Viral Myocarditis

What is Viral Myocarditis?

Myocarditis is a condition that causes inflammation in the heart muscle, which can develop in different patterns and spread to varying degrees. Myocarditis can appear suddenly, take some time to develop, or be a long-lasting condition. The symptoms can range widely and may include feelings of exhaustion, chest pain, heart failure, irregular heartbeats, and even sudden cardiac arrest.

In the United States and other developed countries, viral infections are the most common cause of myocarditis. In developing countries, it can be caused by rheumatic heart disease, Chagas disease, or complications from late-stage HIV/AIDS. Other causes might be toxic myocarditis, related to certain medications that can cause a more hidden form of the condition. The exact number of people affected by myocarditis is unclear due to its varied causes and presentations.

Myocarditis is typically diagnosed based on the patient’s symptoms and confirmed by taking a small piece of heart tissue to examine under a microscope (a procedure called an ‘endomyocardial biopsy’). This procedure looks for specific changes in the tissues and cells that can indicate inflammation.

It’s important to know that myocarditis can happen even in a healthy person and lead to worsening heart failure very quickly. It can be acute, which means it lasts less than two weeks, or chronic, meaning it continues for more than two weeks.

What Causes Viral Myocarditis?

Myocarditis, or inflammation of the heart muscle, can be caused by a variety of factors. Viruses are typically the most common cause. In North America and Europe, parvovirus B-19 and human herpesvirus 6 (HHV 6) are most frequently involved. Other viruses, like Epstein-Barr virus, enterovirus, human cytomegalovirus, and adenovirus can also cause myocarditis. Recent cases linked to COVID-19 and influenza have also been reported.

However, it’s not just viruses. Myocarditis can be caused by bacteria, fungi, and certain types of parasites and worms. There are non-infectious causes as well, such as autoimmune disorders, where your body mistakes its own healthy cells as foreign and attacks them, causing inflammation. Examples include systemic lupus erythematosus, Wegener granulomatosis, and giant cell arteritis, which are all types of autoimmune diseases.

In some people, viral particles can be detected in biopsy samples from the heart muscle. However, in almost 50% to 80% of myocarditis cases, no specific cause is identified.

The heart muscle damage in myocarditis can occur in several ways:

* Direct harm from the infection or other cause.
* An immune response triggered by the infection, causing further harm.
* Release of certain chemicals in the heart muscle known as cytokines, leading to inflammation.
* Early or abnormal cell death, also known as apoptosis.

Risk Factors and Frequency for Viral Myocarditis

Myocarditis, or inflammation of the heart muscle, is a condition that affects about 1.5 million people around the world each year, but the exact number is likely higher since many cases don’t have noticeable symptoms and go undiagnosed. This is especially true in the United States, where many cases are not recognized because people don’t feel sick enough to seek medical care. It has been found that the Coxsackie B virus, a common cause of myocarditis, often does not cause any symptoms and the disease usually follows a non-threatening course.

The disease can occur in people of all ages, but mostly affects those who are young and previously healthy. It is also more likely to affect children, pregnant women and people with weakened immune systems. In some cases, 1% to 5% of all patients with acute viral infections might end up with myocarditis.

The link between myocarditis and COVID-19 is still being researched and the exact numbers are hard to determine. However, studies have shown that cardiac injury occurred in 19% to 28% of COVID-19 patients in Wuhan, China, and those with heart damage generally had worse outcomes. In another study, it was found that 5% of COVID-19 patients had new cases of myocarditis, and the overall death rate after 6 months was 3.9%. People with COVID-19 have a 16 times higher risk of developing myocarditis compared to those without the virus. It is also important to note that the rate of myocarditis in patients hospitalized with COVID-19 significantly increased from 2020 to 2021.

There has been some concern about myocarditis occurring after receiving the COVID-19 mRNA vaccines, but the likelihood seems to be extremely low, at just 0.3 to 5 cases per 100,000 people in the United States and Israel. This most often occurs in young men within a week after the second dose, with the symptoms usually resolving on their own. Moreover, the risk of developing myocarditis from a COVID-19 infection appears to be 100 times higher than the risk from the mRNA vaccines.

