The importance of cardiac MRI as a diagnostic tool in viral myocarditis-induced cardiomyopathy

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Myocarditis is a cardiac disease associated with inflammation and injury of the myocardium.1 The term myocarditis was first introduced in the 19th century. In 1986, in an effort to standardise the diagnostic criteria, a panel consisting of eight cardiac pathologists proposed the Dallas criteria and provided a histopathological categorisation by which the diagnosis of myocarditis could be established.2 However, this classification had several pitfalls, being susceptible to variation in pathological interpretation, sampling error and not considering the exact cause of pathological findings. A clinicopathological classification utilising both histological and clinical features in which four distinct subgroups were subdivided was provided in 1991 and adjusted in 2001 but it has received only limited acceptance. Acute myocarditis (AM) was categorised into a common and a fulminant type depending on whether or not patients received mechanical circulatory support in the management of heart failure. Chronic myocarditis (CM) was subdivided into chronic active and chronic persistent myocarditis. There is consensus that viral infection is responsible for the vast majority of cases in North America and Europe.3,4 Coxsackievirus B3 (CBV3) is considered the dominant viral aetiological agent.5 Other frequently detected viral genomes are enterovirus, adenovirus, parvovirus B19 (PVB19), human herpes virus 6 (HHV6) and Epstein-Barr virus (EBV).6 …