Apathetic Thyroid Storm Presenting as New-Onset Dilated Cardiomyopathy and Cardiogenic Shock.

Thyroid storm is an uncommon but life-threatening endocrine emergency associated with high mortality, and its diagnosis remains largely clinical due to the lack of universally reliable criteria to distinguish it from severe thyrotoxicosis; atypical or "apathetic" forms are particularly rare and can delay recognition. A 49-year-old man with no prior medical history presented with a two-week history of progressive anasarca, palpitations, and nonspecific gastrointestinal symptoms in the absence of fever or agitation and was found to have atrial fibrillation with rapid ventricular response and decompensated heart failure. Laboratory studies showed a suppressed thyroid-stimulating hormone with markedly elevated free T3 and T4, while echocardiography revealed global hypokinesis with an ejection fraction of 25-30%. His Burch-Wartofsky score of 60 supported the diagnosis of thyroid storm. Despite progression to cardiogenic shock, he improved with rate control, aggressive diuresis, esmolol, methimazole, and glucocorticoids without requiring inotropic support; subsequent outpatient evaluation confirmed Graves' disease, and at one year, he remains euthyroid with recovering ventricular function. This case highlights that apathetic thyroid storm may present predominantly with severe cardiomyopathy and shock in the absence of classic hyperadrenergic signs, underscoring the importance of early recognition and prompt targeted therapy for favorable outcomes.