12th March 2024

Aetiology

Causes of myocarditis include:

• Viral: coxsackie A/B most common, adenovirus, influenza, EBV, SARS-CoV-2, polio virus, CMV, HHV-6, 
• Infections: bacterial (Brucella, Mycoplasma, Haemophilus influenzae, Mycobacteria) and fungal (Aspergillus, Candida)
• Protozoan: Trypanosoma cruzi (causing Chagas disease), Toxoplasmosis 
• Drugs:/Toxins: cyclophosphamide, anthracyclines, ethanol, cocaine
• Autoimmune conditions: inflammatory bowel disease, connective tissue diseases, sarcoidosis
• Vaccinations: smallpox vaccine, SARS-COV-2 vaccine

Pathology

Viruses induce myocardial damage in a variety of ways. Enteroviral replication causes cytopathic damage, triggering both cellular and humoral immune responses. The resultant myocardial necrosis releases self-antigens, which are detected by the immune system. These self-antigens have the capability to induce auto-immune reactions within the myocardial tissue, which further exacerbates myocarditis.