Acute Cardiac Arrhythmias in Organophosphate Poisoning: From Bradycardia to Atrial Fibrillation

Atrial fibrillation (AF) secondary to organophosphate poisoning is rare but can be life-threatening. A 53-year-old female with no prior cardiac history presented to the emergency department with altered mental status, excessive salivation, vomiting, and respiratory distress following ingestion of an unknown quantity of 35% emulsified endosulfan pesticide. Electrocardiography initially revealed sinus bradycardia, but within hours, the patient developed rapid, irregular tachycardia with no discernible P waves. Cholinergic toxicity was confirmed based on clinical presentation and reduced serum cholinesterase levels. The patient was treated with atropine for cholinergic symptoms and pralidoxime to reactivate acetylcholinesterase. Beta-blockers and calcium channel blockers were avoided due to concerns about exacerbating hypotension. Instead, rate control was achieved with cautious administration of amiodarone. Supportive measures, including intravenous fluids and oxygen therapy, were provided. Sinus rhythm was restored within 36 hours of initiating treatment. The patient showed progressive clinical improvement, with resolution of AF and normalization of serum cholinesterase levels. She was discharged on day eight with no residual cardiac dysfunction. At the one-month follow-up, the ECG remained normal, and she had no recurrent arrhythmias. Acute AF can be a rare but severe complication of organophosphate poisoning, likely due to autonomic imbalance, electrolyte disturbances, and direct toxic effects on the myocardium.