Myocarditis is separated into several forms. Classification of the types of myocarditis is adjusting continuously. Commonly is so called by a clinical-pathological classification, which combines observable course of the patient´s disease with the findings on her/his heart muscle.

Fulminant myocarditis

Fulminant myocarditis is a quite rare form of the disease, however with a dramatic course, when symptoms of heart failure are observed in the patient. This form is associated with severe changes in the heart function and is characterized by very quick onset, presenting with shortness of breath, high fever and arrhythmias. Symptoms may be observed even two weeks after a viral disease. If the patient overcomes the acute phase of the disease, the prognosis is favourable.

Acute myocarditis

It is the most frequent type of myocarditis. It is characterized by less distinct onset of the disease. Sometimes it is not diagnosed and it may seem as a “severe” flu to the patient. Nevertheless, the course of the acute myocarditis can be complicated, e.g. lower heart ventricle function may be observed. Mostly the first symptoms are preceded by a previous viral disease. The most frequent symptoms are nausea, fever or running temperature, palpitation and chest pain.

Chronic myocarditis

Currently, the term chronic myocarditis is sometimes replaced by the term inflammatory cardiomyopathy. Previously, the chronic myocarditis was classifed as chronic active and persisting myocarditis. Chronic active myocarditis is a form of myocarditis, characterized by its recurrence and even changes to the heart function (mainly the left ventricle) are observable. The course is similar to the course of acute myocarditis. The cause of recurrence is the presence of persisting virus in the heart and/or weak heart muscle inflammation.

Chronic persisting myocarditis is very similar to chronic active myocarditis with the difference being that changes to the left ventricle function and the heart generally are not observed. However, persisting chest pain and palpitation may be observed.

Hypersensitive eosinophilic myocarditis

Hypersensitive eosinophilic myocarditis is a rare form of the disease, which is classified further according to possible causes. Inflammation and necrosis of the myocardium are mediated by eosinophils – cells of the immune system with an important role during allergic reaction and immune response against parasites. Mostly it is induced by hypersensitive allergic reaction against drugs (antibiotics, anticonvulsants – epilepsy); antidepressants, some diuretics, methyldopa or the presence of a parasite in the human body (e.g. Trypanosoma cruzi) or it can be a consequence of another disease. E.g. Hypereosinophilic syndrome (HES), when the concentration of eosinophils in tissues and blood is increased. Patient can pass from the inflammatory phase gradually in thrombotic phase and then to the phase of fibrosis.

Giant cells myocarditis

Giant cells myocarditis is an extremely rare form of myocarditis, which was even classified on the list of rare disease in 2015 in the USA. It is the most aggressive form of myocarditis, accompanied with life-threatening arrhythmias and heart failure. In a quarter of patients it is connected with up-to-now unknown autoimmune processes. Even the treatment is complicated. It consists mainly of immunosuppressive therapy and therapy of corticosteroids (see this page). The most efficient treatment is still heart transplant in this case. But there is a risk of its recurrence.

Heart sarcoidosis

It is a chronic inflammation which apart from the heart may affect even other organs like lungs and kidneys. The heart does not have to be affected in all patients with sarcoidosis. The essence of sarcoidosis it the production of granulomas, “balls” consisting of the immune system cells, in the affected organs what disrupts their normal function. The aetiology of the inflammation is for now unknown. Heart sarcoidosis most commonly manifests with heart failure and arrhythmias which are the biggest danger of this disease.

Myocarditis and autoimmune disorders

Myocarditis may be in some cases a complication of some autoimmune disorders when the body creates antibodies against its own tissues. An example of such disorders is systemic lupus erythematosus (SLE) what is a disease affecting among others skin, lungs and cardiovascular system when antibodies against some internal cell structures are created. In not inconsiderable amount, myocarditis may manifest even in patients with celiac disease, a chronic inflammatory disease of the small intestine. As a result of the inflammation, the permeability of the intestine wall for substances we gain from the food intake is disrupted. In the case of celiac disease, the production of antibodies against the cells of the heart muscle is described as the aetiology of myocarditis. However, also the disrupted permeability of the intestine wall may play a role in this process.

Myocarditis in HIV positive patients

Myocarditis is present in 25-75 % of HIV positive patients. As the aetiology of myocarditis in such patients, there are considered both direct damage to the heart muscle cells caused by HIV virus, and the damage caused by other viruses and bacteria, what is related to the fact that HIV virus affects primarily cells of the immune system which is eventually, among others, unable of effective reaction against infectious diseases. Prognosis of patients with HIV myocarditis is uncertain.

Authors of the opening picture: Kurt Deb, Behrus Djavidani, Stefan Buchner, Florian Poschenrieder, Norbert Heinicke, Stefan Feuerbach, Günter Riegger and Andreas Luchner; Ed Uthman, MD; dr n. med. Krystyna Bielnik, lek. med. Dariusz Młoczkowski, dr n. med. Tadeusz Modrzewski, lek. med. Dorota Snopkowska, prof. dr hab. med. Krzysztof W. Zieliński