Cardiomyopathy, Restrictive

Key Features

Essentials of Diagnosis

• Right heart failure tends to dominate over left heart failure

• Pulmonary hypertension is present

• Amyloidosis is the most common cause

• Echocardiography is key to diagnosis

• Radionuclide imaging or myocardial biopsy can confirm amyloid

General Considerations

• Characterized by impaired diastolic filling with reasonably preserved left ventricular (LV) chamber size

• The diagnosis of cardiac amyloidosis has dramatically increased in the last few years since diagnostic testing has improved and there is an awareness of its prevalence

• Infiltrative disorders beside amyloidosis that can also produce the picture include

  • Sarcoidosis

  • Gaucher disease

  • Hurler syndrome

  • Storage diseases such as

    • Hemochromatosis

    • Fabry disease

    • Glycogen storage diseases

• Noninfiltrative diseases, such as familial cardiomyopathy and pseudoxanthoma elasticum, can be implicated rarely

• Other secondary causes include

  • Diabetes

  • Systemic sclerosis (scleroderma)

  • Radiation

  • Chemotherapy

  • Coronary artery disease

  • Longstanding hypertension

Demographics

• Prevalence of AL amyloid is approximately 12 cases per million

• Prevalence of variant or hereditary ATTR amyloid is about 0.3 cases per million

• Prevalence of wild type ATTR amyloid is 155–191 cases per million

• Many experts believe the actual prevalence of wild type ATTR is much higher

• Wild type (normal) occurs more commonly in the elderly and in men, and previously was referred to as "senile systemic amyloidosis"

• Hereditary or variant ATTR is genetically transmitted, deposition occurs at an earlier age, and has associated neurologic impact

Clinical Findings

Symptoms and Signs

• Angina

• Syncope

• Stroke

• Peripheral neuropathy

• Suggestive physical findings of amyloidosis

  • Periorbital purpura

  • Thickened tongue

  • Hepatomegaly

Differential Diagnosis

• Restrictive cardiomyopathy must be distinguished from constrictive pericarditis; the key feature is that ventricular interaction is accentuated with respiration in constrictive pericarditis and that interaction is absent in restrictive cardiomyopathy

• In addition, the pulmonary arterial pressure is invariably elevated in restrictive cardiomyopathy due to the high pulmonary capillary wedge pressure (PCWP) and is normal in uncomplicated constrictive pericarditis

Diagnosis

• Conduction disturbances are frequently present

• Low voltage on the ECG combined with ventricular hypertrophy on the echocardiogram is suggestive of disease

• Echocardiogram

  • Reveals a small, thickened LV with bright myocardium (speckled), rapid early diastolic filling revealed by the mitral inflow Doppler, and biatrial enlargement

  • Characteristic longitudinal strain patterns may help identify cardiac amyloidosis

  • The LV chamber size is usually normal with a reduced LV ejection fraction (LVEF)

  • Atrial septal thickening may be evident

  • An amyloid variant that primarily affects the atria has been described

• Technetium pyrophosphate imaging (bone scan imaging)

  • Can also identify amyloid deposition in the myocardium

  • Has become the noninvasive imaging modality of choice for diagnosing transthyretin amyloidosis

• Cardiac MRI

  • Presents a distinctive pattern of diffuse hyperenhancement of the gadolinium image in amyloidosis

  • Late gadolinium hyperenhancement of ...