title: Beta-blockade and A1-adenosine receptor agonist effects on atrial fibrillatory rate and atrioventricular conduction in patients with atrial fibrillation.
abstract: OBJECTIVE
  Reduced irregularity of RR intervals in permanent atrial fibrillation (AF) has been associated with poor outcome. It is not fully understood, however, whether modification of atrioventricular (AV) conduction using rate-control drugs affects RR variability and irregularity measures. We aimed at assessing whether atrial fibrillatory rate (AFR) and variability and irregularity of the ventricular rate are modified by a selective A1-adenosine receptor agonist tecadenoson, beta-blocker esmolol, and their combination.
  
  
  RESULTS
  Twenty-one patients (age 58 ± 7 years, 13 men) with AF were randomly assigned to either 75, 150, or 300 μg intravenous tecadenoson. Tecadenoson was administered alone (Dose Period 1) and in combination (Dose Period 2) with esmolol (100 μg/kg/min for 10 min then 50 μg/kg/min for 50 min). Heart rate (HR) and AFR were estimated for every 10 min long recording segment. Similarly, for every 10 min segment, the variability of RR intervals was assessed, as standard deviation, pNN20, pNN50, pNN80, and the root of the mean squared differences of successive RR intervals, and irregularity was assessed by non-linear measures such as regularity index (R) and approximate entropy. A marked decrease in HR was observed after both tecadenoson injections, whereas almost no changes could be seen in the AFR. The variability parameters were increased after the first tecadenoson bolus injection. In contrast, the irregularity parameters did not change after tecadenoson. When esmolol was infused, all the variability parameters further increased.
  
  
  CONCLUSIONS
  Modification of AV node conduction can increase RR variability but does not affect regularity of RR intervals or AFR.
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Via Golgi 39, 20133 Milano, Italy.
authors.forename: Valentina D A
authors.initials: VD
authors.lastname: Corino
authors.forename: Fredrik
authors.initials: F
authors.lastname: Holmqvist
authors.forename: Luca T
authors.initials: LT
authors.lastname: Mainardi
authors.forename: Pyotr G
authors.initials: PG
authors.lastname: Platonov
mesh_terms: D000241:Adenosine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives*; D061605:Administration, Intravenous; D058671:Adrenergic beta-1 Receptor Antagonists / Q000008:administration & dosage* / Q000009:adverse effects; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage* / Q000009:adverse effects; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D001283:Atrioventricular Node / Q000187:drug effects* / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D004562:Electrocardiography; D005260:Female; D005663:Furans / Q000008:administration & dosage* / Q000009:adverse effects; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011412:Propanolamines / Q000008:administration & dosage* / Q000009:adverse effects; D058906:Purinergic P1 Receptor Agonists / Q000008:administration & dosage* / Q000009:adverse effects; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D058671:Adrenergic beta-1 Receptor Antagonists; D000889:Anti-Arrhythmia Agents; D005663:Furans; D011412:Propanolamines; D058906:Purinergic P1 Receptor Agonists; C118601:tecadenoson; D000241:Adenosine; C036604:esmolol
keywords: Atrial fibrillation frequency; Irregularity; RR series; Tecadenoson; Variability