Hyperthyroidism precipitating cardiac arrest in a patient with Brugada pattern

A 38-year-old man previously healthy suffered an out-of-hospital cardiac arrest; he was resuscitated successfully and admitted to the intensive care unit. His initial ECG suggested a Brugada pattern; other laboratory tests revealed low potassium level, low Thyroid Stimulating Hormone (TSH) and high FT4. He was started on carbimazole for hyperthyroidism, along with other supportive care. A comprehensive cardiac evaluation was done, including ajmaline and flecainide tests, results were inconclusive. An implantable cardioverter defibrillator device (ICD) was inserted to prevent such catastrophic events in the future. After discharge and on follow-up, our patient was doing well. His thyroid function test (TFT) was normal; moreover, a follow-up ICD interrogation did not record any arrhythmias. This case report highlighted asymptomatic hyperthyroidism as a precipitant for Brugada pattern resulting in sudden cardiac arrest.