What Is Myocarditis? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Myocarditis is inflammation of the myocardium, the muscle layer of the heart's wall.

The heart wall is made up of three layers:

• The endocardium, the innermost layer that lines the inside of the heart chambers
• The myocardium, the muscle layer that contracts, causing blood to be pumped
• The epicardium, the protective outer layer that is also the innermost layer of the sac containing the heart (pericardium)

In many cases, no specific cause of myocarditis is ever determined.

In other cases, the cause can be identified. Some known causes of myocarditis include:

• Viruses, including those that cause flu-like illnesses, colds, rubella (German measles), gastroenteritis, mononucleosis (mono), and HIV and AIDS
• Bacteria, including those that cause strep throat, staph infections, diphtheria, and Lyme disease
• Parasites, such as toxoplasma and Trypanosoma cruzi, which is transmitted by insects and can cause Chagas disease
• Fungi, such as yeast infections, molds, and fungal infections that are passed through bird droppings
• Drugs, including antibiotics (such as penicillin, sulfa drugs, and azithromycin); diuretics (such as furosemide and hydrochlorothiazide); drugs for epilepsy; and cocaine
• Autoimmune disorders such as lupus, Crohn's disease, rheumatoid arthritis, and celiac disease
• Exposure to certain toxic substances such as arsenic, radiation, or carbon monoxide, per Harvard Health

While anyone can get myocarditis, you're at greater risk if you:

• Have a weak or compromised immune system
• Are exposed to agents known to cause myocarditis (such as cocaine)
• Have previously had myocarditis

• Blood Tests Blood tests can check for inflammation, antibodies to viruses, or other organisms that would signal an infection, or certain enzymes that accumulate when the heart is damaged.
• Electrocardiogram (EKG) An EKG creates a graph of your heart's electrical system and can show abnormalities.
• Holter Monitor This is usually worn for a few days to capture more information about your heart electrical function.
• X-Ray A chest X-ray can be used to look for enlargement of the heart or accumulation of fluid in the heart's sac.
• Magnetic Resonance Imaging (MRI) An MRI can also show heart size, shape and function, as well as swelling, inflammation, or scarring.
• Echocardiogram This uses ultrasound waves to show an image of the beating heart. An echocardiogram can detect issues with the heart’s pumping function, valve problems, if the heart has become enlarged, and the presence of a clot within or around the heart.
• Cardiac Catheterization This involves threading a tiny tube through a vein and into the heart to take measurements or collect a tissue sample (biopsy) to check for inflammation or infection.

In some cases, myocarditis goes away on its own. In other cases, treatment may include:

• Antibiotics to treat bacterial infection
• Antiviral drugs to treat viral infection
• Intravenous immunoglobulin (IVIG), in which a blood product is injected to help boost the immune system
• Steroids to reduce inflammation

If your heart muscle has become weakened, you might be prescribed one of the following medications to help reduce its workload:

• Angiotensin-converting enzyme (ACE) inhibitors can decrease blood pressure, allowing blood to flow through the body more easily. They can also help the heart function recover better when it is weak.
• Angiotensin II receptor blockers have many of the same benefits as ACE inhibitors and are often prescribed as an alternative for patients who cannot tolerate ACE inhibitors.
• Beta-blockers slow the heart rate down and decrease the effects of adrenaline on the heart, lowering blood pressure so the heart has to do less work.
• Diuretics to remove excess water and sodium from the body.

Severe cases of myocarditis may need to be treated with medical procedures, including:

• Ventricular assist devices (VADs) are mechanical pumps implanted into the abdomen or chest and attached to the weakened heart. The devices help pump blood from the lower heart chambers to the rest of your body.
• Intra-aortic balloon pump is a procedure in which a doctor inserts a catheter into a blood vessel in the leg and, with the help of X-ray imaging, guides it to the heart. A balloon is attached to the end of the catheter in the main artery and is inflated and deflated, helping to increase blood flow and lessen the heart’s workload.
• Extracorporeal membrane oxygenation (ECMO) is a device that provides oxygen to the body during severe heart failure. Blood is removed from the body and passes through the ECMO machine where carbon dioxide is removed and oxygen is added before being returned to the body.

Prevention of Myocarditis

There is no specific way to prevent myocarditis, but there are steps you can take to prevent infections that might lead to the condition. These include:

• Practicing good hygiene, including frequent hand washing and using a hand sanitizer when soap and water is not available
• Keeping away from people who are sick with the flu or other viral illness
• Staying up to date on your vaccines, including those that protect against the flu and rubella, diseases that can lead to myocarditis
• Avoiding risky behavior, such as unprotected sex and using illicit drugs
• Minimizing exposure to ticks by wearing long sleeve shirts and long pants and using insect repellents containing DEET when spending time in tick-infested areas

There are a number of possible complications of myocarditis:

• Cardiomyopathy is a condition in which the heart muscle becomes weakened, stretched, or structurally damaged. It often affects the heart’s ability to pump and function properly and can lead to heart failure.
• A heart attack or stroke can occur when the heart muscle is damaged and can’t pump blood, causing the blood to pool in the heart. If the blood clots and blocks an artery supplying blood to the heart, this could lead to a heart attack. If a clot travels to an artery leading to your brain, this can result in a stroke.
• Heart failure is a condition in which the heart is no longer able to pump blood efficiently to the rest of the body. In more serious cases, myocarditis-related heart failure may require a heart transplant.
• Arrhythmias are rapid or irregular heartbeats.
• Sudden cardiac death occurs when the heart suddenly stops beating. If not treated immediately, it becomes fatal.

Some cases of myocarditis are brought on by autoimmune reactions against heart tissues in individuals with autoimmune diseases, such as:

• Systemic lupus erythematosus, which is an inflammatory disease that occurs when the immune system attacks its own tissues. It can affect many areas of the body, including the joints, skin, kidneys, lungs, and heart.
• Crohn's disease, which is a chronic inflammatory bowel disease causing inflammation to the digestive tract, which leads to symptoms of severe diarrhea, abdominal pain, weight loss, fatigue, and malnutrition.
• Rheumatoid arthritis, which is a chronic inflammatory disorder mainly affecting the joints.
• Celiac disease, which is an immune disease in which those affected have an immune reaction to eating gluten, a protein found in wheat, barley, and rye. Over time, this immune reaction leads to inflammation that damages the small intestine.

Favorite Organizations for Essential Information on Myocarditis

Myocarditis Foundation

Founded in 2005, the Myocarditis Foundation is a nonprofit organization dedicated to raising global awareness of myocarditis. The foundation provides resources for patients, families, and healthcare providers and supports research for the scientific advancement of myocarditis treatments.

American Heart Association (AHA)

The AHA is the nation’s oldest and largest nonprofit organization dedicated to heart health. Find resources for heart-healthy living and connect with other patients also dealing with heart-related problems through AHA’s Support Network.

National Organization for Rare Disorders (NORD)

NORD is a patient advocacy organization dedicated to individuals with rare disorders and conditions, including myocarditis. Get the essential facts about myocarditis symptoms, causes, and therapies on NORD’s website.

Additional reporting by Rosalyn Carson-DeWitt, MD.