Nonischemic cardiomyopathy with reduced ejection fraction secondary to hyperthyroidism.

Dilated cardiomyopathy is a form of heart failure characterized by left ventricular dilation with impaired systolic function. Causes may include ischemic heart disease, hypertensive heart disease, valvular heart disease, endocrine disorders, substance use, and viral diseases. This case report describes a patient with new-onset heart failure, initially diagnosed as idiopathic dilated cardiomyopathy with pericarditis secondary to a virus but later found to be secondary to hyperthyroidism.