Antiarrhythmic and electrophysiologic effects of flecainide on acutely induced atrial fibrillation in healthy horses

TY - JOUR

T1 - Antiarrhythmic and electrophysiologic effects of flecainide on acutely induced atrial fibrillation in healthy horses

AU - Haugaard, Maria Mathilde

AU - Pehrson, S.

AU - Carstensen, Helena

AU - Madsen, Mette Flethøj

AU - Hesselkilde, Eva Zander

AU - Præstegaard, K. F.

AU - Diness, J. G.

AU - Grunnet, M.

AU - Jespersen, Thomas

AU - Buhl, Rikke

PY - 2015/1/1

Y1 - 2015/1/1

N2 - Background: Only few pharmacologic compounds have been validated for treatment of atrial fibrillation (AF) in horses. Studies investigating the utility and safety of flecainide to treat AF in horses have produced conflicting results, and the antiarrhythmic mechanisms of flecainide are not fully understood. Objectives: To study the potential of flecainide to terminate acutely induced AF of short duration (≥15 minutes), to examine flecainide-induced changes in AF duration and AF vulnerability, and to investigate the in vivo effects of flecainide on right atrial effective refractory period, AF cycle length, and ventricular depolarization and repolarization. Animals: Nine Standardbred horses. Eight received flecainide, 3 were used as time-matched controls, 2 of which also received flecainide. Methods: Prospective study. The antiarrhythmic and electrophysiologic effects of flecainide were based on 5 parameters: ability to terminate acute pacing-induced AF (≥15 minutes), and drug-induced changes in atrial effective refractory period, AF duration, AF vulnerability, and ventricular depolarization and repolarization times. Parameters were assessed at baseline and after flecainide by programmed electrical stimulation methods. Results: Flecainide terminated all acutely induced AF episodes (n = 7); (AF duration, 21 ± 5 minutes) and significantly decreased the AF duration, but neither altered atrial effective refractory period nor AF vulnerability significantly. Ventricular repolarization time was prolonged between 8 and 20 minutes after initiation of flecainide infusion, but no ventricular arrhythmias were detected. Conclusions and Clinical Importance: Flecainide had clear antiarrhythmic properties in terminating acute pacing-induced AF, but showed no protective properties against immediate reinduction of AF. Flecainide caused temporary prolongation in the ventricular repolarization, which may be a proarrhythmic effect.

AB - Background: Only few pharmacologic compounds have been validated for treatment of atrial fibrillation (AF) in horses. Studies investigating the utility and safety of flecainide to treat AF in horses have produced conflicting results, and the antiarrhythmic mechanisms of flecainide are not fully understood. Objectives: To study the potential of flecainide to terminate acutely induced AF of short duration (≥15 minutes), to examine flecainide-induced changes in AF duration and AF vulnerability, and to investigate the in vivo effects of flecainide on right atrial effective refractory period, AF cycle length, and ventricular depolarization and repolarization. Animals: Nine Standardbred horses. Eight received flecainide, 3 were used as time-matched controls, 2 of which also received flecainide. Methods: Prospective study. The antiarrhythmic and electrophysiologic effects of flecainide were based on 5 parameters: ability to terminate acute pacing-induced AF (≥15 minutes), and drug-induced changes in atrial effective refractory period, AF duration, AF vulnerability, and ventricular depolarization and repolarization times. Parameters were assessed at baseline and after flecainide by programmed electrical stimulation methods. Results: Flecainide terminated all acutely induced AF episodes (n = 7); (AF duration, 21 ± 5 minutes) and significantly decreased the AF duration, but neither altered atrial effective refractory period nor AF vulnerability significantly. Ventricular repolarization time was prolonged between 8 and 20 minutes after initiation of flecainide infusion, but no ventricular arrhythmias were detected. Conclusions and Clinical Importance: Flecainide had clear antiarrhythmic properties in terminating acute pacing-induced AF, but showed no protective properties against immediate reinduction of AF. Flecainide caused temporary prolongation in the ventricular repolarization, which may be a proarrhythmic effect.

U2 - 10.1111/jvim.12496

DO - 10.1111/jvim.12496

M3 - Journal article

C2 - 25328012

SN - 0891-6640

VL - 29

SP - 339

EP - 347

JO - Journal of Veterinary Internal Medicine

JF - Journal of Veterinary Internal Medicine

IS - 1

ER -