Thyrotoxic Cardiomyopathy Unveiled: Insights From a Compelling Case Report

Thyrotoxicosis is a clinical condition characterized by inappropriately elevated thyroid hormone levels in the bloodstream, leading to systemic effects on the body. In fact, the thyrotoxic state has tight regulatory control over the cardiovascular system through genomic and non-genomic mechanisms. This study highlights a rare presentation of thyrotoxic cardiomyopathy (TCM), which, to the best of our knowledge, is one of the very few case reports involving heart failure with preserved ejection fraction (HFpEF) and only atrial involvement, compared to the previous literature. A 37-year-old female presented to the outpatient clinic with abdominal distention and neglected signs and symptoms consistent with thyrotoxicosis for a year. Investigations revealed high N-terminal pro-b-type natriuretic peptide (NT-proBNP) levels of 1788 pg/mL. Cardiac MRI and trans-thoracic echocardiogram (TTE) revealed bilateral atrial dilatation, a left ventricular ejection fraction (LVEF) of 60%, and diastolic dysfunction. Additionally, severe free-flowing tricuspid and mitral valve regurgitation were observed, with no evidence of pericardial effusion or ventricular abnormalities. Therefore, a diagnosis of TCM was suspected and eventually confirmed by excluding other differential diagnoses. Besides a diffuse goiter on ultrasonography, the thyroid panel test revealed low thyroid-stimulating hormone (TSH) levels of <0.01 mIU/L, a free thyroxine T4 of >100 pmol/L, and positive anti-thyroid peroxidase (TPO) and TSH receptor antibodies. Accordingly, a team of endocrinologists, cardiologists, and internists managed the patient with anti-thyroid medications alongside symptomatic treatment. A few days later, she was discharged in good condition, and a follow-up visit was arranged with the endocrinology and cardiology clinics. It is crucial to maintain a high level of suspicion to detect and treat TCM promptly, and a multidisciplinary approach should ideally be employed. This is not only important for the prevention of but also reversing potentially life-threatening cardiovascular complications.