Myocarditis
Also known as: Inflammatory Cardiomyopathy
Myocarditis is an inflammation of the heart muscle (myocardium), most commonly caused by viral infections, that can reduce the heart's ability to pump blood and cause abnormal heart rhythms. It ranges from mild, self-resolving illness to fulminant disease requiring mechanical circulatory support or heart transplantation. Myocarditis is an important cause of sudden cardiac death in young athletes.
Symptoms
Causes
- Viral infections (coxsackievirus B, adenovirus, parvovirus B19, SARS-CoV-2, influenza)
- Autoimmune and inflammatory conditions (giant cell myocarditis, sarcoidosis, lupus)
- Medications and toxins (immune checkpoint inhibitors, certain chemotherapy drugs, cocaine)
- Bacterial, fungal, or parasitic infections (less common)
Risk Factors
- Young adults and athletes
- Recent viral illness
- Autoimmune diseases
- HIV/AIDS
- Cancer treatment with immune checkpoint inhibitors
Diagnosis
- Cardiac MRI with gadolinium enhancement (preferred non-invasive test — Lake Louise criteria)
- Troponin and BNP/NT-proBNP blood tests (elevated in myocardial injury/heart failure)
- Echocardiogram to assess heart function
- ECG showing ST changes, arrhythmias, or conduction abnormalities
- Endomyocardial biopsy (gold standard, but rarely performed unless giant cell myocarditis or unclear diagnosis)
Treatment
- Supportive care and activity restriction until inflammation resolves
- Heart failure medications (ACE inhibitors, beta-blockers, diuretics) as needed
- Immunosuppressive therapy for giant cell myocarditis and autoimmune causes
- Antiarrhythmic medications or temporary pacing for significant arrhythmias
- Mechanical circulatory support (ECMO, ventricular assist device) for fulminant cases
- Avoidance of competitive sports for 3–6 months (per ACC/AHA guidelines)
Prevention
- Avoid vigorous exercise during and shortly after viral illnesses
- Prompt treatment of infections
- Influenza and COVID-19 vaccination (benefits outweigh myocarditis risk)
When to See a Doctor
- Chest pain with shortness of breath, especially after a recent viral illness
- Rapid or irregular heartbeat with lightheadedness
- New onset of fatigue and exercise intolerance
- Leg swelling with breathing difficulty
Frequently Asked Questions
Related Conditions
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