Cardiomyopathies and Myocarditis

Cardiomyopathies and Myocarditis is a topic covered in the Harrison's Manual of Medicine.

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Cardiomyopathies are primary diseases of heart muscle. Table 115-1 summarizes distinguishing presenting features of the three major types of cardiomyopathy. Table 115-2 details the comprehensive initial evaluation of suspected cardiomyopathies.

Ejection fraction (normal >55%)Usually <30% when symptoms severe25–50%>60%
Left ventricular diastolic dimension (normal <55 mm)≥60 mm<60 mm (may be decreased)Often decreased
Left ventricular wall thicknessNormal or decreasedNormal or increasedMarkedly increased
Atrial sizeIncreasedIncreased; may be massiveIncreased
Valvular regurgitationRelated to annular dilationRelated to endocardial involvement; frequent mitral and tricuspid regurgitation, rarely severeRelated to valve-septum interaction; mitral regurgitation
Common first symptomsExertional intoleranceExertional intolerance, fluid retention earlyExertional intolerance; may have chest pain
Congestive symptomsaLeft before right, except right prominent in young adultsRight often dominatesLeft-sided congestion may develop late
ArrhythmiaVentricular tachyarrhythmia; conduction block in Chagas’ disease, and some families. Atrial fibrillation.Ventricular uncommon except in sarcoidosis conduction block in sarcoidosis and amyloidosis. Atrial fibrillation.Ventricular tachyarrhythmias; atrial fibrillation
aLeft-sided symptoms of pulmonary congestion: dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea. Right-sided symptoms of systemic versus congestion: discomfort on bending, hepatic and abdominal distention, peripheral edema.
Clinical Evaluation
Thorough history and physical examination to identify cardiac and noncardiac disordersa
Detailed family history of heart failure, cardiomyopathy, skeletal myopathy, conduction disorders and tachyarrhythmias, sudden death
History of alcohol, illicit drugs, chemotherapy, or radiation therapya
Assessment of ability to perform routine and desired activitiesa
Assessment of volume status, orthostatic blood pressure, body mass indexa
Laboratory Evaluation
Chest radiographa
Two-dimensional and Doppler echocardiograma
Magnetic resonance imaging to assess myocardial inflammation and fibrosis


 Serum sodium,a potassium,a calcium,a magnesiuma

 Fasting glucose (glycohemoglobin in DM)

 Creatinine, a blood urea nitrogena

 Albumin,a total protein,a liver function testsa

 Lipid profile

 Thyroid-stimulating hormonea

 Serum iron, transferrin saturation




 White blood cell count with differential,a including eosinophils

 Erythrocyte sedimentation rate

Initial Evaluation Only in Pts Selected for Possible Specific Diagnosis

Titers for infection in presence of clinical suspicion:

 Acute viral (e.g., coxsackievirus, echovirus, influenza virus)

 Human immunodeficiency virus,

 Chagas’ disease, Lyme disease, toxoplasmosis

Catheterization with coronary angiography in pts with angina who are candidates for interventiona
Serologies for active rheumatologic disease
Endomyocardial biopsy including sample for electron microscopy when suspecting specific diagnosis with therapeutic implications
Screening for sleep-disordered breathing
aLevel I Recommendations from ACC/AHA Practice Guidelines for Chronic Heart Failure in the adult.
Source: From SA Hunt et al: Circulation 112: 2005.

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