title: Efficacy of Cox Maze IV Procedure Using Argon-Based Cryoablation: A Comparative Study with N2O-Based Cryoablation.
abstract: BACKGROUND
  We compared the mid-term results of the Cox maze IV procedure using argon-based cryoablation with a procedure using N2O-based cryoablation.
  
  
  METHODS
  From May 2006 to June 2012, 138 patients (mean age, 58.2±11.0 years) underwent the Cox maze IV procedure. Eighty-five patients underwent the maze procedure using an N2O-based cryoprobe (group N), and 53 patients underwent the maze procedure using an argon-based cryoprobe (group A). Bipolar radiofrequency ablation was concomitantly used in 131 patients. The presence of atrial fibrillation immediately, 6 months, 1 year, and 2 years after surgery was compared.
  
  
  RESULTS
  Early mortality occurred in 6 patients (4.3%). There were no differences in early mortality or postoperative complications between the two groups. Nineteen of 115 patients (16.5%) remained in atrial fibrillation at postoperative 12 months (14 of 80 patients (17.5%) in group N and 5 of 35 patients (14.3%) in group A, p=0.669). There were no differences in the number of patients who remained in atrial fibrillation at any of the time periods except in the immediate postoperative period. A multivariable analysis revealed that the energy source of cryoablation was not associated with the presence of atrial fibrillation at 1 year (p=0.862) and that a fine F wave (<0.1 mV) was the only risk factor predicting the presence of atrial fibrillation at 1 year (p<0.001, odds ratio=20.287).
  
  
  CONCLUSIONS
  The Cox maze IV procedure using an argon-based cryoprobe was safe and effective compared with the maze procedure using an N2O-based cryoprobe in terms of operative outcomes and the restoration of sinus rhythm for up to 2 years after surgery.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul National University College of Medicine.
authors.forename: Kyung-Hak
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul National University College of Medicine.
authors.forename: Jooncheol
authors.initials: J
authors.lastname: Min
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul National University College of Medicine.
authors.forename: Kyung-Hwan
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul National University College of Medicine.
authors.forename: Ho Young
authors.initials: HY
authors.lastname: Hwang
authors.affiliation: Seoul National University Bundang Hospital, Seoul National University College of Medicine.
authors.forename: Jun Sung
authors.initials: JS
authors.lastname: Kim
keywords: Ablation; Arrhythmia; Arrhythmia surgery; Atrial fibrillation; Cryosurgery