Myocarditis Post Infection

Myocarditis post infection is inflammation of the heart muscle that develops after a viral or other infection. While this condition can be worrying, most people make a very good recovery with proper treatment and care.

Table of contents

• What is myocarditis post infection?
• Causes of post-infection myocarditis
• Signs and symptoms
• Who is at risk?
• How is it diagnosed?
• Treatment approaches
• Recovery and living with myocarditis
• What to expect

What is myocarditis post infection?

• Heart muscle (myocardium)

Myocarditis post infection is a disease that causes inflammation of the heart muscle, called the myocardium, following a viral or bacterial infection. The inflammation occurs during or after the course of infection, putting stress on the heart that can remain even after the infection is resolved.^[1][4]

The condition can develop suddenly (or acutely), can be recurring, or it can be long-lasting (or chronic). Most people will recover without any lasting effects. However, in rare cases, if the inflammation is severe, myocarditis can scar the heart muscle. This damage means the heart has to work harder to pump blood and oxygen around the body.^[2]

The inflammation can reduce the heart’s ability to pump blood effectively. When the heart muscle becomes inflamed, it weakens, making it more difficult for the heart to pump. In some cases, this can result in the heart muscle becoming bigger, and over time, weaker. Sometimes, myocarditis can affect the heart’s electrical system, leading to an irregular heartbeat, also known as arrhythmias.^[1][2]

Causes of post-infection myocarditis

Viral infections are the most frequent cause of myocarditis in the United States and other developed countries. In North America and Europe, the most commonly implicated viruses are parvovirus B-19 and human herpesvirus 6 (HHV 6), followed by Epstein-Barr virus, enterovirus, human cytomegalovirus, and adenovirus.^[3]

Other viruses that can cause myocarditis include flu, herpes virus six, coxsackievirus, and SARS-CoV-2 (COVID-19).^[5] In developing countries, rheumatic carditis, Chagas disease, and complications related to advanced HIV/AIDS are important causes of myocarditis.^[3]

Between 6% and 18% of myocarditis patients carry a genetic mutation associated with increased risk of heart muscle disease. Bacterial infections, fungi (rarely), and other contagious diseases can also cause myocarditis, as can exposure to environmental toxins ranging from metal poisons to spider and snake venom.^[4]

Myocarditis can sometimes happen together with pericarditis (inflammation of the lining around the heart) and they have similar symptoms. If you have both myocarditis and pericarditis, this is sometimes known as myopericarditis.^[2]

Signs and symptoms

One of the greatest challenges to the diagnosis and treatment of myocarditis is the lack of specific symptoms. 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 heart problems.^[4]

Common symptoms of myocarditis can include:^[1][4]

• Chest pain
• Shortness of breath, especially after exercise or when lying down
• Fatigue (feeling extremely tired)
• Heart palpitations (feeling like your heart is racing or beating irregularly)
• Swelling of the legs, ankles and feet
• Lightheadedness or feeling like you might faint
• Fever
• Flu-like symptoms such as headache, body aches, joint pain, or sore throat
• A sudden loss of consciousness

When children get myocarditis, symptoms may include difficulty breathing, rapid breathing, chest pain, rapid or irregular heartbeats, fainting, and fever.^[1]

If you are having unexplained chest pain and shortness of breath, seek emergency medical help. Contact a healthcare professional if you have symptoms of myocarditis.^[1]

Who is at risk?

Some of the things that put you at risk for myocarditis can’t be changed. You’re more likely to get myocarditis if you’re a young adult, although people of all ages can get it. You’re also more likely to develop it if you’re male, though females can get it, too.^[5]

Several studies have noted what appears to be a two-part pattern of affected patients, with individuals under age 16 (particularly males) most affected, followed by those over age 50.^[13]

Your genes influence how your body handles inflammation and how likely you are to get myocarditis. If you drink more alcohol than the limit your healthcare provider gives you, this also increases your risk.^[5]

In rare cases, myocarditis has happened in young people who received certain COVID-19 vaccines. Symptoms can start during the first week after receiving the vaccine. Most people who have this reaction to the COVID-19 vaccine recover quickly after treatment. However, the risk from COVID-19 itself is higher than the small risk of rare side effects like this.^[5][12]

How is it diagnosed?

