Cardiomyopathy, Idiopathic Dilated

KEY FEATURES

ESSENTIALS OF DIAGNOSIS

• Left ventricular dilation and systolic dysfunction in the absence of an identifiable etiology or abnormal loading conditions

GENERAL CONSIDERATIONS

• Disease is 3 times more common in African-Americans

• Emerging data suggest that 20–35% of patients with an idiopathic dilated cardiomyopathy may have familial disease

• Some patients may have had an undetected viral myocarditis

• Patients have a lower total mortality rate when compared to other types of dilated cardiomyopathy

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

• Decreased exercise tolerance

• Dyspnea

• Orthopnea

• Paroxysmal nocturnal dyspnea

• Fatigue

• Palpitations

• Presyncope or syncope

PHYSICAL EXAM FINDINGS

• Tachycardia

• Tachypnea

• Jugular venous distention may be present

• Pulmonary rales

• Laterally displaced and diffuse point of maximal impulse; left and right ventricular lifts

• Soft S₁, paradoxically split S₂ with a left bundle branch block

• S₃ and S₄ gallops

• Hepatomegaly due to elevated venous pressures; the liver may be pulsatile with severe tricuspid regurgitation

• Ascites, peripheral edema

• Muscle wasting or other signs of cardiac cachexia

DIFFERENTIAL DIAGNOSIS

• Ischemic cardiomyopathy

• Valvular heart disease

• Hypertensive heart disease

• Toxin-induced cardiomyopathy: alcohol, stimulants (cocaine, methamphetamine), cytotoxic antineoplastic drugs

• Cardiomyopathy related to thyroid dysfunction

• HIV or other inflammatory cardiomyopathy

DIAGNOSTIC EVALUATION

LABORATORY TESTS

• Electrolytes, blood urea nitrogen, and creatinine

• CBC

• Liver function tests

• Cardiac enzymes

• Thyroid function tests, iron studies

• Urine pregnancy test: in women of childbearing age

• Urine toxicology screen

• HIV antibody testing

ELECTROCARDIOGRAPHY

• Supraventricular tachycardia

• Premature ventricular complexes

• Nonspecific ST- and T-wave changes

• Left ventricular hypertrophy or biventricular hypertrophy

• Left bundle branch block common

• Varying degrees of atrioventricular block may be present

IMAGING STUDIES

• Chest x-ray:

  • – Enlarged cardiac silhouette

  • – Pulmonary vascular congestion

  • – Pleural effusions

• Echocardiography:

  • – All 4 cardiac chambers are typically enlarged, and ventricular contractile function is reduced

  • – Varying degrees of mitral and tricuspid regurgitation due to annular dilatation

• Cardiac magnetic resonance (CMR) to evaluate for possible inflammatory myocarditis as etiology

DIAGNOSTIC PROCEDURES

• Left heart catheterization with coronary angiography performed to exclude coronary artery disease

• Endomyocardial biopsy can be considered for patients suspected of inflammatory myocarditis, those with rapidly progressive heart failure, or those with ventricular dysfunction that persists despite medical therapy

• Cardiopulmonary exercise testing can aid in understanding functional status, evaluating etiologies for exercise limitation, and informing prognosis

TREATMENT

CARDIOLOGY REFERRAL

• Any patient with symptomatic or asymptomatic ventricular dysfunction

HOSPITALIZATION CRITERIA

• Decompensated heart failure

• Atrial fibrillation with rapid ventricular response

• Syncope

• Cardiac ...