Heart Inflammation Myocarditis

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Myocarditis is inflammation  of the myocardium — the heart muscle. This inflammation can also cause other changes to the heart muscle cells that may be acute or chronic . Acute myocarditis is typically caused by an infection, like a virus. Chronic myocarditis is typically caused by another medical condition, like an autoimmune disorder. Myocarditis can affect small or large sections of the heart muscle, making it harder for the heart to pump blood.

Myocarditis can lead to other serious heart conditions, such as heart failure, cardiomyopathy, and arrhythmias. Inflammation can extend to the pericardium and cause a condition called myopericarditis. This will cause symptoms of both myocarditis and pericarditis.

Sometimes, the cause of myocarditis is unknown. However, a healthcare provider does not always need to know the cause to treat myocarditis.

Myocarditis can be caused by infections or other factors unrelated to infections.

• Infective myocarditis is caused by infections from viruses (such as COVID-19, HIV, parvovirus B19, or human herpes virus 6), bacteria, fungi, or parasites.
• Non-infective myocarditis is caused by factors that are not infections. Some non-infective causes include medicines (antibiotics such as penicillin, psychiatric medicines such as clozapine, and diuretics such as furosemide and hydrochlorothiazide), autoimmune conditions, other medical conditions such as giant cell myocarditis, and some cancer treatments such as immune checkpoint inhibitors or radiation.

You may not have any symptoms of myocarditis, or you may not notice any symptoms since they could be overshadowed by symptoms of the infection that caused the myocarditis. Myocarditis symptoms will depend on the level of inflammation and whether the pericardium is affected (myopericarditis).

Myocarditis can lead to heart failure, rhythm disturbances, or rarely cardiogenic shock (a condition that occurs when your heart suddenly cannot pump enough blood to your tissues and organs).

Symptoms can be very different from person to person depending on the cause of myocarditis but include:

• Chest pain
• Fatigue
• Trouble breathing
• Abnormal heart rhythms, called arrhythmias
• Fever
• Exercise intolerance (no longer being able to exercise)
• Rash

Often, there are no physical signs of myocarditis. Your healthcare provider will diagnose myocarditis using tests and procedures.

Your healthcare provider may use heart and blood tests to help diagnose myocarditis. Heart tests may include an ECG or EKG, an echocardiogram, cardiac magnetic resonance imaging (MRI), and a chest x-ray. Your provider may test your blood for C-reactive protein and troponin.

Your provider may perform a procedure called endomyocardial biopsy if your other test results are unclear. In an endomyocardial biopsy, a surgeon removes a piece of myocardial tissue for your provider to look at. This procedure is rare.

Once myocarditis is diagnosed, your provider may need to run more tests to find the cause and treat it, if necessary.

Your healthcare provider may prescribe medications or perform a procedure to treat your myocarditis. Treatments may include:

• Medicines that relieve pain and reduce inflammation such as colchicine, non-steroidal anti- inflammatory drugs (NSAIDs), and aspirin. Side effects of these medicines include abdominal pain, nausea, vomiting, and diarrhea.
• Corticosteroids  lower the activity of the body’s immune system. Corticosteroids may be used to treat myocarditis caused by autoimmune  diseases such as lupus.
• Intravenous immunoglobulin  (IVIG) helps control the body’s immune and inflammatory response.
• You may need to stop taking certain medications if they are the cause of your myocarditis.

If myocarditis caused heart failure or arrhythmias, your health care provider will treat those conditions using medicines or procedures. Treatments for heart failure or arrhythmias include:

• Pacemakers, implantable cardioverter defibrillators (ICDs), or left ventricular assist devices (LVADs)
• Medicines for heart failure
• Heart transplant

Myocarditis is a rare complication of COVID-19. It is more common in some groups of people, such as:

• People who are hospitalized for complications related to COVID-19. About 1 in 5 people who are hospitalized with COVID-19 develop heart problems, including myocarditis as well as acute coronary syndrome, arrhythmias, and blood clots.
• People who have other health conditions like high blood pressure, diabetes, and obesity
• Older adults
• Men

Researchers are still working to find the exact link between COVID-19 infection and myocarditis. Many people with COVID-19-induced myocarditis could be treated with supportive care such as fluids, beta-blockers, diuretics). If this treatment is unsuccessful, other medicines like vasopressors, steroids, and antivirals could be used.

Myocarditis is an extremely rare complication of the COVID-19 vaccine (affects less than 20 people per million COVID-19 vaccinations). Myocarditis from the COVID-19 vaccine is less severe than myocarditis caused by COVID-19 itself. The benefits of getting vaccinated outweigh the small risk of vaccine-related myocarditis.