Myocardial fibrosis is a condition that causes scar tissue to build up in your heart. It’s most common after a heart attack, but it can occur at other times as well.

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Myocardial fibrosis, or fibrosis of the myocardium, is the scarring of your heart muscle. Any condition that damages your heart can lead to myocardial fibrosis, but heart attacks are the leading cause.

According to the Centers for Disease Control and Prevention (CDC), about 805,000 people in the United States have a heart attack each year.

Treatment for myocardial fibrosis largely revolves around treating the underlying cause. For example, people with myocardial fibrosis caused by diabetes-induced heart failure are treated for heart failure and diabetes.

In this article, we take a deeper look at myocardial fibrosis, including the types, causes, and treatment options.

Myocardial fibrosis is scarring of the heart muscles due to a sudden or chronic heart injury. “Fibrosis” is the medical term for scarring, and “myocardial” refers to the muscle of your heart.

Producing scar tissue is your body’s way of quickly healing from an injury, but new scar tissue lacks the contractile properties of healthy heart tissue.

Myocardial fibrosis can lead to heart failure. Heart failure occurs when your heart can’t pump enough blood to meet your body’s needs.

Larger amounts of scarring are linked to an increased risk of heart failure.

What is the myocardium?

Your heart is made up of three layers of tissue known as the:

  • epicardium
  • myocardium
  • endocardium

The myocardium is the middle layer of your heart. This layer makes up the bulk of your heart tissue and contains muscle that allows your heart to contract and pump blood.

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Doctors generally divide myocardial fibrosis into two types: replacement and interstitial. Replacement fibrosis happens when scar tissue forms in response to the death of muscle cells. Interstitial fibrosis occurs when scar tissue forms in the space between muscle cells but isn’t directly related to muscle cell death.

Interstitial fibrosis can be subdivided into two other categories: reactive and infiltrative. Reactive interstitial fibrosis occurs when scar tissue forms in response to pressure or blood volume overload, and it’s seen in aging conditions such as diabetes or high blood pressure.

Infiltrative fibrosis occurs when the heart lays down proteins and a group of molecules called “glycosphingolipids.” This kind of fibrosis is seen in Anderson-Fabry disease and amyloidosis.

It’s possible to have replacement and interstitial fibrosis at the same time.

Myocardial fibrosis is the result of underlying heart disease. The loss of heart function due to scarring can lead to heart failure.

Heart failure can cause symptoms such as:

Myocardial fibrosis is caused by chronic or sudden damage to your heart. Damage may result from:

  • heart attacks
  • pressure overload
  • volume overload
  • inflammation
  • toxicity
  • genetic mutations

Myocardial infarction (heart attack)

The leading cause of myocardial fibrosis is myocardial infarction (heart attack). A heart attack occurs when part of your heart doesn’t receive adequate blood flow because of a blockage in your arteries.

The lack of blood flow leads to the death of heart cells. Fibrosis develops when scar tissue replaces dead muscle cells.

Pressure overload

Conditions that cause chronic pressure on your heart can lead to reactive myocardial fibrosis. Scar tissue forms to protect your heart from this increased pressure.

Potential causes include:

Volume overload

Myocardial fibrosis can happen because of conditions that cause an overload of blood volume, such as aortic or mitral regurgitation. These conditions develop when blood flows backward through the heart. Heart failure can also cause an overload of blood volume, which can lead to fibrosis.

Genetic conditions

Some inherited conditions that people are born with can lead to myocardial fibrosis. These conditions include:


Some medications, such as chemotherapy medications, can damage your heart and cause scar tissue to form.

Some chemicals in the environment that disrupt your hormone levels may also increase fibrosis. A 2021 study in mice found evidence that the chemical bisphenol-A (BPA) may induce myocardial fibrosis in rodents.


Some conditions that trigger inflammation can lead to the development of scar tissue formation. These conditions include:

The first test in diagnosing myocardial fibrosis is typically an echocardiogram. This test uses sound waves to capture images of your heart while it’s beating and moving blood through your body. The echocardiogram allows doctors to see how well your heart is functioning and helps them identify any damage to the muscle or valves.

If an echocardiogram shows a weakening of the muscle or other indications of fibrosis, a doctor may then order an MRI scan of your heart.

A type of MRI scan called a “cardiovascular magnetic resonance (CMR) scan” is the current imaging technique of choice for diagnosing myocardial fibrosis. A CMR uses magnetic waves and radiowaves to assess the structure of your heart and blood vessels.

Two CMR image-enhancing techniques play an important role in identifying fibrosis. Late gadolinium enhancement is a CMR method that can be used to look for replacement fibrosis. T1 mapping and extracellular volume fraction is a CMR technique that can be used to look for interstitial fibrosis.

Treatment for myocardial fibrosis largely involves treating the underlying cause. For example, heart attack treatments include:

Treatment for other heart conditions and complications may include:

While no medications specifically treat myocardial fibrosis, many people benefit from medications that treat reduced heart function and low ejection fraction. These medications typically include:

Researchers continue to examine the potential use of medications to break up scar tissue in the heart. Currently, no antifibrotic medications have been approved by the Food and Drug Administration (FDA) for use. Medications under investigation include:

  • renin-angiotensin-aldosterone system inhibitors
  • inflammatory modulators
  • transforming growth factor beta signaling inhibitors
  • matrix metalloproteinases (MMP) inhibitors
  • beta 3 adrenergic receptor modulators
  • chimeric antigen receptor (CAR) T-cell therapy

Myocardial fibrosis is a complication of many different heart conditions and can range in severity from mild to severe. The outlook for people with myocardial fibrosis tends to be better for people with minor scarring.

Research suggests that interstitial fibrosis may be reversible with early treatment, but myocardial fibrosis is a predictor of poor outlook for people with chronic heart failure.

In a 10-year study from 2018, researchers found a 27% increased risk of cardiovascular death in people who received aortic valve replacement with fibrosis compared with people without fibrosis.

Myocardial fibrosis is scarring in your heart caused by different types of heart disease. It can reduce your heart’s ability to contract properly and may lead to heart failure.

Currently, treatment for myocardial fibrosis largely revolves around treating the underlying heart disease. Researchers are investigating therapies to break up scar tissue in the heart. No medications have been FDA approved specifically for myocardial fibrosis, but some studies have found promising results.