Signs and Symptoms of Viral Myocarditis

Viral myocarditis often affects young men and its symptoms can vary a lot. Normally, affected individuals have a history of light flu-like symptoms. These can include a fever, fatigue, muscle pain, vomiting, and diarrhea. In rare cases, patients may experience severe symptoms like breathlessness at rest, palpitations, and sudden heart failure.

It’s common for adults to have chest pain, difficulty breathing, and show several other symptoms like feeling faint, rapid heart rate, and rapid breathing. In some cases, individuals may experience low blood pressure. Chest pain or heart failure symptoms usually indicate that the patient’s condition is serious.

Children’s symptoms often include abnormal breathing and pulling in of the chest wall with each breath they take. Infants typically experience severe symptoms, including a fever, low levels of oxygen leading to bluish skin, difficulty breathing or respiratory failure, and in some cases heart failure. Similar to adults, the severity of initial symptoms impacts their long-term outlook.

The European Society of Cardiology classified acute myocarditis into three types in 2013:

Acute heart disease-like symptoms, including chest pain, changes in the electrical activity of the heart, elevated heart muscle protein levels, and abnormalities in heart wall movement
New onset of progressive heart failure, which includes poor heart function, nonspecific changes in the electrical activity of the heart, heart blocks, or irregular heartbeats
Severe life-threatening conditions, such as low blood pressure requiring medications, mechanical life support, and severe irregular heart rhythms requiring defibrillation

Patients with severe myocarditis often need a heart transplant within five years due to a high rate of heart failure-related death.

The findings from a physical examination for myocarditis are similar to those from heart failure and can include a specific kind of heart rhythm, crackling sounds in the lungs, high heart rate, and swelling in the lower extremities.

Special forms of myocarditis include:

Sarcoid myocarditis, which presents with heart block and associated swelling of the lymph nodes
Giant cell myocarditis, which presents with fast heart rate and heart failure
Acute rheumatic fever, which presents with involuntary body movements, red rash, multiple joint inflammation, and skin lumps

Testing for Viral Myocarditis

If you are experiencing symptoms of myocarditis, your doctor will likely run several tests. These could include an ECG, which is a test that records the electrical activity of your heart. With myocarditis, many people have unusual ECG results such as a fast heartbeat (sinus tachycardia), complex heart rhythms (wide QRS patterns), faint heart signals (low voltage), delayed heartbeat (prolonged QT), inconsistent heartbeat (variable atrioventricular blocks), and signs mimicking heart attack (acute myocardial infarction patterns).

Your doctor might also want to check your blood for certain markers. For instance, if your troponin levels are high, it could mean that your heart muscle has been damaged. Other blood tests include complete blood count, erythrocyte sedimentation rate (ESR) – which measures how quickly your red blood cells settle at the bottom of a tube, and C-reactive protein (CRP) levels. High white blood cell and CRP levels or fast ESR might happen but don’t conclusively indicate myocarditis.

Your doctor may also want to test for certain kinds of viruses, like HIV, hepatitis, Epstein-Barr, coxsackievirus group B, and influenza. They could order a test called IgM titers and if they increase rapidly, it could suggest the presence of an infection in your body. These levels usually fall gradually as the disease progresses, so your doctor might want to repeat the test over time.

In addition to this, imaging tests such as Transthoracic echocardiogram (an ultrasound of the heart) or Cardiac MRI (Magnetic Resonance Imaging) might be used. The Transthoracic echocardiogram can generally show if the heart muscle is functioning well, if there’s motion in the heart walls and if the part of the heart called the left ventricle is working properly. But it’s often not adequate to diagnose myocarditis by itself because it doesn’t always show specific changes related to this disease.

On the other hand, a cardiac MRI offers a more detailed image of the heart and is the best noninvasive imaging tool for both diagnosis and follow-up of myocarditis. It looks for three main signs such as swelling (edema), inflammation (hyperemia and capillary leak), and heart muscle cell death (myocyte necrosis and fibrosis). There are also additional signs like changes in systolic left ventricular function and fluid around the heart (pericardial effusion).

In some cases, a different kind of test called an endomyocardial biopsy might be needed. This involves taking a small sample of heart tissue to examine under a microscope, though it’s not used very often because it’s invasive and doesn’t always affect the treatment plan.

