Myocarditis

What is myocarditis?

Myocarditis is inflammation of your heart muscle (myocardium). This can weaken your heart muscle, making it more difficult for your heart to pump. This rare condition can affect people quickly or slowly over time.

Myocarditis is different from other types of inflammation because each kind happens in a different part of your heart. Pericarditis affects the sac around your heart. Endocarditis is an infection or inflammation of your heart valves.

Rare types of myocarditis include:

• Lymphocytic myocarditis.
• Giant cell myocarditis.
• Fulminant myocarditis.
• Eosinophilic myocarditis.

What does myocarditis feel like?

People with myocarditis often feel fatigued, short of breath, chest pain or the sensation of their heart racing (palpitations). They may feel these symptoms gradually over time, or their symptoms may happen very quickly. People with myocarditis in more advanced stages may show symptoms of heart failure.

How common is myocarditis?

Researchers estimate there are about 1.5 million cases of myocarditis in the world each year. This works out to 10 to 20 people affected out of every 100,000 people.

What are the symptoms of myocarditis?

You may have no symptoms, few symptoms or many symptoms, and they may be more severe in some people than in others. Myocarditis symptoms include:

• Shortness of breath.
• Tiredness.
• Fever.
• Chest pain.
• Heart palpitations.
• Pain in your abdomen.
• Lightheadedness.
• Abnormal heart rhythm.
• Fainting.
• No appetite.
• Feeling weak.
• Swollen legs or feet.
• Being unable to exercise.

What causes myocarditis?

Many times, the cause of myocarditis is unknown. Most often, the cause is a viral infection. These include:

• Flu.
• Herpes virus six.
• Adenovirus.
• Coxsackie virus.
• Parvovirus B19.
• SARS-CoV-2 (COVID-19).

Other causes of myocarditis include:

• Bacteria.
• Fungi (rarely).
• Chagas disease.
• Rheumatic fever.
• Autoimmune diseases like rheumatoid arthritis or lupus.
• Things you’re exposed to, such as radiation or heavy metals.

Side effects from some medicines can bring about myocarditis. These medicines include:

• Medicines for your heart.
• Antidepressants.
• Medicines for seizures.
• Antibiotics.
• Medicines for weight loss.
• Diuretics.
• Benzodiazepines.
• Medicines for psychiatric problems.

Myocarditis and the COVID-19 vaccine

In rare cases, myocarditis has happened in young people who received the Pfizer-BioNTech® or Moderna® vaccines for COVID-19. Symptoms can start during the first week after receiving the vaccine. Most people who have this reaction to the COVID-19 vaccine recover quickly after treatment and can get back to their regular activities when they feel better. However, if you’ve had myocarditis, you should check with a cardiologist before exercising again.

The CDC considers COVID-19 a greater risk than the risk of rare side effects of the vaccine. They recommend the vaccines for young people.

Who is at risk for myocarditis?

Some of the things that put you at risk for myocarditis can’t be changed. You’re more likely to get myocarditis if:

• You’re a young adult. However, people of all ages can get it.
• You’re a man or assigned male at birth (AMAB). But women and people assigned female at birth (AFAB) can get it, too.
• Your body doesn’t react well to inflammation. Although you don’t inherit myocarditis, your genes influence how your body handles inflammation and how likely you are to get myocarditis.
• You drink more alcohol than the limit your healthcare provider gives you.

Some medical treatments increase your risk of myocarditis. These include:

• Dialysis.
• Implanted heart devices.
• Radiation.
• Treatments for heart problems.
• Having a central venous line.

Having one of these medical problems can put you at a higher risk of getting myocarditis:

• Diabetes.
• HIV/AIDS.
• Skin injuries or infections.
• Cancer treated with certain medicines.
• Eating disorders.
• End-stage kidney disease.
• A chest injury.

What are the possible complications of myocarditis?

In some people, myocarditis can bring on other issues, such as:

• Cardiomyopathy.
• Lung issues.
• Arrhythmia.
• Fainting.
• Heart failure.
• Cardiogenic shock.
• Sudden cardiac death.

How is myocarditis diagnosed?

Your healthcare provider will use the following to diagnose myocarditis:

• Physical exam.
• Medical history.
• Tests.

What tests will be done to diagnose myocarditis?

Your healthcare provider may order tests to help them decide if you have myocarditis or something else.

These tests include:

• MRI (magnetic resonance imaging).
• Heart biopsy.
• PET (positron emission tomography) scan.
• Chest X-ray.
• Cardiac catheterization.
• ECG/EKG (Electrocardiogram).
• Echocardiogram.
• Blood tests.

Does myocarditis go away?

If you have a mild case, it may go away on its own. If not, your provider can order medicines for you.

What is the treatment for myocarditis?

To treat myocarditis, your healthcare provider may want you to take medication. These include:

• Medicines for heart failure.
• Corticosteroids.
• Intravenous (IV) immunoglobulin.

If your myocarditis led to heart failure or an abnormal heart rhythm and your case is serious, you may need surgery to implant a:

• LVAD (left ventricular assist device).
• Pacemaker.
• Donor heart.

How can I reduce my risk?

Unfortunately, it’s very hard to avoid many of the things that cause myocarditis. Your best bet is to wash your hands often and stay healthy to keep from getting infections that can bring about myocarditis. It’s also important to stay up to date on the flu vaccine. Limiting your alcohol intake and not taking prohibited drugs are other risk factors you can manage.

What is my prognosis with myocarditis?

Many people can live for years without problems after myocarditis treatment. Other people may need to keep taking medication. There’s a small risk of myocarditis happening again.

For some people, myocarditis can lead to dilated cardiomyopathy and they may need a heart transplant. Almost 20% of sudden deaths in young people have a connection to myocarditis.

The survival rate for myocarditis is 80% one year after having it and 50% five years later.

How do I take care of myself with myocarditis?

Once you’ve had myocarditis, you can get it again years later. Tell your provider if you get symptoms again. For your best chance of staying healthy:

• Be sure to keep your follow-up appointments with your provider.
• Keep taking prescribed medicines.
• Don’t exercise until your provider says you can.
• Limit salt in your diet.
• Stop using tobacco products.
• Don't drink alcohol.

Also, they may want to repeat some tests used for diagnosis. These include:

• Echocardiogram.
• MRI (magnetic resonance imaging).

What questions should I ask my doctor?

• What caused my myocarditis?
• Will I need treatment for my myocarditis?
• What can I do to stay healthy?

A note from Cleveland Clinic

Myocarditis is a rare condition that can weaken your heart muscle. Unfortunately, there are many causes of myocarditis that are hard to avoid. While symptoms can be severe in some people, many people can live for years without myocarditis becoming a problem again after treatment. The best thing you can do is keep your follow-up appointments with your provider, keep taking the medicines they prescribed for you and let them know if you get symptoms again.