title: Treatment of atrioventricular nodal re-entrant tachycardia by cryoablation with an 8-mm-tip catheter versus radiofrequency ablation.
abstract: OBJECTIVE
  Catheter cryoablation (CRYO) may eliminate inadvertent atrioventricular block (AVB) in the treatment of atrioventricular nodal reentrant tachycardia (AVNRT). However, higher recurrence was observed with CRYO delivered by 4 mm or 6 mm-tip catheter. This study was performed to investigate whether a comparably low treatment failure and recurrence rate as in radiofrequency (RF) ablation is achievable by CRYO with an 8-mm-tip catheter.
  
  
  METHODS
  This is a retrospective case-control study including 40 patients with AVNRT treated with CRYO (n = 20) using an 8 mm-tip catheter or RF ablation (n = 20) from March 2009 to March 2011. Treatment failure was defined as the composite of acute procedural failure including inadvertent permanent AVB and documented recurrence.
  
  
  RESULTS
  Acute procedural success of 90% (18/20) and 95% (19/20) were achieved in CRYO and RF ablation group, respectively (p = 0.998), with no permanent AVB in either group. With Kaplan-Meier analysis, there was no significant difference between the treatment groups in terms of recurrence rate (5.6% [1/18] vs. 0%; log-rank test p = 0.304) and treatment failure (15% [3/20] vs. 5% [1/20]; log-rank test p = 0.301). Shorter fluoroscopy time (15 ± 8.6 vs. 25.2 ± 12.1 min; p = 0.005) and more energy applications (median 4 [2-15] vs. 2 [1-8]; p = 0.005) were observed in the CRYO group compared with RF ablation group.
  
  
  CONCLUSIONS
  Compared to RF ablation, CRYO with an 8-mm-tip catheter for treating AVNRT achieves a comparable acute procedural success, comparably low recurrence rate and composite endpoint of treatment failure. Shorter fluoroscopy time and more energy applications were observed in the CRYO group.
authors.affiliation: Princess Margaret Hospital, 2-10 Princess Margaret Hospital Road, Lai Chi Kok, Kowloon, Hong Kong. ngaiyinchan@yahoo.com.hk
authors.forename: Ngai-Yin
authors.initials: NY
authors.lastname: Chan
authors.forename: Ngai-Shing
authors.initials: NS
authors.lastname: Mok
authors.forename: Chi-Chung
authors.initials: CC
authors.lastname: Choy
authors.forename: Chun-Leung
authors.initials: CL
authors.lastname: Lau
authors.forename: Pui-Shan
authors.initials: PS
authors.lastname: Chu
authors.forename: Ho-Chuen
authors.initials: HC
authors.lastname: Yuen
authors.forename: Suet-Ting
authors.initials: ST
authors.lastname: Lau
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D017115:Catheter Ablation / Q000379:methods; D016009:Chi-Square Distribution; D003452:Cryosurgery / Q000379:methods*; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D016019:Survival Analysis; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome