Myocarditis is an inflammatory disease of the myocardium of the focal or diffuse characteristic caused primarily by a viral agent. It is a condition with a varied manifestation and course including asymptomatic cases, new-onset dilated cardiomyopathy, heart arrhythmias, heart failure, cardiogenic shock or sudden death. There is not a unanimous definition of myocarditis and inflammatory cardiomyopathy considering their different evaluating criteria.

In 2008, ICMP was classified in the classification of cardiomyopathies of the European Society of Cardiology to dilated cardiomyopathies and it is defined by the presence of chronic inflammatory cells in the myocardium in association with the left ventricular dilatation and reduced ejection fraction.


The determination of the epidemiology of myocarditis and ICMP is complicated as a result of a lot of factors including  challenging diagnosis land varied course and manifestation because of what mild forms of myocarditis do not have to be diagnosed.

In the present, the incidence of myocarditis in Europe is considered approximately 131 cases per 1 million inhabitants per year. Based on Global Burden of Disease study, over 2,5 million cases of myocarditis and cardiomyopathies was reported worldwide in 2015 including 156 thousand cases of acute myocarditis. Moreover, both groups reported over 20% increase of cases when comparing with 2005.

In approximatelly 50 % of patients, myocarditis heals up almost without any consequences, in 30 % it progresses in chronicity and in approximatelly 10 to 120 % it may manifestate with acute worsening of the clinical state what may in extreme cases results in heart transplant or death.


Aetiology of myocarditis is highly varied and includes both infectious and non-infectious agents. The introduction of PCR and electron microscopy for the analysis of bioptically taken samples of the myocardium of patients with myocarditis had a big importance for the discovery of infectious agents causing the disease. The most frequent cause of myocarditis and ICMP are considered infectious agents.

The most frequent viral agents of myocarditis and ICMP generally are considered PVB19, human herpes virus 6, cytomegalovirus and Epstein-Barr virus.

Nevertheless, enteroviruses (primarily Coxsackie), adenoviruses, hepatitis C virus and influenza virus still remain relatively important viral agents of myocarditis and ICMP.  In the Czech Republic, myocarditis caused by Borellia burgdorferi has relatively often incidence.

Nonnegligible parts of aetiology of myocarditis are also different cardiotoxic drugs, ethanol and addictive drugs, hypersensitive allergic reactions nd systematic inflammatory disorders






The knowledge about myocarditis and ICMP is still limited. It is determined by their varied aetiology and sometimes not quite cleared autoimmune processes which have been detected in myocarditis. Most of the information about the pathogenesis of these conditions comes from experimental mouse models whereas the best explored is myocarditis caused by enteroviruses and adenoviruses.

Generally, pathogenesis of myocarditis is classified into three successive phases: acute phase (viremia), subacute phase and chronic (sometimes called myopathic) phase.

It is presumed that a number of aspects contribute to the development of myocarditis and/or ICMP like genetic predisposition supported by the fact that in some individuals whose encountered with an infectious agent causing myocarditis, the disease did not develop.



Macroscopic changes of the heart are observed in severe forms of myocarditis when the dilatation of the heart chambers and changes in the myocardial consistence may occur.

The histological finding may be very various. The most common one is lymphocytic infiltrate occurring in myocarditis with viral and toxic aetiology, further in Borellia burgdorferi infection, vasculitis, and other systematic disorders. In bacterial myocarditis, infiltrate contains neutrophils. Eosinophilic infiltrate is characteristic for eosinophilic myocarditis, some systematic disorders (like Churg Strauss syndrome) and parasitic aetiology of myocarditis. Aschoff bodies may be observed in rheumatic fever connected with myocarditis.

In the case of the cardiac sarcoidosis, granulomatous infiltrate is detected.