Myocarditis and inflammatory cardiomyopathy: microbiological and molecular biological aspects

Myocarditis is an inflammatory disease of the myocardium associated with cardiac dysfunction. The natural history of myocarditis is frequently characterised by the evolution in dilated cardiomyopathy. Due to its variable clinical manifestation from latent to very severe clinical forms, such as acute congestive heart failure and sudden death, its prevalence is still unknown and probably underestimated. In spite of the development of various diagnostic modalities, early and definite diagnosis of myocarditis still depends on the detection of inflammatory infiltrates in endomyocardial biopsy specimens according to the Dallas criteria. Routine application of immunohistochemistry, used for identification and characterisation of inflammatory cell populations, has now significantly increased the sensistivity of the diagnosis of inflammatory cardiomyopathy. Various molecular techniques, such as PCR, gene sequencing and real-time PCR, often applied on the same endomyocardial specimen, have become an essential part of the diagnostic armamentarium for rapid, specific and sensitive identification of infective agents. The correct application of molecular techniques will allow increasingly more information to be obtained: new epidemiology, new patient risk stratification and overall more appropriate medical treatment.