Cardiomyopathy, Restrictive

KEY FEATURES

ESSENTIALS OF DIAGNOSIS

• Symptoms and signs of left or right heart failure

• Normal left and right ventricular size and systolic function with dilated atria

• Abnormalities of diastolic ventricular function suggestive of reduced ventricular compliance

• Increased ventricular filling pressure (left > right) and reduced cardiac output

GENERAL CONSIDERATIONS

• Rare disease of the myocardium accounting for approximately 5% of all cases of primary cardiomyopathies

• Three major causes include cardiac amyloidosis, cardiac sarcoidosis, and cardiac hemochromatosis. Other causes include idiopathic, endomyocardial fibrosis, eosinophilic endomyocarditis, metastatic malignancy, carcinoid heart disease, mediastinal radiation, and following heart transplantation

• Disease course varies depending on the pathology

• Important to distinguish from constrictive pericarditis, which may have similar clinical and hemodynamic findings

• Pathophysiology involves abnormal myocardial stiffness leading to a precipitous rise in ventricular diastolic filling pressures with a reduction in left ventricular filling volume and cardiac output

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

• Gradually progressive dyspnea and exercise intolerance

• Fatigue and weakness

• Chest pain

• Palpitations

• Dizziness and syncope

• Increasing abdominal girth (ascites)

• One-third of patients may present with thromboembolic events

PHYSICAL EXAM FINDINGS

• Reduced pulse pressure

• Tachycardia

• Increased jugular venous pressure with rapid X and Y descents

• Kussmaul sign in the jugular venous pulse (increase with inspiration)

• Loud S₃

• Murmurs of mitral and tricuspid regurgitation may be present

• Evidence of abdominal ascites

• Liver may be palpable and pulsatile

• Peripheral edema

• Decreased breath sounds due to pleural effusions

• Pulmonary rales may be heard

DIFFERENTIAL DIAGNOSIS

• Dilated cardiomyopathy with restrictive physiology

• Hypertrophic cardiomyopathy

• Constrictive pericarditis

DIAGNOSTIC EVALUATION

LABORATORY TESTS

• Complete blood count with peripheral smear: to rule out eosinophilia

• Serum iron concentrations, percent saturation of total iron binding capacity, and serum ferritin levels to exclude hemochromatosis

• Serum protein electrophoresis and serum and urine immunofixation to exclude light-chain deposition disease

ELECTROCARDIOGRAPHY

• Sinus rhythm, sinus tachycardia, or atrial arrhythmias may be present

• Varying degrees of atrioventricular block may be present

• Low QRS voltage

• Nonspecific ST-segment and T-wave abnormalities

IMAGING STUDIES

• Chest x-ray:

  • – Increased cardiothoracic ratio due to dilated atria with normal ventricular size

  • – Increased pulmonary vasculature and interstitial edema with Kerley B lines

  • – Pleural effusions may be present

• Two-dimensional echocardiography findings:

  • – Normal systolic right and left ventricular function with normal or increased wall thickness, with normal or reduced ventricular cavity size

  • – Markedly dilated left and right atria

  • – A ventricular mural thrombus may be present

  • – Color Doppler evidence of mitral, tricuspid, or pulmonic valve regurgitation may be present

  • – Mitral inflow, pulmonary venous, and tissue Doppler evidence of restrictive diastolic filling pattern

  • – Non-Doppler speckle-tracking strain ...