Cardiomyopathy, Restrictive

Key Features

• 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

  • Rapid early filling is present with diastolic dysfunction

  • Normal or near normal ejection fraction (EF) with normal size left ventricle (LV)

• MRI and cardiac catheterization are helpful

• Radionuclide imaging or myocardial biopsy can confirm amyloid

Clinical Findings

• Symptoms may include angina, syncope, stroke and peripheral neuropathy

• Characterized by impaired diastolic filling with reasonably preserved contractile function

• In Africa, endomyocardial fibrosis is seen

• Other causes of restrictive cardiomyopathy

  • Infiltrative cardiomyopathies (eg, hemochromatosis, sarcoidosis)

  • Connective tissue diseases (eg, scleroderma)

• Restrictive cardiomyopathy must be distinguished from constrictive pericarditis

Diagnosis

• ECG

  • 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

  • Biatrial enlargement

  • LV chamber size is usually normal with a reduced LVEF

  • Atrial septal thickening

• Technetium pyrophosphate imaging (bone scan imaging)

  • Can identify amyloid deposition in the myocardium

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

• With typical scintigraphic findings in patients without a monoclonal gammopathy, biopsy is no longer necessary for diagnosis

• Cardiac MRI presents a distinctive pattern of diffuse hyperenhancement of the gadolinium image in amyloidosis

• Rectal, abdominal fat, or gingival biopsies can confirm systemic involvement

• Endomyocardial biopsy is required to confirm that cardiac amyloid is present

• Mass spectroscopy is recommended on all tissue in question

• TTR gene sequencing is recommended in patients in whom the TTR wild type or TTR mutant variant is suspected

Treatment

• Tafamidis

  • Treatment of choice for transthyretin amyloidosis cardiomyopathy

  • Results from the Transthyretin Amyloidosis Cardiomyopathy Clinical Trial (ATTR-ACT) showed

    • Substantially improved survival

    • Reduced hospitalization

    • Improved quality of life for patients with transthyretin amyloidosis cardiomyopathy

• Diuretics can help, but excessive diuresis can produce worsening kidney dysfunction

• Loop diuretics, thiazides, and aldosterone antagonists are all useful

• Ultrafiltration devices allow for improved diuresis

• Beta-blockers help slow heart rates and improve filling

• Corticosteroids

  • May be helpful in sarcoidosis

  • More effective for the conduction abnormalities than the heart failure

• In amyloidosis, treatment depends on the type of amyloid protein and extent of disease

  • First-line treatment for AL amyloidosis includes alkylator-based chemotherapy or high-dose melphalan followed by autologous stem cell transplantation

  • In familial amyloidosis with transthyretin deposition, liver transplantation may be an option

  • Cardiac transplantation has been used in primary cardiac amyloidosis and no evidence for systemic involvement