Supraventricular tachycardia mimicking ventricular tachycardia during flecainide treatment

Abstract

As a class IC antiarrhythmic drug, flecainide can produce marked widening of the QRS complex. This effect is use dependent,1 indicating that widening of the QRS complex becomes more prominent during faster heart rates. Widening of the QRS complex during tachycardia in patients treated with flecainide can be extreme due to this use dependency. It may create difficulty in determining the origin of the tachycardia, especially if bundle branch block (BBB) supervenes. This report describes flecainide-induced wide complex tachycardias of supraventricular origin, mimicking ventricular tachycardia (VT). © 1988.