Myocarditis

Myocarditis is an inflammation of the heart muscle that can reduce the heart’s ability to pump blood effectively. While the condition affects thousands of people each year, many individuals and even some physicians are unfamiliar with it, making proper diagnosis and treatment essential for recovery.

Table of contents

• What is myocarditis
• Associated anatomy
• Symptoms and warning signs
• Causes and risk factors
• How myocarditis is diagnosed
• Treatment approaches
• Recovery and lifestyle changes

What is myocarditis

Myocarditis is inflammation of the heart muscle, called the myocardium^[1]. The condition can reduce the heart’s ability to pump blood and may cause chest pain, shortness of breath, and rapid or irregular heartbeats^[1]. Myocarditis is classified as a rare disease but is estimated to affect thousands of adults and children each year^[2]. Researchers estimate there are about 1.5 million cases of myocarditis in the world each year, which works out to 10 to 20 people affected out of every 100,000 people^[4].

The condition can develop suddenly, can be recurring, or it can be long-lasting^[5]. Some people with early myocarditis don’t have symptoms, while others have mild symptoms^[1]. People with myocarditis often feel fatigued, short of breath, chest pain or the sensation of their heart racing^[4]. They may feel these symptoms gradually over time, or their symptoms may happen very quickly^[4].

In severe cases, myocarditis weakens the heart so that the rest of the body doesn’t get enough blood. Clots can form in the heart, leading to a stroke or heart attack^[1]. However, most people will recover without any lasting effects. 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^[5].

Associated anatomy

• Heart muscle (myocardium)
• Heart chambers (right and left atria, right and left ventricles)

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^[2]. Two upper heart chambers called the right and left atria receive blood that returns to the heart from the body. 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^[2].

Symptoms and warning signs

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 at all. When they are present, symptoms may point to the viral infection itself or suggest other cardiac problems such as a heart attack^[2].

Common myocarditis symptoms include^[1][2]:

• Chest pain
• Fatigue
• Swelling of the legs, ankles and feet
• Rapid or irregular heartbeats, called arrhythmias
• Shortness of breath, at rest or during activity
• Lightheadedness or feeling like you might faint
• Flu-like symptoms such as headache, body aches, joint pain, fever or sore throat
• Heart palpitations
• A sudden loss of consciousness

Sometimes, myocarditis symptoms are like symptoms of a heart attack. If you are having unexplained chest pain and shortness of breath, seek emergency medical help^[1].

When children get myocarditis, symptoms may include difficulty breathing, rapid breathing, chest pain, rapid or irregular heartbeats, fainting, and fever^[1]. Typical symptoms of myocarditis in children include chest pain and sometimes fever. More rarely, children may experience palpitations, dizziness, or lightheadedness, or may pass out^[6].

Causes and risk factors

Many times, the cause of myocarditis is unknown. Most often, the cause is a viral infection^[4]. 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^[2].

Viral infections that can cause myocarditis include^[4]:

• Flu
• Herpes virus six
• Adenovirus
• Coxsackie virus
• Parvovirus B19
• SARS-CoV-2 (COVID-19)

Other causes of myocarditis include^[2][4]:

• Bacteria
• Fungi (rarely)
• Chagas disease
• Rheumatic fever
• Autoimmune diseases like rheumatoid arthritis or lupus
• Things you’re exposed to, such as radiation or heavy metals
• Cancer, bacterial infections and other contagious diseases
• Exposure to environmental toxins ranging from metal poisons to spider and snake venom

Between 6% and 18% of myocarditis patients carry a genetic mutation associated with increased risk of cardiomyopathy^[2]. 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^[2].

Side effects from some medicines can bring about myocarditis. These medicines include medicines for your heart, antidepressants, medicines for seizures, antibiotics, medicines for weight loss, diuretics, benzodiazepines, and medicines for psychiatric problems^[4].

You’re more likely to get myocarditis if you’re a young adult, though people of all ages can get it. You’re also more likely to get it if you’re male, though females can get it too^[4]. Although you don’t inherit myocarditis, your genes influence how your body handles inflammation and how likely you are to get myocarditis^[4].

Currently there are no known lifestyle choices or medical treatments that can prevent myocarditis^[2].

