Overview

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 heart to be enlarged.

An enlarged heart may be the result of a short-term stress on the body, such as pregnancy, or a medical condition, such as the weakening of the heart muscle, coronary artery disease, heart valve problems or abnormal heart rhythms.

Certain conditions may cause the heart muscle to become thicker or cause one of the chambers of the heart to dilate, making the heart larger. Depending on the condition, an enlarged heart may be temporary or permanent.

An enlarged heart may be treatable by correcting the cause. Treatment for an enlarged heart can include medications, medical procedures or surgery.

Symptoms

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

  • Shortness of breath
  • Abnormal heart rhythm (arrhythmia)
  • Swelling (edema)

When to see a doctor

An enlarged heart is easier to treat when it's detected early, so talk to your doctor if you have concerns about your heart.

Seek emergency medical care if you have any of these signs and symptoms, which may mean you're having a 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

If you have new signs or symptoms that might be related to your heart, make an appointment to see your doctor.

Causes

An enlarged heart can be caused by conditions that cause your heart to pump harder than usual or that damage your heart muscle. Sometimes the heart gets larger and becomes weak for unknown reasons. This is known as idiopathic cardiomegaly.

A heart condition you're born with (congenital), damage from a heart attack or an abnormal heartbeat (arrhythmia) can cause your heart to enlarge. Other conditions associated with an enlarged heart include:

  • High blood pressure. Your heart may have to pump harder to deliver blood to the rest of your body, enlarging and thickening the muscle.

    High blood pressure can cause the left ventricle to enlarge, causing the heart muscle eventually to weaken. High blood pressure may also enlarge the upper chambers of your heart.

  • Heart valve disease. Four valves in your heart keep blood flowing in the right direction. If the valves are damaged by conditions such as rheumatic fever, a heart defect, infections (infectious endocarditis), an irregular heartbeat (atrial fibrillation) connective tissue disorders, certain medications or radiation treatments for cancer, your heart may enlarge.
  • Cardiomyopathy. This disease of the heart makes it harder for your heart to pump blood throughout your body. As it progresses, your heart may enlarge to try to pump more blood.
  • High blood pressure in the artery that connects your heart and lungs (pulmonary hypertension). Your heart may need to pump harder to move blood between your lungs and your heart. As a result, the right side of your heart may enlarge.
  • Fluid around your heart (pericardial effusion). Accumulation of fluid in the sac that contains your heart may cause your heart to appear enlarged on a chest X-ray.
  • Blocked arteries in your heart (coronary artery disease). With this condition, fatty plaque in your heart arteries obstruct blood flow through your heart vessels, which can lead to a heart attack. When a section of heart muscle dies, your heart has to pump harder to get adequate blood to the rest of your body, causing it to enlarge.
  • Low red blood cell count (anemia). Anemia is a condition in which there aren't enough healthy red blood cells to carry adequate oxygen to your tissues. Untreated, chronic anemia can lead to a rapid or irregular heartbeat. Your 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.
  • Excessive iron in the body (hemochromatosis). Hemochromatosis is a disorder in which your body doesn't properly metabolize iron, causing it to build up in various organs, including your heart. This can cause an enlarged left ventricle due to weakening of the heart muscle.
  • Rare diseases that can affect your heart, such as amyloidosis. Amyloidosis is a condition in which abnormal proteins circulate in the blood and may be deposited in the heart, interfering with your heart's function and causing it to enlarge.

Risk factors

You may be at increased risk of developing an enlarged heart if you have any of the following risk factors:

  • High blood pressure. Having a blood pressure measurement higher than 140/90 millimeters of mercury.
  • A family history of enlarged hearts or cardiomyopathy. If an immediate family member, such as a parent or sibling, has had an enlarged heart, you may be more susceptible.
  • Congenital heart disease. If you're born with a condition that affects the structure of your heart, you may be at increased risk.
  • Heart valve disease. The heart has four valves — aortic, mitral, pulmonary and tricuspid — that open and close to direct blood flow through your heart. Conditions that damage the valves may cause the heart to enlarge.

Complications

The risk of complications from an enlarged heart depends on the part of the heart that is enlarged and the cause.

Complications of an enlarged heart can include:

  • Heart failure. An enlarged left ventricle, one of the most serious types of enlarged heart, increases the risk of heart failure. In heart failure, your heart muscle weakens, and the ventricles stretch (dilate) to the point that the heart can't pump blood efficiently throughout your body.
  • Blood clots. Having an enlarged heart may make you more susceptible to forming blood clots in the lining of your heart. If clots enter your bloodstream, they can block blood flow to vital organs, even causing a heart attack or stroke. Clots that develop on the right side of your heart may travel to your lungs, a dangerous condition called a pulmonary embolism.
  • Heart murmur. For people whose hearts are enlarged, two of the heart's four valves — the mitral and tricuspid valves — may not close properly because they become dilated, leading to a backflow of blood. This flow creates sounds called heart murmurs. Although not necessarily harmful, heart murmurs should be monitored by your doctor.
  • Cardiac arrest and sudden death. Sometimes an enlarged heart can lead to disruptions in your heart's beating rhythm. Heart rhythms that are too slow to move blood or too fast to allow the heart to beat properly can result in fainting or, in some cases, cardiac arrest or sudden death.

Prevention

Tell your doctor if you have a family history of conditions that can cause an enlarged heart, such as cardiomyopathy. If cardiomyopathy or other heart conditions are diagnosed early, treatments may prevent the disease from worsening.

Controlling risk factors for coronary artery disease — tobacco use, high blood pressure, high cholesterol and diabetes — helps to reduce your risk of an enlarged heart and heart failure by reducing your risk of a heart attack.

You can help reduce your chance of developing heart failure by eating a healthy diet and not abusing alcohol or using illicit drugs. Controlling high blood pressure with diet, exercise and possibly medications also prevents many people who have an enlarged heart from developing heart failure.