ECG Diagnosis: Flecainide Toxicity

Joel T Levis, MD, PhD, FACEP, FAAEM

Perm J 2012 Fall;16(4):53

Flecainide acetate is a Vaughn-Williams class IC antiarrhythmic and a sodium channel blocking agent used mainly for the treatment of supraventricular dysrhythmias.1 Adverse cardiac effects include moderate negative inotropic action and depression of all major conduction pathways.2 With increasing concentration, flecainide's action on conduction pathways is manifested on electrocardiogram as an increased PR interval and QRS duration. Toxicity is suggested when a 50% increase in QRS duration (0.18 sec) or 30% prolongation in PR interval (0.26 sec) occurs. The QTc interval can also be prolonged in cases of flecainide overdose.3 Treatment of acute flecainide overdose includes administration of activated charcoal (for patient presenting early in course of ingestion), administration of sodium bicarbonate (reverses action of sodium channel blockade), pressors (eg, dobutamine) for profound hypotension, and transthoracic or transvenous pacing.1,4



1.    Brazil E, Bodiwala GG, Bouch DC. Fatal flecainide intoxication. J Accid Emerg Med 1998 Nov;15(6):423-5.
2.    Winkelmann BR, Leinberger H. Life-threatening flecainide toxicity. A pharmacodynamic approach. Ann Intern Med 1987 Jun;106(6):807-14.
3.    Timperley J, Mitchell AR, Brown PD, West NE. Flecainide overdoseā€”support using an intra-aortic balloon pump. BMC Emerg Med 2005 Dec 12;5:10. DOI:
4.    Rognoni A, Bertolazzi M, Peron M, et al. Electrocardiographic changes in a rare case of flecainide poisoning: a case report. Cases Journal 2009 Dec 3;2:9137. DOI:


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