Myocarditis  is classified as a rare disease but is estimated to affect thousands of  adults and children in the U.S. and around the world each year.  3.1  million cases of myocarditis were diagnosed in 2017 (statistics posted  in Lancet, November 2018). Because many individuals – and even  physicians – are unfamiliar with this condition, the Myocarditis  Foundation was established in 2005 to provide a trusted resource for  those affected by myocarditis. Here, we’ll review the disease’s causes,  symptoms, treatment and more to answer your most pressing questions.

In simple terms, myocarditis is a disease that causes inflammation of  the heart muscle. This inflammation enlarges and weakens the heart,  creates scar tissue and forces it to work harder to circulate blood and  oxygen throughout the body.

While we often associate cardiovascular conditions with elderly  populations, myocarditis can affect anyone, including young adults,  children and infants. In fact, it most often affects otherwise healthy,  young, athletic types with the high-risk population being those of ages  from puberty through their early 30’s, affecting males twice as often as  females. Myocarditis is the 3rd leading cause of Sudden Death in children and young adults.

Your heart is a four-chambered, muscular pump about the size of an  adult fist. Normally, the heart beats 60 to 100 times per minute,  pumping blood throughout your body with each beat.

Two upper heart chambers called the right and left atria (each is  called an atrium) receive blood that returns to the heart from the body.  Veins carry this returning blood to the atria. When the muscles of the  atria contract, blood is squeezed into the two larger, lower heart  chambers called the right and left ventricles. When the muscles of the  ventricles contract, blood is propelled through arteries to the entire  body. The pumping of the ventricles creates the pulse you feel in your  wrist or neck.

Myocarditis in a mouse heart. Cardiac inflammation stains purple.

Viral infections are a leading cause of myocarditis. Inflammation  occurs during the course of infection, putting stress on the heart that  remains even after the infection is resolved. Cancer, bacterial  infections and other contagious diseases can also cause myocarditis, as  can exposure to environmental toxins ranging from metal poisons to  spider and snake venom.

A significantly smaller group of individuals with autoimmune conditions, may develop giant cell myocarditis.  This variation of the disease often results in rapid deterioration but  may still respond successfully to treatment, especially when diagnosed  early. Currently there are no known lifestyle choices or medical  treatments that can prevent myocarditis.

One of the greatest challenges to the diagnosis and treatment of  myocarditis is the lack of specific symptoms of myocarditis. In many  cases, individuals experience no symptoms of myocarditis at all. When  they are present, symptoms may point to the viral infection itself or  suggest other cardiac problems such as a heart attack. Common symptoms  of myocarditis can include, but are not limited to:

• Shortness of breath, especially after exercise or when lying down
• Fatigue
• Heart palpitations
• Chest pain or pressure
• Light headedness
• Swelling in the hands, legs, ankles and feet
• A sudden loss of consciousness

If any of these symptoms are detected, it’s important to speak to your doctor right away.

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.
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After treatment, many patients live long, full lives free from the  effects of myocarditis. For others, however, ongoing cardiovascular  medication or even a heart transplant may be needed. Overall,  myocarditis which can cause dilated cardiomyopathy, are thought to  account for up to 45 percent of heart transplants in the U.S. today.

Healthy lifestyle changes can also support proper heart function.  Your doctor may recommend that you reduce sodium in your diet, avoid  alcohol, limit fluid intake and quit smoking. It’s also generally  advised that you avoid competitive sports and other rigorous exercise  for a period after diagnosis, to be determined by the cardiologist. And  while it’s possible for the disease to come back, more-so in giant cell  myocarditis, it is extremely rare.

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).

No lifestyle changes or medical treatments are known to prevent viral myocarditis.

Because myocarditis is rare, information is limited regarding its  causes and effective treatments. Myocarditis is not believed to be  inherited. No genes are known to predispose people to myocarditis.

Source: https://www.myocarditisfoundation.org/about-myocarditis/