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What is cardiomyopathy?

Cardiomyopathy is a disease of the heart muscle characterized by an abnormally large, thick, or stiff heart muscle. It may affect only the heart’s lower chambers (ventricles), or both the lower and upper chambers (atria).

Cardiomyopathy causes damage to tissue around the heart, as well as heart muscle cells. In severe cases, the heart becomes so weak that it can’t pump blood properly. This can lead to heart failure or irregular heartbeats (arrhythmias). In some cases, cardiomyopathy also involves a buildup of scar tissue or fat within the heart muscle. In rare cases, the heart muscle can’t relax and blood can’t fill the heart properly.

Cardiomyopathy is very often a “time-will-tell” disease. Symptoms can vary and the progression of the disease can be unpredictable.

What are the types of cardiomyopathy?

There are many forms of cardiomyopathy. The main types include:

Dilated cardiomyopathy (DCM)

DCM is the most common type and occurs when the main pumping chamber of the heart muscle is too stretched out (dilated). Dilated cardiomyopathy makes the heart unable to pump blood effectively.

Hypertrophic cardiomyopathy (HCM)

HCM makes the heart muscle too thick. Usually, the thickening occurs in the muscle of the left ventricle in the heart, often involving the wall between the heart’s two ventricles.

Restrictive cardiomyopathy

Restrictive cardiomyopathy is a rare type of cardiomyopathy that causes the heart muscle to become very rigid or stiff. This makes it difficult for the ventricles of the heart to properly fill with blood.

Arrhythmogenic right ventricular cardiomyopathy (ARVC)

ARVC is a rare form of cardiomyopathy that affects only one in 5,000 people. It occurs when the muscle of the heart’s right ventricle is replaced by thick or fatty scar tissue. The scarring “scrambles” electrical signals within the heart and can make it difficult for the heart to pump blood.

Cardiomyopathy | Symptoms & Causes

What are the symptoms of cardiomyopathy?

Some children with cardiomyopathy have few to no signs of illness at first, while others may be seriously affected by shortness of breath, dizziness, and other symptoms shortly after birth.

Dilated cardiomyopathy symptoms

Many children with dilated cardiomyopathy (DCM) don’t have any symptoms. Those who do may have one or more of the following symptoms, which may vary depending on the age of the child:

  • Abdominal pain
  • Chest pain
  • Chronic fatigue
  • Chronic loss of appetite or inability to feed
  • Frequent irritability without a visible cause
  • Frequent vomiting
  • Pale or clammy skin
  • Rapid breathing
  • Rapid or “racing” heartbeat
  • Shortness of breath
  • Slow or delayed growth

Hypertrophic cardiomyopathy symptoms

Children with hypertrophic cardiomyopathy (HCM) may have symptoms during physical activity, or their symptoms may come on suddenly and unpredictably. Common symptoms signs include:

  • Abnormal heart rhythm
  • Chest pain
  • Dizziness
  • Fainting

Restrictive cardiomyopathy symptoms

Symptoms of restrictive cardiomyopathy can vary greatly from child to child. Many children have no noticeable symptoms, others have very mild symptoms, while others have clear warning signs that become progressively worse if the disease is not treated.

Symptoms can include:

  • Fatigue
  • Persistent coughing
  • Shortness of breath during exercise or right after exercise
  • Shortness of breath at night (while resting or sleeping)
  • Shortness of breath while lying flat
  • Swelling in the abdomen
  • Swelling in the feet or ankles
  • Poor growth or failure to gain weight

Arrhythmogenic right ventricular cardiomyopathy symptoms

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is often difficult to diagnose because many people never have symptoms or develop symptoms suddenly after not having any problems.

Symptoms can include:

  • Abnormal heart rhythm
  • Fainting
  • Lightheadedness or dizziness
  • Racing heartbeat
  • Shortness of breath
  • Swelling in the abdomen
  • Swelling in the legs

What are the causes of cardiomyopathy?

Some forms of cardiomyopathy run in families. Anyone with a family history of cardiomyopathy, heart attack, or arrhythmias should be screened. Genetic testing can detect about 50 about percent of cases. In other cases, cardiomyopathy develops because of another medical condition. In many cases, however, there is no clear cause for cardiomyopathy (idiopathic cardiomyopathy).

Dilated cardiomyopathy causes

In many cases, DCM occurs without a known reason.

When the cause can be determined, reasons include:

  • Myocarditis, an inflammation of the heart muscle that usually stems from a viral infection
  • Certain metabolic diseases
  • Certain genetic disorders, like muscular dystrophy
  • Inheriting the condition from a parent

Some less common causes of DCM are:

  • Connective tissue disorders, such as rheumatoid arthritis
  • Coronary artery disease
  • Diabetes that is not properly controlled
  • Obesity
  • Substance abuse
  • Thyroid disease

Hypertrophic cardiomyopathy causes

Hypertrophic cardiomyopathy (HCM) has a strong inherited component. At least half of all children with HCM have a parent or sibling with some enlargement in their heart muscle, although these family members may not have any symptoms themselves.

