title: Chronicity of atrial fibrillation affects duration of sinus rhythm after transthoracic cardioversion of dogs with naturally occurring atrial fibrillation.
abstract: BACKGROUND
  Atrial fibrillation (AF) in dogs can be managed by electrical cardioversion to sinus rhythm, but early recurrence of AF occurs in some dogs. In humans, the commonly evaluated clinical variables for prediction of early relapse of AF are left atrial size and duration of AF. It is unclear whether the duration of AF affects maintenance of sinus rhythm after cardioversion in dogs with spontaneous AF.
  
  
  OBJECTIVE
  That duration of sinus rhythm after cardioversion is related to the chronicity of AF.
  
  
  METHODS
  Forty-one consecutive dogs that had undergone successful transthoracic cardioversion for spontaneous AF were evaluated.
  
  
  METHODS
  The relationship between the duration of documented AF and the duration of sinus rhythm after cardioversion was statistically evaluated using data obtained retrospectively. The effects of structural heart disease and pretreatment with amiodarone were also evaluated.
  
  
  RESULTS
  The presence of structural heart disease and the duration of documented AF had significant effects on maintenance of sinus rhythm after cardioversion (P <.001 and P=.022, respectively). The duration of documented AF was inversely related to the duration of sinus rhythm (P=.022) in dogs with and without structural heart disease.
  
  
  CONCLUSIONS
  Estimates of duration of sinus rhythm based on the duration of documented AF are provided for dogs with and without heart disease allowing prediction of risk for early AF relapse.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA. jmbright@colostate.edu
authors.forename: J M
authors.initials: JM
authors.lastname: Bright
authors.forename: J
authors.initials: J
authors.lastname: zumBrunnen
mesh_terms: D000638:Amiodarone / Q000627:therapeutic use; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D001281:Atrial Fibrillation / Q000628:therapy / Q000662:veterinary*; D002908:Chronic Disease; D004283:Dog Diseases / Q000628:therapy*; D004285:Dogs; D004554:Electric Countershock / Q000662:veterinary*; D012008:Recurrence; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D000889:Anti-Arrhythmia Agents; D000638:Amiodarone