Multiparametric cardiovascular magnetic resonance in patients with myocarditis with consecutive follow-up and a comparison between non-COVID-19 and COVID-19-associated myocarditis.

Background: The pattern of myocardial injury and dysfunction development during follow-up is unclear in patients with myocarditis. This study aims to explore the developmental pattern of myocardial injury and cardiac dysfunction during the follow-up of myocarditis by cardiac magnetic resonance (CMR) and differences in short-term follow-up CMR performance between patients with coronavirus disease 2019 (COVID-19)-associated myocarditis (CAM) and non-COVID-19-associated myocarditis (NCAM). Methods: Data of patients with clinically diagnosed myocarditis who underwent follow-up CMR were retrospectively collected. Patients were divided into the NCAM follow-up and CAM follow-up groups. A portion of patients with normal CMR and volunteers was categorized as control. Qualitative and quantitative assessments of CMR images were used to analyze cardiac structure, function and myocardial damage; compare the differences between the groups; and reveal the developmental pattern in the consecutive follow-up for patients with myocarditis. Results: This study included 75 patients with NCAM, 25 patients with CAM and 75 cases as control group. Compared with the control group, there was an increase in left ventricular volume, right ventricular volume, extracellular volume in the NCAM follow-up (the last time) group, left ventricular volume, right ventricular ejection fraction, global radial strain (GRS), global circumferential strain, global longitudinal strain (GLS), post-contrast T1 value were decreased. The area under the curve of the GLS was the best (0.836) in discriminating between the two groups, with 78.7% sensitivity and 84.0% specificity. The discriminatory efficacy of the combined right ventricular ejection fraction, GRS, and GLS multiparameter showed the best area under the curve at 0.847, with 80.0% sensitivity and 85.3% specificity. Between the CMR parameter of short- (3 months), medium-, and long-term follow-up (>6 months) for patients with NCAM, a decrease in native T1 (1,256.50±18.63 Conclusions: This study revealed that myocarditis led to myocardial damage, cardiac remodeling, and dysfunction during follow-up. An improvement in myocardial edema in the medium- and long-term follow-up groups was observed. In the short-term follow-up, CAM showed more severe myocardial edema. These findings may contribute to the clinical assessment and management of post-myocarditis status.