Rapid progression of heart failure secondary to radioactive iodine treatment of hyperthyroidism: A case report

BACKGROUND: The deterioration of thyroid health is involved in the progression of heart failure (HF). This is usually a lengthy process, so there are almost no reports on its rapid development. Here we report a case of a young male who rapidly developed hypothyroid cardiomyopathy secondary to radioactive iodine treatment, suggesting that severe HF might occur even after a short period of hypothyroidism. CASE SUMMARY: A 26-year-old man was referred to our hospital for HF presenting with dyspnea on exertion and chest discomfort lasting for 1 mo. He received radioactive iodine treatment for hyperthyroidism 1 year ago and had an almost normal echocardiogram 6 mo ago. Admission echocardiogram and cardiac magnetic resonance (CMR) revealed left ventricle (LV) global hypokinesia and severely depressed systolic function. In addition, late gadolinium enhancement indicated no obvious changes in the myocardium. Thyroid function tests showed decreased serum levels of thyroid hormone (TH) and elevated thyroid-stimulating hormone. Based on an exclusionary examination, the patient was diagnosed with hypothyroid cardiomyopathy and was started on replacement therapy. His HF symptoms were completely relieved during the six-month follow-up, and echocardiogram and CMR revealed recovered LV size and ejection fraction. CONCLUSION: This report demonstrates that severe fluctuations in TH levels may lead to acute HF, which can completely recover with timely thyroid hormone replacement. In addition, our findings highlight the importance of routinely detecting cardiac function in patients treated with radioactive iodine.