title: Amiodarone reduces the prevalence of T wave alternans in a population with ventricular tachyarrhythmias.
abstract: BACKGROUND
  Testing for the presence of microvolt T wave alternans (TWA) is useful for arrhythmic risk stratification. Whether antiarrhythmic pharmacotherapy affects the presence of TWA is unknown. We tested whether patients with known ventricular tachyarrhythmias who were receiving amiodarone were less likely to manifest TWA as compared with those not receiving amiodarone.
  
  
  RESULTS
  Forty-four patients with a history of ventricular tachyarrhythmias and an implantable cardioverter defibrillator (ICD) implanted at least 1 month earlier underwent TWA testing. In this group, 14 patients were receiving amiodarone and 30 were not. Indeterminate test results occurred in 13 patients without a significant difference in those receiving or not receiving amiodarone. In the 31 patients with determinate TWA testing, a positive test was less likely in those receiving amiodarone (1 of 9 [11%]) as compared with those not receiving amiodarone (14 of 22 [64%]; P = 0.04). During a follow-up period averaging 0.9 +/- 0.2 years, the presence of TWA (P = 0.04) and decreased left ventricular ejection fraction (P = 0.05) predicted appropriate ICD therapy for ventricular tachyarrhythmias.
  
  
  CONCLUSIONS
  The prevalence of TWA was decreased in a chronic ventricular tachyarrhythmic population receiving amiodarone as compared with a population not receiving amiodarone.
authors.affiliation: Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis 46202-4800, USA. wgroh@iupui.edu
authors.forename: W J
authors.initials: WJ
authors.lastname: Groh
authors.forename: T S
authors.initials: TS
authors.lastname: Shinn
authors.forename: E E
authors.initials: EE
authors.lastname: Engelstein
authors.forename: D P
authors.initials: DP
authors.lastname: Zipes
mesh_terms: D000328:Adult; D000368:Aged; D000638:Amiodarone / Q000008:administration & dosage*; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage*; D017147:Defibrillators, Implantable; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000503:physiopathology* / Q000628:therapy*
chemical_list: D000889:Anti-Arrhythmia Agents; D000638:Amiodarone