Marked Q-T prolongation due to encainide therapy.
Encainide is a type Ic antiarrhythmic 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.
Davies
W
W
University of Wisconsin-Milwaukee Clinical Campus, Sinai Samaritan Medical Center.
Jazayeri
M
M
Tchou
P
P
D000813:Anilides / Q000627:therapeutic use*; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D004569:Electroencephalography; D016700:Encainide; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008875:Middle Aged; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000188:drug therapy* / Q000503:physiopathology
D000813:Anilides; D000889:Anti-Arrhythmia Agents; D016700:Encainide