Restrictive cardiomyopathy

Background

• Muscle is stiff from fibrosis or infiltrating process (e.g. amyloidosis, hemochromatosis)
• Form of diastolic dysfunction (difficulty filling); ventricular endocardial thickening or myocardial infiltration-->high filling pressures, impaired diastolic filling-->mitral and/or tricuspid regurgitation--> venous pulmonary hypertension
  • Ventricular EF typically normal, though systolic function may deteriorate in absence of compensatory hypertrophy
• If nodal/conduction tissues affected by infiltrative/fibrotic process, may cause SA or AV block
• Must distinguish from constrictive pericarditis

Causes of Restrictive Cardiomyopathy

• Idiopathic
• Familial non=infiltrative disease
• Infiltrative disease (amyloidosis, sarcoidosis, Gaucher, Hurler)
• Storage diseases (hemochromatosis, Fabry, glycogen/lysosomal storage diseases)
• Diabetes
• Scleroderma
• Endomyocardial fibrosis (hypereosinophilic syndrome, medication toxicity)
• Radiation, chemotherapy (doxorubicin)
• Metastatic disease, carcinoid syndrome

Clinical Features

• Exertional dyspnea, orthopnea, PND
• Peripheral edema
• Fatigue, +/- syncope, angina from poor cardiac output
• +/- Arrhythmias, AV block
• Quiet precordium
• Crackles
• JVD
• +/- murmur from mitral/tricuspid regurgitation

Differential Diagnosis

Cardiomyopathy

• Dilated cardiomyopathy
• Hypertrophic cardiomyopathy
• Restrictive cardiomyopathy
• Peripartum cardiomyopathy
• Takotsubo cardiomyopathy
• Arrhythmogenic right ventricular dysplasia

Evaluation

• Consider if CHF but no evidence of cardiomegaly or systolic dysfunction
• ECG
  • Typically nonspecific ST/TW abnormalities
  • Other features may include low voltage, pathologic Q waves, LVH, AV block

showing ST-segment and T-wave abnormalities

• CXR- heart typically normally sized, though can be enlarged in advanced stages of some underlying disease processes
• Echocardiography
  • Normal LVEF
  • Elevated LV filling pressures, impaired longitudinal contraction
  • +/- dilated atria, myocardial hypertrophy
• Definitive diagnosis may require MRI, catheterization, biopsy

Management

• Symptom-directed
  • Diuretics for edema or pulmonary vascular congestion
    • Caution as cardiac output preload dependant
  • Caution with afterload reduction as may cause profound hypotension
  • Treat arrhythmias
    • Avoid digoxin in amyloidosis as sensitivity to dig-induced arrhythmias common

See Also

• Cardiomyopathy (main)

References

https://www.merckmanuals.com/professional/cardiovascular-disorders/cardiomyopathies/restrictive-cardiomyopathy