Early diagnosis of myocarditis is important to preventing long-term heart damage. To diagnose myocarditis, a healthcare professional examines you and listens to your heart with a stethoscope. Blood and imaging tests may be done to check your heart health.^[6]

Myocarditis is diagnosed based on clinical presentation. Diagnosis is classically confirmed by endomyocardial biopsy (a procedure where a tiny sample of heart tissue is removed for examination) via established criteria. However, if this is not available, other studies can guide clinicians to diagnose post-infection myocarditis when appropriate.^[3][13]

Tests to diagnose myocarditis include:^[6]

• Blood tests: Blood tests are usually done to check for a heart attack, inflammation and infection. A cardiac enzyme test can check for proteins related to heart muscle damage. Antibody blood tests may help learn if you had an infection linked to myocarditis.
• Electrocardiogram (ECG or EKG): This quick and painless test shows how the heart is beating and can reveal signal patterns that indicate irregular heartbeats.
• Chest X-ray: A chest X-ray shows the size and shape of the heart and lungs. It can tell if there’s fluid in or around the heart that might be related to heart failure.
• Heart MRI (cardiac MRI): This test uses magnetic fields and radio waves to create detailed images of the heart. It can help diagnose myocarditis by showing the heart’s size, shape and structure.
• Echocardiogram: Sound waves create moving images of the beating heart. This test can show the heart’s size and how well blood flows through the heart and heart valves.
• Cardiac catheterization and heart muscle biopsy: A doctor places a thin, flexible tube called a catheter into a blood vessel in the arm or groin and guides it to an artery in the heart.

It is important to evaluate patients to rule out other potential causes of myocarditis. Where available, healthcare providers evaluate for potential causes, particularly acute COVID-19 illness, current SARS-CoV-2 infection, as well as other viral causes.^[12]

Treatment approaches

There is no cure at present for myocarditis. Physicians treat the disease’s symptoms, which can include rapid or irregular heartbeats and heart failure. In some cases, however, an underlying condition may be treated alongside cardiac symptoms to support recovery.^[10]

Treatment is largely supportive and may include oxygen therapy, intravenous hydration, diuretics (medicines that help remove excess fluid), steroids, and antivirals. Treatment for myocarditis may include medicines, procedures or surgeries.^[1][13]

Your physician will likely admit you to the hospital for treatment after a myocarditis diagnosis. This is especially common in children, who are typically admitted to a pediatric intensive care unit. If the heart is severely weakened, medical devices can help restore proper functioning. These include defibrillators (devices that deliver an electric shock to restore normal heart rhythm), ventricular assist devices (VADs), which pump blood throughout the heart’s chambers and the body, and extracorporeal membrane oxygenation (ECMO) machines, which filter carbon dioxide from the blood and add oxygen.^[10]

While these medications and devices may help alleviate heart symptoms, a transplant may be required when damage is too extensive for the heart to heal. In these situations, these treatments help stabilize the heart until an appropriate donor organ becomes available.^[10]

Recovery and living with myocarditis

Some patients are able to fully recover from myocarditis, while others will experience long-lasting symptoms. Recovery times are different for everyone. It can take as little as a few months or up to seven years to fully recover from this condition.^[17]

Your physician may ask you to avoid competitive sports and other intense exercises for a time after diagnosis and treatment. As a general rule, physical activity should be avoided for at least three to six months after being diagnosed with myocarditis. When you begin exercising again, start slowly and pace yourself as you regain your strength and abilities.^[17][18]

If you have severe myocarditis that weakens the heart muscle and affects your physical function, you may need to work with a physical therapist during your recovery. There are also cardiac rehabilitation programs that your doctor may recommend. These programs help patients recover and improve their heart health through monitored exercise.^[17]

Lifestyle changes are often recommended after myocarditis, including:^[10][14][15]

• A low-sodium diet and eating heart-healthy foods like fruits, vegetables, nuts, and salmon
• Limited fluid intake
• Elimination of alcohol
• Smoking cessation
• Avoiding caffeinated products and energy drinks which can make your heart work harder
• Getting plenty of rest
• Staying hydrated

While many individuals require a short course of heart medicines, others will need to take these medicines for life. You can also expect regular follow-up exams and tests to monitor your condition.^[10]

Individuals with myocarditis should try to avoid germs as best they can. A simple and effective way to prevent infections is washing your hands regularly. Getting vaccinated is another step to staying healthy. Medical professionals suggest people get the flu shot every year and the pneumonia vaccine every five years.^[14]

What to expect

With effective treatment, most people will make a very good recovery. After treatment, most people recover and can live their normal lives. However, some people will have more serious complications and will need specialist treatment.^[2]

Most people will recover without any lasting effects. But in rare cases, if the inflammation is severe, myocarditis can scar the heart muscle. Severe myocarditis weakens the heart so that the rest of the body doesn’t get enough blood. Blood clots can form in the heart, leading to a stroke or heart attack.^[1][2]

Important factors that affect how well someone recovers include the degree of left and right heart chamber dysfunction, heart block, and specific types of myocarditis. There’s also a possibility of myocarditis recurring in patients.^[7][17]

Researchers estimate there are about 1.5 million cases of myocarditis in the world each year. In 2021, 1.3 million cases of myocarditis were diagnosed worldwide.^[4][5]