The cause of myocarditis is not always known. Causes that are known are:
- Infectious—from bacteria, protozoa, viruses, or fungi
- Toxic—from medicines, or exposure to heavy metals, toxins, shock, or radiation
- Problems of the immune system—allergic reactions, heart transplant rejection, or autoimmune disease
Myocarditis may not cause symptoms. When symptoms happen, they may be:
- Flu-like symptoms—such as fever, tiredness, muscle pain, vomiting, loose stools (poop), and weakness
- Fast or uneven heartbeats
- Chest pain
- Leg swelling
- Problems breathing
- Loss of consciousness
- Sudden, unexpected death
Myocarditis can lead to heart failure.
It can be hard to diagnosis myocarditis. There is no specific test for it. Other causes of heart problems must be ruled out first.
The doctor will ask about symptoms and past health. A physical exam will be done. Tests may include:
- Blood tests—to look for signs of heart damage or infection
- ECG—to see the heart’s electrical activity
- Biopsy—a sample of heart tissue is removed for testing (rare)
Images of the heart may be taken with:
- MRI scan
The first line of treatment is support care. The goal is to manage symptoms and slow or prevent more damage. Care will often require a hospital stay.
When possible, the cause will be treated. For example:
- Antibiotics—for bacterial infections
- Antiviral medicine—for viral infections
- Medicines to adjust the immune system—for autoimmune disorders (such as systemic lupus erythematosus or scleroderma )
If heart failure is present, it may be treated with:
- Medicines to support the heart
- An implanted device to help pump blood—if other treatments do not help
- A heart transplant—for severe heart damage
This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.
Edits to original content made by Denver Health.
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American Heart Association http://www.heart.org
National Heart, Lung, and Blood Institute https://www.nhlbi.nih.gov
Health Canada https://www.canada.ca
Heart and Stroke Foundation of Canada http://www.heartandstroke.ca
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Myocarditis. Health—Johns Hopkins Medicine wesbite. Available at: https://www.hopkinsmedicine.org/health/conditions-and-diseases/myocarditis. Accessed September 6, 2021.
Tschöpe C, Ammirati E, et al. Myocarditis and inflammatory cardiomyopathy: current evidence and future directions. Nat Rev Cardiol. 2021;18(3):169-193.
Understand your risk for heart failure. American Heart Association website. Available at: https://www.heart.org/en/health-topics/heart-failure/causes-and-risks-for-heart-failure/understand-your-risk-for-heart-failure#.WiAtp1WnFQI. Accessed September 6, 2021.