Epicardial pulsed field ablation at atrial ganglionated plexi sites: an electrophysiological and histological analysis in pigs

Abstract Background Endocardial atrial fibrillation (AF) ablations using thermal energy sources modulate ganglionated plexi (GP). Contrarily, endocardial pulsed field ablation (PFA) has minimal effect on GP located within the epicardial fat-pads. Purpose To determine structural and antiarrhythmic effects of direct epicardial PFA-delivery to atrial GP-sites. Methods Group-1: Epicardial PFA-delivery to GP sites (n=6 pigs). Group-2: Sham-operated (n=2 pigs). Thoracotomy was performed and five epicardial GP-sites were identified and targeted by saline-irrigated bipolar PFA (1,000V, 100μs, 120-pulses, ECG-synchronised). Local atrial electrogram (EGM) amplitude, atrial effective refractory period (aERP) and AF (inducibility and duration) were investigated. Histology was performed on samples from treatment-adjacent structures. Results In Group-1, 120 PFA-pulses were successfully delivered epicardially to each GP-site. Local EGM-amplitudes did not change after PFA-delivery. GPs showed lower intensity of S100-protein expression within the cytoplasm and membrane with preservation of adjacent atrial myocardium. The aERP at the higher and lower lateral right atrium increased from 123±34ms to 173±47ms (p=0.0358) and from 122±32ms to 221±16ms (p=0.0063) after PFA-treatment, respectively. Total AF-inducibility decreased from 100% to 33%, inducible AF-duration decreased from 4.4±0.6min (including 2 cardioversions) at baseline to 1.3±2.1min (including 1 cardioversion) after PFA-delivery (decrease: -3.2±2min, p=0.007). In one pig, the feasibility of thoracoscopic epicardial PFA delivery at all anatomical GP-sites was shown. Conclusion Epicardial PFA-delivery to anatomical GP-sites is feasible in open-chest or thoracoscopic approach, and acutely decreases GP S100-protein intensity, prolongs aERP and reduces AF-inducibility and duration.