title: Reduction over time of QTc prolongation in patients with sotalol after cardioversion of atrial fibrillation.
abstract: BACKGROUND
  Sotalol is recommended to prevent relapse of atrial fibrillation after cardioversion (CV). Sotalol prolongs the action potential by blocking the rapid component of the delayed rectifier potassium current, which results in corrected QT (QTc) prolongation on the electrocardiogram. Pronounced QTc prolongation may lead to proarrhythmias and sudden death.
  
  
  OBJECTIVE
  We investigated the dynamics of the QTc interval during the week after CV in patients treated with sotalol compared with patients treated with a β-blocker.
  
  
  METHODS
  Patients who underwent elective CV for persistent atrial fibrillation and maintained sinus rhythm for 1 week were included prospectively. All patients were on the highest tolerable stable dose of metoprolol or sotalol. Twelve-lead electrocardiograms were recorded 1 hour and 1 week after CV.
  
  
  RESULTS
  A total of 104 patients on sotalol and 104 on metoprolol were included; clinical characteristics between groups were comparable. One hour after CV, the QTc interval was significantly longer in sotalol-treated patients than in metoprolol-treated patients (465 ± 25 ms vs 423 ± 30 ms; P ≤ .0001). After 1 week, the QTc interval was reduced by -20.3 ± 24 ms in sotalol-treated patients (P ≤ .001); no such effect was seen in metoprolol-treated patients (-2.5 ± 18 ms; P = 0.28). The heart rate was stable during the week in both groups. In multivariate analysis of sotalol-treated patients, factors contributing to pronounced reduction in the QTc interval were longer QTc interval after CV and renal function.
  
  
  CONCLUSIONS
  The QTc interval is significantly reduced during the week after CV to sinus rhythm in sotalol-treated patients. This provides insight into the increased risk of proarrhythmias in the immediate time period after CV.
authors.affiliation: Department of Clinical Science and Education, Division of Cardiology, Karolinska Institute, South Hospital, Stockholm, Sweden. Electronic address: hanna.lenhoff@sodersjukhuset.se.
authors.forename: Hanna
authors.initials: H
authors.lastname: Lenhoff
authors.affiliation: Statistik Georg Ferber GmbH, Riehen, Switzerland.
authors.forename: Börje
authors.initials: B
authors.lastname: Darpö
authors.affiliation: Statistik Georg Ferber GmbH, Riehen, Switzerland.
authors.forename: Georg
authors.initials: G
authors.lastname: Ferber
authors.affiliation: Department of Clinical Sciences, Karolinska Institute, Danderyd Hospital, Stockholm, Sweden.
authors.forename: Mårten
authors.initials: M
authors.lastname: Rosenqvist
authors.affiliation: Department of Clinical Science and Education, Division of Cardiology, Karolinska Institute, South Hospital, Stockholm, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Frick
mesh_terms: D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000628:therapy*; D004305:Dose-Response Relationship, Drug; D004554:Electric Countershock; D004562:Electrocardiography / Q000187:drug effects*; D005260:Female; D005500:Follow-Up Studies; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D011446:Prospective Studies; D013015:Sotalol / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D000889:Anti-Arrhythmia Agents; D013015:Sotalol
keywords: Antiarrhythmic; Atrial fibrillation; Cardioversion; QT interval; Sotalol