Introduction
Autoimmune myocarditis is a condition that affects the heart. This condition is described by inflammation of the heart muscle, known as the myocardium. The actual cause of this condition is unknown, but it has been found that it is caused when the immune system of the body mistakenly attacks the healthy tissues of the body. Moreover, clinical features such as myocardial damage and inflammation are similar to autoimmune myocarditis. Therefore, the symptoms and pathogenesis of autoimmune myocarditis will overlap with myocarditis in general.
What Is an Autoimmune Disease?
The immune system of the body helps in protecting the body against infections and disease by attacking harmful foreign organisms such as bacteria or viruses. The immune system detects and destroys these foreign objects before causing any problems. However, in the case of autoimmune diseases, the immune system of the body starts attacking the healthy cells of the body by mistake, as it cannot tell the difference between healthy and harmful invaders. The actual reason behind this behavior of the immune system is still unknown.
What Is Myocarditis?
Myocarditis is the inflammation of the heart muscle, known as the myocardium. The inflammation of this heart muscle can greatly affect the ability of the heart to pump blood. This can cause chest pain, shortness of breath, or irregular heart beating. In the case of severe myocarditis, the heart muscle can get seriously affected, which will cause a shortage of blood in the body and cause blood clots formation in the heart and cause a heart attack, which can be fatal.
What Are the Causes of Myocarditis?
Myocarditis may occur due to various conditions, such as drugs or infections. However, in some cases, the cause may be unknown.
Some of the common causes that lead to myocarditis include -
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Viruses - Various viruses can cause myocarditis, including adenovirus, Covid-19 virus, hepatitis B and C, herpes simplex virus, and parvovirus. Other infections, such as gastrointestinal infections caused by echoviruses, Epstein-Barr virus, and German measles, can also cause myocarditis.
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Bacteria - Different types of bacteria can cause myocarditis, including Staphylococcus and Streptococcus.
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Parasites - Such as Trypanosoma cruzi and Toxoplasma, can lead to myocarditis. These get transmitted via insects and can cause conditions such as Chagas disease.
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Fungi - A fungal infection may lead to myocarditis. This is mostly seen in people with weak immune systems, such as yeast infections (Candida), molds (Aspergillus), and Histoplasma.
Other uncommon causes of myocarditis include -
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Exposure to chemicals or radiation can lead to myocarditis.
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Certain medications or illegal drugs (drug-induced myocarditis) include anti-cancer drugs, antibiotics, and anti-seizure drugs.
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Other inflammatory disorders include lupus, giant cell arteritis, Wegener's granulomatosis, and Takayasu's arteritis.
What Are the Symptoms of Autoimmune Myocarditis?
Generally, people with early myocarditis do not show any symptoms, and some show mild symptoms, which include -
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Chest pain.
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Fatigue.
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Irregular heartbeats (arrhythmias).
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Rapid heartbeat (tachycardia).
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Shortness of breath.
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Light-headedness.
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Flu-like symptoms include body aches, joint pain, fever, or sore throat.
Symptoms of myocarditis in children include -
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Difficulty in breathing.
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Chest pain.
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Fever.
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Fainting.
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Rapid or irregular heartbeats (arrhythmias).
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Rapid breathing.
What Is the Epidemiology of Autoimmune Myocarditis?
The actual rate of myocarditis is difficult to determine. In most cases, laboratory tests and other investigations are not performed. However, it has been found that the annual incidence of myocarditis is approximately 17 per 100,000 people. Additionally, only two percent of the cases are found to be fatal, which is seen in severe forms of myocarditis. This fatal myocarditis is commonly seen in young adults with slight male predominance.
What Is the Diagnosis of Autoimmune Myocarditis?
The early diagnosis of myocarditis is essential to prevent long-term damage. The initial examination involves a physical examination in which the healthcare provider will examine the heart with the help of a stethoscope. Based on that, various tests can be performed, such as blood and imaging tests which helps in determining the severity of the condition. Some of the tests include -
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Blood Tests - These tests help determine the inflammation and infection in the body and the amount of damage done to the heart.
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Electrocardiogram (ECG) - This helps determine the pattern of heartbeat and irregular heartbeats (arrhythmias) can be found through this test.
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Chest X-Ray - The radiographic examination helps determine the size and shape of the heart.
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Heart MRI (Magnetic Resonance Imaging) - Another option by which the size, shape, and structure can be examined is via cardiac MRI, which gives more detailed images of the heart.
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Echocardiogram - In this test, sound waves are used to create moving images of the heart to check the blood flow and functioning of the heart and can help determine the presence of fluid around the heart.
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Heart Muscle Biopsy - A tiny sample of the heart muscle tissue is examined for inflammation or infection.
What Is the Treatment for Autoimmune Myocarditis?
The treatment for autoimmune myocarditis is the same as general myocarditis. The causes and symptoms of both these conditions are the same, but treatment is also the same. The treatment usually depends upon the severity and the type of myocarditis -
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Angiotensin-converting Enzyme (ACE inhibitors) - These drugs help lower blood pressure and remodel the heart muscle.
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Beta Blockers - Helps treat irregular heartbeat (arrhythmias) and remodel the heart muscle.
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Diuretics - Help decrease fluid accumulation in the body.
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Corticosteroids - Help reduce inflammation in the body.
Surgeries may also be done in serious cases, including heart transplantation.
What Are the Complications of Autoimmune Myocarditis?
Generally, myocarditis does not cause serious complications, but permanent damage to the heart muscle can occur in the severe form of myocarditis. Some of the common complications of myocarditis include -
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Heart Failure - In cases with untreated myocarditis, the heart muscle may weaken with time and stop pumping blood properly. In severe cases, heart transplantation may need to be done for heart failure.
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Heart Attack - If the heart muscle gets damaged and cannot pump blood and the blood starts collecting in the heart in the form of clots which can lead to blocking one of the arteries of the heart, causing a heart attack.
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Arrhythmia (Irregular Heartbeat) - Damage to the heart muscles can lead to irregular heartbeats, increasing the risk of stroke.
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Cardiac Death - In case of severe arrhythmias, the heart may stop beating, leading to sudden cardiac death without any treatment.
Conclusion
Most autoimmune myocarditis does not cause any serious complications and may resolve independently. Moreover, a person with myocarditis gets treated by taking medicines. However, in some cases, this condition can reoccur and cause the same symptoms that it causes in the initial stage.
