Myocarditis is an inflammation of the heart muscle (myocardium). Myocarditis can affect your heart muscle and your heart's electrical system, reducing your heart's ability to pump and causing rapid or abnormal heart rhythms (arrhythmias).
A viral infection usually causes myocarditis, but it can result from a reaction to a drug or be part of a more general inflammatory condition. Signs and symptoms include chest pain, fatigue, shortness of breath, and arrhythmias.
Severe myocarditis weakens your heart so that the rest of your body doesn't get enough blood. Clots can form in your heart, leading to a stroke or heart attack.
Treatment for myocarditis depends on the cause.
If you have a mild case of myocarditis or are in the early stages, you might have no symptoms or mild ones, such as chest pain or shortness of breath.
In serious cases, the signs and symptoms of myocarditis vary, depending on the cause of the disease. Common myocarditis signs and symptoms include:
Rapid or abnormal heart rhythms (arrhythmias)
Shortness of breath, at rest or during physical activity
Fluid retention with swelling of your legs, ankles and feet
Other signs and symptoms of a viral infection, such as a headache, body aches, joint pain, fever, a sore throat or diarrhea
Myocarditis in children
When children develop myocarditis, they might have signs and symptoms including:
Rapid or abnormal heart rhythms (arrhythmias)
When to see a doctor
Contact your doctor if you have symptoms of myocarditis, particularly chest pain and shortness of breath. If you've had an infection, be alert 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.
Often, the cause of myocarditis isn't identified. Potential causes are many, but the likelihood of developing myocarditis is rare. Potential causes 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. Numerous bacteria can cause myocarditis, including 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. This disease is much more prevalent 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 drugsthat 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.
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 pools 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 before becoming lodged, you can have a stroke.
Rapid or abnormal heart rhythms (arrhythmias). Damage to your heart muscle can cause arrhythmias.
Sudden cardiac death. Certain serious arrhythmias can cause your heart to stop beating (sudden cardiac arrest). It's fatal if not treated immediately.
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 viral symptoms, 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 rubella and influenza — diseases that can cause myocarditis.
Early diagnosis is key 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 might include:
Electrocardiogram (ECG). This noninvasive test shows your heart's electrical patterns and can detect abnormal rhythms.
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 indicate heart failure.
MRI. Cardiac MRI will show 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 might detect enlargement of your heart, poor pumping function, valve problems, a clot within the heart or fluid around your heart.
Blood tests. These measure white and red blood cell counts, as well as levels of certain enzymes that indicate damage to your heart muscle. Blood tests can also detect antibodies against viruses and other organisms that might indicate a myocarditis-related infection.
Cardiac catheterization and endomyocardial 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.
In many cases, 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.
In mild cases, persons should avoid competitive sports for at least three to six months. Rest and medication to help your body fight off the infection causing myocarditis might be all you need. Although antiviral medications are available, they haven't proved effective in the treatment of most cases of myocarditis.
Certain rare types of viral myocarditis, such as giant cell and eosinophilic myocarditis, respond to corticosteroids or other medications to suppress your immune system. In some cases caused by chronic illnesses, such as lupus, treatment is directed at the underlying disease.
Drugs to help your heart
If myocarditis is causing heart failure or arrhythmias, your doctor might hospitalize you and prescribe drugs or other treatments. For certain abnormal 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 medications to reduce your heart's workload or help you eliminate excess fluid, including:
Angiotensin-converting enzyme (ACE) inhibitors. These medications, such as enalapril (Vasotec), captopril (Capoten), lisinopril (Zestril, Prinivil) and ramipril (Altace), relax the blood vessels in your heart and help blood flow more easily.
Angiotensin II receptor blockers (ARBs). These medications, such as losartan (Cozaar) and valsartan (Diovan), relax the blood vessels in your heart and help blood flow more easily.
Beta blockers. Beta blockers, such as metoprolol (Lopressor, Toprol-XL), bisoprolol and carvedilol (Coreg), work in multiple ways to treat heart failure and help control arrhythmias.
Diuretics. These medications, such as furosemide (Lasix), relieve sodium and fluid retention.
Treating severe cases
In some severe cases of myocarditis, aggressive treatment might include:
Intravenous (IV) medications. These might improve the heart-pumping function more quickly.
Ventricular assist devices. Ventricular assist devices (VADs) are mechanical pumps that help 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 the heart to recover or while waiting for other treatments, such as a heart transplant.
Intra-aortic balloon pump. Doctors insert a thin tube (catheter) in a blood vessel in your leg and guide it to your heart using X-ray imaging. Doctors place a balloon attached to the end of the catheter in the main artery leading out to the body from the heart (aorta). As the balloon inflates and deflates, it helps to increase blood flow and decrease the workload on the heart.
Extracorporeal membrane oxygenation (ECMO). With severe heart failure, this device can provide oxygen to the body. When blood is removed from the body, it passes through a special membrane in the ECMO machine that removes carbon dioxide and adds oxygen to the blood. The newly oxygenated blood is then returned to the body.
The ECMO machine takes over the work of the heart. This treatment may be used to allow the heart to recover or while waiting for other treatments, such as a heart transplant.
In the most severe cases, doctors might consider urgent heart transplantation.
Some people 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 normal activities.
If you have lingering heart damage, it's important to keep salt to a minimum, restrict the amount of fluids you drink, drink a minimum amount of alcohol, if any, and avoid smoking. Your doctor will let you know what your fluid intake should be, as well as the amount of salt that's OK for you to include in your diet.
Preparing for an appointment
You're likely to start by seeing your primary care doctor, or in the case of severe symptoms, an emergency room doctor. You might then be referred to a doctor trained in heart conditions (cardiologist) and possibly a doctor trained in infectious disease.
Here's some information to help you get ready for your appointment.
What you can do
Make a list of:
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
Take a family member or friend along, if possible, to help you remember the information you'll receive.
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.
What to expect from your doctor
Your doctor is likely to ask you a number of questions, including:
Have you recently gotten over another illness?
Have you traveled out of the country recently?
Does anything seem to improve your symptoms?
What, if anything, appears to worsen your symptoms?