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.

Introduction: We sought to investigate the net effect of wide area circumferential radiofrequency catheter ablation (WACA) on the atrial (LA) geometry. Methods and results: Seventy-one patients, who underwent a second PVI procedure, after index procedure of point-by-point WACA, for recurrent paroxysmal (n=31) or persistent (n=40) atrial fibrillation (AF) in our center were included. A three-dimension rotational angiography of the left atrium (3D-RA) under rapid ventricular pacing was performed immediately before ablation, at index and repeat ablation in all patients. LA geometry in terms of volume, sphericity and surface were assessed in all patients between first and second PVI. There was a statistical significant reduction of the LA volume (65,6 ± 14 ml/m2 vs 62,2 ± 15 ml/m2, p<0,001) and of the surface of the LA (74,4 ± 11,2 vs 70,4 ± 11,2 cm2/m2, p<0,001), whereas the sphericity of the LA increased significantly (82 ± 2% vs. 83 ± 2%, p=0,004) in all 71 patients. Patients with paroxysmal AF showed significant decrease of the LA volume (121,8 ± 25,7 vs 116 ± 32 ml, p=0,008) and increase of the LA sphericity (82,3 ± 2,1 vs 83,1 ± 2%, p=0,009). Patients with persistent AF showed significant decrease of the LA volume (133,5 ± 32 vs 126 ± 32 ml, p=0,005), but only a trend towards increased sphericity (82,4 ± 2,8 vs 83 ± 2,4%, p=ns). Conlusions: WACA results into significant reduction of the LA volume, LA surface area and into significant increase of the LA sphericity in treated patients with recurrent AF.