title: Interatrial Conduction Time Can Predict New-Onset Atrial Fibrillation After Radiofrequency Ablation of Isolated, Typical Atrial Flutter.
abstract: BACKGROUND
  Many patients with successful atrial flutter (AFL) ablation will develop atrial fibrillation (AF) during follow-up. This study aimed to determine whether prolonged interatrial conduction time (IACT) is associated with risk for new-onset AF after ablation of isolated, typical AFL.
  
  
  METHODS
  Participants were 80 consecutive patients who underwent successful radiofrequency ablation of isolated, typical AFL from 2004 to 2012. Patients with any history of AF prior to AFL ablation were excluded. IACT was defined as the interval from the earliest onset of the P-wave on the ECG to the latest activation in the coronary sinus catheter during sinus rhythm measured after AFL ablation. New-onset AF was identified from 12-lead ECGs, 24-hour ambulatory monitoring, and device interrogations.
  
  
  RESULTS
  During a mean follow-up of 4.1 ± 2.5 years after successful AFL ablation, 22 patients (27.5%) developed new-onset AF. Cox regression multivariate analysis demonstrated that IACT was the independent predictor of new-onset AF after AFL ablation (hazard ratio: 1.03; 95% confidence interval: 1.00-1.06; P = 0.02). IACT was accurate in predicting new-onset AF (AUC = 0.70). The optimal cut-off point of IACT for predicting new-onset AF was 120 milliseconds (sensitivity 47.6%, specificity 89.8%). Kaplan-Meier curves showed that new-onset AF after AFL ablation was significantly higher in patients with IACT ≥120 milliseconds than in patients with IACT< 120 milliseconds (P = 0.0016).
  
  
  CONCLUSIONS
  Prolonged IACT predicted new-onset AF after ablation of isolated AFL. This finding may contribute to guiding decisions regarding the maintenance of anticoagulation after AFL ablation.
authors.affiliation: Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Ryuta
authors.initials: R
authors.lastname: Henmi
authors.affiliation: Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Ejima
authors.affiliation: Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Morio
authors.initials: M
authors.lastname: Shoda
authors.affiliation: Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Daigo
authors.initials: D
authors.lastname: Yagishita
authors.affiliation: Department of Cardiology, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Nobuhisa
authors.initials: N
authors.lastname: Hagiwara
keywords: P-wave; atrial fibrillation; atrial flutter; catheter ablation; cavotricuspid isthmus ablation; interatrial conduction time