Myocarditis

Overview

Myocarditis is a rare but serious condition characterized by inflammation in the middle muscular layer of the heart wall, known as the myocardium. When the heart muscle becomes inflamed, it can disrupt the heart’s electrical system, resulting in abnormal or rapid heartbeats called arrhythmias. Myocarditis can also lead to the weakening of the heart muscle and the development of cardiomyopathy.

There are several causes of myocarditis, including viral infections, drug reactions, and general inflammatory conditions. In cases of severe myocarditis, the weakened heart muscle fails to pump sufficient blood to the rest of the body. This can lead to the formation of blood clots in the heart, which can result in stroke or heart attack.

The treatment for myocarditis typically involves a combination of medications, procedures, or surgeries aimed at reducing inflammation, managing symptoms, and supporting heart function.

Symptoms

Myocarditis can manifest with a range of symptoms, which can vary in severity from person to person. The common symptoms of myocarditis include:

• Chest pain
• Fatigue
• Swelling in the legs, ankles, and feet
• Rapid or irregular heartbeat (arrhythmias)
• Shortness of breath, both at rest and during physical activity
• Light-headedness or a feeling of faintness
• Flu-like symptoms, such as headache, body aches, joint pain, fever, or sore throat

When myocarditis occurs in children, the symptoms may include:

• Difficulty breathing
• Chest pain
• Fainting
• Fever
• Rapid breathing
• Rapid or irregular heart rhythms (arrhythmias)

If you experience symptoms of myocarditis that resemble a heart attack, such as unexplained chest pain, rapid heartbeats, or shortness of breath, it is crucial to contact your healthcare provider immediately. Seek emergency medical assistance or call for help if your symptoms are severe.

Causes

Potential causes of myocarditis include:

• Viruses: Several viruses have been associated with myocarditis, including those responsible for the common cold (adenovirus), COVID-19, hepatitis B and C, parvovirus (which causes fifth disease, a mild rash in children), and herpes simplex virus. Gastrointestinal infections (echoviruses), mononucleosis (Epstein-Barr virus), and German measles (rubella) can also lead to myocarditis. Additionally, HIV, the virus that causes AIDS, can cause myocarditis.
• Bacteria: Certain bacteria can cause myocarditis, such as staphylococcus, streptococcus, and bacteria that cause diphtheria and Lyme disease.
• Parasites: Parasites like Trypanosoma cruzi and toxoplasma can cause myocarditis. Some parasites are transmitted by insects and can lead to Chagas disease, which is more prevalent in Central and South America than in the United States.
• Fungi: Myocarditis can be caused by fungal infections, especially in individuals with weakened immune systems. Yeast infections like candida, molds such as aspergillus, and histoplasma commonly found in bird droppings are among the fungi associated with myocarditis.
• Certain medications or illegal drugs: Myocarditis can be induced by certain medications, including those used for cancer treatment, antibiotics like penicillin and sulfonamides, some anti-seizure medications, and cocaine.
• Chemicals or radiation: Exposure to substances like carbon monoxide and radiation can occasionally lead to inflammation of the heart muscle.
• Other inflammatory diseases: Inflammatory conditions such as lupus, Wegener’s granulomatosis, giant cell arteritis, and Takayasu’s arteritis may cause myocarditis.
• COVID-19 vaccine: Rare cases of myocarditis have occurred in young individuals after receiving the Pfizer-BioNTech® or Moderna® COVID-19 vaccines. Most recover quickly with treatment and can resume regular activities but should consult a cardiologist before exercising. CDC recommends vaccination for young people, considering COVID-19 a greater risk than vaccine side effects.