title: Use of propafenone for conversion of chronic atrial fibrillation in horses.
abstract: OBJECTIVE
  To investigate effects of IV administration of propafenone for naturally occurring and experimentally induced chronic atrial fibrillation in horses.
  
  
  METHODS
  2 horses with naturally occurring atrial fibrillation and 4 horses with pacing-induced atrial fibrillation.
  
  
  METHODS
  Horses received a bolus of propafenone (2 mg/kg, IV over 15 minutes). If atrial fibrillation persisted after 20 minutes, a continuous infusion of propafenone (7 microg/kg/min) was given for 120 minutes. Before, during, and after treatment, plasma propafenone concentrations, hematologic and serum biochemical values, and electolyte concentrations analyses were determined and clinical signs were monitored. Surface ECGs were recorded. If propafenone treatment failed, quinidine sulfate was administered.
  
  
  RESULTS
  Bolus and continuous infusion induced minimal adverse effects. During the 15-minute bolus administration, a slight increase in heart rate was observed and horses appeared more sensitive to external stimuli. Throughout treatment, no significant changes were observed in respiratory rate, QRS or corrected QT duration, or results of hematologic analyses. Although a significant increase in F-wave interval and atrial fibrillation cycle length was observed and plasma propafenone concentrations (569 to 1,268 ng/mL) reached the human therapeutic range (64 to 1,044 ng/mL), none of the horses cardioverted to sinus rhythm. Sinus rhythm could be restored in all horses via standard oral administration of quinidine.
  
  
  CONCLUSIONS
  A slow IV bolus of 2 mg of propafenone/kg followed by a continuous infusion of 7 microg/kg/min over 2 hours was not an effective treatment for chronic atrial fibrillation in horses.
authors.affiliation: Department of Large Animal Internal Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium.
authors.forename: Dominique
authors.initials: D
authors.lastname: De Clercq
authors.forename: Gunther
authors.initials: G
authors.lastname: van Loon
authors.forename: Rene
authors.initials: R
authors.lastname: Tavernier
authors.forename: Rene
authors.initials: R
authors.lastname: Verbesselt
authors.forename: Piet
authors.initials: P
authors.lastname: Deprez
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001281:Atrial Fibrillation / Q000188:drug therapy / Q000662:veterinary*; D004452:Echocardiography / Q000662:veterinary; D004562:Electrocardiography / Q000662:veterinary; D006734:Horse Diseases / Q000188:drug therapy*; D006736:Horses; D007275:Injections, Intravenous / Q000662:veterinary; D011405:Propafenone / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*
chemical_list: D011405:Propafenone