What is Myocarditis?

The picture on the right shows viral myocarditis, which caused Janna Apple to collapse on Dec. 3. Courtesy Pathologic Anatomy Atlas

Myocarditis is an uncommon condition that can be caused by a viral infection or a self-directed immune response (when the immune system attacks the body, such as in autoimmune diseases like rheumatoid arthritis or lupus). Rare cases have also been associated with a variety of infections, toxic injuries, adverse drug reactions, and even cancer.

What Causes Myocarditis?

Myocarditis can be caused by many viruses, but the most common are those associated with upper respiratory tract infections. Less commonly, other contagious diseases, including Lyme disease, may cause myocarditis. Rarely, myocarditis has been caused by cocaine use or exposure to toxic agents including metal poisons or snake or spider bites.

Most cases of myocarditis are not infectious. There is no known risk of infection to family members of people with myocarditis.

What are the Symptoms of Myocarditis?

Although most cases of myocarditis have no symptoms and are only identified by an electrocardiogram or by blood tests, the most common symptom of myocarditis is shortness of breath during exercise or exertion. This symptom usually develops 7 to 14 days after a viral illness and can progress to shortness of breath at night, which may require that you sit up to breathe.

Other symptoms may include fatigue, heart palpitations and chest pain or pressure. The legs also may swell. Rarely, myocarditis causes a sudden loss of consciousness that may be due to abnormal heart rhythms. 

In summary, patients may experience some, all or none of the following symptoms: shortness of breath, chest pain, lightheadedness, irregular heartbeat, sudden loss of consciousness.

How is Myocarditis Diagnosed?

The majority of cases of myocarditis have no symptoms and are not diagnosed. However, when a person develops symptoms, common tests for myocarditis include the following:

–An Electrocardiogram: Electrical activity of your heart is detected by electrodes taped to your skin. This activity is recorded as waves that represent the electrical forces in the different parts of the heart.

–A Chest X-Ray: A chest X-ray produces an image on film that outlines your heart, lungs and other structures in your chest. From a chest X-ray, your physician learns information such as the size and shape of your heart.

–An Echocardiogram (abbreviated echo): Sound waves (too high-pitched to be heard) are used to make an image of your heart or analyze blood flow. The sound waves are sent into your body from a transducer, a small plastic device. The sound waves are reflected back from internal structures, returning to the transducer and producing images of the heart and its structures.

–Less frequently, a cardiac magnetic resonance imaging (MRI) scan may be done to diagnose myocarditis. An MRI creates images using a magnetic field and radio waves.

–Occasionally, a heart biopsy is required to confirm the diagnosis.

How is Myocarditis Treated?

Myocarditis is commonly treated with medications used to treat heart failure. Rest and a low-salt diet are often recommended. Steroids and other medications also may be used to reduce heart inflammation.

More rarely, if an abnormal heart rhythm is present, treatment may require additional medications, a pacemaker or even a defibrillator.

Can Myocarditis Recur?

Yes, myocarditis can recur, and in some cases can lead to a chronically enlarged heart (called dilated cardiomyopathy). There is no known way to prevent recurrence of myocarditis. However, the risk of recurrence is low (probably about 10 to 15 percent).

If you have questions about this information or about your condition, talk to a member of your health-care team.

Information courtesy Myocarditis Foundation