Definition

Myocarditis is an inflammation of the heart’s muscular wall, the myocardium. Although rare, it can be devastating. Myocarditis can occur with no symptoms and remain undiagnosed.

Causes

Many cases of myocarditis have no identifiable cause. This is called idiopathic myocarditis. When a cause is identified, it falls into one of 3 categories:

• Infectious—bacterial, viral, or fungal
• Toxic—medications, or exposure to heavy metals, toxins, or physical agents (shock, radiation)
• Immune-mediated—allergic reactions, heart transplant rejection, or autoantigens (which may be present in autoimmune disorders)

Risk Factors

There are no known risk factors for developing myocarditis.

Symptoms

Some people have no symptoms of myocarditis. In those that have them, symptoms can vary from person-to-person depending on the cause and the severity. Symptoms may appear slowly or come on suddenly.

• Flu-like complaints, including fever, fatigue, muscle pain, vomiting, diarrhea, and weakness
• Rapid or irregular heart rate
• Chest pain
• Shortness of breath and respiratory distress
• Loss of consciousness
• Sudden, unexpected death

Sudden, intense myocarditis can lead to heart failure.

Diagnosis

The diagnosis of myocarditis is often difficult. There is no specific test for it. Many other causes of heart problems must be ruled out. To do this, your doctor will ask about your symptoms and medical history. A physical exam will be done.

Tests may include:

• Blood tests to look for specific cardiac enzymes
• Electrocardiogram (EKG)—records the heart’s activity by measuring electrical currents through the heart muscle
• Chest x-ray
• Biopsy —removal of a sample of heart tissue to test for infection

Imaging tests evaluate the heart and surrounding structures:

• Echocardiogram
• MRI scan

Treatment

The universally recommended therapy for myocarditis is bedrest, no physical activity, and supplemental oxygen. Corticosteroids may be given to help inflammation. You will most likely be admitted to a hospital.

Specific treatment is directed at the underlying cause if possible. For instance:

• If the cause is a bacterial infection, antibiotics are prescribed.
• If it is viral, antiviral agents will be prescribed.
• Immunosuppressive therapy may be used if myocarditis is due to an autoimmune disorder such as lupus or scleroderma.

If heart failure symptoms are present, medications are given to support the function of the heart. These include diuretics, ACE-inhibitors, beta-blockers, and anti-arrhythmic agents.

Additionally, a defibrillator, which helps maintain the normal rhythm of the heart, may be implanted into your chest. Severe cases may require a cardiac transplant.

Prevention

To help reduce your chance of myocarditis, reduce your exposure to identified causes:

• Practice good hygiene to avoid the spread of infection. For example, wash your hands regularly.
• Always use latex condoms during sexual activity.
• Have sex with only one partner, who has sex only with you.
• Do not use illegal drugs.

National Heart, Lung, and Blood Institute http://www.nhlbi.nih.gov

Health Canada http://www.hc-sc.gc.ca

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Myocarditis. EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed
Updated March 6, 2013. Accessed December 30, 2014.

Understand your risk of heart failure. American Heart Association website. Available at:
http://www.heart.org/HEARTORG/Conditions/HeartFailure/UnderstandYourRiskforHeartFailure/Understand-Your-Risk-for-Heart-Failure_UCM_002046_Article.jsp
Updated October 24, 2014. Accessed December 30, 2014.