Introduction:
Cryoablation to achieve pulmonary vein isolation (PVI) to treat paroxysmal atrial fibrillation (PAF) is well established.1 Cryoballoon treatment has been available for PVI since the Arctic FrontTm (Medtronic, MN, USA) was launched over 15 years ago.2 STOP-AF demonstrated first generation cryoballoon superiority to AADs,3 and later Fire and ICE demonstrated comparable efficacy of cryoballoon to RF ablation.4 FIRE and ICE showed comparable efficacy of radiofrequency and cryoballoon but cryoablation has a distinct safety profile compared to RF, shifting primary safety events from heat associated pericarditis/perforation to cold associated phrenic nerve impairment and PV stenosis.4 Despite over a decade of use the safety profile of cryoablation remains relatively unchanged.5-10
Recently a novel 28 mm cryoballoon system that operates under markedly lower pressure and maintains constant balloon size during cooling became available for clinical studies.11 Additionally, a second generation of this novel cryoballoon that allows inflation and ablation at 2 sizes, 28mm or 31mm, has also become available.12 At present there is limited long-term (1yr) outcome data on this novel cryoballoon, and little data available on the safety or effectiveness of the novel variable size cryoballon12 While multiple studies have reported both acute procedural data,13-16 and chronic 1 year outcomes,17-19 only a few reports of large patient cohorts exist.13,14,18,20,21
FROZEN AF is an international multi-center, open-label, prospective, single-arm study to determine the safety and performance of a novel cryoballoon system for treatment of PAF, and an extension arm which examined the safety and performance of a novel variable size cryoballon.