Hypocalcemic Dilated Cardiomyopathy Following Total Thyroidectomy: A Reversible Complication of Secondary Hypoparathyroidism

Abstract

Aims: To highlight a rare but reversible cause of heart failure and emphasize the diagnostic importance of metabolic screening in patients with unexplained dilated cardiomyopathy, particularly those with a history of thyroid surgery. Introduction: Severe hypocalcemia is an uncommon yet treatable cause of myocardial dysfunction and dilated cardiomyopathy (DCM), most frequently occurring in the setting of secondary hypoparathyroidism following total thyroidectomy. This condition is often underrecognized, as clinical presentation may be dominated by neuromuscular manifestations or seizures, overshadowing cardiac involvement. Early metabolic correction can lead to complete recovery of cardiac function. Case Presentation: A 42-year-old woman with a history of total thyroidectomy presented with acute decompensated heart failure (New York Heart Association class IV), recurrent seizures, and neuromuscular symptoms. Investigations revealed profound hypocalcemia (4.2 mg/dL), suppressed parathyroid hormone levels, and severe biventricular systolic dysfunction (left ventricular ejection fraction [LVEF] 18%), without evidence of coronary artery disease or myocardial fibrosis on cardiac magnetic resonance imaging. Initiation of high-dose calcium and vitamin D supplementation for secondary hypoparathyroidism, alongside cautious guideline-directed heart failure therapy, resulted in progressive normalization of ventricular function, with LVEF improving from 18% at presentation to 50% at three-month follow-up. Discussion: This case illustrates the critical role of calcium in myocardial excitation–contraction coupling and underscores the potential for complete reversibility of hypocalcemia-induced cardiomyopathy. The diagnosis should be considered in any patient with unexplained systolic dysfunction, particularly in the presence of a history of neck surgery. Key diagnostic clues include prolonged QTc interval on electrocardiography, global hypokinesia on echocardiography, and the absence of alternative etiologies. Conclusion: Hypocalcemic DCM is a reversible entity that requires a high index of suspicion. Routine measurement of serum calcium, phosphate, and parathyroid hormone levels is essential in the evaluation of non-ischemic cardiomyopathy, especially in post-thyroidectomy patients. Timely diagnosis and metabolic correction can prevent irreversible myocardial damage and restore normal cardiac performance.