Restrictive cardiomyopathy refers to changes in and weakening of the heart muscle, which causes the heart to fill poorly, squeeze poorly, or both.

Cardiomyopathy - restrictive; Infiltrative cardiomyopathy

In restrictive cardiomyopathy, the heart is of normal size or only slightly enlarged. However, it cannot relax normally during the time between heartbeats when the blood returns from the body (diastole).

Later in the disease, the heart may not pump blood strongly. The abnormal heart function can affect the lungs, liver, and other body systems. Restrictive cardiomyopathy may affect either or both ventricles. It is usually associated with a disease of the heart muscle.

Although restrictive cardiomyopathy is a rare condition, the most common causes are amyloidosis and scarring of the heart from an unknown cause (idiopathic myocardial fibrosis). It can occur after a heart transplant.

Other causes of restrictive cardiomyopathy include:

• Carcinoid heart disease
• Diseases of the heart lining (endocardium), such as endomyocardial fibrosis and Loeffler's syndrome (rare)
• Iron overload (hemochromatosis)
• Sarcoidosis
• Scarring after radiation or chemotherapy
• Scleroderma
• Tumors of the heart

Symptoms of heart failure are most common. Usually, these symptoms develop slowly over time. However, sometimes symptoms start very suddenly and are severe.

Common symptoms are:

• Cough
• Difficulty breathing or shortness of breath
  • At night
  • Especially with activity
  • When lying flat
• Fatigue, poor exercise tolerance
• Loss of appetite
• Swelling of the abdomen
• Swelling of the feet and ankles
• Uneven or rapid pulse

Other symptoms may include:

• Chest pain
• Decreased alertness or concentration
• Low urine production
• Need to urinate at night (in adults)

An examination may show:

• Enlarged (distended) or bulging neck veins
• Enlarged liver
• Lung crackles and abnormal or distant heart sounds when listening to the chest with a stethoscope
• Fluid backup into the hands and feet
• Signs of heart failure

Tests for restrictive cardiomyopathy include:

• Cardiac catheterization and coronary angiography
• Chest CT scan
• Chest x-ray
• ECG (electrocardiogram)
• Echocardiogram and Doppler study
• MRI of the heart
• Nuclear heart scan (MUGA, RNV)
• Serum iron studies
• Serum or urine protein tests

Restrictive cardiomyopathy may be hard to tell apart from constrictive pericarditis. A biopsy of the heart muscle or cardiac catheterization may help confirm the diagnosis, but is not often done.

When the cause of any cardiomyopathy can be found, that condition is treated.

Few treatments are known to be effective for restrictive cardiomyopathy. The main goal of treatment is to control symptoms and improve quality of life.

The following treatments may be used to control symptoms or prevent problems:

• Blood thinning medications, either aspirin or warfarin
• Chemotherapy (in some situations)
• Diuretics to remove fluid and help improve breathing
• Medications to prevent or control uneven or abnormal heart rhythms
• Steroids for some causes

A heart transplant may be considered if the heart function is very poor and the patient has severe symptoms.

People with this condition often develop heart failure that gets worse. Problems with "leaky" heart valves may also occur.

People with restrictive cardiomyopathy may be heart transplant candidates. The outlook depends on the cause of the condition, but it is usually poor. Average survival after diagnosis is 9 years.

Call your health care provider if you have symptoms of restrictive cardiomyopathy.

Hare JM. The dilated, restrictive, and infiltrative cardiomyopathies. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 68.