title: Modification of the circadian pattern of ventricular tachyarrhythmias by beta-blocker therapy.
abstract: BACKGROUND
  Sudden cardiac death exhibits a circadian variation and predominantly occurs during morning hours, Beta-adrenergic antagonists have shown to blunt this morning peak. However, previous reports studying the effects of beta blockers on the circadian variation did not analyze the underlying cause of sudden cardiac death. It thus remains unclear whether ventricular tachyarrhythmias are influenced by beta-blocker therapy.
  
  
  OBJECTIVE
  This study tested the hypothesis that beta-blocking agents blunt the morning peak of life-threatening ventricular tachyarrhythmias.
  
  
  METHODS
  In 87 patients who were treated and monitored with an implantable cardioverter defibrillator, the circadian distribution of ventricular tachyarrhythmias terminated by appropriate shocks was analyzed and compared in those receiving beta blockers versus those not receiving beta-blocker therapy.
  
  
  RESULTS
  Tachyarrhythmic episodes in the absence of beta-blocker therapy (n = 344) exhibited a circadian variation with a distinct morning peak (16, 38, 28, and 18% of episodes at 0-6, 6-12, 12-18, and 18-24 h, respectively, p < 0.001). In contrast, tachyarrhythmic episodes during beta-blocker therapy (n = 104) were equally distributed over time (22, 27, 24, and 27% of episodes at 0-6, 6-12, 12-18, and 18-24 h, respectively, p = 0.95). The circadian distribution of episodes was significantly different in patients with and those without beta blockade (p < 0.05).
  
  
  CONCLUSIONS
  Beta-adrenergic antagonists influence the circadian distribution of malignant ventricular tachyarrhythmias in patients with an implantable cardioverter defibrillator. The blunted morning peak of tachyarrhythmic events during beta blockade supports the hypothesis that a sympathetic surge is involved in the circadian pattern of malignant arrhythmias.
authors.affiliation: Department of Cardiology and Pulmology, Klinikum Benjamin Franklin, Free University, Berlin, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Behrens
authors.forename: C
authors.initials: C
authors.lastname: Ehlers
authors.forename: T
authors.initials: T
authors.lastname: Brüggemann
authors.forename: W
authors.initials: W
authors.lastname: Ziss
authors.forename: R
authors.initials: R
authors.lastname: Dissmann
authors.forename: M
authors.initials: M
authors.lastname: Galecka
authors.forename: S N
authors.initials: SN
authors.lastname: Willich
authors.forename: D
authors.initials: D
authors.lastname: Andresen
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D002940:Circadian Rhythm; D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000209:etiology; D017147:Defibrillators, Implantable; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000188:drug therapy / Q000503:physiopathology* / Q000628:therapy; D014693:Ventricular Fibrillation / Q000188:drug therapy / Q000503:physiopathology* / Q000628:therapy
chemical_list: D000319:Adrenergic beta-Antagonists