What is Acute Myocarditis (Inflammation of the Heart)?
Myocarditis is a condition where the heart muscle, or myocardium, becomes inflamed, leading to tissue damage or death. Once known as inflammatory myocarditis, it often affects younger people. There are different types of myocarditis: acute, fulminant, chronic active, and chronic persistent. Most cases are acute myocarditis, accounting for about 65% of all myocarditis cases, and it is usually caused by a viral illness. But, sometimes, non-infectious factors can also cause it. The inflammation could be localized to a certain area of the heart muscle or spread throughout.
The symptoms can vary, and may include fever, minor chest pain, irregular heartbeat, heart failure, heart-induced shock, or even death. Diagnosing myocarditis can be difficult, and the usual treatment approach involves providing support to manage the symptoms.
What Causes Acute Myocarditis (Inflammation of the Heart)?
Acute myocarditis, inflammation of the heart muscle, can have many causes and is generally divided into two categories: infectious and non-infectious. However, it’s worth noting that in half of the cases, the cause remains unidentified. When a cause is found, viral infections are often the culprit.
In terms of infectious causes:
- Viruses: The most common viruses linked with myocarditis include Coxsackie and echoviruses. Others include HIV, adenovirus, hepatitis B and C, Parvovirus B19, poliovirus, and Epstein-Barr virus.
- Bacteria: Certain bacteria like legionella, staphylococci, Salmonella, Shigella, streptococci, Clostridium, and tuberculosis are known to cause myocarditis.
- Parasites: Certain diseases caused by parasites, such as trichinosis and schistosomiasis, could also lead to myocarditis.
- Protozoa: Protozoan infections, like those caused by Trypanosoma cruzi (related to Chagas disease) and Toxoplasmosis gondii, can result in myocarditis.
- Spirochetes: These bacteria, including Borrelia burgdorferi, have also been linked to myocarditis.
Non-infectious causes include:
- A range of conditions, such as eosinophilic myocarditis (an uncommon form of myocarditis), systemic lupus erythematosus, polymyositis, and dermatomyositis (all auto-immune diseases).
- Cardiotropic drugs and broader systemic diseases like sarcoidosis, inflammatory bowel diseases, or giant cell arteritis can trigger myocarditis.
- Myocarditis could also be a complication of acute rheumatic fever, exposure to venoms and certain chemicals like hydrocarbons, or the body rejecting a heart transplant.
Risk Factors and Frequency for Acute Myocarditis (Inflammation of the Heart)
Acute myocarditis, or inflammation of the heart muscle, is a disease that varies greatly in how it shows up and is hard to diagnose as a result. This makes it difficult to get an accurate understanding of how common it is. We do know, however, that it tends to affect younger adults and seems to occur equally among men and women of all races. The parts of the world where it happens most can also differ widely.
- The Global Burden of the Disease report from 2019 states that the estimated rate of the disease is 6.1 out of every 100,000 people.
- Some estimates have reported the occurrence as high as 10 to 22 out of every 100,000 people, totaling around 1.5 million cases worldwide in 2013.
- About 5% of people who come down with a severe viral illness tend to also show signs of myocarditis.
- In patients who come to the doctor with chest pain similar to a heart attack, slightly raised levels of a heart protein called Troponin-I, and no signs of heart disease, as many as 13% were found to have myocarditis when examined using cardiac magnetic resonance imaging.
Signs and Symptoms of Acute Myocarditis (Inflammation of the Heart)
Acute myocarditis is a medical condition that can present itself in many ways. It can be as mild as showing no symptoms or causing a slight fever, to as serious as leading to sudden cardiac death. The onset and the progression of the condition can be either rapid or gradual, and it does not have any distinctive clinical symptoms that can confirm its presence immediately.
Common symptoms reported by patients could include fever, general discomfort, fatigue, chest pain, palpitations, labored breathing, or fainting spells. The chest pain they experience may be confused with the pain caused by pericarditis or severe central pain, which could remind one of the pain of acute coronary syndrome. Furthermore, prior to diagnosis of acute myocarditis, it is common to find a history of having a recent acute illness with fever, such as a respiratory infection, in nearly 60% of patients.
