[ANMCO/SIC Consensus document on the management of myocarditis]

Myocarditis is an inflammatory heart disease that can occur acutely, as in acute myocarditis, or persistently, as in chronic myocarditis or chronic inflammatory cardiomyopathy. Different agents can induce myocarditis, with viruses being the most common triggers. Generally, acute myocarditis affects relatively young people and men more than women. Myocarditis has a broad spectrum of clinical presentations and evolution trajectories, although most cases resolve spontaneously. Patients with reduced left ventricular ejection fraction, heart failure symptoms, advanced atrioventricular block, sustained ventricular arrhythmias or cardiogenic shock (the latter known as fulminant myocarditis) are at increased risk for death and heart transplantation. The presentation of chronic inflammatory cardiomyopathy may be more subtle, with progressive symptoms of heart failure or appearance of rhythm disturbance, not rarely preceded by an infective episode. Autoimmune disorder or systemic inflammatory conditions can be another significant predisposing substrate of myocarditis, especially in women. Emerging causes of myocarditis are drug-related like the new anticancer therapies, the immune checkpoint inhibitors. In this Italian Association of Hospital Cardiologists (ANMCO) and Italian Society of Cardiology (SIC) expert consensus document on myocarditis, we propose diagnostic strategies for identifying possible causes of the disease and factors associated with increased risk. Finally, we propose potential treatments and when referring patients to tertiary centers, especially for high-risk patients. Even if endomyocardial biopsy is the invasive diagnostic tool for making definitive diagnosis and differentiation of histological subtypes (i.e., lymphocytic vs eosinophilic vs giant cell myocarditis), it is not always readily available in all centers. Thus, we propose when this exam is mandatory or when it can be postponed or substituted by cardiac magnetic resonance imaging. This document reflects the Italian perspective on managing patients with myocarditis and their follow-up, considering also current US and European scientific position statements.