Role of Endomyocardial Biopsy in Diagnostics of Myocarditis

Endomyocardial biopsy as the cornerstone of diagnostics has been re-evaluated throughout the years, leaving unanswered questions on the precedence of it. The reported incidence of myocarditis has increased during the pandemic of coronavirus disease 2019 (COVID-19), reinforcing discussions on appropriate diagnostics of myocarditis. By analysis of evidence-based literature published within the last demi-decade, we aimed to summarize the most recent information in order to evaluate the current role of endomyocardial biopsy in diagnostics and management of myocarditis. For the most part, research published over the last five years showed ongoing uncertainty regarding the use, informativeness, safety and necessity of performing a biopsy. Special circumstances, such as fulminant clinical course or failure to respond to empirical treatment, were reconfirmed as justified indications, with a growing applicability of non-invasive diagnostic approaches for most other cases. We concluded that endomyocardial biopsy, if performed properly and with adjunct diagnostic methods, holds a critical role for treatment correction in specific histological subtypes of myocarditis and for differential diagnosis between immune-mediated myocarditis and secondary infections due to immunosuppressive treatment. A high level of possible misdiagnosing was detected, indicating the need to review terminology used to describe findings of myocardial inflammation that did not meet Dallas criteria.