Age, gender, and body size can affect the size of the left atrium, but several medical conditions can also be responsible.

The left atrium is one of the four chambers of the heart. It’s located in the upper half of the heart and on the left side of your body.

The left atrium receives newly oxygenated blood from your lungs. It then pumps this blood into the left ventricle through the mitral valve. From the left ventricle, the oxygen-rich blood is pumped out through the aortic valve to be distributed to the tissues of your body via your circulatory system.

In some cases, the left atrium can become enlarged. Read on to find out why this happens and what the possible complications are.

Some people with an enlarged left atrium may not experience any symptoms. If you do experience symptoms, they may include:

Your doctor can diagnose enlargement of the left atrium using an imaging method called echocardiography. An echocardiogram uses sound waves to take pictures of the structure of your heart.

During an echocardiogram, you lie on a table while the doctor places small electrodes onto your chest. The doctor then passes a probe across your chest. The probe produces sound waves that bounce off of your heart and then return to the probe. The information returned to the probe is then turned into images that are displayed on a screen in the room.

CT and MRI scans can also be used for diagnosis of left atrial enlargement.

The following factors can influence the size of the left atrium:

  • Age. It’s important to note that normal aging itself isn’t a cause. Instead, changes that occur to your body as you age can influence the size of the left atrium.
  • Gender. Men typically have a larger left atrium than women.
  • Body size. The size of the left atrium increases with body size.

The following conditions can lead to the enlargement of the left atrium:

Hypertension (high blood pressure)

Left atrial enlargement is often present in people with high blood pressure. A review of 15 studies over the last 12 years found that left atrial enlargement is present in 16 to 83 percent of people with either treated or untreated high blood pressure. Try to incorporate these foods into your diet if you have hypertension.

Dysfunction of the mitral valve

A few conditions involving the mitral valve can lead to left atrial enlargement. The mitral valve connects the left atrium to the left ventricle.

In mitral stenosis, the mitral valve is narrowed. This makes it difficult for the left ventricle to be filled.

In mitral regurgitation, blood leaks out of the left ventricle and backward into the left atrium. This condition can be caused by either structural or functional issues with the mitral valve or the left ventricle.

In both mitral stenosis and mitral regurgitation, it’s more difficult for the left atrium to pump blood into the left ventricle. This can lead to an increase in pressure in the left atrium, which in turn leads to enlargement.

Dysfunction of the left ventricle

If there’s a problem with your left ventricle, the pressure in the left atrium will increase in order to be able to fill the left ventricle properly. This increase in pressure can lead to enlargement of the left atrium. In this case, the amount of enlargement in the left atrium can reveal the level of dysfunction of the left ventricle.

Atrial fibrillation

This is an arrhythmia (irregular heartbeat) that increases the risk of stroke and heart failure. In this condition, the two upper chambers of your heart, or atria, beat out of sync with the two lower chambers, or ventricles. Atrial fibrillation can happen occasionally, or it can be permanent.

It’s unclear if atrial fibrillation is a cause or a complication of left atrial enlargement.

Enlargement of the left atrium has been associated with poor outcomes for the following cardiovascular conditions:

  • Atrial fibrillation. This is associated with increased mortality and has been listed as both a cause and complication of left atrial enlargement. One study found that every 5-millimeter increase in left atrium diameter increased the risk of developing atrial fibrillation by 39 percent.
  • Stroke. In a study of older people, an increase in left atrium size was found to be independently predictive of a first ischemic stroke. The risk of stroke increases if a person also has atrial fibrillation.
  • Congestive heart failure. A study of older people found that left atrium size was predictive of congestive heart failure.

Once left atrial enlargement has occurred, treatment revolves around addressing the factors that caused it.

High blood pressure can be treated in the following ways:

  • taking medications, such as beta-blockers, calcium channel blockers, alpha-beta-blockers, and diuretics
  • eating a heart-healthy diet
  • limiting salt
  • being physically active and maintaining a healthy weight
  • limiting alcohol
  • managing stress

Treatment for mitral stenosis can include:

Your doctor may recommend surgery if you have mitral regurgitation with symptoms. You may also be advised to have surgery if you don’t have symptoms but there’s evidence of left ventricle dysfunction.

There are many possible treatments for atrial fibrillation. Some of these can include:

  • rhythm and rate control medications
  • anticoagulant medications to reduce the risk of blood clots
  • electrical cardioversion procedure to electrically reset the heart when medications aren’t effective
  • pulmonary vein ablation procedure when medications aren’t tolerated or effective
  • pacemaker implantation for a slow heart rate

There are ways to lower your risk of developing left atrial enlargement and its complications.


  • Keep high blood pressure and high cholesterol under control.
  • Eat heart-healthy foods.
  • Avoid using alcohol and tobacco products.
  • Maintain an active lifestyle.
  • Try to lose weight if you’re overweight.
  • Reduce stress, as this can lead to problems with heartbeat.
  • Let your doctor know if you have a family history of heart or cardiovascular conditions.
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There are many treatments for the conditions that cause left atrial enlargement. These range from medications and lifestyle changes to surgical interventions. It’s important to remember that treatment of this condition goes hand in hand with treating the conditions that caused it.

Once diagnosed with left arterial enlargement, you may be at risk for additional cardiovascular complications if you don’t take measures to keep conditions like high blood pressure and arrhythmias in control.

If you have a family history of cardiovascular disease or heart conditions, be sure to let your doctor know so that they can monitor your cardiovascular health.