Remember, all these tests are important tools that help your doctor assess your condition, monitor your progress and inform your treatment plan. If you have any questions or concerns about these tests, be sure to discuss them with your doctor.

Treatment Options for Viral Myocarditis

Myocarditis, or inflammation of the heart muscle, is primarily treated by supporting the patient’s body to maintain heart function. This includes limiting physical activity, controlling heart rhythm, and managing the symptoms of Congestive Heart Failure (CHF), a condition that happens when the heart can’t pump blood as well as it should.

If someone is suspected to have myocarditis, they should be admitted to the hospital, regardless of whether they have symptoms or not. This is so they can be closely monitored for heart rhythm problems and signals that the heart is struggling to function normally. Doctors will use a test called a transthoracic echocardiogram to look at the heart. If a patient has chest pain, the doctor may want to do a scan or a special examination of the heart’s arteries.

Patients with heart failure, a condition where the heart isn’t able to pump enough blood to meet the body’s needs, and problems with their heart’s chambers, should receive treatment according to current guidelines for heart failure. This could involve water pills (diuretics) and medication to help the heart beat more efficiently (inotropes). Additionally, long-term use of medications that relax and open up narrowed blood vessels (ACE inhibitors) would be advised.

Doctors advise avoiding heart-damaging drugs and anti-inflammatory painkillers (NSAIDs) as these can slow down the heart’s recovery and make inflammation worse. Some patients may need blood thinners. Also, it’s best to be careful when using drugs that control heart rhythm (antiarrhythmics) as these can have potentially harmful effects that worsen heart failure. The use of aspirin is uncertain for acute myocarditis, and beta-blockers, medications that slow the heart rate, should be avoided in patients with blocks in the heart’s electrical system. Heart block patients may need a temporary pacemaker, and if the symptoms last, they may need a permanent pacemaker before leaving the hospital.

During the active phase of the disease, it’s important that patients restrict their physical activity. In severe cases where the patient is in shock due to heart failure, assistance with machines like an intra-aortic balloon pump or the Impella system, which help pump blood around the body, might be needed.

However, multiple studies have not found any benefits to anti-viral and immune-suppressing treatments for myocarditis. Chronic viral myocarditis treatment is similar to the current guidelines for heart failure. Initial beliefs that viral myocarditis was completely curable have been challenged. The outlook for patients with myocarditis depends on the extent of inflammation and symptom severity. Severe cases may require a mechanical assist device and the patient may have to be considered for a heart transplant if a matching donor is found.

European guidelines suggest waiting until the active phase of inflammation has passed before putting in an automatic implantable cardioverter defibrillator (AICD) – a device that helps the heart maintain normal rhythm. Yet, recent studies showed that patients who had dangerous heart rhythm problems during their acute myocarditis and had an early AICD implant for protection had higher chances of severe heart rhythm problems in the following three years. Therefore, heart patients with rhythms like sustained ventricular tachycardia or ventricular fibrillation may benefit from having an AICD implanted before leaving the hospital. Patients with a specific level of heart function should leave the hospital with a wearable heart rhythm device and receive the best possible medical treatment before being reevaluated for an AICD after 3 months.

Patients with minor symptoms tend to get better on their own, but full recovery can take several months. Regular heart checks with echocardiograms are crucial. If the patient fails to improve, a referral to a specialist heart center for consideration of supportive devices or a heart transplant may be necessary.

When diagnosing myocarditis, doctors need to be sure they aren’t dealing with other conditions that could cause similar symptoms. These conditions could include:

Carnitine deficiency
Coarctation of the aorta
Coronary artery anomalies
Cardiac tumor
Dilated cardiomyopathy
Endocardial fibroelastosis
Enteroviral infections
A genetic disorder called von Gierke disease
Another genetic condition called glycogen-storage disease type II
Medial necrosis of coronary arteries
Nonviral myocarditis
Shock
Valvar aortic stenosis
Viral pericarditis

Each of these conditions require different treatments, so it’s essential for the doctor to accurately diagnose the cause of the symptoms.

