title: Effects of flecainide acetate on ventricular tachyarrhythmia and fibrillation in dogs with recent myocardial infarction.
abstract: The antiarrhythmic and antifibrillatory actions of the class IC antiarrhythmic agent flecainide acetate were examined in urethane-anesthetized dogs with recent myocardial infarction. The intravenous administration of flecainide in a loading dose of 1.0 mg/kg (n = 7) or 2.0 mg/kg (n = 6), followed by a maintenance infusion of 1.0 mg/kg/h to achieve plasma drug concentrations considered clinically therapeutic, failed to significantly elevate the electrical threshold current required to provoke ventricular fibrillation at infarct zone, border zone and non-infarct zone stimulation sites in postinfarction dogs. In 8 dogs which responded to baseline programmed stimulation with inducible sustained ventricular tachycardia, flecainide administered as 1.0 or 2.0 mg/kg loading doses followed by a 1.0 mg/kg/h maintenance infusion failed to prevent ventricular tachycardia initiation in any animal tested, although the post-treatment ventricular tachycardia cycle lengths were prolonged compared to baseline values (pre: 178 +/- 11 ms vs post: 202 +/- 17 ms, p less than 0.05). Flecainide administration apparently facilitated the induction of newly sustained ventricular tachycardia in 3 previously noninducible postinfarction dogs. The development of acute posterolateral ischemia at a site remote from previous anterior myocardial infarction resulted in the development of ventricular fibrillation in 4 of 11 (36%) saline-treated postinfarction dogs vs a cumulative 10 of 12 (83%) flecainide-treated, baseline noninducible postinfarction dogs (p less than 0.05 vs saline-treated). The incidence of sudden ischemic ventricular fibrillation was 7 of 7 (100%) among flecainide-treated baseline inducible postinfarction dogs. These data suggest that flecainide acetate may have only limited efficacy in preventing ventricular tachycardia or ventricular fibrillation soon after myocardial infarction.
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D004558:Electric Stimulation; D005260:Female; D005424:Flecainide / Q000097:blood / Q000494:pharmacology / Q000627:therapeutic use*; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009203:Myocardial Infarction / Q000150:complications / Q000188:drug therapy*; D013610:Tachycardia / Q000517:prevention & control*; D014693:Ventricular Fibrillation / Q000517:prevention & control*
chemical_list: D005424:Flecainide