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What Is the Most Common Cause of Myocarditis?

Myocarditis is the inflammation of the heart. Viral infections are the most common cause of myocarditis, including Parvovirus B19, Human Herpesvirus 6, and Enterovirus (Coxsackie Virus). Other causes include bacterial infections, tick-borne diseases, cancer, autoimmune conditions, and more.
Myocarditis is the inflammation of the heart. Viral infections are the most common cause of myocarditis, including Parvovirus B19, Human Herpesvirus 6, and Enterovirus (Coxsackie Virus). Other causes include bacterial infections, tick-borne diseases, cancer, autoimmune conditions, and more.

Myocarditis is inflammation of the heart muscle, which enlarges and weakens the heart. There are different forms of myocarditis, which can range from mild to serious to life-threatening. It is considered a rare disease though it can affect anyone from children to adults, and males or females. 

Types of myocarditis include: 

  • Viral myocarditis
  • Giant cell myocarditis
  • Lymphocytic myocarditis
  • Eosinophilic myocarditis
  • Granulomatous myocarditis

Viral infections are the most common cause of myocarditis. Infections cause inflammation, which stresses the heart and remains even after the infection goes away. Common viral infections that can cause myocarditis to include:

Other causes of myocarditis include: 

  • Bacterial infections 
  • Tick-borne diseases
    • Borrelia burgdorferi
    • Ehrlichia species
    • Babesia species
    • Trypanosoma cruzi (which causes Chagas disease)
  • Other types of infections
    • Fungi
    • Protozoa
  • Cancer
  • Autoimmune conditions (which can lead to a type of myocarditis called giant cell myocarditis)
  • Exposure to environmental toxins 
    • Metal poisons 
    • Spider and snake venom
    • Alcohol
    • Radiation
    • Certain chemicals, such as hydrocarbons and arsenic
  • Certain medications such as the anti-cancer drug doxorubicin
  • Allergic reactions to antibiotics, including sulfonamides and penicillin

What Are Symptoms of Myocarditis?

Often, people do not experience any symptoms of myocarditis. Symptoms of myocarditis can be vague and general and may be symptoms of the causative agent, such as the viral infection. Symptoms of myocarditis may be preceded by days to weeks with a mild, flu-like illness. When symptoms are present, they may include:

  • Shortness of breath, especially after exercise or when lying down
  • Trouble breathing 
  • Decreased ability to exercise
  • Fatigue/tiredness
  • Lightheadedness
  • Heart palpitations/fast heartbeat/feeling of fluttering in the chest
  • Changes in a heartbeat, such as the heart feeling as if it’s “skipping” a beat
  • Chest pain that improves when leaning forward and worsens when lying back 
  • The sensation of tightness, pressure, or squeezing in the chest
  • Swelling in the hands, legs, ankles, and feet
  • Sudden loss of consciousness

How Is Myocarditis Diagnosed?

Because myocarditis is often asymptomatic, most cases remain undiagnosed. When patients have symptoms, tests used to diagnose myocarditis include:

  • Blood tests to measure the levels of enzymes normally in the heart
  • Electrocardiogram (ECG)
  • Chest X-ray
  • Coronary angiography
  • Echocardiogram (“echo”)
  • Cardiac magnetic resonance imaging (MRI) scan 
  • Cardiac catheterization (“cardiac cath”) 
  • Heart biopsy (occasionally used to confirm a diagnosis)

What Is the Treatment for Myocarditis?

Treatment for myocarditis depends on the cause and severity and may include:

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References
https://www.myocarditisfoundation.org/

https://www.uptodate.com/contents/myocarditis-the-basics?search=Myocarditis&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1

https://emedicine.medscape.com/article/156330-medication#showall

https://rarediseases.org/rare-diseases/myocarditis/