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.

Aims: Saline-irrigated radiofrequency ablation (RFA) for atrial fibrillation (AF) is limited by the absence of reliable thermal feedback limiting the utility of temperature monitoring for power titration. The DiamondTemp (DT) ablation catheter allow efficient temperature-controlled irrigated ablation. We sought to assess the 1-year clinical safety and efficacy of the DT catheter in treating drug-refractory paroxysmal AF. Methods and results: The TRAC-AF trial (NCT02821351) is a prospective, multi-center (n=4), single-arm study that enrolled patients with symptomatic, drug-refractory paroxysmal AF. Using the DT catheter, point-by-point ablation was performed around all pulmonary veins (PVs) to achieve PV isolation (PVI). Ablation was performed in a temperature-control mode (60oC, max 50 W) until the split-tip EGM amplitude decreased by ≤75%. The primary efficacy endpoints included acute procedural success and freedom from AF at 12 months. A total of 62 patients (age 60.3 ± 11.4 years; 60% male) were evaluated after AF ablation using the DT catheter. The mean fluoroscopy and RF ablation times were 9.4±6.4 min and 19.8±8.6 min, respectively. Acute isolation of all PVs was achieved in 100% of patients. There were no steam pops and there were not seen any char or caugulum on the catheter tip after ablation. There were very few serious procedure/device-related adverse events including a single case of cardiac tamponade (1.6%). At 1 year, the freedom from AF was 74.2%. Conclusion: This first in man series demonstrates that temperature-controlled irrigated RFA with the DT catheter is efficient, safe, and effective in the treatment of paroxysmal AF.