One‐year outcomes of pulmonary vein isolation with a novel cryoballoon: Primary results of the FROZEN AF trial

Abstract

IntroductionCryoablation 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 multicenter, open‐label, prospective, single‐arm study on the safety and performance of a novel cryoballoon system for treatment of PAF.Methods and ResultsThe 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 one 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 28 mm cryoballoon in 325 drug refractory PAF patients. Complete PVI was achieved in 95.7% of patients. In cryoablation lesions longer than 60 s, 60.1% of PV isolations required only a single cryoballoon application. Procedure related complications included: phrenic nerve palsy [temporary 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 28/31 mm variable size cryoballoon. A single temporary PNP occurred in this group, which resolved before discharge. Freedom from documented recurrence at 12 months in these pts was 82.0%.ConclusionsThis novel cryoballoon may facilitate PVI to treat PAF, providing more options to address the variety of anatomies present in patients with PAF. This cryoballoon system proved to be safe and effective for treatment of patients with drug refractory or drug intolerant PAF.

Frozen too: Adopt the new or let it go?

“…The overall complication rate was low at 4.0%. These results are comparable to those of STOP-AF PAS, a study that bears most resemblance to the FROZEN AF trial 3,5 (Table 1). While the overall efficacy reported is high, it is not significantly higher than that noted with prevalent technologies, and was noted in absence of continuous rhythm monitoring with 24 h holter monitoring provided only at 12 months with twice a month trans-telephonic monitoring, thus introducing the possibility of underdiagnosing subclinical recurrence.…”

“…1 The efficacy of cryoballoon ablation is known to be comparable to radiofrequency ablation, however novel technologies within the realm of contemporary cryoablation have yet to be explored. 2,3 Ellenbogen et al report the results of an international multicenter, open-label, prospective, single-arm study on the safety and performance of PolarX™ (BosSci), a new cryoballoon system for treatment of paroxysmal atrial fibrillation. 3 Compared to the current standard of care Medtronic cryoablation system, the Boston Scientific system differs in its design.…”

“…2,3 Ellenbogen et al report the results of an international multicenter, open-label, prospective, single-arm study on the safety and performance of PolarX™ (BosSci), a new cryoballoon system for treatment of paroxysmal atrial fibrillation. 3 Compared to the current standard of care Medtronic cryoablation system, the Boston Scientific system differs in its design. The FlexCath™…”

Pulmonary Vein Isolation with a Novel Size-Adjustable Cryo-Balloon Catheter: A Tailored Ablation Protocol

“…In the event of an esophageal temperature drop, the larger balloon configuration appeared to facilitate prolonged freezing. During ablation with the small balloon configuration, the ablation is typically performed deeper in the vein compared to the larger balloon configuration [13]. In theory, ablation with the larger balloon configuration shifts the ablation site more into the atrium, creating a greater distance between the ablation site and the individual position of the esophagus, thus allowing for a longer freeze.…”

“…In the FIT extension arm of the FROZEN-AF trial, in 64% of the PV, the larger balloon configuration was utilized at the discretion of the interventionalist [13]. In numerical terms, the large balloon configuration was therefore used around 3.8 times more frequently in this study than with our protocol.…”