In severe cases, the symptoms are similar to that of serious heart failure, including shortness of breath, chest discomfort, palpitations, or fainting. It can also lead to unstable vital signs and life-threatening irregular heartbeats. In some cases, patients might show reduced left ventricular ejection fraction, persistent irregular heartbeats, or symptoms of reduced cardiac output.
Physical checks may show signs of heart failure, like a specific type of heart rhythm, lung rales, and swelling in the extremities. If the pericardium is involved, a frictional pericardial rub maybe audible upon checking the heart sounds. Patient showing heart enlargement may have a continuous murmur created by mitral valve regurgitation.
Apart from heart-related symptoms, patients may also show symptoms related to the systemic sickness that’s leading to the myocarditis. For example, they might present enlarged lymph nodes if they have sarcoidosis, rashes if they have eosinophilic myocarditis, or swift, jerky, involuntary movement, joint pain, and skin nodules if they have acute rheumatic fever. Patients suffering from Chagas disease, caused by Trypanosoma cruzi, may have difficulty swallowing, whereas neurological symptoms can be found in patients infected with diphtheria.
Testing for Acute Myocarditis (Inflammation of the Heart)
Diagnosing acute myocarditis can be difficult due to a variety of symptoms and similarities with other health issues. Young patients who experience signs of the disease but have no traditional risk factors for coronary artery disease should be particularly examined for the possibility of acute myocarditis. If patients have recently experienced an illness with fever or display signs of connective tissue disease, this could advance the suspicion of myocarditis.
A broad set of tests and procedures exist to aid in diagnosing and evaluating acute myocarditis:
1. A complete blood count can be useful, especially if there’s an increase in a type of white blood cell called “eosinophils”.
2. Levels of substances released by the body when inflammation is present, such as C-reactive protein, interleukin, or interferon could also be tested.
3. Heart-specific proteins like Troponin-I or T levels can be high in more than half the patients with confirmed myocarditis. Another substance, called a pro-Brain natriuretic peptide, may also be higher than normal.
4. An Electrocardiogram (EKG) can show a variety of irregularities in the heart’s function that can signify myocarditis. In some cases, the changes in the EKG reading may suggest a serious heart condition.
5. Chest X-rays can also be helpful to evaluate your heart’s size and detect any issues in the lungs. However, X-rays aren’t especially diagnostic of myocarditis.
6. An echocardiogram which uses sound waves to produce a live image of your heart, can evaluate the level of damage and check for diseases affecting the heart valves or clots within the heart.
7. Cardiac magnetic resonance imaging (MRI) is emerging as a useful tool for evaluating suspected myocarditis. This scan helps visualize specific areas of inflammation within the heart.
8. Coronary angiography, a kind of X-ray that looks at the blood vessels in your heart, can be very useful in ruling out coronary artery disease.
9. In some cases, the body’s response to a virus can be measured by looking at antibody levels, but this is not frequently done.
10. An endomyocardial biopsy, a procedure where a small sample of heart tissue is taken for examination, is the most reliable method for diagnosing myocarditis. However, it is often bypassed due to its invasive nature and potential for variability in results.
Treatment Options for Acute Myocarditis (Inflammation of the Heart)
The primary aim of managing acute myocarditis is to support the heart and maintain the patient’s health. There are several steps taken to ensure this:
The first is managing heart failure (HF). This involves using medications like beta-blockers, renin-angiotensin-aldosterone (RAAS) inhibitors, mineralocorticoid receptor antagonists (MRA), sodium-glucose co-transporter-2 inhibitors, and diuretics. Depending on the patient’s cardiovascular health, different steps may be needed. If a patient has sudden heart failure, for instance, doctors might halt beta-blockers and use diuretics. If the patient is stable and has a malfunctioning left ventricle, a renin-angiotensin-aldosterone inhibitor is usually initiated swiftly. A beta-blocker is then started once the patient’s condition allows. If the patient’s heart failure is severe, devices like an intra-aortic pump or a left ventricular assist device may be used.
