Low-Dose Atropine-Triggered Atrial Fibrillation in Chlorpyrifos Plus Cypermethrin Poisoning: A Rare Case Report and Review of Literature

Poisoning with Organophosphates (OP) and/or Pyrethroids (PYR) pesticides is common. We present a rare case of OP+PYR poisoned patient who suffered from Atrial Fibrillation (AF) at the beginning of treatment by a low dose of atropine and reviewed the literature. 

A 50-year-old man had ingested about 5-10 ml of a mixture of chlorpyrifos/cypermethrin.  Half an hour later, he went to the rural hospital and 2 hr later, after gastrointestinal decontamination, he was referred to the clinical toxicology department with normal vital signs except normal sinus tachycardia [Heart rate (HR)]=105. On admission, he had nausea, vomiting, diarrhea, mild sialorrhea, symmetric mid-size pupils, wet skin, and bilateral moist rales in his lungs. His cardiac rhythm changed to rapid AF (HR >140 beats/min) after treatment with 3 mg midazolam followed by 0.3 mg of atropine (0.1 mg every 1-3 min). Atropine administration was discontinued and he was treated with 0.5 mg of digoxin. 6 hr later, his arrhythmia disappeared and all cardiac and laboratory evaluations changed to normal except reduced serum cholinesterase activity.  

AF may be induced by Organophosphates (OP) and Pyrethroids (PYR) intoxication or during the treatment by atropine. We could not find any known risk factor (cardiac or medical issues) for AF in the current case. It may be suggested that poisoning with OP, PYR (alone or mixed) or atropine (in general or in low dose), or combination is the trigger of AF. However, AF is not life threating and can easily cure by antiarrhythmic therapy.