Atrial fibrillation in hypothyroidism

A 27-year-old woman presented with palpitation, chest pain, and shortness of breath in the emergency room. Electrocardiogram revealed atrial fibrillation. Subsequent work-up was normal including oxygen saturation, chest X-ray, electrolytes, and echocardiogram, but showed clear evidence of primary hypothyroidism (sensitive thyroid stimulating hormone (TSH) of 14 mcIU/ ml and free T4 < 0.5 ng/dl). She was treated with appropriate thyroxin replacement without recurrence of atrial fibrillation.