Expert Committee On The Definition Of Viral Cardiomyopathy

Because isolation of the virus from swabs or tissue is possible in only the acute phase of infection, it is unlikely to succeed in patients with longer-lasting diseases or chronic infections. Enteroviruses, therefore, have been isolated effectively in pediatric patients only. A higher sensitivity is achieved with molecular techniques (eg, gene amplification), which are significantly more sensitive than standard histochemical techniques for the detection of viral proteins. Except for human immunodeficiency virus, hepatitis C, and cytomegalovirus, serologic assessment of antiviral antibodies appeared to be of limited diagnostic value with respect to the actual disease status of the patients and for the critical issue of whether the viral genome is present in the myocardium.

The World Heart Federation expert panel reached a consensus on current diagnostic approaches to viral heart disease by means of an international, multicenter, and blinded interlaboratory study. The assessment of viral nucleic acid in the myocardium with the polymerase chain reaction (PCR) technique was the first choice of methods because of its rapidity, wide availability, high sensitivity, and specificity.

The highest sensitivity and reproducibility for the detection of enteroviral genomes were achieved with frozen tissue (100%) in 5 of 9 centers. Reverse transcription (RT) PCR of enterovirus RNA from fixed embedded tissue was less reliable. Detection of enterovirus sequences in formalin-fixed samples was not convincing. The incidence of hepatitis C virus in formalin-fixed tissue (15%) was remarkable. PCR for the genomic sequences of DNA viruses in formalin-fixed tissue is less critical, and adenovirus (12.5%-22.5%), cytomegalovirus (5%), and Epstein-Barr virus (2.5%) could also be detected in formalin-fixed tissue. New data from several laboratories indicate that parvovirus B19 should also be included in the list of cardiotropic viruses with a prevalence well over or in the range of enterovirus.11 An overview of the incidence of a positive viral PCR in the literature and our own myocarditis registry is given in Table 4-2.

On the basis of the interlaboratory analysis, the World Heart Federation expert panel on viral cardiomyopathies has given for the first time a reliable comparative analysis of cardiac tissue samples infected in part with cardiotropic viruses.

Perimyocarditis is defined as pericardial effusion and cardiomegaly or segmental wall motion abnormality. Demonstration of pericardial effusion (in the absence of neoplastic, postirradiation, or postinjury syndromes; systemic disorders; metabolic disorders; or uremia) ascertains the inflammatory epicardial or pericardial process; cardiac dilatation or wall motion abnormality shows the myocardial involvement.12-14 Viral pericarditis is nearly always associated with underlying epicardial and myocardial lesions,15 which lead to the use of myopericarditis16 or more precisely perimyocarditis.12 Because myocarditis is not associated regularly with pericardial effusion, the clinical entities overlap but are not identical. For these patients, a biopsy with demonstration of active inflammation is helpful.

Table 4-2

Bacterial and Viral Etiology of Myocarditis, Dilated Cardiomyopathy, and Pericarditis

Patients positive, %

Table 4-2

Bacterial and Viral Etiology of Myocarditis, Dilated Cardiomyopathy, and Pericarditis

Patients positive, %

Pathogen

Type

Myocarditis

0 0

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