title: Chemical cardioversion of atrial fibrillation or flutter with ibutilide in patients receiving amiodarone therapy.
abstract: BACKGROUND
  Ibutilide is a class III drug that is used for the cardioversion of atrial arrhythmias, but it can cause torsade de pointes. Amiodarone also prolongs the QT interval but rarely causes torsade de pointes. There are no studies in which the concomitant use of the 2 agents was examined. The purpose of the present study was to assess the efficacy and safety of cardioversion with combination therapy in patients with atrial fibrillation or flutter.
  
  
  RESULTS
  The study included 70 patients who were treated with long-term oral amiodarone and were referred for elective cardioversion of atrial fibrillation (57 of 70, 81%) or flutter (13 of 70, 19%). Patients were taking amiodarone (153+/-259 days, mean+/-SD) and were administered 2 mg intravenous ibutilide. Left ventricular ejection fraction was measured with echocardiography. The QT intervals were measured on 12-lead ECG. Fifty-five patients (79%) had structural heart disease. Patients were in arrhythmia for 196+/-508 days before cardioversion, with a left ventricular ejection fraction of 50+/-11%. In patients with atrial fibrillation, 22 (39%) of 57 and 7 (54%) of 13 patients with flutter converted within 30 minutes of infusion. Thirty-nine patients who did not convert after ibutilide were treated with electrical cardioversion, and 35 (90%) of 39 patients were successfully converted. The QT intervals were further prolonged after ibutilide for the group from 371+/-61 to 479+/-92 ms (P:<0.001). There was 1 episode of nonsustained torsade de pointes (1 of 70, 1.4%) after ibutilide.
  
  
  CONCLUSIONS
  The use of ibutilide converted 54% of patients with atrial flutter and 39% of patients with atrial fibrillation who were treated with long-term amiodarone. Despite QT-interval prolongation after ibutilide, only 1 episode of torsade de pointes occurred. Our observations suggest that combination therapy may be a useful cardioversion method for chronic atrial fibrillation or flutter.
authors.affiliation: Cardiovascular Research Institute and Section of Cardiac Electrophysiology, University of California, San Francisco 94143-1354, USA.
authors.forename: K
authors.initials: K
authors.lastname: Glatter
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
authors.forename: K
authors.initials: K
authors.lastname: Chatterjee
authors.forename: G
authors.initials: G
authors.lastname: Modin
authors.forename: J
authors.initials: J
authors.lastname: Cheng
authors.forename: S
authors.initials: S
authors.lastname: Kayser
authors.forename: M M
authors.initials: MM
authors.lastname: Scheinman
mesh_terms: D000368:Aged; D000638:Amiodarone / Q000627:therapeutic use*; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D001282:Atrial Flutter / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D004359:Drug Therapy, Combination; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013318:Stroke Volume; D013449:Sulfonamides / Q000009:adverse effects / Q000627:therapeutic use*; D016171:Torsades de Pointes / Q000139:chemically induced
chemical_list: D000889:Anti-Arrhythmia Agents; D013449:Sulfonamides; C067192:ibutilide; D000638:Amiodarone