title: Cryoablation outcomes for AV nodal reentrant tachycardia comparing 4-mm versus 6-mm electrode-tip catheters.
abstract: BACKGROUND
  Cryoablation is increasingly used to treat atrioventricular nodal reentrant tachycardia (AVNRT). It is unknown whether larger electrode-tip cryocatheters improve outcomes without compromising safety.
  
  
  OBJECTIVE
  This study sought to compare acute and long-term success with 4-mm versus 6-mm electrode-tip cryocatheters for AVNRT.
  
  
  METHODS
  We conducted a 2-group cohort study on 289 patients, age 45.5 +/- 15.9 years (76.8% female), who underwent transcatheter cryoablation as a first-time procedure for AVNRT with 4-mm (N = 152) or 6-mm (N = 137) electrode-tip catheters.
  
  
  RESULTS
  Acute procedural success was achieved in 90.7% (95% confidence interval 86.9% to 93.7%) with no difference between the 2 electrode-tip sizes. A shorter fluoroscopy time (16.1 +/- 11.3 versus 20.3 +/- 14.9 minutes, P = .0096) and trend toward briefer procedural duration (166.6 +/- 49.1 versus 173.5 +/- 53.0 minutes, P = NS) were noted with 6-mm electrode tips. Transient AV block occurred in 5.2%, with complete recovery in 4.4 +/- 2.6 seconds. Over a median follow-up of 155 days, recurrences were less common with 6-mm electrode tips. Actuarial event-free survival rates at 1, 3, 6, and 12 months with 6-mm versus 4-mm electrode-tip cryocatheters were 96.7%, 93.4%, 91.9%, and 88.5% versus 89.9%, 87.0%, 84.1%, and 77.1%, respectively, with no recurrence thereafter (P = .0457). In multivariate analyses adjusting for baseline imbalances and medical therapy postablation, cryoablation with a 4-mm-tip catheter incurred a 2.5-fold increased risk of recurrence (hazard ratio 2.5, 95% confidence interval 1.0 to 6.1, P = .0420).
  
  
  CONCLUSIONS
  In patients with AVNRT, cryoablation with 6-mm electrode-tip catheters is safe and is associated with fewer recurrences on long-term follow-up compared with 4-mm electrode-tip cryocatheters.
authors.affiliation: Electrophysiology Service, Montreal Heart Institute, Montreal, Quebec, Canada.
authors.forename: Lena
authors.initials: L
authors.lastname: Rivard
authors.forename: Marc
authors.initials: M
authors.lastname: Dubuc
authors.forename: Peter G
authors.initials: PG
authors.lastname: Guerra
authors.forename: Paul
authors.initials: P
authors.lastname: Novak
authors.forename: Denis
authors.initials: D
authors.lastname: Roy
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: Paul
authors.initials: P
authors.lastname: Khairy
mesh_terms: D000328:Adult; D001283:Atrioventricular Node / Q000503:physiopathology*; D003452:Cryosurgery / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D012107:Research Design; D012307:Risk Factors; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000401:mortality / Q000601:surgery*; D016896:Treatment Outcome