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Mar 07, 2022
6 min read

Myocarditis: symptoms and causes

Myocarditis refers to inflammation of the heart muscle or myocardium. It’s usually caused by a virus, but other things like certain medications, bacterial infections, toxins, and pregnancy can cause it. Some cases of myocarditis are mild and resolve on their own. Others need treatment to avoid serious complications like heart failure, abnormal heart rhythms, and even sudden death. There’s no vaccine for myocarditis, but other vaccines can prevent infections that lead to myocarditis.

Disclaimer

If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

Having a virus isn’t often cause for concern—a few days of congestion, cough, body aches, and fever and you’re back to normal after some rest and lots of fluids. 

But if you start to notice new symptoms like chest pain, a racing heartbeat, and difficulty breathing, one possible reason could be a complication called myocarditis or inflammation of the heart. 

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What is myocarditis? 

Myocarditis is inflammation of the heart muscle or myocardium. This condition is somewhat uncommon, affecting roughly 1.5 million people worldwide each year (Kang, 2022). 

Myocarditis can happen on its own or alongside a condition called pericarditis, which is inflammation of the heart lining. Myocarditis is usually caused by a viral infection, but there are other risk factors we’ll discuss below. 

Myocarditis symptoms

Myocarditis can be mild without any noticeable symptoms. Other times it’s severe and affects your heart’s ability to pump blood. Symptoms of myocarditis include (Ammirati, 2018): 

  • Chest pain
  • Fever
  • Passing out (syncope)
  • Dizziness
  • Fatigue
  • Shortness of breath or difficulty breathing
  • Racing heartbeat (palpitations) 
  • Body aches or joint pain
  • Cough, stuffy nose, and sore throat (symptoms of a recent virus)

Diagnosing myocarditis

Myocarditis is diagnosed mostly based on your symptoms. Other tests a healthcare provider may use to diagnose the condition include (Marholdt, 2004; Cooper, 2007): 

  • Blood tests: A troponin blood test measures the levels of troponin (proteins found in the muscle tissue of the heart) to see whether the heart muscle is injured. 
  • Electrocardiogram: An ECG or EKG records electrical signals in your heart to determine if there’s an abnormal heart rhythm. 
  • X-ray or MRI: Chest X-rays help visualize structures in the chest like the heart and lungs. Another type of imaging is an MRI (magnetic resonance imaging), which might help identify injured heart muscle. 
  • Sonogram: A heart sonogram (also called an echocardiogram) looks directly at the heart, its size, and how it moves. 
  • Biopsy: This is when a sample of heart muscle tissue is taken and examined under a microscope. Biopsies aren’t done often but may help diagnose myocarditis if other test results aren’t clear. 

Causes of myocarditis

Viruses are the most common causes of myocarditis. Many viruses cause inflammation that damages the myocardium including coxsackievirus (causes hand, foot, and mouth disease), Epstein-Barr virus (causes mononucleosis), cytomegalovirus, influenza, hepatitis C, HIV, parvovirus, and coronavirus

Viruses aren’t the only way to get myocarditis. Other possible causes include (Cooper, 2009; Caforio, 2013): 

  • Chemicals: Exposure to chemicals and toxins can injure the myocardium. These include recreational substances like alcohol and cocaine, prescription medications, chemotherapy drugs, and mood stabilizers like lithium. Metals like iron, copper, and lead can also cause damage. 
  • Bacterial infections: Bacteria can lead to inflammation of the myocardium. Some common culprits include Staphylococcus aureus (which causes staph infections), Haemophilus influenzae, mycoplasma, and Streptococcus pneumoniae. Other bacterial infections that cause myocarditis include Lyme disease and sexually transmitted infections like syphilis and chlamydia
  • Medical conditions: People with autoimmune diseases or health conditions that affect the immune system can develop myocarditis. Some examples include lupus, scleroderma, and sarcoidosis.

Other things that may factor into the development of myocarditis include pregnancy, radiation therapy, yeast or fungal infections, parasite infections, spider bites, and scorpion stings.

Does myocarditis go away on its own? 

Mild myocarditis may go away without causing long-term complications. 

More severe cases of myocarditis usually need treatment to avoid severe complications including: 

  • Abnormal heart rhythms (arrhythmias)
  • Dilated cardiomyopathy (a stretched, enlarged heart that can’t pump)
  • Heart failure
  • Sudden death (rare but possible)

Myocarditis treatment

Myocarditis affects the heart’s ability to pump, so medications that relieve strain on the heart can be recommended––if treatment is necessary. Drugs used to treat myocarditis include beta-blockers, ACE inhibitors, and diuretics. Your healthcare provider may also suggest resting and limiting physical activity for a while until your heart has recovered (Caforio, 2013). 

If first-choice medications don’t work, some drugs can be prescribed off-label including steroids, antibodies, and immunosuppressive drugs (medications that affect the immune system) (Caforio, 2013). 

If the myocarditis is severe and doesn’t respond to medication, a machine called ECMO (extracorporeal membrane oxygenation) or a device called a VAD (ventricular assist device) can be used to support the heart. The last option if all else fails is a heart transplant (Chen, 2005; Topkara, 2006). 

Is there a myocarditis vaccine? 

Unfortunately, there isn’t a vaccine specifcally for myocarditis. That said, several vaccines prevent infections that lead to the condition including:

  • The flu shot (for influenza virus)
  • Pneumococcal vaccine
  • Hib vaccine (for Haemophilus influenzae type b)
  • COVID-19 vaccines 
  • Hepatitis B vaccine
  • Polio vaccine
  • MMR vaccine (for measles, mumps, and rubella viruses)

Myocarditis is most commonly caused by viral infections, but it may occur from medication, a bacterial infection, or even pregnancy. It’s important to follow up with a healthcare provider if you experience any signs of myocarditis. 

References

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  2. Ammirati, E., Frigerio, M., Adler, E. D., Basso, C., Birnie, D. H., Brambatti, M., et al. (2020). Management of Acute Myocarditis and Chronic Inflammatory Cardiomyopathy: An Expert Consensus Document. Circulation. Heart Failure, 13(11), e007405. doi:10.1161/CIRCHEARTFAILURE.120.007405. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7673642/ 
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  4. Chen, Y. S., Yu, H. Y., Huang, S. C., Chiu, K. M., Lin, T. Y., Lai, L. P., et al. (2005). Experience and result of extracorporeal membrane oxygenation in treating fulminant myocarditis with shock: what mechanical support should be considered first? The Journal of Heart and Lung Transplantation, 24(1), 81–87. doi:10.1016/j.healun.2003.09.038. Retrieved from https://pubmed.ncbi.nlm.nih.gov/15653384/ 
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  13. Topkara, V. K., Dang, N. C., Barili, F., Martens, T. P., George, I., Cheema, F. H., et al. (2006). Ventricular assist device use for the treatment of acute viral myocarditis. The Journal of Thoracic and Cardiovascular Surgery, 131(5), 1190–1191. doi:10.1016/j.jtcvs.2005.08.073. Retrieved from https://www.jtcvs.org/article/S0022-5223(06)00130-9/fulltext#secd5413354e438 
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