Reversible Left Ventricular Systolic Dysfunction Associated With Subclinical Hypothyroidism: A Case Report From Tanzania

Subclinical hypothyroidism (SCH), defined by an elevated serum thyroid-stimulating hormone (TSH) concentration with a normal free thyroxine (FT4) concentration, has been associated with adverse cardiovascular remodeling and an increased risk of heart failure. We report the case of a 35-year-old woman from Tanzania with a five-year history of progressive multinodular goiter and hypothyroid symptoms who presented with heart failure with reduced ejection fraction (HFrEF), severe hypertension, and echocardiographic features of a dilated cardiomyopathic phenotype, including a left ventricular ejection fraction (LVEF) of 40%. She was treated with gradually titrated levothyroxine in conjunction with guideline-directed medical therapy for HFrEF and antihypertensive treatment. During 12 months of follow-up, she achieved biochemical euthyroidism, complete resolution of hypothyroid and heart failure symptoms, restoration of sinus rhythm, and objective reverse left ventricular remodeling with recovery of LVEF from 40% to 60%, fulfilling contemporary criteria for heart failure with improved ejection fraction. Although the relative contribution of thyroid hormone replacement, blood pressure control, and heart failure therapy cannot be determined, this case highlights the potential role of SCH as a reversible contributor to left ventricular systolic dysfunction and emphasizes the importance of early recognition, comprehensive cardiovascular evaluation, and multidisciplinary management in patients presenting with concomitant thyroid and cardiac disease.