What is an enlarged heart?

An enlarged heart (cardiomegaly) means that your heart is bigger than normal. Your heart can become enlarged if the muscle works so hard that it thickens, or if the chambers widen.

An enlarged heart isn’t a disease. It’s a symptom of a heart defect or condition that makes the heart work harder, such as cardiomyopathy, heart valve problems, or high blood pressure.

An enlarged heart can’t pump blood as efficiently as a heart that’s not enlarged. This can lead to complications like stroke and heart failure.

Sometimes an enlarged heart doesn’t cause any symptoms. When symptoms do occur, they can include:

  • shortness of breath
  • an irregular heart rhythm (arrhythmia)
  • swelling in the legs and ankles caused by fluid buildup (edema)
  • fatigue
  • dizziness

Symptoms that indicate a medical emergency include:

  • chest pain
  • trouble catching your breath
  • pain in your arms, back, neck, or jaw
  • fainting

Your heart can enlarge because of a condition you’re born with — congenital — or a heart problem that develops over time.

Any disease that makes your heart work harder to pump blood through your body can cause an enlarged heart. Just as the muscles of your arms and legs get bigger when you work them, your heart gets bigger when you work it.

The most common causes of an enlarged heart are ischemic heart disease and high blood pressure. Ischemic heart disease occurs when narrowed arteries, caused by fatty deposits that build up in your arteries, prevent blood from getting to your heart.

Other conditions that can make your heart enlarge include:


Cardiomyopathy is a progressive heart disease with several types. Diseases that damage the heart muscle can cause it to enlarge. The more damage that occurs, the weaker and less able to pump the heart becomes.

Heart valve disease

Infections, connective tissue diseases, and some medications can damage the valves that keep blood flowing in the right direction through your heart. When blood flows backwards, the heart has to work harder to push it out.

Heart attack

During a heart attack, blood flow to part of the heart is blocked completely. The lack of oxygen-rich blood damages the heart muscle.

Thyroid disease

The thyroid gland produces hormones that regulate the body’s metabolism. Both overproduction (hyperthyroidism) and underproduction (hypothyroidism) of these hormones can affect the heart rate, blood pressure, and size of the heart.

Irregular heart rhythm (arrhythmia)

If you have an irregular heartbeat, instead of beating in its familiar lub-dub pattern, the heart flutters or beats too slowly or quickly. An irregular heart rhythm can cause blood to back up in the heart and eventually damage the muscle.

Congenital conditions

Congenital cardiomegaly is a heart disorder you’re born with. Congenital heart defects that cause this symptom include:

Other possible causes of an enlarged heart include:

You’re more likely to get cardiomegaly if you’re at risk for heart diseases. Risk factors include:

  • high blood pressure
  • obesity
  • sedentary lifestyle
  • parent or sibling with an enlarged heart
  • past heart attack
  • metabolic disorders, like thyroid disease
  • heavy or excessive drug or alcohol use

Your doctor will start with a physical exam and a discussion of your symptoms. A number of different tests can check the structure and function of your heart. A chest X-ray may be the first test your doctor does because it can show whether your heart is enlarged.

Tests like these can help your doctor find the cause of the enlargement:

  • Echocardiogram (ECG or EKG) uses sound waves to look for problems with your heart’s chambers.
  • Electrocardiogram monitors the electrical activity in your heart. It can diagnose an irregular heart rhythm and ischemia.
  • Blood tests check for substances in your blood produced by conditions that cause an enlarged heart, like thyroid disease.
  • A stress test involves walking on a treadmill or pedaling a stationary bike while your heart rhythm and breathing are monitored. It can show how hard your heart is working during exercise.
  • Computerized tomography (CT) scans use X-rays to produce detailed images of your heart and other structures in your chest. It can help diagnose valve disease or inflammation.
  • Magnetic resonance imaging (MRI) uses strong magnets and radio waves to produce pictures of your heart.

In pregnancy

During pregnancy, doctors can use a test called a fetal echocardiogram to diagnose heart defects in the unborn baby. This test uses sound waves to create pictures of the baby’s heart.

Your doctor might recommend a fetal echocardiogram if you have a family history of cardiomegaly or heart defects, or if your baby has a genetic disorder like Down syndrome.

Your doctor will prescribe a treatment plan for the condition that’s causing your enlarged heart. For example:

Other procedures can fix congenital heart defects. If you try a few treatments and they don’t work, you may need a heart transplant.

Lifestyle changes

You can manage an enlarged heart with lifestyle changes like these:

  • Exercise. Exercise on most days of the week. Ask your doctor which types of exercises are safest for you.
  • Quit smoking. Methods like nicotine replacement products and therapy can help you stop.
  • Lose weight. Losing weight, especially if you’re overweight, can help.
  • Limit certain foods. Limit salt, cholesterol, and saturated and trans fats in your diet.
  • Avoid certain things. Avoid alcohol, caffeine, and drugs like cocaine.
  • Relax. Practice relaxation techniques like meditation or yoga to reduce stress.

The conditions that cause cardiomegaly can damage the heart muscle. They can lead to complications if left untreated. This includes:

  • Heart failure. When the left ventricle enlarges, it can lead to heart failure. Then the heart isn’t able to pump enough blood to the body.
  • Blood clots. When the heart doesn’t pump as well as it should, blood can pool and clump together into clots. A blood clot can travel to the brain and get stuck in a blood vessel there, causing a stroke.
  • Heart murmur. When valves in your heart don’t close properly, they create an abnormal sound called a murmur.
  • Cardiac arrest. If your heart is enlarged, it may not get enough blood which can lead to cardiac arrest. The heart can stop working properly, which can cause sudden death.

You may not be able to prevent conditions that occur before birth. Yet you can prevent later damage to your heart that can make it enlarge by:

You should also see your doctor for regular checkups to make sure your heart is healthy. If you have a heart problem, you might also need to see a cardiologist.

Your outlook depends on the underlying cause of your enlarged heart. Following the treatment plan your doctor recommends can help keep your heart healthy and prevent any complications.