Myocarditis: Etiology, Pathogenesis, and Their Implications in Clinical Practice

Abstract

Myocarditis is an inflammatory disease of the myocardium caused by infectious or non-infectious agents. It can lead to serious short-term and long-term sequalae, such as sudden cardiac death or dilated cardiomyopathy. Due to its heterogenous clinical presentation and disease course, challenging diagnosis and limited evidence for prognostic stratification, myocarditis poses a great challenge to clinicians. As it stands, the pathogenesis and etiology of myocarditis is only partially understood. Moreover, the impact of certain clinical features on risk assessment, patient outcomes and treatment options is not entirely clear. Such data, however, are essential in order to personalize patient care and implement novel therapeutic strategies. In this review, we discuss the possible etiologies of myocarditis, outline the key processes governing its pathogenesis and summarize best available evidence regarding patient outcomes and state-of-the-art therapeutic approaches.

Keywords: dilated cardiomyopathy; heart failure; immunosuppressive therapy; inflammatory cardiomyopathy; myocarditis.

Figure 1

Triphasic model of myocarditis pathogenetic mechanisms based on clinical observations and experimental data [9,13,14,15,16,17,18,19]. Created with BioRender.com.

Figure 2

Histological classification of myocarditis on EMB. (A) Acute lymphocytic myocarditis. An infiltrate rich in CD3(+) lymphocytes (red stain) with concomitant myocytolysis is visible. (B) Eosinophilic infiltrate present in biopsy specimen of patient with eosinophilic myocarditis. (C) Giant cell myocarditis with visible area of inflammation and giant cell infiltration. (D) Massive myocardial fibrosis (blue) visualized using Masson’s trichrome stain. Created with BioRender.com.