Background: Graves' disease is the most common cause of hyperthyroidism. Untreated hyperthyroidism can lead to thyrotoxic cardiomyopathy and consequent acute heart failure, a life-threatening condition requiring support with extracorporeal membrane oxygenation (ECMO). Surgery is one of the treatment modality for Graves' disease. However, subtotal thyroidectomy is not the best surgical strategy because it is associated with higher recurrence rate.
Case Presentation: A 36-year-old woman presented to the emergency department with out-of-hospital cardiac arrest. The patient called 911 because of shortness of breath, but she was found to have loss of consciousness on the ambulance. Advanced cardiac life support protocol was initiated, and she regained spontaneous circulation. Electrocardiogram showed atrial fibrillation with rapid ventricular response (heart rate of 160 beats per minute). Chest X-ray revealed cardiomegaly with features of pulmonary edema. Two hours later, the patient was placed on mechanical circulatory support with ECMO because of recurrent pulseless electrical activity cardiac arrest. The surgical scar over anterior neck and her exophthalmos made us suspect that the patient might have recurrent Graves' disease, which was confirmed by subsequent laboratory findings. Tracing back her past medical history, she had Graves' disease for more than ten years. She underwent subtotal thyroidectomy three years ago, but had no medical surveillance thereafter. Her cardiovascular function improved after five days of ECMO support with medical treatment for thyroid crisis. She was eventually discharged after 20 days of hospitalization.
Conclusion: Untreated hyperthyroidism is potentially fatal, and must be considered as part of the differential diagnosis in a patient presenting with acute heart failure. Patients with Graves' disease who underwent subtotal thyroidectomy remain at the risk of developing recurrent hyperthyroidism, thus regular follow-up is necessary.