The second step is managing any irregular heart rhythms. Myocarditis often leads to abnormal heart rhythms like atrial or ventricular arrhythmias or complete heart block. For patients with a fast but stable heart rhythm and no indications of poor blood supply to the body, beta-blockers can be used. Amiodarone and dofetilide are alternatives for sustained ventricular arrhythmias. If a patient’s heart block is severe, a temporary or permanent pacemaker could be fitted. Once the acute illness is under control, the patient may receive an implantable cardioverter defibrillator if necessary.
The third step involves using other medications. Immunosuppressive therapy is usually avoided because it hasn’t shown to provide noticeable benefits, except in patients with certain systemic autoimmune or inflammatory diseases. Antiviral therapy, used to combat viral causes of myocarditis, is not routinely used either as its effectiveness is uncertain. Use of non-steroid anti-inflammatory drugs is also avoided as they could potentially hinder the healing of heart muscle tissues. Blood thinning medication is only used in patients with evidence of a clot in the heart or those who have irregular heartbeats.
Lastly, lifestyle changes are recommended for patients with acute myocarditis. Exercise is to be avoided, particularly competitive sports, for at least 3-6 months after onset. Future exercise and activity recommendations will depend on regular follow-up appointments for clinical assessment, echocardiograms, and heart monitoring. Patients are also advised to limit alcohol consumption to one drink per day.
What else can Acute Myocarditis (Inflammation of the Heart) be?
Here are some conditions that a person might have instead of, or along with, a heart attack:
- Sudden severe heart condition (acute coronary syndrome)
- Narrowing of the heart arteries (coronary vasospasm)
- Heart muscle damage due to stress (stress cardiomyopathy)
These conditions can show symptoms very similar to those of a heart attack and need to be considered when making a diagnosis.
What to expect with Acute Myocarditis (Inflammation of the Heart)
The outcomes for heart conditions can vary greatly depending on the severity and underlying cause of the disease. Factors such as severe heart failure, sustained irregular heartbeats, and reduced function of the left side of the heart (less than 50%), all lead to higher chances of adverse cardiovascular outcomes. Other conditions that account for worse results are the need for heart-stimulating drugs, medicines to increase blood pressure, or support from mechanical heart devices.
People who manage to survive the early stages of the disease generally have more positive outcomes. However, long-term observation reveals that at least half of these patients develop heart muscle disease. The one-year mortality rate for acute myocarditis, a condition that involves inflammation of the heart muscle, is 20%, and this increases to 56% within four years.
The prognosis for patients with fulminant myocarditis, a severe form of the aforementioned disease, is worse. These patients have higher mortality rates and lower chances of survival without needing a transplant. If the viral genome that caused the condition persists, the prognosis worsens and determines the effectiveness of treatment. The prospects for eosinophilic myocarditis and giant cell myocarditis patients are also less favorable. However, those who show a soluble Fas-ligand, a protein that controls immune system responses, at the onset of the disease, generally have better outcomes, while those with anti-myosin autoantibodies have worse outcomes.
Possible Complications When Diagnosed with Acute Myocarditis (Inflammation of the Heart)
- Left ventricle, or main pumping chamber of the heart, not working properly
- Right ventricle, or secondary pumping chamber of the heart, failing
- Irregular heartbeat, also known as arrhythmia
- Possibility of death
Preventing Acute Myocarditis (Inflammation of the Heart)
Patients need to understand that the symptoms of this disease can vary from person to person. They should be alert to new symptoms such as fever, tiredness, shortness of breath during exercise or when lying down, heart palpitations, or fainting. If they experience any of these, it is advisable to seek further medical evaluation.
Typically, diagnosing this illness takes time since doctors need to rule out other diseases and carry out a range of tests. The process involves teamwork from various healthcare professionals, including a heart doctor (cardiologist), a heart imaging specialist, a procedure specialist for potential mechanical support procedures, a heart failure expert, and a rehabilitation specialist.
During recovery from a severe inflammation of the heart (acute myocarditis), regular rehabilitation is necessary. It’s important for patients to recognize that recovery may vary – some people may regain normal heart function after the acute illness, while others might not completely recover and might need lifelong heart medication.
