Nonviral Myocarditis

German physician Joseph Friedrich Sobernheim coined the term "myocarditis" in 1837, which translates to "inflammation of the myocardium." However, for a long time, there was no clear consensus on what truly constituted myocarditis. In the nineteenth and early twentieth century, the term was a catch-all diagnosis for many non-valvular heart diseases, including what we now recognize as hypertensive and ischemic heart diseases. Even after myocardial ischemia emerged as a separate and significant entity, the term "myocarditis” was used interchangeably with other cardiomyopathies. The confusion partly stemmed from the diversity of its clinical manifestations, which can range anywhere from nonspecific symptoms like fever, myalgias, diminished exercise tolerance to hemodynamic collapse and sudden death. It was only in 1995 that the World Health Organization and the International Society and Federation of Cardiology classified the different cardiomyopathies and defined myocarditis as "an inflammatory disease of the myocardium, diagnosed by established histological, immunological, and immunohistochemical criteria." However, as the diagnosis relies on the infrequently performed endomyocardial biopsy (EMB), its actual incidence remains unknown. Myocarditis can be mild and self-limiting with minimal ventricular dysfunction, to fulminant with severe hemodynamic compromise requiring inotropic agents or mechanical circulatory support. When associated with cardiac dysfunction, the term for the condition is inflammatory cardiomyopathy.