title: Chronic amiodarone therapy impairs the function of the superior sinoatrial node in patients with atrial fibrillation.
abstract: BACKGROUND
  The mechanisms underlying amiodarone-induced sinoatrial node (SAN) dysfunction remain unclear, so we used 3-dimensional endocardial mapping of the right atrium (RA) to investigate.
  
  
  RESULTS
  In a matched-cohort design, 18 patients taking amiodarone before atrial fibrillation (AF) ablation (amiodarone group) were matched for age, sex and type of AF with 18 patients who had undergone AF ablation without taking amiodarone (no-amiodarone group). The amiodarone group had a slower heart rate than the no-amiodarone group at baseline and during isoproterenol infusion. Only the amiodarone group had sick sinus syndrome (n=4, 22%, P=0.03) and abnormal (>550ms) corrected SAN recovery time (n=5, 29%; P=0.02). The median distance from the junction of the superior vena cava (SVC) and RA to the most cranial earliest activation site (EAS) was longer in the amiodarone group than in the no-amiodarone group at baseline (20.5 vs. 10.6mm, P=0.04) and during isoproterenol infusion (12.8 vs. 6.3mm, P=0.03). The distance from the SVC-RA junction to the EAS negatively correlated with the P-wave amplitudes of leads II (r=-0.47), III (r=-0.60) and aVF (r=-0.56) (P<0.001 for all).
  
  
  CONCLUSIONS
  In a quarter of the AF patients, amiodarone causes superior SAN dysfunction, which results in a downward shift of the EAS and reduced P-wave amplitude in leads II, III and aVF at baseline and during isoproterenol infusion.
authors.affiliation: Division of Cardiology, Department of Medicine, Yonsei University College of Medicine.
authors.forename: Hee-Sun
authors.initials: HS
authors.lastname: Mun
authors.forename: Changyu
authors.initials: C
authors.lastname: Shen
authors.forename: Hui-Nam
authors.initials: HN
authors.lastname: Pak
authors.forename: Moon-Hyoung
authors.initials: MH
authors.lastname: Lee
authors.forename: Shien-Fong
authors.initials: SF
authors.lastname: Lin
authors.forename: Peng-Sheng
authors.initials: PS
authors.lastname: Chen
authors.forename: Boyoung
authors.initials: B
authors.lastname: Joung
mesh_terms: D000368:Aged; D000638:Amiodarone / Q000009:adverse effects* / Q000494:pharmacology; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D006325:Heart Atria / Q000473:pathology / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012849:Sinoatrial Node / Q000473:pathology / Q000503:physiopathology
chemical_list: D000638:Amiodarone