Myokarditis

Myokarditis, also known as myocarditis, is an inflammation of the myocardium, the muscular layer of the heart. It can result from infections, immune-mediated processes, or exposure to cardiotoxic substances. Viral infections are a common cause, with enteroviruses, adenovirus, parvovirus B19, and others implicated; bacteria, fungi, and parasites may also be involved. Autoimmune diseases such as systemic lupus erythematosus, sarcoidosis, hypersensitivity reactions, and toxic exposures (alcohol, cocaine, chemotherapy, immune checkpoint inhibitors) are recognized causes.

Clinical features vary from mild to fulminant. Patients may present with chest pain, fatigue, dyspnea, palpitations, or syncope. Signs of heart failure or arrhythmias can occur; fever may be present with infectious etiologies.

Diagnosis is based on history, exam, and tests. Electrocardiography may show non-specific or arrhythmic changes; troponin is often elevated. Echocardiography assesses ventricular function. Cardiac MRI can reveal edema and late gadolinium enhancement. Coronary angiography excludes obstructive disease. Endomyocardial biopsy is considered in selected cases or when the etiology remains unclear.

Management emphasizes treating the underlying cause and supporting cardiac function. Heart failure therapy and arrhythmia management are used as indicated; activity is restricted during recovery. Immunosuppressive therapy may be considered for specific autoimmune etiologies; antiviral therapy is not routinely beneficial. Severe cases may require inotropic support or temporary mechanical circulatory support.

Prognosis ranges from full recovery to progression to dilated cardiomyopathy with persistent symptoms. Many patients improve within weeks to months, but some sustain ongoing ventricular dysfunction or arrhythmias. Long-term prognosis depends on injury severity, cause, and response to treatment.