Myocarditis

Key points

• Causes: viral (coxsackie, HIV) · bacteria (diphtheria, clostridia) · spirochaetes (Lyme disease) · protozoa (Chagas' disease, toxoplasmosis) · autoimmune · drugs (doxorubicin)
• Parvovirus B19 and human herpes virus 6 are currently considered the most common causes of viral myocarditis (in the 1990s the enteroviruses, including coxsackievirus); also adenovirus, hepatitis C, cytomegalovirus, echovirus, influenza and Epstein-Barr virus
• Presentation: usually a young patient with an acute history — chest pain and SOB; trouble sleeping or lying flat at night and exertional dyspnoea after a flu-like illness suggest viral myocarditis
• May progress to dilated cardiomyopathy (reduced LVEF, myocardial dyssynchrony, thinning of the left ventricular wall, dilated LV) and cause a cardioembolic stroke