title: Time-Dependent Changes in QT Dynamics after Initiation and Termination of Paroxysmal Atrial Fibrillation.
abstract: BACKGROUND
  Little is known about time-dependent changes in QT dynamics after initiation of atrial fibrillation (AF) and after restoration of sinus rhythm (SR) in patients with paroxysmal AF.
  
  
  METHODS
  Beat-to-beat QT and RR intervals in CM5 lead were measured automatically in 13 patients with both AF and SR on the single 24-hour Holter electrocardiology recording. QT-RR relation was analyzed at six periods of time: 1 hour before AF onset (Pre(0-1h)), 0-1 hour and 4-5 hours after AF onset (AF(0-1h) and AF(4-5h)), and 0-1 hour, 2-3 hours, and 4-5 hours after the restoration of SR (SR(0-1h), SR(2-3h), and SR(4-5h)).
  
  
  RESULTS
  QT-RR slope was gradually decreased after AF onset and gradually returned to the baseline level after restoration of SR. The slope became greater at SR(4-5h) than at AF(4-5h) and AF(0-1h). In patients receiving antiarrhythmic drugs (AADs; n = 5), QT-RR slope was greater at SR(4-5h) than in those not receiving AADs (n = 8).
  
  
  CONCLUSIONS
  In patients with paroxysmal AF, bradycardia-dependent QT prolongation was attenuated during AF, and was corrected and gradually augmented along with continuation of SR, especially in patients receiving AADs. This could increase the risk of developing torsade de pointes.
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Clinical Research and Ethics Center, University of Toyama, Toyama, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Mizumaki
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan.
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Nishida
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan.
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Kataoka
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Nakatani
authors.affiliation: Second Department of Internal Medicine, Graduate School of Medicine, University of Toyama, Toyama, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
mesh_terms: D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008133:Long QT Syndrome / Q000209:etiology / Q000503:physiopathology* / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D000889:Anti-Arrhythmia Agents
keywords: Holter ECG recording; QT interval; QT-RR relation; atrial fibrillation; torsade de pointes