[Indication for myocardial biopsy in myocarditis and dilated cardiomyopathy]

Abstract

This review may serve as a basis for evaluating publications on the topic "myocardial biopsy for myocarditis and dilated cardiomyopathy" in the clinical practice. The literature is particularly analyzed to answer the question, whether an endomyocardial catheter biopsy is indicated in patients with these myocardial disorders in the clinical routine besides its unequivocal scientific value. The judgment of the biopsy samples has been based on the classically histological and for years on the additional immunohistochemical and molecular biological-virological examination. The analysis of the literature data shows that outside scientific studies there is no indication to perform myocardial biopsy, or in other words, this procedure is not suitable for diagnosis, therapy, detection of early stages or prognostic evaluation in the disease spectrum "myocarditis, inflammatory heart disease, dilated cardiomyopathy". Reasons are the subjectivity in the judgment and interpretation of bioptic findings resulting in considerable interobserver variability, a missing standardization in biopsy performance, methods of examination and diagnostic criteria, the bioptic sampling error, missing therapeutic and prognostic consequences and potentially severe complications in performing myocardial biopsies. So far, the specificity of inflammatory changes in patients with dilated cardiomyopathy has not been proven in controlled blinded studies. The bioptic changes could be understood also as an unspecific inflammatory process in front of increasing pathophysiological evidence for myocardial inflammation in any form of heart failure. In addition, regarding the specific etiology of dilated cardiomyopathy, primarily a genetic, noninfectious or autoimmunologic origin plays an increasing role. The favorable clinical course and the very good prognosis of the acute, clinically diagnosed or supposed viral myocarditis should also be taken into account for the evaluation of myocardial biopsy. It should also be considered that the proof of causality between acute myocarditis and dilated cardiomyopathy is still lacking. Regarding the diagnosis "inflammatory cardiomyopathy" and multiple inflammatory subsets among patients with dilated cardiomyopathy or unclear regional contraction disorder, there is no adequate clinical validation of different diagnostic methods, criteria and interpretations so far. It is missleading to replace the well-established clinical diagnosis myocarditis by the bioptic diagnosis "inflammatory cardiomyopathy". However, endomyocardial catheter biopsy is clearly indicated in rare patients with fulminant myocarditis, giant-cell myocarditis and myocardial storage disease. Its probably underestimated role in sarcoid heart disease still needs to be clarified by systematic studies.