title: Pulmonary vein isolation using a second-generation cryoballoon catheter: a randomized comparison of ablation duration and method of deflation.
abstract: BACKGROUND
  Optimal cryoballoon ablation parameters for pulmonary vein (PV) isolation remain to be defined. We conducted a randomized preclinical trial to compare 2- versus 4-minute ablation lesions and assess the safety of active (forced) cryoballoon deflation.
  
  
  RESULTS
  Thirty-two dogs underwent PV isolation with a second-generation 23 mm cryoballoon catheter. The left superior (LSPV) and inferior (LIPV) PVs were randomized in a factorial design to (1) a single 2- versus 4-minute cryoapplication, and (2) passive versus active cryoballoon deflation. Animals were survived for 30 days, after which histopathologic analysis was performed. Acute PV isolation was attained in 89.8% of PVs after a single application (93.8% LSPV, 85.2% LIPV; P = 0.2823). Mean time to PV isolation was 29.5 ± 18.5 seconds. Although 4-minute lesions were associated with a thicker neointima than 2-minute lesions (223.8 μm versus 135.6 μm; P = 0.007), no differences were observed in procedural characteristics (freezing temperature, rewarming time), rates of acute PV isolation, or the achievement of complete circumferentially transmural lesions at 30 days (78.7% overall; 86.2% for 2 minutes vs 70.0% for 4 minutes; P = 0.285). Active deflation was associated with faster balloon rewarming but not with significant differences in mean or maximum neointimal thickness.
  
  
  CONCLUSIONS
  A single application with the second-generation cryoballoon catheter results in a high rate of PV isolation. The degree of vascular injury was not increased by active balloon deflation and no differences in acute efficacy or mature transmural circumferential lesions were observed with 2- versus 4-minute applications.
authors.affiliation: Electrophysiology Service, Department of Cardiology, Montreal Heart Institute, Université de Montréal, Montreal, Canada.
authors.forename: Jason G
authors.initials: JG
authors.lastname: Andrade
authors.forename: Marc
authors.initials: M
authors.lastname: Dubuc
authors.forename: Peter G
authors.initials: PG
authors.lastname: Guerra
authors.forename: Evelyn
authors.initials: E
authors.lastname: Landry
authors.forename: Nicolas
authors.initials: N
authors.lastname: Coulombe
authors.forename: Hugues
authors.initials: H
authors.lastname: Leduc
authors.forename: Léna
authors.initials: L
authors.lastname: Rivard
authors.forename: Laurent
authors.initials: L
authors.lastname: Macle
authors.forename: Bernard
authors.initials: B
authors.lastname: Thibault
authors.forename: Mario
authors.initials: M
authors.lastname: Talajic
authors.forename: Denis
authors.initials: D
authors.lastname: Roy
authors.forename: Paul
authors.initials: P
authors.lastname: Khairy
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000601:surgery; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D003452:Cryosurgery / Q000295:instrumentation / Q000379:methods*; D004285:Dogs; D009206:Myocardium / Q000473:pathology; D011667:Pulmonary Veins / Q000473:pathology / Q000601:surgery*; D011897:Random Allocation