Myocarditis and COVID-19

Several recent studies show that the COVID-19 virus and vaccines may cause myocarditis. An estimated three in every 1,000 patients hospitalized due to a COVID-19 infection may be at risk for developing acute myocarditis^[16].

In rare cases, myocarditis has happened in young people who received the Pfizer-BioNTech or Moderna vaccines for COVID-19. 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 and can get back to their regular activities when they feel better^[4]. However, if you’ve had myocarditis, check with a cardiologist before starting to exercise again. The CDC says the risk from COVID-19 is higher than the small risk of rare side effects like this, and continues to recommend the vaccine^[4].

How myocarditis is 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. Imaging tests can help confirm myocarditis and determine its severity^[7].

Myocarditis is diagnosed through a complete medical history and physical examination, as well as tests to specifically evaluate heart abnormalities^[6]. Tests to diagnose myocarditis include^[7]:

• 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. Your healthcare professional can look for signal patterns on an ECG to learn if you have irregular heartbeats.
• Chest X-ray: A chest X-ray shows the size and shape of the heart and lungs. A chest X-ray can tell if there’s fluid in or around the heart that might be related to heart failure.
• Heart MRI, also called a cardiac MRI: This test uses magnetic fields and radio waves to create detailed images of the heart. A cardiac MRI shows the heart’s size, shape and structure. It can help diagnose myocarditis.
• Echocardiogram: Sound waves create moving images of the beating heart. An echocardiogram can show the heart’s size and how well blood flows through the heart and heart valves. An echocardiogram can see if there’s fluid around the heart.
• 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. It’s guided to an artery in the heart. Dye flows through the catheter to help the heart arteries show up more clearly on X-rays.

Treatment approaches

Treatment for myocarditis may include medicines, procedures or surgeries^[1]. There is no cure at present for myocarditis. Physicians treat the disease’s symptoms, which can include tachycardia (rapid heart rate), arrhythmias and heart failure^[9].

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^[9]. Children with myocarditis are admitted to the hospital so they can be monitored for arrhythmias. In many cases, treatment is supportive and the heart muscle inflammation improves on its own with time. In other cases, children may receive anti-inflammatory medications to decrease heart muscle inflammation more rapidly^[6].

If the heart is severely weakened, medical devices can help restore proper functioning. These include defibrillators, 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^[9].

While these medications and devices may help alleviate cardiac 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^[9].

Although inflammation in myocardial disease can resolve spontaneously, often specific treatment directed against the causative agent is required. For viral cardiomyopathy and myocarditis, intravenous immunoglobulin treatments can frequently resolve inflammation^[11].

Recovery and lifestyle changes

Recovery times vary depending on the specific type of myocarditis diagnosed. It can take as little as a few months or up to seven years to fully recover from this condition. However, with the right treatment, most people will recover well from myocarditis. There’s also a possibility patients will not suffer from long-term effects on the heart^[19].

Some patients are able to fully recover from myocarditis, while others will experience long-lasting symptoms. Your physician may ask you to avoid competitive sports and other intense exercises for a time after diagnosis and treatment^[9]. As a general rule, physical activity should be avoided for at least three to six months after being diagnosed with myocarditis^[19].

Additionally, lifestyle changes are often recommended, including^[9]:

• A low-sodium diet
• Limited fluid intake
• Elimination of alcohol
• Smoking cessation

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. To ensure your hands are clean, use soap and wash them for at least 20 seconds. Using hand sanitizer and staying home when sick will also reduce your contact with germs^[12].

Healthcare providers may prescribe individuals with medicine after a diagnosis, dependent on any symptoms. Patients often take diuretics, ACE inhibitors, and beta-blockers to combat their symptoms. Your doctor may suggest you take pain relievers as well to ease any pain and to possibly prevent blood clots from developing^[12]. While many individuals require a short course of cardiovascular medications, others will need to take these medicines for life^[9].

You can also expect regular follow-up exams and tests to monitor your condition^[9]. 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^[19].

Eating heart-healthy foods like fruits, vegetables, nuts, and salmon is recommended. Refrain from consuming foods with high sodium counts, as well as saturated and trans fats. Refrain from caffeinated products and energy drinks which can stimulate your heart rate making it work harder and not allow it to heal as well^[12][13].