Myocardial Injury After COVID-19 Vaccine-Associated Myocarditis: Natural History

Background : An uncommon side effect of the mRNA-based COVID-19 vaccine is acute myocarditis. The natural history of this problem is poorly understood. Methods : In 20 consecutive patients meeting the criteria, baseline and convalescent cardiac magnetic resonance (CMR) imaging evaluations were carried out. current Lake Louise mRNA-based vaccination criteria within 10 days of acute myocarditis. Between baseline and convalescence, CMR-based changes in left ventricular volumes, mass, ejection fraction (LVEF), tissue inflammation markers (native T1 and T2 mapping), and fibrosis markers (late gadolinium enhancement [LGE] and extracellular volume [ECV]) were evaluated. Clinical results and cardiac symptoms were recorded. Conclusions : Beyond three months of recovery in this young patient group, COVID-19 mRNA vaccineeassociated myocarditis demonstrated rapid improvements in CMRbased indices of edoema, contractile function, and overall LGE burden. However, regional fibrosis after edoema resolution was frequently seen, which supported the need for continuous observation.