Severe Hyponatremia-Induced Takotsubo Cardiomyopathy

We report the case of a 79-year-old woman with background of chronic hyponatremia secondary to syndrome of inappropriate antidiuretic hormone secretion (SIADH) who presented with chest pain and marked troponin elevation in the absence of an identifiable emotional stressor. Initial investigations revealed severe hyponatremia (serum sodium 122 mmol/L) and elevated cardiac enzymes. Her electrocardiogram showed normal sinus rhythm with deep, symmetrical T wave inversions in the inferior and precordial leads. Other investigations revealed apical akinesia on echocardiography and apical ballooning on the left ventriculogram. Coronary angiography showed unobstructed coronary arteries. Further investigations supported the diagnosis of SIADH, for which she was treated with fluid restriction and demeclocycline. The patient responded well with gradual normalisation of her sodium levels and improvement in symptoms. Follow-up imaging showed normal biventricular systolic function and resolution of apical ballooning. Given the temporal association and lack of alternative triggers, we hypothesize that profound hyponatremia contributed to the development of Takotsubo cardiomyopathy (TCM). This case highlights the potential for severe hyponatraemia to act as a precipitating factor in TCM.