What to expect with Viral Myocarditis

People with a mild case of myocarditis, an inflammation of the heart muscle, usually have a good chance of recovery. However, factors like low ejection fraction (a measure of the amount of blood pumped out of the heart), left bundle branch block (a condition that slows down the electrical signals that make your heart beat), and syncope (fainting spells) can negatively affect the prognosis. Complications can include the development of varying degrees of heart block, a condition which may require a device to regulate heart beating. In its most serious form, myocarditis can lead to heart failure (cardiogenic shock), which is the most common cause of death associated with this condition, particularly in women after childbirth.

Cardiac MRI, a type of imaging scan that takes detailed pictures of the heart, is an effective tool for predicting complications and diagnosing viral myocarditis. When the scan shows certain changes (referred to as LGE) within the first five days of the onset of symptoms, it is closely linked to poor outcomes such as sudden cardiac death, severe irregular heartbeats, hospitalization, and heart transplants, even in those with a normal measure of heart function or LVEF. If these changes persist on subsequent scans without the presence of swelling, it suggests permanent scarring of the heart tissue, indicating a poor prognosis.

Another measure called the global longitudinal strain, evaluated with echocardiography (an ultrasound of the heart) and cardiac MRI, is useful for prognosis. In myocarditis, a decrease in this measure can predict a higher risk of irregular heartbeats in the future. Negative outcomes are associated with the presence of LGE changes and decreased global longitudinal strains, while the absence of these changes is generally a positive sign.

Patients with a severe form of myocarditis called fulminant myocarditis can have a favorable long-term prognosis if the disease is caught and treated early with supportive care. One study demonstrated a survival rate of 93% at 11 years in such cases. For those with less severe disease, the prognosis was still generally good, with survival rates ranging from 56% to 83% over a span of 3 to 5 years.

Possible Complications When Diagnosed with Viral Myocarditis

High amounts of physical activity during an acute stage of myocarditis may increase the risk of sudden heart death. So, professional athletes should avoid taking part in competitive events for about 3 to 6 months from the start of their myocarditis. This applies no matter what, regardless of how severe it is, their age, or their gender. Before returning to competitive sports, they should have a thorough medical evaluation and testing.

Dangerous irregular heartbeats should be appropriately treated with an AICD, a device that can correct these heartbeats. The most common reason for these irregular heartbeats during acute myocarditis could be due to reasons like

the body breaking down cells in response to an infection
inflammatory changes
an increase in swelling
release of signaling proteins that cause inflammation
problems with pathways connecting cells
abnormal handling of calcium due to problems with iron channels

Also, Long-term myocarditis can also result in irregular heartbeats due to prolonged inflammation, scar formation, and issues with the ventricles, the main pumping chambers of the heart.

Recovery from Viral Myocarditis

Regular check-ups every 3 months are important because recovery can take months or even years. For those who have received a heart transplant, it’s essential to stay connected with their transplant team for appropriate aftercare.

Preventing Viral Myocarditis

It’s important for patients to understand the need for vaccines against diseases like measles, rubella, polio, influenza, and mumps. Vaccines help to protect against these diseases. For those dealing with heart failure, doctors often recommend a diet low in salt. This helps to manage fluid buildup, which can worsen heart failure. Additionally, they should avoid hard physical activities to prevent putting added stress on the heart.

Frequently asked questions

Viral myocarditis is a condition that causes inflammation in the heart muscle and is the most common cause of myocarditis in the United States and other developed countries.

In almost 50% to 80% of myocarditis cases, no specific cause is identified.

The signs and symptoms of Viral Myocarditis can vary depending on the age group affected. Here are the signs and symptoms for different age groups: For adults: - Chest pain - Difficulty breathing - Feeling faint - Rapid heart rate - Rapid breathing - Low blood pressure - Severe symptoms like breathlessness at rest, palpitations, and sudden heart failure indicate a serious condition For children: - Abnormal breathing - Pulling in of the chest wall with each breath - Fever - Bluish skin due to low levels of oxygen - Difficulty breathing or respiratory failure - Heart failure in some cases - Severity of initial symptoms impacts long-term outlook For infants: - Fever - Bluish skin due to low levels of oxygen - Difficulty breathing or respiratory failure - Heart failure in some cases - Severity of initial symptoms impacts long-term outlook In general, affected individuals may also have a history of light flu-like symptoms such as: - Fever - Fatigue - Muscle pain - Vomiting - Diarrhea It's important to note that chest pain or heart failure symptoms usually indicate a serious condition. Additionally, severe myocarditis can lead to a high rate of heart failure-related death, and patients may require a heart transplant within five years.

