Chapter 117: Cardiomyopathies and Myocarditis

Cardiomyopathies are primary diseases of heart muscle. Table 117-1 summarizes distinguishing presenting features of the three major types of cardiomyopathy (CMP). Table 117-2 details the comprehensive initial evaluation of suspected cardiomyopathies.
TABLE 117-1: Presentation with Symptomatic Cardiomyopathy
 DILATEDRESTRICTIVEHYPERTROPHIC
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 familial forms. Atrial fibrillationVentricular uncommon except in sarcoidosis, conduction block in sarcoidosis and amyloidosis. Atrial fibrillationVentricular tachyarrhythmias; atrial fibrillation
aLeft-sided symptoms of pulmonary congestion: dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea. Right-sided symptoms of systemic venous congestion: hepatic and abdominal distention, discomfort on bending, peripheral edema.
TABLE 117-2: Initial Evaluation of Cardiomyopathy
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
Electrocardiograma
Chest radiographa
Two-dimensional and Doppler echocardiograma
Magnetic resonance imaging to assess myocardial inflammation and fibrosis
Chemistry:
 Serum sodium,a potassium,a calcium,a magnesiuma
 Fasting glucose (glycohemoglobin in diabetes mellitus)
 Creatinine,a blood urea nitrogena
 Albumin,a total protein,a liver function testsa
 Lipid profile
 Thyroid-stimulating hormonea
 Serum iron, transferrin saturation
 Urinalysis
 Creatine kinase isoforms
 Cardiac troponin
Hematology:
 Hemoglobin/hematocrita
 White blood cell count with differential,a including eosinophils
 Erythrocyte sedimentation rate
Initial Evaluation When Specific Diagnoses Are Suspected
DNA sequencing for genetic disease; panel selection based on phenotype
Titers for infection in presence of clinical suspicion:
 Acute viral (e.g., coxsackievirus, echovirus, influenza)
 Human immunodeficiency virus
 Chagas’ disease, Lyme disease, toxoplasmosis
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.

There's more to see -- the rest of this topic is available only to subscribers.