Dilated cardiomyopathy is a progressive, usually irreversible, disease causing global systolic (contractile) dysfunction with heart failure. Often, there are ventricular and supraventricular arrhythmias, conduction system abnormalities, and thromboembolism; sudden death may occur, typically in later stages of disease.
From a pathologic standpoint, the term dilated cardiomyopathy is generally used to designate an idiopathic process, in the absence of long-standing hypertension, toxin exposure, or chronic alcoholism (secondary dilated cardiomyopathy). Most patients are middle aged or older at the time of onset; younger patients with dilated cardiomyopathy often have a family history and a genetic predisposition (familial dilated cardiomyopathy).
Congestive heart failure with global left ventricular dysfunction, mimicking dilated cardiomyopathy, may also occur in patients with coronary ischemia and valve disease.
Dilated cardiomyopathy is characterized by ventricular chamber enlargement and systolic dysfunction with normal left ventricular wall thickness (see the image below).
Right ventricular dilatation and dysfunction may be present but are not necessary for the diagnosis.
Gross heart specimen from a patient with dilated cardiomyopathy who died in end-stage heart failure. Defibrillator leads are in the right heart. The ventricles are dilated with normal ventricular wall thicknesses, imparting an appearance of thin ventricular walls. The ventricles are dilated more than the atria.
Dilated cardiomyopathy is a diffuse process, and cardiomyocytes of both ventricles (see the image below) are involved; atrial function is also decreased. A primary heart muscle disease, dilated cardiomyopathy has no clear cause. Heart transplantation is the treatment of choice.
Heart section from a cardiac explant in a patient with end-stage cardiomyopathy. Note the cardiomyocyte multinucleation. The change is nonspecific and can be seen in heart failure from any cause.