PO-04-052 FLECAINIDE INDUCED WIDE COMPLEX TACHYCARDIA

Abstract

Flecainide is a class IC antiarrhythmic that blocks cardiac sodium channels and is used to treat a variety of supraventricular tachyarrhythmias. Flecainide has use dependent properties with a greater effect at higher heart rates and carries a risk of atrial flutter with 1:1 AV conduction, Describing a case of wide complex tachycardia secondary to flecainide use. N/A A 72-year-old female with COPD, diabetes, history of typical atrial flutter, and persistent atrial fibrillation treated with flecainide and diltiazem called EMS when she awoke with sudden onset dyspnea and epigastric pain. EMS found her diaphoretic, tachycardic, and normotensive. EKG showed a wide complex tachycardia (WCT) with rate 230 bpm. She received an amiodarone bolus but remained in WCT. In the ER, she became hypotensive and was electrically cardioverted to sinus rhythm with resolution of dyspnea and hypotension. She was started on heparin and amiodarone drips. Troponin peaked at 0.04 ng/mL. A coronary angiogram showed no significant coronary artery disease and a transthoracic echocardiogram showed ejection fraction 60-65% with normal wall motion. However, a prior EKG on flecainide was reviewed and demonstrated atrial flutter with a 2:1 AV conduction and an atrial rate of 230 bpm. The WCT was most likely due to atrial flutter with 1:1 AV conduction and aberrancy. Flecainide slows conduction velocity in myocardial tissue, increasing the cycle length of the flutter circuit, and this can allow for 1:1 AV conduction with atrial flutter. Flecainide also demonstrates use dependent properties, with more sodium blocking effect at higher heart rates, and this can cause QRS widening in the setting of tachycardia. Although flecainide is also reported to cause ventricular tachycardia, the patient’s heart rate was exactly the same as a prior atrial rate in atrial flutter, so this was felt to be atrial flutter with 1:1 conduction and aberrancy. The patient’s flecainide and diltiazem were discontinued, and she was started on amiodarone. Medications should be reviewed as a possible cause of WCT after structural and ischemic causes are ruled out. While not a common cause of WCT, flecainide can organize atrial fibrillation into atrial flutter, which could result in 1:1 AV conduction, aberrancy, and wide complex tachycardia.