The Silent Endocrine Killer: Myxoedema Coma Presenting as Refractory Bradycardia and Recurrent Cardiac Arrest

Myxoedema coma is a rare but life-threatening endocrine emergency representing the extreme manifestation of severe hypothyroidism. Cardiovascular manifestations are common; however, refractory bradycardia progressing to recurrent cardiac arrest is uncommon and may pose major challenges during resuscitation. Here, we report the case of a woman in her late 50s who presented with recurrent syncope, convulsive episodes, altered sensorium, shock, and severe bradycardia following poor compliance with thyroid hormone replacement after total thyroidectomy. Despite repeated administration of atropine and high-dose vasopressor support, the patient developed multiple episodes of cardiac arrest requiring prolonged cardiopulmonary resuscitation, transcutaneous pacing, and temporary transvenous pacing. Laboratory evaluation revealed severe hypothyroidism with markedly elevated thyroid-stimulating hormone and low free thyroid hormone levels, consistent with myxedema coma. Management included stress-dose steroids, enteral levothyroxine, vasopressor support, mechanical ventilation, and temporary pacing, resulting in gradual hemodynamic and neurological recovery. This case report highlights the importance of recognizing severe hypothyroidism as a reversible cause of refractory bradycardia and cardiac arrest. Early thyroid hormone replacement, empirical corticosteroids, and timely pacing support can be lifesaving in such critically ill patients.