Summary
Encainide is a type Ic antiarrhythmie agent. During encainide therapy, mild Q-T interval prolongation can be seen, usually associated with prolongation of the Q-R-S interval. The present case report describes an unusual and marked prolongation of the Q-T interval with no Q-R-S interval prolongation in a patient who was treated with encainide for atrioventricular nodal reentrant tachycardia. The drug metabolite profile in this patient's serum indicated an unusual elevation of the 3-methoxy-O-demethyl encainide metabolite, versus O-demethyl encainide. This elevated metabolite level suggests that 3-methoxy-O-demethyl encainide has a significant effect on prolongation of repolarization. An abnormal metabolism of encainide may be the underlying mechanism by which some patients would manifest an unusual prolongation of Q-T interval during encainide therapy.
Similar content being viewed by others
References
Roden DM, Reele SB, Higgins SB, et al. Total suppression of ventricular arrhythmias by encainide. N Engl J Med 1980; 302: 877–882.
Kesteloot H, Stroobandt R. Clinical experience with encainide (MJ 9067) a new antiarrhythmic drug. Eur J Clin Pharmacol 1979; 16: 323–326.
Abdollah H, Brugada P, Green M, et al. Clinical efficacy and electrophysiologic effects of intravenous and oral encainide in patients with accessory atrioventricular pathways and supraventricular arrhythmias. Am J Cardiol 1984; 54: 544–549.
Carey ELJR, Duff HJ, Roden DM, et al. Encainide and its metabolites. J Clin Invest 1984; 73: 539–547.
Gren GB, Varghese PJ, Katz RJ, Ross AM. Arrhythmogenicity of encainide. The role of QT interval (abstr), Am J Cardiol 1981; 47: 498A.
Chesnie B, Podrid P, Lown B, Raeder E. Encainide for refractory ventricular tachyarrhythmia. Am J Cardiol 1983; 52: 495–500.
Conrad GJ, Ober RE. Metabolism of flecainide. Am J Cardiol 1984; 53: 41B-51B.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Davies, W., Jazayeri, M. & Tchou, P. Marked Q-T prolongation due to encainide therapy. Cardiovasc Drug Ther 2, 283–286 (1988). https://doi.org/10.1007/BF00054634
Issue Date:
DOI: https://doi.org/10.1007/BF00054634