myocarditis

Myocarditis is an inflammation of the myocardium, the heart's muscular layer, which can impair pumping and electrical function. It has a broad etiologic spectrum, including infections, autoimmune processes, toxins, and hypersensitivity reactions. It may be acute or chronic and can affect any age group.

Viral infection is the most common cause worldwide, with agents such as enteroviruses, adenoviruses, parvovirus B19, human herpesvirus 6, and SARS-CoV-2. Bacterial, fungal, and parasitic infections can also trigger myocarditis. Autoimmune diseases, immune checkpoint inhibitors, hypersensitivity to drugs, and toxins may contribute.

Clinical features range from asymptomatic to chest pain, palpitations, dyspnea, fatigue, syncope, and signs of heart failure or arrhythmias. Fulminant myocarditis presents with abrupt hemodynamic collapse but may recover with aggressive supportive care.

Diagnosis combines history, exam, and testing. Electrocardiography may show nonspecific changes or arrhythmias. Cardiac troponin is often elevated. Echocardiography assesses function; cardiac magnetic resonance imaging detects edema and late gadolinium enhancement. Endomyocardial biopsy can confirm diagnosis, but the Dallas criteria are outdated and immunohistology is now emphasized. Clinical context guides biopsy use.

Management centers on supportive care and treating the underlying cause. Standard heart failure therapies may be used as tolerated. Immunosuppressive therapy is considered in selected autoimmune forms. Antiviral therapy is limited to specific pathogens. Most patients recover, but some develop dilated cardiomyopathy or persistent symptoms.

Epidemiology and prognosis vary by cause and severity. The condition is relatively rare but can affect any age; outcomes range from full recovery to chronic heart failure or arrhythmias. Prevention focuses on reducing infectious risks where possible and avoiding toxin exposure; vaccination can help against some etiologies.