A rare cause of dilated cardiomyopathy: hypocalcemia.

Dilated cardiomyopathy (DCM) is characterized by systolic dysfunction and is usually idiopathic. A rare cause of reversible DCM is hypocalcemia. Calcium plays a key role in myocardial contraction. Hypocalcemia can lead to a decrease in contraction, left ventricular systolic dysfunction, and heart failure with reduced ejection fraction (EF). Hypocalcemia-related reversible DCM reports are rare. Herein, we present two cases with heart failure caused by hypocalcemia developed due to hypoparathyroidism. The first case presented with severe heart failure and an extremely low serum calcium level (4.4 mg/dL) due to idiopathic hypoparathyroidism. The second case, which was also admitted with heart failure due to hypocalcemia, had iatrogenic hypoparathyroidism due to a subtotal thyroidectomy. In both cases, patients had reduced left ventricular systolic functions (EF was 33% and 42%, respectively). After calcium replacement and heart failure treatment, calcium levels were normalized. A significant and rapid improvement in heart failure was achieved in both cases (EF 60% and 50%, respectively). Serum calcium levels should always be measured in patients with heart failure, and the etiology of hypocalcemia should be sought. In addition to the standard pharmacotherapy of heart failure with reduced EF, calcium supplementation is essential for treating these patients.