Cardiomyopathy, Dilated

Key Features

• Annual incidence is 4–8 cases per 100,000 population in the United States and Europe

• Although usually idiopathic, identifiable causes of dilated cardiomyopathy include

  • Viral myocarditis

  • Untreated tachyarrhythmias

  • Left heart obstructive lesions

  • Congenital abnormalities of the coronary arteries

  • Medication toxicity (eg, anthracycline)

  • Genetic (eg, dystrophin gene defects, sarcomeric mutations)

  • Metabolic diseases (inborn errors of fatty acid oxidation and mitochondrial oxidative phosphorylation defects)

Clinical Findings

• Presenting symptoms can resemble a viral respiratory infection, pneumonia, or asthma

• Decreased exercise tolerance

• Failure to thrive

• Diaphoresis

• Tachypnea

• As the heart continues to deteriorate, congestive signs such as hepatomegaly and rales develop

• Prominent gallop can be appreciated on examination

Diagnosis

• Chest radiograph shows generalized cardiomegaly with or without pulmonary venous congestion

• Electrocardiography

  • Sinus tachycardia with ST-T segment changes

  • Criteria for right and left ventricular hypertrophy may be met

  • QT interval may be prolonged

  • Supraventricular arrhythmias may be present; evaluation is critical because this arrhythmia is one of the treatable and reversible causes of dilated cardiomyopathy in children

• Echocardiography

  • Shows LV and left atrial enlargement with decreased LV-shortening fraction and ejection fraction

  • The calculated end-diastolic and end-systolic dimensions are increased and mitral insufficiency is commonly seen

  • A careful evaluation for evidence of structural abnormalities(especially coronary artery anomalies or left heart obstructive lesions) must be performed, especially in infant patients

• Cardiac catheterization is useful to evaluate hemodynamic status and coronary artery anatomy

• Endomyocardial biopsies can aid in diagnosis; specimens may show inflammation consistent with

  • Acute myocarditis

  • Abnormal myocyte architecture

  • Myocardial fibrosis

• Electron micrographs may reveal evidence of mitochondrial or other metabolic disorders

• Polymerase chain reaction testing may be performed on biopsied specimens to detect viral genome products in infectious myocarditis

• Cardiopulmonary stress testing is useful

  • For measuring response to medical therapy

  • As an objective assessment of the cardiac limitations on exercise

Treatment

• Combinations of afterload-reducing agents and diuretics used in outpatient management

• Aspirin or warfarin may be used to prevent thrombus formation in the dilated and poorly contractile cardiac chambers

• Antiarrhymthmic therapy is sometimes necessary

• Therapy of the underlying cause of cardiomyopathy is always indicated unless contraindicated

• Cardiac transplantation is considered if medical management is unsuccessful