Acute autonomic modulation after pulmonary vein isolation: real-world evidence from the Swiss-AF PVI Registry

Background Pulmonary vein isolation (PVI) is the cornerstone therapy for atrial fibrillation (AF) and may modulate cardiac autonomic function (CAF) due to the close anatomical relationship between the PV antra and atrial ganglionated plexi. Thermal PVI using radiofrequency (RF) or cryoballoon energy (CB) has been associated with acute reductions in heart rate variability (HRV) and increases in resting heart rate, consistent with transient parasympathetic withdrawal (1,2). In some studies, greater post-ablation HRV reduction was linked to lower AF recurrence, suggesting that autonomic modification may contribute to procedural efficacy (3,4). Pulsed field ablation (PFA) has emerged as a non-thermal alternative for PVI. Data suggest relative preservation of perivascular autonomic structures after PFA, potentially resulting in less pronounced autonomic modulation (5). Purpose We aimed to investigate immediate effects of PVI on CAF in a real-world cohort from the Swiss-AF PVI registry (University Hospital, Switzerland). Methods Consecutive patients undergoing first-time PVI were prospectively included. Five-minute high-resolution digital ECG recordings were obtained immediately before PVI and prior to discharge. CAF was assessed using periodic repolarization dynamics (PRD), deceleration capacity (DC), standard deviation of normal-to-normal intervals (SDNN), root mean square of successive differences (RMSSD), mean heart rate (MHR), and HRV triangular index (HRVI). Primary endpoint was the acute change of CAF between baseline and post-ablation assessment. Results 281 patients (age 68 [61–75] years; 31% female) were analyzed. Median CHA2DS2-VA score was 2 (IQR 1–3; mean 2.3±1.6). EHRA class III–IV symptoms were present in 15%, hypertension in 54.7%, diabetes in 11.6%, coronary artery disease in 12.9%, prior MI in 7.4%, prior PCI in 9.8%, prior stroke or TIA in 6.2%, heart failure in 14.3%, and renal insufficiency in 9.2%. Oral anticoagulation was used in 92.2% and beta-blockers in 67.2%. Energy sources were predominantly PFA (90.6%), followed by dual energy (RF + PFA) in 6.3%, RF alone in 1.8%, and CB in 1.3%. At baseline, the median CAF was PRD 5.97°, DC 4.99 ms, SDNN 58.8 ms, RMSSD 32.5 ms and HRVI 14.6. After PVI, PRD increased to 7.02°, while DC, SDNN, RMSSD, and HRVI decreased to 3.47 ms, 40.6 ms, 22.1 ms, and 11, respectively (p<0.001, Figure). MHR showed a modest, non-significant rise from 66.1 to 67.6 bpm. Conclusions In this cohort with predominantly PFA-based PVI, significant acute alterations in CAF were observed two days after ablation. Despite the non-thermal nature of PFA, autonomic parameters showed a pattern consistent with parasympathetic withdrawal and sympathetic predominance. These findings suggest that even contemporary PVI strategies are associated with early autonomic modulation. Further studies are warranted to determine the persistence of these changes and their relationship with outcomes.