Acute electrophysiological effects of flecainide acetate on cardiac conduction and refractoriness in man.

Abstract

SUMMARY The electrophysiological effects of flecainide acetate (2 mg/kg as an intravenous infusion over five minutes) were assessed in 47 patients undergoing electrophysiological study. Seven patients had normal electrophysiology, 16 had a direct accessory atrioventricular pathway, 12 had dual atrioventricular nodal (AH) pathways, five had paroxysmal ventricular tachycardia, six had conduction system disease, and one patient had a left atrial tachycardia.No significant change occurred in sinus cycle length. The PA interval, AH interval, and HV interval were all significantly prolonged. The QRS complex duration increased significantly. The QT interval showed slight prolongation due entirely to the increase in QRS duration.Refractoriness of the atrial and ventricular myocardium was slightly prolonged, but was significant only at ventricular level. No significant change occurred in refractoriness of the norma atrioventricular node. Pronounced prolongation of retrograde "fast" AH pathway refractoriness was observed in those patients with dual AH pathways. Anterograde and retrograde accessory pathway refractoriness were both greatly increased.These electrophysiological properties strongly suggest that flecainide will be useful in the management of a wide variety of cardiac arrhythmias. It should be administered, however, with caution to patients with pre-existing conduction system disease. Because repolarisation is not delayed flecainide is unlikely to induce ventricular arrhythmias related to prolongation of the QT interval.Flecainide acetate4 (N-(2-piperidylmethyl)-2,5-bis (2,2,2-trifluoroethoxy) benzaamide acetate) belongs to a unique series of trifluoroethoxybenzamides' 2 which have proven antiarrhythmic activity against a variety of experimentally induced arrhythmias. [3][4][5] Human pharmacokinetic studies have shown that flecainide is almost completely absorbed after oral administration, undergoes minimal hepatic biotransformation, and has a long plasma elimination half-life ranging from 11 to 22 hours,67 properties that are highly desirable for the long term use of antiarrhythmic agents.This study was undertaken to investigate the acute electrophysiological effects of intravenous flecainide on cardiac conduction and refractoriness in man.

Antiarrhythmic and Electrophysiologic Effects of Flecainide on Acutely Induced Atrial Fibrillation in Healthy Horses

“…Our study identified no flecainide‐induced changes in aERP, indicating that flecainide did not have an influence on atrial repolarization at the chosen stimulation rates. Depending on the model, flecainide has been reported to have variable effects on aERP in vivo 16, 17, 18, 19, 20. In humans, some reported a slight but not significant flecainide‐induced increase in aERP, whereas others reported significant and use‐dependent increases 20, 34.…”

“…QRS durations were measured as a surrogate for the effect of flecainide on ventricular conduction velocity, and our results were in agreement with results reported by others 1, 2. Because of sodium channel blockade, and hence depressant effects on cardiac conduction, a flecainide‐induced widening of QRS was expected 20, 40. In humans, recommendations are that flecainide treatment should be discontinued if QRS prolongation exceeds 25% of baseline 36, 41.…”

“…In our study, QTc was significantly prolonged between 6 and 25 minutes after flecainide infusion was started. To obtain a more specific ventricular repolarization time, JTc intervals were calculated, and in contrast to what has been documented in humans,20 flecainide temporarily prolonged JTc in horses. The present study however did not identify any potentially dangerous ventricular arrhythmias, which is in agreement with other studies 1, 3.…”

Effects of flecainide on ectopic atrial automaticity and conduction.

“…9 Although its effect on refractoriness in normal tissue is relatively small, flecainide significantly prolongs the refractory period of accessory pathways,8 making this a particularly effective agent in the treatment of reentrant tachycardias that use such tissues.…”

Comparative haemodynamic effects of intravenous lignocaine, disopyramide and flecainide in uncomplicated acute myocardial infarction

“…Flecainide, a new class 1C antiarrhythmic agent is an effective broad spectrum anti-arrhythmic (Hellestrand et al, 1982;Hodges et al, 1982;Anderson et al, 1981;Duff et al, 1981;Duran et al, 1982;Anderson et al, 1984). In common with other class 1 agents it induces mild depression of cardiac function in stable coronary artery disease (Legrand et al, 1983;Serruys et al, 1983;Josephson et al, 1984).…”