Three Empty Bottles and a Wide QRS: Rapid Alkalinization Rescue in Propafenone Overdose.

Abstract

Propafenone is a class IC anti-arrhythmic agent with potent fast sodium channel blockade whose overdose may result in profound intraventricular conduction delay and malignant ventricular arrhythmias. Management strategies are largely derived from isolated case reports, and consensus guidelines are lacking. We describe a case of a young man with a history of supraventricular tachycardia who presented following intentional polysubstance ingestion, including at least 600 mg of propafenone. On presentation, he was hypoxemic, acidotic, and minimally responsive. Electrocardiography revealed sustained wide complex tachycardia with marked QRS widening. Initial laboratory testing demonstrated normal electrolyte levels with a modestly elevated troponin, along with severe anion-gap metabolic acidosis, elevated lactate levels, acute kidney injury, and toxic acetaminophen concentrations. Intravenous sodium bicarbonate was initiated to achieve mild alkalemia, along with aggressive electrolyte correction and supportive intensive care. Within 1 h of bicarbonate therapy, the ventricular tachycardia resolved with rapid narrowing of the QRS complex and restoration of sinus rhythm. Serial electrocardiograms over the ensuing 24 h showed continued normalization of conduction. This case highlights the electrophysiologic manifestations of propafenone toxicity and underscores the value of QRS duration as a dynamic marker of toxicity severity and treatment response. Early alkalinization with intravenous sodium bicarbonate may rapidly correct conduction disturbances and stabilize malignant arrhythmias in severe class IC anti-arrhythmic overdose.