Rationale and design of the FreezeAF trial: a randomized controlled noninferiority trial comparing isolation of the pulmonary veins with the cryoballoon catheter versus open irrigated radiofrequency ablation in patients with paroxysmal atrial fibrillation

Abstract

Background: Atrial fibrillation is the most commonly encountered clinical arrhythmia, and there are an increasing number of patients with paroxysmal atrial fibrillation treated by catheter ablation. The criterion standard is the isolation of the pulmonary veins (PVs) using radiofrequency (RF) energy in combination with an open irrigated tip catheter. The procedure remains technically challenging with a significant number of complications. So far, no randomized comparisons between the outcome of cryoballoon versus RF ablation are available.

Study design: The object of this randomized clinical trial is to compare the efficacy of isolating the PVs with either the cryoballoon or the open irrigated tip RF catheter. Two hundred forty-four patients with paroxysmal atrial fibrillation will be randomized for either RF or cryoballoon. With both techniques, PV isolation will be performed. Primary end point of the study is freedom from atrial fibrillation without antiarrhythmic drugs and without persistent complications at 6 and 12 months. Clinical success will be evaluated using Holter electrocardiogram and event recordings for at least 7 days. Within 6 months, no redo procedure is performed; and a redo after 6 months is performed with the previously used energy source. Secondary end points include the mid- and long-term clinical success, procedural data, and cost-effectiveness.

Conclusion: The FreezeAF trial will examine for the first time in a randomized trial whether PV isolation with the cryoballoon is not relevantly inferior to open irrigated RF ablation in patients with paroxysmal atrial fibrillation during follow-up. It will additionally directly compare acute procedural success and safety of the procedures.