Viral myocarditis can be caused by various viruses, including parvovirus B-19, human herpesvirus 6 (HHV 6), Epstein-Barr virus, enterovirus, human cytomegalovirus, adenovirus, and viruses associated with COVID-19 and influenza.

The doctor needs to rule out the following conditions when diagnosing Viral Myocarditis: - Carnitine deficiency - Coarctation of the aorta - Coronary artery anomalies - Cardiac tumor - Dilated cardiomyopathy - Endocardial fibroelastosis - Enteroviral infections - A genetic disorder called von Gierke disease - Another genetic condition called glycogen-storage disease type II - Medial necrosis of coronary arteries - Nonviral myocarditis - Shock - Valvar aortic stenosis - Viral pericarditis

The types of tests needed for viral myocarditis include: - ECG (Electrocardiogram) to record the electrical activity of the heart and detect any abnormalities. - Blood tests to check for markers such as troponin levels, complete blood count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels. - Testing for certain viruses like HIV, hepatitis, Epstein-Barr, coxsackievirus group B, and influenza using IgM titers. - Imaging tests such as Transthoracic echocardiogram (ultrasound of the heart) and Cardiac MRI (Magnetic Resonance Imaging) to assess the heart's function and look for specific changes related to myocarditis. - In some cases, an endomyocardial biopsy may be needed to examine a small sample of heart tissue under a microscope.

Viral myocarditis is primarily treated by supporting the patient's body to maintain heart function. This includes limiting physical activity, controlling heart rhythm, and managing the symptoms of Congestive Heart Failure (CHF). Treatment for viral myocarditis is similar to the current guidelines for heart failure. Medications such as water pills (diuretics), inotropes to help the heart beat more efficiently, and ACE inhibitors to relax and open up narrowed blood vessels may be prescribed. It is important to avoid heart-damaging drugs, anti-inflammatory painkillers (NSAIDs), and drugs that control heart rhythm (antiarrhythmics) as they can slow down the heart's recovery and worsen inflammation. In severe cases, mechanical assist devices or a heart transplant may be necessary. Regular heart checks with echocardiograms are crucial for monitoring and evaluating the patient's progress.

When treating Viral Myocarditis, there are several side effects to consider. These include: - Slowing down the heart's recovery and worsening inflammation by using heart-damaging drugs and anti-inflammatory painkillers (NSAIDs). - Potentially harmful effects that worsen heart failure when using drugs that control heart rhythm (antiarrhythmics). - Uncertainty regarding the use of aspirin for acute myocarditis. - The need for caution when using beta-blockers in patients with blocks in the heart's electrical system. - The potential need for blood thinners in some patients. - The possibility of requiring a temporary pacemaker or a permanent pacemaker for patients with heart block. - The risk of severe heart rhythm problems in the following three years for patients who had an early AICD implant for protection during acute myocarditis. - The increased risk of sudden heart death with high amounts of physical activity during the acute stage of myocarditis, particularly for professional athletes. - The potential need for referral to a specialist heart center for consideration of supportive devices or a heart transplant if the patient fails to improve. - The possibility of irregular heartbeats due to prolonged inflammation, scar formation, and issues with the ventricles in cases of long-term myocarditis.

The prognosis for viral myocarditis can vary depending on the severity of the condition and the presence of certain factors. However, in general: - Patients with a mild case of viral myocarditis usually have a good chance of recovery. - Factors such as low ejection fraction, left bundle branch block, and syncope can negatively affect the prognosis. - Complications can include varying degrees of heart block, and in its most serious form, viral myocarditis can lead to heart failure (cardiogenic shock), which is the most common cause of death associated with this condition, particularly in women after childbirth. - Cardiac MRI and echocardiography can be useful tools for predicting complications and assessing prognosis.

You should see a cardiologist for viral myocarditis.