DMD and the heart

Last updated March 3, 2025, by Lindsey Shapiro, PhD
Fact-checked by Patrícia Silva, PhD

The heart is made mostly of muscle, which is why almost all people with Duchenne muscular dystrophy (DMD) — a genetic disease that causes progressive weakness and wasting in muscles throughout the body — will develop heart problems by the time they reach adulthood.

Knowing that you are going to eventually be dealing with heart issues can add to the stress of living with DMD. While there’s no way to completely prevent it, with the right care and management, people with DMD can live for many years with heart disease.

To protect your heart health, it’s critical to see a cardiologist at least every year after diagnosis so your doctor can monitor and promptly treat any problems. Similar to the general recommendations for most people, making healthy lifestyle adaptations, such as eating a healthy diet and getting appropriate exercise, can help keep the heart healthy and delay having more serious complications.

How DMD affects the heart

DMD is the most common form of muscular dystrophy. It is caused by mutations in the DMD gene, which is responsible for the production of the dystrophin protein. Dystrophin helps protect muscles against damage due to wear and tear due to repeated contractions over time. DMD-causing mutations usually lead to basically not having dystrophin, which is the reason for DMD symptoms of progressive muscle weakness and degeneration.

The heart is primarily made of a specialized muscle tissue called the myocardium, or cardiac muscle. This is what enables the cardiac contractions — known more simply as heartbeats — that pump blood through the body.

As with other types of muscle cells, not having dystrophin in DMD makes cardiac muscle cells more vulnerable to damage. It ultimately weakens the myocardium over time, compromising its ability to pump blood. Heart cells die off and are replaced by scar tissue, known as fibrosis, and fat.

Nearly all people with DMD develop some degree of cardiomyopathy, or heart muscle disease, by the time they are adults. Heart issues are often first seen during adolescence but can appear at any time, including in children younger than 10.

Having significant cardiac issues predicts worse outcomes for people with DMD. While lung disease used to be the leading cause of death, it’s now cardiovascular disease. This is due to improvements in respiratory care, and because more people with DMD are living into adulthood.

Women and girls who carry DMD-causing mutations but who don’t have the disease may also be at risk of developing heart problems. It’s estimated that as many as 50% of carriers will develop cardiac issues.

Common heart issues for people with DMD

People with DMD can experience a range of different heart issues throughout their lives, typically starting with dilated cardiomyopathy, where the heart’s chambers become enlarged and weakened, which impairs the heart’s ability to effectively pump blood. Much like other symptoms, DMD heart problems are generally progressive, with worsening cardiomyopathy leading to other cardiac problems over time. Though DMD carrier heart problems are usually more mild than those of patients, they can range in severity.

Dilated cardiomyopathy

The main heart problem experienced in DMD is dilated cardiomyopathy. It occurs when the heart muscle stretches, becoming thinner and weaker than usual, and the heart’s chambers — especially its main pumping chamber, the left ventricle — become enlarged.

Muscle tissue on the walls of the left ventricle is increasingly replaced by widespread scar tissue — a condition medically known as myocardial fibrosis — which makes dilated cardiomyopathy worse. Ultimately, it becomes harder and harder for the heart to pump out blood with as much force as is needed.

The age at which people with DMD are diagnosed with cardiomyopathy can vary substantially, but for many people with DMD signs of the heart disease start during adolescence. Worsening cardiomyopathy is usually what leads to other cardiac manifestations of DMD, such as arrhythmias and heart failure.

Arrhythmias (irregular heart rhythms)

As cardiomyopathy progresses, people may develop arrhythmias, or irregular heart rhythms that can manifest as a heart rate that’s too slow, too fast, or inconsistent.

There are various types of arrhythmias a person with DMD might experience, which can affect the lower chambers of the heart (ventricular arrhythmia) or upper chambers of the heart (atrial arrhythmia). Depending on the type, arrhythmias can feel like a fluttering or racing heart, or a feeling like the heart has skipped a beat. The most common type of arrhythmia that occurs in DMD is sinus tachycardia, which is when the heart beats faster than normal.

Not all arrhythmias cause significant problems, but some, especially ventricular arrhythmias, can lead to life-threatening consequences such as cardiac arrest — when the heart suddenly stops beating — if a more regular heartbeat is not restored quickly.

Heart failure

For many people with DMD, progressing cardiomyopathy eventually leads to heart failure, where the heart muscle has weakened so substantially it can no longer pump enough blood to effectively meet the body’s demands.

Cardiomyopathy that develops into heart failure is a leading cause of death in DMD. Cardiac treatment in DMD generally tries to delay the progression of cardiomyopathy to heart failure.

Warning signs and symptoms

People with DMD often don’t have any obvious signs of heart disease or have symptoms that are very subtle. In fact, heart disease is usually first discovered after a cardiologist runs a test. Because some of the classic signs of heart failure are most noticeable during physical activity, it’s not surprising that it can go undiagnosed in people with DMD, who may have limited mobility and may not be able to walk.

