Myocarditis

Date Updated: 11/30/2021

Overview

Myocarditis is an inflammation of the heart muscle (myocardium). The inflammation can reduce the heart's ability to pump and cause rapid or irregular heart rhythms (arrhythmias).

Infection with a virus usually causes myocarditis. Sometimes myocarditis can result from a reaction to a drug or be part of a more general inflammatory condition. Signs and symptoms of myocarditis include chest pain, fatigue, shortness of breath, and rapid or irregular heartbeats.

Severe myocarditis weakens the heart so that the rest of the body doesn't get enough blood. Clots can form in the heart, leading to a stroke or heart attack.

Treatment for myocarditis depends on the cause.

Symptoms

If you're in the early stages of myocarditis, you might have mild symptoms such as chest pain, rapid or irregular heartbeats, or shortness of breath. Some people with early-stage myocarditis don't have any symptoms.

The signs and symptoms of myocarditis vary, depending on the cause of the disease. Common myocarditis signs and symptoms include:

Chest pain
Rapid or irregular heartbeat (arrhythmias)
Shortness of breath, at rest or during activity
Fluid buildup with swelling of the legs, ankles and feet
Fatigue
Other signs and symptoms of a viral infection such as a headache, body aches, joint pain, fever, a sore throat or diarrhea

Sometimes, myocarditis symptoms may be similar to a heart attack. If you are having unexplained chest pain and shortness of breath, seek emergency medical help.

Myocarditis in children

When children develop myocarditis, they might have signs and symptoms including:

Fever
Fainting
Breathing difficulties
Rapid breathing
Chest pain
Rapid or irregular heart rhythms (arrhythmias)

When to see a doctor

Contact your doctor if you have symptoms of myocarditis, particularly chest pain and shortness of breath. Symptoms of myocarditis can resemble a heart attack. Get emergency medical help if you have unexplained chest pain and shortness of breath.

If you've had an infection, watch for the symptoms of myocarditis and let your doctor know if they occur. If you have severe symptoms, go to the emergency room or call for emergency medical help.

Causes

Often, the cause of myocarditis isn't identified. There are many potential causes but the risk of developing myocarditis is rare.

Potential causes of myocarditis include:

Viruses. Many viruses are commonly associated with myocarditis, including the viruses that cause the common cold (adenovirus); COVID-19; hepatitis B and C; parvovirus, which causes a mild rash, usually in children (fifth disease); and herpes simplex virus.

Gastrointestinal infections (echoviruses), mononucleosis (Epstein-Barr virus) and German measles (rubella) also can cause myocarditis. It's also common in people with HIV, the virus that causes AIDS.
Bacteria. Bacteria that can cause myocarditis include staphylococcus, streptococcus, the bacterium that causes diphtheria and the tick-borne bacterium responsible for Lyme disease.
Parasites. Among these are such parasites as Trypanosoma cruzi and toxoplasma, including some that are transmitted by insects and can cause a condition called Chagas disease. Chagas disease is much more common in Central and South America than in the United States, but it can occur in travelers and in immigrants from that part of the world.
Fungi. Yeast infections, such as candida; molds, such as aspergillus; and other fungi, such as histoplasma, often found in bird droppings, can sometimes cause myocarditis, particularly in people with weakened immune systems.

Myocarditis also sometimes occurs if you're exposed to:

Medications or illegal drugs that might cause an allergic or toxic reaction. These include drugs used to treat cancer; antibiotics, such as penicillin and sulfonamide drugs; some anti-seizure medications; and some illegal substances, such as cocaine.
Chemicals or radiation. Exposure to certain chemicals, such as carbon monoxide, and radiation can sometimes cause myocarditis.
Other diseases. These include disorders such as lupus, Wegener's granulomatosis, giant cell arteritis and Takayasu's arteritis.

Complications

Usually, myocarditis goes away without permanent complications. However, severe myocarditis can permanently damage your heart muscle, possibly causing:

Heart failure. Untreated, myocarditis can damage your heart's muscle so that it can't pump blood effectively. In severe cases, myocarditis-related heart failure may require a ventricular assist device or a heart transplant.
Heart attack or stroke. If your heart's muscle is injured and can't pump blood, the blood that collects in your heart can form clots. If a clot blocks one of your heart's arteries, you can have a heart attack. If a blood clot in your heart travels to an artery leading to your brain, you can have a stroke.
Rapid or irregular heart rhythms (arrhythmias). Damage to your heart muscle can cause an arrhythmia.
Sudden cardiac death. Certain serious arrhythmias can cause your heart to stop beating (sudden cardiac arrest). It's deadly if not treated immediately.

Prevention

There's no specific prevention for myocarditis. However, taking these steps to prevent infections might help:

Avoid people who have a viral or flu-like illness until they've recovered. If you're sick with symptoms of a viral infection, try to avoid exposing others.
Follow good hygiene. Regular hand-washing can help prevent spreading illness.
Avoid risky behaviors. To reduce your chances of getting an HIV-related myocardial infection, practice safe sex and don't use illegal drugs.
Minimize exposure to ticks. If you spend time in tick-infested areas, wear long-sleeved shirts and long pants to cover as much of your skin as possible. Apply tick or insect repellents that contain DEET.
Get your vaccines. Stay up to date on the recommended vaccines, including those that protect against COVID-19, rubella and influenza — diseases that can cause myocarditis. Rarely, the COVID-19 vaccine can cause inflammation of the heart muscle (myocarditis) and inflammation of the outer heart lining (pericarditis), especially in males ages 12 through 17. Talk to your health care provider about the benefits and risks of vaccines.

