An enlarged heart (cardiomegaly) isn't a disease, but rather a sign of another condition.

The term "cardiomegaly" refers to an enlarged heart seen on any imaging test, including a chest X-ray. Other tests are then needed to diagnose the condition that's causing the enlarged heart.

An enlarged heart

Enlarged heart, in heart failure

If the heart weakens, as it can with heart failure, it begins to enlarge. This forces the heart to work harder to pump blood to the rest of the body.

Heart damage and certain types of heart disease can cause an enlarged heart. Sometimes short-term stress on the body, such as pregnancy, can cause the heart to get larger. Depending on the condition, an enlarged heart may be temporary or permanent.

Treatment for an enlarged heart may include medications, medical procedures or surgery.


In some people, an enlarged heart (cardiomegaly) causes no signs or symptoms. Others may have these signs and symptoms of cardiomegaly:

  • Shortness of breath, especially while lying flat
  • Waking up short of breath
  • Irregular heart rhythm (arrhythmia)
  • Swelling (edema) in the belly or in the legs

When to see a doctor

An enlarged heart may be easier to treat when it's detected early. Talk to your health care provider if you have concerns about your heart.

Call 911 or your local emergency number if you have signs and symptoms of a potential heart attack:

  • Chest pain
  • Discomfort in other areas of the upper body, including one or both arms, the back, neck, jaw, or stomach
  • Severe shortness of breath
  • Fainting


An enlarged heart (cardiomegaly) can be caused by damage to the heart muscle or any condition that makes the heart pump harder than usual, including pregnancy. Sometimes the heart gets larger and becomes weak for unknown reasons. This condition is called idiopathic cardiomyopathy.

Conditions associated with an enlarged heart include:

  • Heart condition present at birth (congenital heart defect). Problems with the structure and function of the heart can cause the heart muscle to get larger and weak.
  • Damage from a heart attack. Scarring and other structural heart damage can make it harder for the heart to pump enough blood to the body. The strain can lead to heart swelling and eventual heart failure.
  • Diseases of the heart muscle (cardiomyopathy). Cardiomyopathy often makes the heart rigid or thick. It can make it harder for the heart to pump blood.
  • Fluid buildup in the sac around the heart (pericardial effusion). A collection of fluid in the sac that contains the heart can cause heart enlargement that can be seen on a chest X-ray.
  • Heart valve disease. Four valves in the heart keep blood flowing in the right direction. Disease or damage to any of the valves may interrupt blood flow and cause the heart chambers to get larger.
  • High blood pressure (hypertension). If you have high blood pressure, the heart may have to pump harder to deliver blood to the rest of the body. The strain can cause the heart muscle to grow larger and become weak.
  • High blood pressure in the arteries in the lungs (pulmonary hypertension). The heart has to work harder to move blood between the lungs and the heart. The strain may lead to thickening or enlargement of the right side of the heart.
  • Low red blood cell count (anemia). In anemia, there's a lack of healthy red blood cells to carry proper levels of oxygen to the body's tissues. The heart must pump more blood to make up for the lack of oxygen in the blood.
  • Thyroid disorders. Both an underactive thyroid gland (hypothyroidism) and an overactive thyroid gland (hyperthyroidism) can lead to heart problems, including an enlarged heart.
  • Too much iron in the body (hemochromatosis). Iron can build up in various organs, including the heart. This can cause the lower left heart chamber to swell.
  • Unusual protein deposits in the heart (cardiac amyloidosis). This rare disease causes a protein called amyloid to collect in the blood and get stuck in body organs, including the heart. Amyloid protein deposits in the heart cause an irreversible thickening of the heart wall. The heart has to work harder to fill with blood.
  • Aerobic exercise. In some athletes, the heart becomes enlarged as a response to frequent and prolonged exercise. Usually, this type of enlarged heart isn't considered a disease and doesn't need treatment.
  • Fat around the heart. Some people have extra fat around the heart that can appear on a chest X-ray. Unless there are other heart conditions associated, no treatment is necessary.

Risk factors

Things that can increase the risk of an enlarged heart (cardiomegaly) include:

  • A family history of heart muscle disease (cardiomyopathy). Some types of cardiomyopathy run in families. Tell your health care provider if a parent or sibling has a history of a thick, rigid or enlarged heart.
  • High blood pressure. This means having a blood pressure measurement higher than 140/90 millimeters of mercury.
  • Heart diseases. Any problem affecting the heart, including congenital heart defects or heart valve disease, may lead to heart enlargement. It's important to follow a healthy lifestyle and have regular health checkups to manage heart disease.


The risk of complications from an enlarged heart depends on the part of the heart affected and the cause. Complications of an enlarged heart can include:

  • Heart failure. Heart failure may occur if the left lower heart chamber (left ventricle) becomes enlarged. In heart failure, the heart can't pump the proper amount of blood throughout the body.
  • Blood clots. Blood clots may form in the lining of the heart. A blood clot that forms on the right side of the heart can travel to the lungs (pulmonary embolism). If a clot blocks blood flow, you could have a heart attack or stroke.
  • Leaky heart valve (regurgitation). Heart enlargement may prevent the mitral and tricuspid heart valves from closing, causing blood to leak backward. The interrupted blood flow creates a sound called a heart murmur. Although not necessarily harmful, heart murmurs should be monitored by a health care provider.
  • Cardiac arrest and sudden death. An enlarged heart may cause the heart to beat too fast or too slow. The irregular heartbeat (arrhythmia) may lead to fainting, cardiac arrest or sudden death.


Tell your health care provider if anyone in your family has or had cardiomyopathy or other health conditions that caused an enlarged heart. When diagnosed early, proper treatment of the underlying condition may prevent the enlarged heart from getting worse.

Following a heart-healthy lifestyle can help prevent or manage some conditions that can lead to an enlarged heart. Take these steps to help prevent an enlarged heart:

  • Monitor and manage high blood pressure, high cholesterol and diabetes.
  • Take any prescribed medications as directed.
  • Eat a nutritious, balanced diet.
  • Get regular exercise.
  • Avoid or limit alcohol.
  • Don't smoke.
  • Don't use illegal drugs.

May 04, 2022

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