Some possible warning signs of heart disease in DMD may include:

• feeling more tired than usual
• weight loss
• abdominal pain
• appetite loss or vomiting
• trouble sleeping
• difficulties doing normal daily activities
• shortness of breath during exercise
• chronic cough. 

As heart failure progresses, it may cause additional symptoms, such as:

• shortness of breath when sitting still or lying down
• weight gain or swelling in the feet, ankles, legs, or torso
• fainting spells
• irregular heartbeats or heart palpitations.

Reach out to your cardiologist if you notice any possible symptoms of a heart problem. Your doctor will be able to run tests to look for signs that heart disease is getting worse or heart failure is developing.

Diagnosing heart problems

It is recommended that people with DMD see a cardiologist as soon as they’re diagnosed with the condition, and then once a year regardless of whether there are, as yet, any signs of heart problems. If there are issues with your heart, you may need to see a cardiologist more often. It’s also recommended that female carriers of DMD mutations be evaluated by a cardiologist every 3-5 years starting in their late teens or early 20’s.

A cardiologist has a number of ways to monitor heart function:

• An electrocardiogram, also known as an ECG or EKG, records the electrical activity of the heart to identify changes in heart rate or rhythm. It is often used to diagnose arrhythmias, previous heart attacks, and other issues. 
• An echocardiogram, often called an echo, is a type of ultrasound that uses sound waves to create pictures of the heart. It shows doctors how well the heart is pumping blood, and can help diagnose heart failure or heart valve problems, among other issues.
• Cardiac MRI uses magnets and radio waves to create more detailed images of the heart. It can help diagnose a variety of cardiac problems, including the presence of fibrosis. A doctor might order it if other tests show cause for concern and a more detailed look at the heart is needed.

In some cases, a doctor might want to monitor a person’s heart activity when the individual is at home. To do that, the clinician might recommend a Holter monitor, which is essentially a tiny wearable EKG that’s worn for 24 hours a day. The monitor will collect data about heart rate and rhythm while you go about your regular life.

Treatment

As of now, there isn’t a way to completely prevent cardiomyopathy in DMD. But treatments similar to the ones used for managing heart failure in the general population can help delay cardiac declines.

It is recommended that people with DMD start on heart medications at the first sign that there’s an issue, or by age 10, even if cardiac tests are still normal. This is because it’s practically certain that all individuals with DMD will develop heart disease at some point. Medications can help slow heart disease progression and prevent DMD heart failure.

Angiotensin-converting enzyme (ACE) inhibitors, which help lower blood pressure and make it easier for the heart to pump blood, are generally the first-line treatment for managing DMD heart problems. A related class of medications called angiotensin receptor blockers can also be used if ACE inhibitors are not well tolerated.

Other medications that can help manage heart issues in DMD include:

• beta blockers, which help the heart beat more slowly
• diuretics, including mineralocorticoid blockers, which remove extra water from the body to lower the volume of blood the heart has to pump.

DMD treatment generally involves corticosteroids that are started early in life to help slow the loss of muscle function. These medications may also help protect the heart muscle. However, corticosteroids cause changes in weight and blood pressure that have a negative effect on heart function. Your doctor can track how you’re responding to corticosteroids and if any changes need to be made to support heart health.

As heart disease progresses, more invasive approaches might be required to keep the heart functioning:

• A pacemaker is a small device, implanted under the skin of the chest, that sends electrical pulses to help the heart beat at a normal rate and rhythm.
• An implantable cardioverter defibrillator, or ICD, is also implanted under the skin and monitors the heart’s rhythm. If it detects an irregular or problematic rhythm, it will send an electrical shock to the heart to reset it.
• A ventricular assist device, or VAD, may be considered to treat severe heart failure. It works as a pump to help the heart send blood to the rest of the body when it cannot do so on its own.

While a heart transplant may be an option in cases of severe heart failure, this procedure historically has been rarely considered for people with DMD due to the high risk of complications.

Prevention and healthy lifestyle changes

While you can’t entirely stop DMD heart problems, making healthy lifestyle changes under the supervision of your doctors can help protect the heart and delay potential heart failure. Lifestyle factors recommended for heart health in DMD are similar to ones that would be recommended for all people. Among the tips for health heart in DMD:

• Maintain a healthy diet that’s low in saturated fats, sodium (salt), and sugary or processed foods, but high in healthy fats, fruits and veggies, lean proteins, and whole grains.
• Avoid smoking and alcohol.
• Manage stress as well as possible.
• Exercise regularly and moderately within your physical limits.

Importantly, while exercise is helpful to keep the heart strong, it’s also key not to overexert yourself. A physical therapist can help come up with an appropriate exercise plan that’s safest in your case.

It’s also important to take any heart medications exactly as prescribed by your doctor and to make sure you have regular check-ups with a cardiologist to monitor your cardiac health. Always talk with your healthcare team before making any substantial lifestyle changes, as they’ll be able to guide you in the safest and most effective ways to protect your heart and improve your overall outlook.

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