Viral Myocarditis
Viral myocarditis is an inflammation of the heart muscle caused by viral infections. While it can affect anyone, this condition most commonly strikes otherwise healthy young adults and can range from mild cases with no symptoms to severe complications that require urgent medical attention.
Table of contents
- What is viral myocarditis?
- What causes viral myocarditis?
- Symptoms and warning signs
- Who is at risk?
- How is it diagnosed?
- Treatment and recovery
- Possible complications
- Prevention and reducing your risk
- Living with viral myocarditis
What is viral myocarditis?
Viral myocarditis is an inflammatory disease of the heart muscle, known as the myocardium. The inflammation can affect the heart either in small areas or throughout the muscle, making it harder for the heart to pump blood effectively[1].
- Heart muscle (myocardium)
This condition can develop in three different ways. Acute myocarditis occurs suddenly and lasts less than two weeks. Subacute myocarditis develops more gradually, while chronic myocarditis persists for more than two weeks[1]. The involvement of the heart muscle can be either focal, affecting only specific areas, or diffuse, spreading throughout the heart[1].
Viral myocarditis is relatively uncommon but affects a significant number of people worldwide. Researchers estimate approximately 1.5 million cases occur globally each year, which translates to about 10 to 20 people out of every 100,000[4][10].
What causes viral myocarditis?
In the United States and other developed countries, viral infections are the most common cause of myocarditis[1]. The virus infects the heart muscle and triggers an inflammatory response in the body. While the immune system works to fight off the virus, this process can inadvertently damage the heart tissue[3].
In North America and Europe, the viruses most frequently responsible for myocarditis are parvovirus B-19 and human herpesvirus 6 (HHV 6). Other common viral causes include Epstein-Barr virus, enterovirus, human cytomegalovirus, adenovirus, and Coxsackievirus[1][3].
Additional viruses that can lead to myocarditis include the flu virus, herpes virus, rubella (German measles), varicella (chickenpox), mumps, measles, and hepatitis A and C[4]. More recently, SARS-CoV-2, the virus that causes COVID-19, has also been linked to myocarditis[3][4].
The inflammation typically occurs during the viral infection or shortly afterward. In many cases, people have no preceding symptoms of a cold, cough, nasal congestion, or rash and only become aware of the infection when heart problems develop[15].
Symptoms and warning signs
The symptoms of viral myocarditis can vary widely from person to person. Some people experience no symptoms at all, while others may have mild to severe manifestations[2][4].
Common symptoms in adults include chest pain or pressure, which affects more than one-third of patients[19]. Many people experience fatigue and notice a significant decrease in their ability to perform physical activities[1][3]. Shortness of breath, especially during activity or when lying down, is another frequent complaint[2].
Other symptoms may include rapid or irregular heartbeats, called arrhythmias, which may feel like the heart is racing or fluttering. Some people experience lightheadedness, fainting, swelling in the legs, ankles and feet, and fever[2][4]. Flu-like symptoms such as headache, body aches, joint pain, or sore throat may also occur[2].
When children develop myocarditis, symptoms can include difficulty breathing, rapid breathing, chest pain, rapid or irregular heartbeats, fainting, and fever[2].
Because myocarditis symptoms can sometimes resemble those of a heart attack, anyone experiencing unexplained chest pain and shortness of breath should seek emergency medical help immediately[2].
Who is at risk?
Viral myocarditis can affect anyone of any age, but it most commonly occurs in otherwise healthy young adults[19]. The condition is slightly more prevalent in men than in women[8].
Some factors that increase the risk of developing myocarditis cannot be changed. People whose bodies don’t react well to inflammation may be more susceptible, as genes influence how the body handles inflammation and the likelihood of developing myocarditis[4].
Consuming more alcohol than recommended by healthcare providers can increase risk[4]. Certain medical treatments also elevate the risk, including dialysis, implanted heart devices, radiation, and treatments for heart problems[4].
How is it diagnosed?
Early diagnosis of myocarditis is important for preventing long-term heart damage[7]. Diagnosis begins with a medical history review and physical examination. A healthcare professional will listen to the heart with a stethoscope and look for signs of heart problems[7].
Several tests may be used to diagnose myocarditis. Blood tests are commonly performed to check for signs of a heart attack, inflammation, and infection. A cardiac enzyme test can detect proteins related to heart muscle damage, while antibody blood tests may help determine if there was an infection linked to myocarditis[7].
An electrocardiogram (ECG or EKG) is a quick and painless test that shows how the heart is beating. Healthcare professionals can examine signal patterns on an ECG to identify irregular heartbeats[7].
A chest X-ray shows the size and shape of the heart and lungs and can reveal if there is fluid in or around the heart that might be related to heart failure, a condition where the heart cannot pump enough blood to meet the body’s needs[7].
Cardiac magnetic resonance imaging (MRI) uses magnetic fields and radio waves to create detailed images of the heart. This test shows the heart’s size, shape, and structure and can help diagnose myocarditis[7][8].
An echocardiogram uses sound waves to create moving images of the beating heart. It can show the heart’s size and how well blood flows through the heart and heart valves, and can detect fluid around the heart[7].
