CO may lead to persistent or reversible myocardial damage, mainly due to myocardial hypoxaemia and direct action of CO on the heart.13 Binding to myoglobin may reduce oxygen availability in the heart and cause arrhythmias and cardiac dysfunction.14 Cardiovascular effects of CO poisoning include tachycardia, hypotension, dysrhythmia, ischaemia, infarction, and, in some cases, cardiac arrest.15,16 Previous studies reported that episodes of atrial fibrillation, premature ventricular beats and sinus tachycardia developed in patients with acute CO poisoning.6,7. Here, MB is linked to cardiac arrhythmia.