168-05: The FIRE and ICE Trial: looking beyond the primary efficacy and safety endpoints

Abstract

Purpose: Two widely used ablation strategies exist to manage symptomatic patients with drug-refractory paroxysmal atrial fibrillation (AF): radiofrequency current (RFC) and cryoballoon catheter ablation (CBA). Recent evidence confirms that pulmonary vein isolation (PVI) is fundamental to AF ablation strategy. FIRE and ICE compared the efficacy and safety of RFC and CBA in a randomized non-inferiority trial design. Results of the primary efficacy and safety endpoints were presented at ACC 2016. However, there are secondary endpoints (e.g. demographic characterization of atrial arrhythmia recurrence/re-ablation, assessment of Quality of Life (QoL), and further descriptions of device-related adverse events) that have yet to be released. Methods: Each randomized group included the most recently marketed generation of ablation catheters, including the ThermoCool SmartTouchw RFC catheter and the Arctic Front Advance cryoballoon catheter. Patients with drug refractory paroxysmal AF were randomized 1:1 and to either ablation strategy. Patients were followed at 3, 6, 12-months, and every 6 months thereafter up to 33 months to assess study endpoints. Examinations included medical histories, physical examination, 12-lead ECG, and 24 hour Holter monitor review. QoL surveys were assessed at baseline and biannually thereafter. Key secondary endpoints were 1) time to recurrent AF; 2) mean number of re-ablations; and 3) QoL changes at 12 months compared with baseline. Results: FIRE and ICE is the largest randomized trial to evaluate the efficacy and safety of CBA vs. RFC ablation in patients with paroxysmal AF. The study enrolled a total of 769 subjects from 16 centers in 8 European countries; the primary endpoint analysis required 249 subjects to reach the primary efficacy endpoint. A total of 384 subjects were randomly assigned RFC ablation and 378 subjects CBA. Beyond the primary endpoint analysis, further subgroup analyses (catheter mix and patient demographics) have been conducted and key secondary endpoints will be presented. Conclusions: Fundamentally, the two ablation strategies differ in terms of the energy source (burning vs. freezing), the mode of energy application (point-by-point ablation vs. "single-shot"), and catheterhandling learning curves. Some of these differences were resulted in significant differences in patient and procedural outcomes. The trial confirms that both ablation strategies should be considered gold standards for the treatment of patients with paroxysmal AF.