after ablation using PFA versus thermal ablation. METHODS ADVENT was a randomized pivotal study comparing PFA (pentaspline catheter) with thermal ablation (radiofrequency [RF] or cryoballoon [CB]) for treating paroxysmal AF. Baseline HR was acquired from a pre-ablation 12-lead ECG, while follow-up HRs, as well as HRV (SDNN, SDANN) metrics, were derived from 72-hour Holter monitors at 6 and 12-months. RESULTS This study included 379 paroxysmal AF patients undergoing PFA (n=194) or thermal ablation (n=185; n=102 RF, n=83 CB) completing 6 and 12-month Holter monitors. Compared to PFA, thermal patients had significantly greater increases in HR from baseline to 6 months (ΔHR; 10.1 vs. 5.9bpm; p=0.02) and 12 months (ΔHR; 8.8 vs. 5.2bpm; p=0.03). This increase in HR at 6 and 12 months was similar between CB and RF (p=0.94 and 0.83, respectively). HRV, both SDNN and SDANN, were significantly lower at both 6- and 12-month after thermal ablation compared to PFA (p<0.01). CONCLUSIONS PFA's effect on the autonomic nervous system was attenuated compared to thermal ablation. Whether this affects long-term freedom from AF or symptomatic bradycardia/pauses after AF ablation requires further study.