Tachycardia-Induced Cardiomyopathy Secondary to Iatrogenic Chronic Hyperthyroidism

This case describes a middle-aged woman found to have tachycardia-induced cardiomyopathy secondary to chronic liothyronine overuse. Despite a non-specific presenting complaint, she was found clinically to have heart failure and evidence of fluid overload. ECG showed that she was in atrial flutter. A chest X-ray showed marked cardiomegaly and bilateral pleural effusions. Imaging of the abdomen showed a dilated inferior vena cava and evidence of systemic congestion. Trans-thoracic echocardiography showed a left ventricular ejection fraction of under 30%. Thyroid function tests showed a severely suppressed endogenous thyroid function. The patient was admitted under cardiology and given diuresis, including a stay in intensive care following an episode of acute hypotension. After stabilisation and discharge, her endogenous thyroid function and left ventricular systolic function are slowly recovering, and she reverted spontaneously to sinus rhythm.