Sudden cardiac arrest associated with myxedema coma due to undiagnosed hypothyroidism: a case report

BACKGROUND: Myxedema coma, which occurs due to hypothyroidism, is a rare and life-threatening condition. Some patients have hemodynamic dysfunction, which consequently leads to cardiac arrest. The rarity of this condition makes it difficult to determine the cause of cardiac arrest. It is important to diagnose myxedema coma based on clinical findings, including physical examination and laboratory parameters. We present a case of undiagnosed and untreated hypothyroidism that initially caused myxedema coma and then led to cardiac arrest. CASE PRESENTATION: A 56-year-old woman who had no medical history was transferred to our hospital for the management of return of spontaneous circulation due to sudden cardiac arrest. Findings of laboratory tests revealed that she had hypothyroidism. On physical examination, she was found to have a puffy face, thin eyebrows, and severe systemic non-pitting edema. Therefore, the patient was clinically diagnosed with myxedema coma, which was the cause of cardiac arrest. She was treated with thyroid hormone and hydrocortisone, resulting in improvement in her general condition, except for the neurological dysfunction. CONCLUSIONS: This case suggests that myxedema coma is caused by undiagnosed and untreated hypothyroidism, leading to sudden cardiac arrest. Our findings are useful in the differential diagnosis of hypothyroidism based on characteristic physical examination findings. Clinicians should be aware of the differential diagnosis of myxedema coma based on findings from physical examination and laboratory testing of thyroid function, and the treatment should be started immediately.