Myocarditis is an inflammatory condition of the heart muscle, or myocardium. This inflammation can enlarge and weaken the heart, reducing its ability to pump blood effectively. Over time, scar tissue may form, further straining the heart. The condition can develop suddenly or progress slowly, and while many cases are mild, severe instances can lead to significant heart problems.
Myocarditis Symptoms and Presentation
The signs of myocarditis differ depending on the cause and severity of the inflammation. Some individuals experience sharp or stabbing chest pain, similar to a heart attack, which can feel like pressure or tightness in the chest that spreads to the neck and shoulders.
Patients may also notice heart palpitations, which feel like a fluttering, racing, or pounding in the chest. These sensations can be a sign of an abnormal or fast heartbeat, known as an arrhythmia.
Shortness of breath, either during activity or at rest, is a frequent complaint. Many people also report significant fatigue and weakness that interferes with daily activities. As the heart’s pumping function becomes compromised, swelling (edema) in the legs, ankles, and feet can develop.
When a virus is the cause, myocarditis is often preceded by flu-like symptoms. These can include fever, headache, body aches, joint pain, and a sore throat. The appearance of these symptoms a week or two before chest pain or shortness of breath can indicate myocarditis.
Common Causes and Risk Factors
The most frequent trigger for myocarditis is a viral infection. When the body fights a virus, it produces cells that can release inflammatory chemicals into the heart muscle. Common culprits include coxsackievirus B, adenovirus, parvovirus B19, and human herpesvirus 6. Viruses such as influenza and SARS-CoV-2 (the virus causing COVID-19) are also recognized causes.
Other infections can also lead to myocarditis, though they are less common. These include bacteria like Staphylococcus and Streptococcus, fungi such as Candida and Aspergillus, and parasites like Trypanosoma cruzi, which causes Chagas disease. These pathogens provoke a similar inflammatory response.
Autoimmune diseases are another risk factor. In conditions like lupus and rheumatoid arthritis, the immune system can malfunction and attack heart muscle cells. This autoimmune response causes inflammation in the myocardium.
Exposure to certain toxins and drugs can induce myocarditis. These substances include illegal drugs like cocaine, specific prescription medications for chemotherapy or seizures, and environmental toxins such as heavy metals. All are capable of triggering inflammation in the heart muscle.
Myocarditis can occur as a rare side effect of certain vaccinations, including mRNA COVID-19 vaccines. However, this is an uncommon event. The risk of developing myocarditis from a COVID-19 infection is substantially higher than the risk from the vaccine.
The Diagnostic Process
Diagnosing myocarditis is challenging because its symptoms mimic other heart and lung conditions. A physician begins with a medical history and physical exam. A series of tests is required to confirm the diagnosis and rule out other possibilities.
Blood tests are a standard first step to look for elevated cardiac enzymes, like troponin, which are released when the heart muscle is damaged. Blood work also checks for markers of inflammation, such as C-reactive protein.
An electrocardiogram (ECG or EKG) records the heart’s electrical activity. This non-invasive test can detect abnormal rhythms or patterns that suggest the heart muscle is damaged or inflamed, showing how myocarditis affects the electrical system.
A chest X-ray can show the heart’s size and shape and reveal fluid in the lungs, a sign of heart failure. A cardiac MRI is especially useful as it can directly show inflammation, swelling, and scar tissue within the heart muscle, offering clear evidence of myocarditis.
The most definitive diagnostic tool is an endomyocardial biopsy. This invasive procedure involves collecting a small sample of heart muscle tissue to be examined under a microscope. The tissue is examined for the specific cellular patterns of inflammation that confirm myocarditis, but is reserved for severe cases.
Treatment and Management Approaches
The goals of myocarditis treatment are to reduce inflammation, manage symptoms, and address the underlying cause. Treatment is tailored to the individual’s severity and trigger. In many mild cases, the condition resolves with supportive care and rest.
If a specific infection is the cause, it will be treated directly, such as with antibiotics for a bacterial infection. For most viral causes, there is no direct cure, so treatment focuses on supporting heart function while the body fights the virus.
Medications are used to help the heart recover and function more efficiently. Doctors may prescribe drugs like ACE inhibitors, beta-blockers, or diuretics to reduce the heart’s workload and manage fluid retention, giving it time to heal.
To control the inflammation, corticosteroids or other immunosuppressant drugs may be administered. These are useful in cases linked to autoimmune diseases, as they calm the overactive immune response and help prevent further damage to the heart muscle.
Physical rest is a fundamental component of recovery. Patients are advised to avoid strenuous activities and competitive sports for several months to allow the heart muscle to heal completely. In severe cases, more advanced support may be needed, including a ventricular assist device (VAD) or, in rare instances, a heart transplant.