Diagnosis

Early diagnosis of myocarditis is important to preventing long-term heart damage. After a physical examination, your doctor might order one or more tests to confirm that you have myocarditis and determine its severity. Tests to diagnose myocarditis might include:

Electrocardiogram (ECG or EKG). This quick and painless test shows your heart's electrical patterns and can detect irregular heartbeats.
Chest X-ray. An X-ray image shows the size and shape of your heart, as well as whether you have fluid in or around the heart that might be related to heart failure.
Heart MRI (Cardiac MRI). A cardiac MRI shows your heart's size, shape and structure. This test can show signs of inflammation of the heart muscle.
Echocardiogram. Sound waves create moving images of the beating heart. An echocardiogram can show your heart size and how well your heart is pumping. The test can also reveal valve problems, a clot within the heart or fluid around your heart.
Blood tests. Blood tests used to diagnose or confirm myocarditis include a complete blood count and a test to check the levels of certain proteins (enzymes) that signal heart muscle damage. Other blood tests can be done to determine if you have antibodies against viruses and other organisms that might cause a myocarditis-related infection.
Cardiac catheterization and heart muscle biopsy. A small tube (catheter) is inserted into a vein in your leg or neck and threaded into your heart. In some cases, doctors use a special instrument to remove a tiny sample of heart muscle tissue (biopsy) for analysis in the lab to check for inflammation or infection.

Treatment

In many people, myocarditis improves on its own or with treatment, leading to a complete recovery. Myocarditis treatment focuses on the cause and the symptoms, such as heart failure.

Medications

People with mild myocarditis may only need rest and medication.

Corticosteroids. Certain rare types of viral myocarditis, such as giant cell and eosinophilic myocarditis, may improve with corticosteroids or other medications to suppress your immune system.
Heart medications. If myocarditis is causing heart failure or arrhythmias, you may need to stay in the hospital. Your doctor will prescribe drugs or other treatments, depending on your signs and symptoms. For example, if you have certain irregular heart rhythms or severe heart failure, you may be given medications to reduce the risk of blood clots forming in your heart.

If your heart is weak, your doctor might prescribe blood pressure medications to reduce the strain on your heart or help your body remove excess fluid. These medications may include diuretics, beta blockers, angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs).
Medications to treat chronic conditions. If myocarditis is caused by a chronic illnesses, such as lupus, treatment is directed at the underlying disease.

Surgeries and procedures

If you have severe myocarditis, you will need aggressive treatment, which might include:

IV medications. Medications given through a vein are used to quickly improve your heart's ability to pump.
Ventricular assist devices (VAD). A VAD is a device that helps pump blood from the lower chambers of your heart (the ventricles) to the rest of your body. VADs are used in people who have weakened hearts or heart failure. This treatment may be used to allow your heart to recover or while you're waiting for other treatments, such as a heart transplant.
Intra-aortic balloon pump. The doctor inserts a thin tube (catheter) into a blood vessel in your leg and guides it to your heart using X-ray imaging. A balloon attached to the end of the catheter inflates and deflates in the main artery leading out to the body from the heart (aorta). An intra-aortic pump helps increase blood flow and decrease the strain on your heart.
Extracorporeal membrane oxygenation (ECMO). An ECHO machine mimics the function of the lungs. It removes carbon dioxide and adds oxygen to the blood. If you have severe heart failure, this device can provide oxygen to your body. During ECMO, blood is removed from the body, passed through the ECMO machine and then returned to the body.

The ECMO machine takes over the work of your heart. This treatment may be used to allow the heart to recover or while waiting for other treatments, such as a heart transplant.
Heart transplant. If you have very severe myocarditis, your doctor might recommend urgent heart transplantation.

Some people with myocarditis might have chronic and irreversible damage to the heart muscle requiring lifelong medications, while other people need medications for just a few months and then recover completely. Either way, your doctor is likely to recommend regular follow-up appointments, including tests to evaluate your condition.

Lifestyle and home remedies

Rest and reducing the workload on your heart is an important part of recovery. Your doctor will likely tell you what type of physical activity you can do during the months your heart is healing and when you can resume regular activities.

If you have myocarditis, you should avoid competitive sports for at least 3 to 6 months.

If you have lingering heart damage, it's important to:

Limit salt
Restrict the amount of fluids you drink (your doctor will tell you what your fluid intake should be)
Avoid or drink only a minimum amount of alcohol
Avoid smoking.

Preparing for an appointment

You're likely to start by seeing your primary care doctor. If you have severe symptoms, you might see an emergency room doctor. You'll likely be referred to a doctor trained in heart conditions (cardiologist) and possibly a doctor trained in infectious disease.

What you can do

Here's some information to help you get ready for your appointment. Write down the following details:

Your symptoms, including any that might seem unrelated to the reason for which you scheduled the appointment, and when they began
Key personal information, including recent illnesses and their symptoms, recent travel locations, and your and your family's medical history
All medications, vitamins or other supplements you take, including doses
Questions to ask your doctor

For myocarditis, basic questions to ask your doctor include:

What's the most likely cause of my symptoms?
What are other possible causes?
What tests do I need?
How is myocarditis treated?
What side effects can I expect from treatment?
Are there alternatives to the primary approach you're suggesting?
I have other health conditions. How can I best manage these conditions together?
Do I need to restrict my activities?
Are there brochures or other printed material I can have? What websites do you recommend?

Don't hesitate to ask other questions. Take a family member or friend along to your appointment, if possible, to help you remember the information you'll receive.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, including:

Have you recently been sick or have you recovered from another illness?
Have you traveled out of the country recently?
Does anything seem to improve your symptoms?
What, if anything, makes your symptoms worse?