HCM is caused by a defect in the genes that control the manufacture of the proteins of the heart muscle.

Restrictive cardiomyopathy causes

Restrictive cardiomyopathy is not typically inherited, and many children have no identifiable cause for their disease.

When there is known cause, these may include:

  • Chemotherapy treatments for certain cancers
  • Radiation treatments to the chest for certain cancers
  • Sarcoidosis
  • Scleroderma
  • Diseases of the heart lining, including endomyocardial fibrosis and Loeffler’s syndrome
  • Too much iron in the heart (hemochromatosis)
  • An abnormal protein buildup in the muscle of the heart (amyloidosis)
  • Tumors in the heart
  • A buildup of scar tissue in the heart

Arrhythmogenic right ventricular cardiomyopathy causes

ARVC often runs in families. At least 30 to 50 percent of all people with ARVC have family members with the disease. Researchers are working to identify precisely which gene mutations and chromosomes are involved in the onset of ARVC.

Cardiomyopathy | Diagnosis & Treatments

How is cardiomyopathy diagnosed?

Because the symptoms of cardiomyopathy can be diverse, it is often misdiagnosed as asthma, an infection, or a gastrointestinal problem.

In children who have no symptoms, cardiomyopathy is sometimes diagnosed when the child has a chest X-ray that shows an enlarged heart or an echocardiogram for another reason.

If your child’s doctor suspects cardiomyopathy, he or she may order one or more of the following tests:

How is cardiomyopathy treated?

Your child's treatment options will be determined by the type of cardiomyopathy he or she has, as well as the specific symptoms. A child with no symptoms might not need medication or other treatment right away. Instead, the cardiologist will monitor your child to gauge the progression of the disease.

A child with more serious symptoms may need additional tests to give the treatment team more detailed information about how the cardiomyopathy is affecting the heart and the rest of the body.

Many children with cardiomyopathy do well with medication alone. Others need surgery to improve the function of valves, and in the most severe cases, some children need a heart transplant.

Medication for cardiomyopathy

There are several different types of medications for cardiomyopathy, depending on which type your child has and the symptoms.

  • Angiotestin converting enzyme (ACE) inhibitors are drugs that dilate blood vessels in the body, fighting the constricting effect caused by heart failure.
  • Antiarrhythmic medications combat the abnormal heart rhythms caused by irregular electrical activity within the heart.
  • Beta blockers block certain chemicals from binding to nerve receptors in the heart, slowing the heart rate and lowering blood pressure.
  • Blood thinners or anticoagulants help prevent the formation of blood clots, especially in children with the dilated form of cardiomyopathy.
  • Diuretics prevent the buildup of fluid in the body and can help breathing by reducing fluid in the lungs. These drugs may also be helpful in treating scar tissue on the heart.

Surgical treatments for cardiomyopathy

There are several options for treating cardiomyopathy using surgery or minimally-invasive procedures.


For some children with cardiomyopathy — particularly HCM — an implantable cardioverter-defibrillator (ICD) can be a life-saving option. This tiny instrument, about the size of a deck of cards, is placed in the chest to monitor the child's heartbeat. If the child has an arrhythmia, the defibrillator will administer a precise electrical pulse to restore normal heart rhythm.


Pacemaker implantation is minimally invasive option for some children with cardiomyopathy. The pacemaker — a small electronic device — is inserted directly under the skin, where it sends electric signals to the child's heart, controlling and monitoring the heart rate. The procedure can be performed under local anesthesia in a matter of hours.

Radiofrequency ablation

Radiofrequency ablation is another type of minimally invasive treatment that can be very effective for some children with cardiomyopathy due to arrhythmia. A small, needle-like probe is inserted into the scarred tissue of the heart muscle, sending out radiofrequency waves that burns away the scar tissue and the arrhythmia.

Surgical removal of some heart muscle

In serious cases of hypertrophic cardiomyopathy, the treatment team may perform a surgery called a septal myectomy or septal myomectomy. This procedure involves the removal of a portion of the thickened muscle in the heart, widening the channel in the heart's ventricle that leads to the aortic valve. The procedure has a very good success rate, and most children have improved blood flow throughout the heart and body.

Ventricular assist device

In certain types of cardiomyopathy, a ventricular-assist device (VAD) can be used to help recover the heart and normalize the heart’s function. After the heart’s function has returned to normal, the VAD will be removed and the child will be monitored for any further heart problems. This approach using the VAD is called a “bridge to recovery.”

Heart transplant

Children with the most severe cases of cardiomyopathy may need a heart transplant if other methods don’t manage symptoms. While your child is waiting for an available heart, a VAD may be used to support the heart. In many cases, children can return to school and other activities while waiting for a transplant.

How we care for cardiomyopathy

At the Boston Children’s Hospital Cardiomyopathy Program, our cardiologists, cardiac surgeons, and nurses, cardiac imaging professionals, and other clinicians have years of expertise in treating not only the multiple forms of cardiomyopathy in children, but also the various stages of the disease.

Cardiomyopathy | Programs & Services