Flecainide acetate does not alter the energy requirements for direct ventricular defibrillation using sequential...

Flecainide acetate is a recently approved class 1c antiarrhythmic agent indicated for patients with serious ventricular arrhythmias. Because flecainide may be used in patients with automatic implantable defibrillators, we assessed the effect of flecainide on ventricular defibrillation energy requirements in a pig model. Different doses of flecainide maintaining plasma levels in the "subtherapeutic" (six pigs), "therapeutic" (eight pigs), and "supratherapeutic" (eight pigs) range were administered to three groups of pigs. A fourth group (six pigs) served as a time control and was given normal saline only. Episodes of ventricular fibrillation were induced and then terminated using sequential truncated trapezoidal direct current shocks delivered by a tripolar internal defibrillator system. Energy requirements for defibrillation were assessed by measuring defibrillation threshold and also by comparing shifts in the curves relating energy with percent successful defibrillation. Flecainide failed to alter defibrillation requirements at any dose. We conclude that ventricular defibrillation energy requirements are not affected by flecainide in our pig model. Both the defibrillation threshold technique and the comparison of curves relating success of defibrillation to energy yielded similar results suggesting that either can be used to assess energy requirements for defibrillation.