In some cases, doctors may perform cardiac catheterization and heart muscle biopsy. A thin, flexible tube called a catheter is placed into a blood vessel in the arm or groin and guided to an artery in the heart. During this procedure, a small tissue sample may be taken from the heart muscle for examination[7]. This biopsy is classically used to confirm the diagnosis through established histologic, immunologic, and immunohistochemical criteria[1].
Treatment and recovery
The treatment for viral myocarditis depends on the severity of the condition. Many cases of acute viral myocarditis caused by viruses like coxsackievirus clear up on their own within a few days or weeks, leaving no negative health effects[19].
The most important aspect of treatment is cardiac rest for three to six months to allow the heart to heal. This means no exercise, no lifting weights, and no sports[3]. Simple walking on flat surfaces for short periods of time is usually allowed once the person feels better, but this depends on the specific case and the recommendations of the cardiologist[3]. Cardiac rest is crucial so that the heart muscle can focus on keeping the person alive without being pushed to work harder than necessary during the healing period[3].
Treatment is mainly symptomatic in nature[3]. Healthcare providers may prescribe various medications depending on the symptoms. These can include anti-inflammatory drugs, antiviral medications, medications to manage heart failure, drugs to control blood pressure, and medicines to regulate abnormal heart rhythms[3].
Patients may need to take diuretics, which help remove excess fluid from the body, ACE inhibitors, and beta-blockers to combat symptoms. Pain relievers may be suggested to ease discomfort and possibly prevent blood clots from developing[11]. If prescribed blood thinners, it is essential to take them exactly as instructed and to inform other healthcare providers about this medication[11].
In severe cases, patients may require mechanical support for the heart or even a heart transplant[3].
Possible complications
While many people recover completely from viral myocarditis, some may experience complications. The presentation can vary greatly in symptomatic patients, ranging from generalized fatigue and malaise to more serious conditions like congestive heart failure (CHF), cardiogenic shock (a condition where the heart suddenly cannot pump enough blood), arrhythmias, and cardiac arrest[1].
Myocarditis can occur in an otherwise healthy person and quickly result in progressive heart failure[1]. Severe myocarditis weakens the heart so that the rest of the body doesn’t get enough blood. Blood clots can form in the heart, leading to a stroke or heart attack[2].
If left misdiagnosed or untreated, viral myocarditis can lead to dilated cardiomyopathy or chronic heart failure[3]. Some people develop long-lasting or chronic myocarditis that can cause serious complications[19].
In rare cases, approximately 6 to 14 percent of sudden cardiac death events in athletes are attributed to myocarditis[16]. The mechanism by which myocarditis causes sudden cardiac death is attributed to both focal cellular electrical instability and reduced blood flow to heart tissue, leading to dangerous heart rhythms or sometimes heart block[16].
Prevention and reducing your risk
Currently, there are no known lifestyle choices or medical treatments that can prevent myocarditis[10][11]. However, there are steps you can take to reduce your risk of developing the condition.
Since viral infections are the most common cause, limiting contact with germs is important. Washing your hands regularly is a simple and effective way to prevent infections. To ensure hands are clean, use soap and wash them for at least 20 seconds. Using hand sanitizer and staying home when sick will also reduce contact with germs[11].
Getting vaccinated is another step to staying healthy. Medical professionals suggest people get the flu shot every year and the pneumonia vaccine every five years[11].
Reducing sodium intake can help, as eating high amounts of salt can increase blood pressure[17]. Consuming a diet low in sodium, saturated fats, and trans fats while emphasizing heart-healthy foods like fruits, vegetables, nuts, and salmon is recommended[11][12].
Reducing alcohol consumption is also important. Men should limit themselves to two drinks a day, and women should confine themselves to one drink to maintain heart health[11]. Abstaining from smoking is crucial, as cigarettes contain chemicals that can damage the heart and potentially cause further complications[11].
Refraining from caffeinated products and energy drinks, which can stimulate heart rate and make the heart work harder, allows better healing[11].
Living with viral myocarditis
After a diagnosis of viral myocarditis, lifestyle adjustments can help support recovery and prevent further complications. While lifestyle does not impact the chances of getting myocarditis, it will influence the experience with the disease after diagnosis[11].
The doctor may recommend decreasing physical activity and avoiding rigorous athletic activities like heavy lifting or competitive sports for three to six months to allow the heart to heal[11]. Before returning to sports or intense exercise after acute myocarditis, it is important to check with a cardiologist[4].
Adjusting your diet to include heart-healthy foods is beneficial. Eating nutrient-dense foods supports the heart’s healing process and reduces the risk of further inflammation[12]. A nutritionist or dietitian can help develop a personalized meal plan that supports recovery[12].
Patients should take all prescribed medications exactly as instructed and report any side effects to their doctor. It is important to inform healthcare providers about all other medications or vitamins being taken, as many can interfere with prescribed treatments[11].
Most people will recover without any lasting effects from viral myocarditis[13]. However, some people will have more serious complications and will need specialist treatment. With effective treatment, most people make a very good recovery[13].
