Reversible Dilated Cardiomyopathy Secondary to Severe Hypothyroidism: A Case Report from Indiana University Health

Abstract

Background: Dilated cardiomyopathy (DCM) can be a rare but treatable cause of severe hypothyroidism. Untimely recognition and thyroid hormone replacement therapy can lead to significant recovery of cardiac function, while delayed diagnosis can lead to more advanced heart failure. This is a very unusual case of severe hypothyroidism-induced DCM after prolonged levothyroxine treatment was stopped after complete thyroidectomy.
Case Presentation: A 45-year-old woman with a history of Graves' disease following total thyroidectomy developed gradually worsening dyspnea, orthopnea, bilateral lower extremity edema, fatigue, constipation, cold intolerance, and 40 lb weight gain after stopping levothyroxine for about five months. Laboratory tests showed severe hypothyroidism (TSH 24.5 mIU/L; free T4 0.09 ng/dL) and high levels of B-type natriuretic peptide (BNP) (496 pg/mL). An electrocardiogram showed Q waves in leads V1 and V2 and T-wave inversions in V3, V4, and V5. TTE revealed severe left ventricular (LV) dilatation, global hypokinesis and LV ejection fraction (LVEF) of ~10%. Obstructive coronary artery disease was ruled out by coronary angiography. The patient was treated with levothyroxine replacement therapy along with guideline-directed medical therapy of heart failure. At 2 months follow up, LV EF had improved to about 40% with significant clinical improvement.
Conclusion: This case is a good reminder of the role of severe hypothyroidism as a potentially reversible cause of non-ischemic dilated cardiomyopathy. In patients with an apparently unexplained case of heart failure or dilated cardiomyopathy, particularly those who have had thyroid surgery or have been non-compliant with thyroid hormone replacement therapy, it would be prudent to consider routine thyroid function testing. Early diagnosis and rapid restoration of euthyroidism and multidisciplinary management can lead to good myocardial recovery without the need for unnecessary advanced heart failure interventions.