CORRESPONDENCE: LETTER TO THE EDITOR
Myocarditis Mimicking Arrhythmogenic Right Ventricular Cardiomyopathy
Alex Hørby Christensen, MD* and
Jesper Hastrup Svendsen, MD
* Department of Cardiology, Section 2142, Copenhagen University Hospital, Blegdamsvej 9, 2100 Copenhagen OE, Denmark (Email: alexhc{at}dadlnet.dk).
We have read with interest the paper by Pieroni et al. (1) addressing myocarditis as a common differential diagnosis to arrhythmogenic right ventricular cardiomyopathy (ARVC). Among 30 patients noninvasively fulfilling Task Force criteria (2) for ARVC, they found that 15 patients actually had myocarditis based on 3-dimensional electroanatomic voltage mapping-guided endomyocardial biopsy. Voltage-guided biopsy is an elegant way of obtaining histological material from areas of the right ventricle with electrical signs of regional abnormalities and may facilitate the diagnostic workup. However, we have the following questions/concerns about the study by Pieroni et al. (1):- 1 Myocardial inflammation. Numerous previous reports document myocardial inflammation as a frequent finding (up to 80% of patients) in ARVC (3,4). The authors report, surprisingly, that none of their ARVC patients had accompanying inflammation. Furthermore, the results are not consistent with a recent report from another Italian group investigating autopsy material and explanted hearts in geno-positive ARVC patients (5). That study showed accompanying inflammatory infiltrations in 10 of 10 patients and no evidence of an infective etiopathogenesis (5). Have the authors considered the possibility that the inflammatory infiltrations seen in the "myocarditis" group are part of the ARVC phenotype and that fibrofatty replacements may occur later in the course of the disease? This possible difference in disease development may also explain the benign course seen in the group in the relatively short follow-up period.
- 2 Viral genome in the myocardium. Five of the 15 patients classified as having myocarditis had the presence of viral genome (parvo B19 virus in 3 cases, influenza virus in 2 cases) in the myocardium documented by PCR. Different viruses may persist in asymptomatic individuals without being pathogenic. A recent report from Italy showed 12 of 19 asymptomatic individuals had detectable parvo B19 deoxyribonucleic acid in their myocardium (6). In addition, ARVC patients may have increased susceptibility of having myocarditis as a secondary phenomenon.
- 3 Molecular genetics. No mutation screening of desmosomal genes was performed. Given the lack of reference diagnostic modality for ARVC, the frequency of desmosomal mutations in both groups is highly relevant. A positive molecular genetics finding in the "myocarditis" group would reclassify the patient into the "ARVC" group.
Based on the abovementioned observations, the results presented by Pieroni et al. (1) should be confirmed in larger ARVC cohorts with supplementary desmosomal mutation screening.
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1. Pieroni M, Dello RA, Marzo F, et al. High prevalence of myocarditis mimicking arrhythmogenic right ventricular cardiomyopathy: differential diagnosis by electroanatomic mapping-guided endomyocardial biopsy J Am Coll Cardiol 2009;53:681-689.[Abstract/Free Full Text]2. McKenna WJ, Thiene G, Nava A, et al. Diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy. Task Force of the Working Group Myocardial and Pericardial Disease of the European Society of Cardiology and of the Scientific Council on Cardiomyopathies of the International Society and Federation of Cardiology. Br Heart J 1994;71:215-218.[Free Full Text] 3. Basso C, Thiene G, Corrado D, Angelini A, Nava A, Valente M. Arrhythmogenic right ventricular cardiomyopathy. Dysplasia, dystrophy, or myocarditis?. Circulation 1996;94:983-991.[Abstract/Free Full Text] 4. Burke AP, Farb A, Tashko G, Virmani R. Arrhythmogenic right ventricular cardiomyopathy and fatty replacement of the right ventricular myocardium: are they different diseases? Circulation 1998;97:1571-1580.[Abstract/Free Full Text] 5. Basso C, Carturan E, Bauce B, et al. Myocarditis and genetically determined arrhythmogneic right ventricular cardiomyopathy: no evidence of an infective etiopathogenesis(abstr) Eur Heart J 2008;29(Suppl):309. 6. Corcioli F, Zakrzewska K, Rinieri A, et al. Tissue persistence of parvovirus B19 genotypes in asymptomatic persons J Med Virol 2008;80:2005-2011.[CrossRef][Web of Science][Medline]
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Reply
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J. Am. Coll. Cardiol. 2009 54: 665-666.
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