title: Intravenous amiodarone homogeneously prolongs ventricular repolarization in patients with life-threatening ventricular tachyarrhythmia.
abstract: BACKGROUND
  The most critical adverse effects of class III drugs are marked QT prolongation and torsade de pointes. Even though intravenous amiodarone (iv-Amio) is a representative class III drug, it peculiarly inhibits both clinical ventricular tachycardia/fibrillation (VT/VF) and proarrhythmic effects. To test the hypothesis that iv-Amio homogeneously prolongs repolarization, we evaluated electrocardiographic changes before and during short-term amiodarone therapy, focusing closely on the ventricular dispersion of repolarization.
  
  
  METHODS
  Twenty-seven consecutive patients treated with iv-Amio for VT/VF as a first-line antiarrhythmic therapy were enrolled in this study. Twelve-lead electrocardiography was recorded before and during amiodarone therapy to evaluate the following electrocardiographic intervals: R-R, QRS, QT, QRS to T-peak (QTp), and T-peak to T-end (Tp-e; as an index of dispersion of repolarization). Repolarization indices were corrected to the heart rate by Bazett's method (QTc, c-QTp, c-Tp-e).
  
  
  RESULTS
  Amiodarone suppressed VT/VF in 19/27 (70%) patients without conferring any proarrhythmic effect. The QTc, c-QTp, and R-R interval were significantly prolonged during amiodarone (476±45ms vs 511±45ms, p<0.05; 338±40ms vs 364±35ms, p<0.05; 762±272ms vs 870±189ms, p<0.05; respectively), whereas the c-Tp-e and QRS durations did not change significantly (139±33ms vs 145±41ms, p=0.25; 96±20ms vs 97±21ms, p=0.33; respectively).
  
  
  CONCLUSIONS
  Iv-Amio homogeneously prolongs repolarization and properly inhibits original VT/VF recurrence without inducing torsade de pointes.
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kinki University, Osaka, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Kotake
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kinki University, Osaka, Japan. Electronic address: kuritat@med.kindai.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kurita
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kinki University, Osaka, Japan.
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Akaiwa
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kinki University, Osaka, Japan.
authors.forename: Ryobun
authors.initials: R
authors.lastname: Yasuoka
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kinki University, Osaka, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Motoki
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kinki University, Osaka, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kobuke
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kinki University, Osaka, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Iwanaga
authors.affiliation: Division of Cardiology, Department of Medicine, Faculty of Medicine, Kinki University, Osaka, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Miyazaki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000638:Amiodarone / Q000008:administration & dosage / Q000627:therapeutic use*; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012189:Retrospective Studies; D017180:Tachycardia, Ventricular / Q000188:drug therapy* / Q000503:physiopathology; D016896:Treatment Outcome
chemical_list: D000889:Anti-Arrhythmia Agents; D000638:Amiodarone
keywords: Amiodarone; Antiarrhythmic drug; Electrocardiogram; QTc interval; Torsade de pointes