Introduction: Cryoablation therapy for pulmonary vein isolation (PVI) to treat paroxysmal atrial fibrillation (PAF) is well established. A novel 28 mm cryoballoon system designed to operate under low pressure to safely reach a lower nadir temperature and maintain constant balloon size during cooling has not been prospectively studied in a large patient population for safety and efficacy. The FROZEN AF (NCT04133168) trial was an international multi-center, open-label, prospective, single-arm study on the safety and performance of a novel cryoballoon system for treatment of PAF. Methods and Results: The study enrolled patients at 44 sites in 10 countries across North America, Europe, and Asia. Subjects were indicated for PVI treatment of PAF and had failed or were intolerant of 1 or more antiarrhythmic drugs. Procedural outcomes were defined based on the 2017 HRS consensus statement. Follow-up was performed at 7 days, 3, 6, and 12 months. Data are reported as mean±SD or Median (IQR). PVI was performed with a 28mm cryoballoon in 325 drug refractory PAF patients. Complete PVI was achieved in 95.7% of patients. In cryoablation lesions longer than 60s, 60.1% of PV isolations required only a single cryoballoon application. Procedure related complications included: phrenic nerve palsy [transient 4 (1.2%), persistent 0 (0.0%)], cardiac tamponade/perforation 2 (0.6%), and air embolism 1 (0.3%). Freedom from documented atrial arrhythmia recurrence at 12 months was 79.9% (AF 82.7%, AFL 96.5%, AT 98.1%), Antiarrhythmic drugs (AAD) were continued or re-initiated in 26.8% of patients after the 3-month blanking period. Additionally, an extension arm enrolled 50 pts for treatment with 28/31mm variable size cryoballoon. A single temporary PNP occurred in this group, which resolved prior to discharge. Freedom from documented recurrence at 12 months in these pts was 82.0%. Conclusions: This novel cryoballoon may facilitate PVI to treat PAF, providing more options to address the variety of anatomy present in patients with PAF. This cryoballoon system was safe and effective for treatment of patients with drug refractory or drug intolerant PAF.

Introduction: Pulsed electric field (PEF) ablation relies on the intersection of a critical voltage gradient with tissue to cause cell death. Field-based lesion formation with PEF technologies may still depend on catheter-tissue contact (CTC). The purpose of this study was to assess the impact of CTC on PEF lesion formation with an investigational large area focal (LAF) catheter in a preclinical model. Methods: PEF ablation via a 10-spline LAF catheter was used to create discrete RV lesions and atrial lesion sets in 10 swine (8 acute, 2 chronic). Local impedance (LI) was used to assess CTC. Lesions were assigned to 3 cohorts using LI above baseline: No Tissue Contact (NTC: ≤∆10Ω, close proximity to tissue), Low Tissue Contact (LTC: ∆11-29Ω), and High Tissue Contact (HTC: ≥∆30Ω). Acute animals were infused with triphenyl tetrazolium chloride (TTC) and sacrificed ≥2hrs post-treatment. Chronic animals were remapped 30 days post-index procedure and stained with infused TTC. Results: Mean (±SD) RV treatment sizes between LTC (n=14) and HTC (n=17) lesions were not significantly different (depth: 5.65±1.96mm vs 5.68±2.05mm, p=0.999; width: 15.68±5.22mm vs 16.98±4.45mm, p=0.737) while mean treatment size for NTC lesions (n=6) was significantly smaller (1.67±1.16mm depth, 5.97±4.48mm width, p<0.05). For atrial lesion sets, acute and chronic conduction block were achieved with both LTC (N=7) and HTC (N=6), and NTC resulted in gaps. Conclusions: PEF ablation with a specialized LAF catheter in a swine model is dependent on CTC. LI as an indicator of CTC may aid in the creation of consistent transmural lesions in PEF ablation.

Introduction: Catheter ablation is a cornerstone of the therapy for the paroxysmal atrial fibrillation. The importance of effective lesion size formation during pulmonary vein isolation is gauged through conduction recovery and recurrence of arrhythmia. Therefore, lesion size index (LSI) It is designed to utilize traditional intraprocedural parameters and predict the procedural success. The impact of the optimal LSI index and the respective segments of the pulmonary veins has not been commonly evaluated. We aimed to assess whether higher and targeted LSI on the different segments of pulmonary veins could actually leads to better clinical outcomes of paroxysmal atrial fibrillation ablation. Methods: Retrospective analyses of drug-refractory paroxysmal atrial fibrillation patients who underwent first catheter ablation were conducted. Targeted LSI of 6.5 at the anterior wall and 5.2 at the posterior wall, roof and floor of pulmonary vein was applied. The primary endpoint was defined as arrhythmias recurrence assessed by routine electrocardiograms and 24 hours ambulatory electrocardiographic monitoring at 3, 6, and 12 months postablation. Results: Among the included 39 patients, the single-procedure 12-months freedom from arrhythmias was reached in 92.3% patients. Interestingly, there was no tendency towards a increased number of adverse effects using higher LSI index. Conclusion: Atrial fibrillation ablation guided by targeted LSI value showed efficiency on the freedom from arrhythmias during 1-year follow up period without harmful effects.

Aims Periprocedural pulmonary vein isolation (PVI) anticoagulation requires balancing between the risk of bleeding and thromboembolism. Intraprocedural anticoagulation is monitored by activated clotting time (ACT) and there are no guidelines which specify an initial unfractionated heparin (UFH) dose. We aimed to assess differences in ACT values and UFH dosage during PVI in patients on different oral anticoagulants. Methods We conducted international, multi-centre, registry-based study. Consecutive patients with atrial fibrillation (AF) undergoing PVI, on uninterrupted anticoagulation therapy, were analysed. Before the transseptal puncture, UFH bolus of 100 U/kg was administered regardless of the anticoagulation drug. Results A total of 873 AF patients were included (median age 61 years, IQR 53-66; female 30%). There were 248, 248, 189, 188 patients on warfarin, dabigatran, rivaroxaban, and apixaban, respectively. Mean initial ACT was 257±50 sec, overall procedural ACT 295±45 sec and total UFH dose 158±60 IU/kg. Patients who were receiving warfarin and dabigatran compared to patients receiving rivaroxaban and apixaban had: (i) significantly higher initial ACT values (262±57 and 270±48 vs. 248±42 and 241±44 sec, p<0.001), (ii) significantly higher ACT throughout PVI (309±46 and 306±44 vs. 282±37 and 272±42 sec, p<0.001), and (iii) needed lower UFH dose during PVI (140±39 and 157±71 vs. 171±52 and 172±70 IU/kg). Conclusion There are significant differences in ACT values and UFH dose during PVI in patients receiving different anticoagulants. Patients on warfarin and dabigatran had higher initial and overall ACT values and needed lower UFH dose to achieve adequate anticoagulation during PVI than patients on rivaroxaban and apixaban.