Myocarditis is inflammation of the muscles of the heart. It's a rare but serious complication of many illnesses, although it is usually caused by a viral infection, most commonly parvovirus. However, it can also be caused by parasites, bacteria, fungus, allergies, and toxins. In most of the world, Chagas disease is the leading cause. It can also be the result of an autoimmune response. It's often accompanied by pericarditis. It's one of the leading causes of sudden death in otherwise healthy adults (accounting for about 20% of sudden deaths in this age group) and is often either the direct cause or a contributing cause to the death of patients with AIDS.
Typically, it presents with severe pain in the chest, the result of the heart becoming less able to pump blood. Such cases are clearly medical emergencies. However, most cases resolve spontaneously without treatment.
Myocarditis is difficult to diagnose. Mere inflammation will not support a diagnosis, as this can be a result of other trauma or shock, including a heart attack. A heart biopsy is definitive, but invasive and dangerous. However, tests such as an EKG, sed rate, MRI, CRP, and IgM can point to the same diagnosis.
Treatment for myocarditis depends on the underlying cause, but in all cases treatment of symptoms and supportive care is called for. This can include digoxin, diuretics, and ACE inhibitors. However if the disease progresses, a heart transplant may be the only option.