Autonomic changes in heart rate after pulsed field ablation for atrial fibrillation: insights from a prospective study

Background Thermal modalities (radiofrequency and Cryoballoon) tend to affect ganglionated plexi (GPs) during atrial fibrillation (AF) which tends to result in an increase in resting heart rate (HR) after ablation. Pulsed field ablation (PFA) is non-thermal with tissue-selective properties which might spare the GPs and might not result in a similar effect to thermal ablation. Purpose To determine whether PFA alters patients’ resting HR after ablation and to evaluate associated between number of PF lesions and changes in HR. Methods We retrospectively analyzed 53 patients with paroxysmal (52.8%), persistent (43.4%), and long-standing persistent (3.8%) AF who underwent PFA using a Pentaspline Catheter (Farapulse, Boston Scientific Inc.). Each patient’s resting HR was recorded systematically pre-ablation and then post-ablation (either prior to same-day discharge or within 24 hours post-ablation). Mean pre- vs post-PFA HR were compared with paired statistical tests. Additionally, we performed a baseline-adjusted ANCOVA (post-op HR ~ pre-op HR + total lesions) to evaluate the independent association between number of PF lesions with post-op HR. Results In our study cohort, the baseline mean resting HR was 71.2 ± 13.8 beats/min, and post-procedure HR was 69.7 ± 10.8 beats/min (difference not significant, p = 0.46). The median ΔHR was 0 beats/min (IQR –9 to +7); which further indicates no consistent change in HR change. Resting HR increased in 26 patients (49%), decreased in 22 (42%), and remained unchanged in 5 (9%), Figure 1. A median of 61 lesions (IQR 52–72, range 14–97) were delivered per procedure. However, in the ANCOVA model adjusting for pre-op HR, greater lesion count was independently associated with a modestly lower post-op HR (β ≈ −0.22 bpm per lesion; p = 0.013), corresponding to ~2 bpm lower per additional 10 lesions (Figure 2). Conclusion In this single-center cohort, PFA did not significantly alter resting heart rate. After adjusting for baseline HR and accounting for PF lesions, there was a small, but independent association between greater number of PF lesions and a slightly lower post-op HR. These findings suggest that PFA likely has GP properties, which are different from the thermal modalities for AF. This autonomic preservation could benefit patients by reducing unwanted chronotropic effects post-ablation, while achieving effective freedom from AF.