Acute myocarditis: 2024 state of the art

Acute myocarditis (AM) is an inflammatory injury of the myocardium secondary to infections, systemic autoimmune disorders, medications, or toxic agents. The patient's genetic underground is a likely concurrent aetiology/contributory mechanism recently implicated in a proportion of AM. This review focuses on some critical new concepts of AM, updated indications for endomyocardial biopsy when cardiac magnetic resonance imaging is not sufficient or feasible, and estimation of long-term events after discharge. Furthermore, studies exploring AM as the cause of sudden cardiac death will be examined to assess the characteristics of patients who die due to AM before hospital admission. Managing the most severe clinical presentation, termed fulminant myocarditis (FM) characterized by haemodynamic instability due to ventricular arrhythmias or severe acute pump failure, will be summarized. Specific issues aimed to reduce the high mortality rate of FM, like early recognition, referring these patients from spoke centres to a hub centre, timely temporary mechanical circulatory support when indicated, early endomyocardial biopsy, and eventually immunosuppression, will be briefly discussed. Immune checkpoint inhibitors and desmosomal gene variant-associated AM will be highlighted as paradigmatic new forms of myocarditis.