Abstract 20433: Viral Myocarditis: Viral Genome Detection Yield on Endomyocardial Biopsy is Influenced by Methodological Factors
Introduction: Myocarditis is diagnosed on endomyocardial biopsy (EMB) by histological, immune-histochemical and molecular techniques to detect viral genomes. The role of EMB for the diagnosis and its contribution to patient management has been addressed by a Consensus document of American and European Cardiovascular Pathology Societies.
Hypothesis: Different methods of tissue fixation and the number of myocardial samples could impact on viral genome yield on EMB.
Methods: Consecutive EMBs referred at our Institution for histology/ immunohistochemistry evaluation in the time interval 1996-2012 were enrolled. Molecular investigation by RT-PCR and PCR technique was performed in all EMBs with inflammatory cardiomyopathy diagnosis at histology and immunohistochemistry.
Results: A total of 467 EMBs have been diagnosed as myocarditis: 79 in pediatric (1 month to 18 years; 47M/ 32F) and 388 adult (19 to 75 years; 256M/132 F) patients (pts.). Viral etiology was identified in 28 (36%) pediatric and 101 (26%) adult pts, and the most prevalent type of viruses were enterovirus (8/28, 36%; 26/101, 24%). In a more recent subgroup of 137 EMBs (virus positive 30/137, 22%) seasonality, type of fixation and number of EMB samples were assessed. The seasonal distribution of myocarditis was higher in winter than in other seasons (33% vs. autumn 28%, spring 20% and summer 19%) without any significant difference in terms of virus positive EMBs. The number of EMB samples per pt. was ≤3 (either formalin or RNAlater) in 94/137 (69%) and >3 in 43/137 (31%), with a lower prevalence of virus positive in the former (17/94, 18% vs. 13/43, 30%). Eighty-one EMB samples were frozen while 56 were paraffin embedded, with a higher prevalence of viral genome in the former (26/81, 32% vs. 4/56, 7%; p=0.001).
Conclusions: The diagnosis of myocarditis on EMB samples requires standardized protocols including molecular techniques. Viral genomes are identifiable in more than one third of pediatric and one fourth of adult cases. Methodological factors like the type of tissue fixation and the number of samples could impact on viral genome detection on EMB.
Author Disclosures: E. Carturan: None. S. Rizzo: None. G. Thiene: None. C. Basso: None.
- © 2014 by American Heart Association, Inc.