Introduction: Pulsed Field Cryoablation (PFCA) is a dual-energy cardiac ablation modality consisting of short-duration ultra-low temperature cryoablation (ULTC) followed immediately by pulsed field ablation (PFA) delivered from the same catheter. It is hypothesized that PFCA may improve contact stability during PFA, while maintaining lesion depth and effectiveness of ULTC. Methods: PARALELL is a first-in-human multicenter study evaluating safety and effectiveness of a novel PFCA catheter and system in patients with persistent atrial fibrillation (PsAF) using the combination of pulmonary vein (PVI) and posterior wall (PWI) isolation. Results: 66 patients were ablated at six sites. Groin hematoma in one patient was the only serious procedure- or device-related adverse event recorded in the study. Per protocol, acute effectiveness was evaluated in 46 patients, including 31 patients with post-hoc analysis of cryogenic energy per lesion. After an average of 21.1 ± 9.3 lesions per patient the rates of PVI and PWI were 95.7% (176/184) and 97.7% (42/43), respectively. The average cryogenic energy per patient was highly predictive of acute isolation success with ROC AUC = 0.944 and 100% rates of both PVI and PWI in 24 patients in the optimal energy cohort. Grade I microbubbles and faint muscle contractions were detected in 1.1% and 0.5% of ablations, respectively. Conclusion: This initial multi-center experience suggests that PFCA can be efficiently performed for PVI and PWI using a single versatile catheter system, with high acute success and good early safety profile. The evaluation of the chronic 12-month effectiveness of PFCA is ongoing.

Background: Modulation of the cardiac autonomic nervous system (ANS) is a promising adjuvant therapy in the treatment of atrial fibrillation (AF). In pre-clinical models, pulsed field (PF) energy has the advantage of selectively ablating the epicardial ganglionated plexi (GP) that govern the ANS. Objective: This study aims to demonstrate the feasibility and safety of epicardial ablation of the GPs with PF during cardiac surgery with a primary efficacy outcome of prolongation of the atrial effective refractory period (AERP).  Methods: In a single-arm, prospective analysis, patients with or without a history of AF underwent epicardial GP ablation with PF during coronary artery bypass grafting (CABG). AERP was determined immediately pre- and post- GP ablation to assess cardiac ANS function. Holter monitors were performed to determine rhythm status and Heart Rate Variability (HRV) at baseline and at 1 month post-procedure.   Conclusions:  This study demonstrates the safety and feasibility of epicardial ablation of the GP using PF to modulate the ANS during cardiac surgery. Large, randomized analyses are necessary to determine whether epicardial PF ablation can offer a meaningful impact on the cardiac ANS and reduce AF. Results: Of 24 patients, 23 (96%) received the full ablation protocol. No device-related adverse effects were noted. GP ablation resulted in a 20.7% ± 19.9% extension in AERP (P < 0.001). Post-operative AF was observed in 7 (29%) patients. Holter monitoring demonstrated an increase in mean heart rate (74.0±8.7 vs 80.6±12.3, P=0.01). There were no significant changes in HRV. There were no study-related complications.