Partially Resolving Myocardial Fibrosis Following the mRNA COVID-19 Vaccine: An MRI Based Case Report

Introduction: Myocarditis is a disease that has varying degrees of clinical manifestations. Furthermore, its diagnosis and management can pose as a challenge to clinicians. With over 250 million people receiving the mRNA covid vaccine, there have been rare reports of myocarditis, pericarditis or other cardiovascular involvement. However, its natural course remains unclear. Case: We report a 30-year-old healthy male who was hospitalized 3 days after the second dose of the covid-19 vaccination. He had high cardiac laboratory markers (cardiac troponin I peak of 22 ng/mL, normal <0.03 ng/mL). He had a subsequent coronary angiogram and echocardiogram that were normal and was hence diagnosed with myocarditis. After week 3, his symptoms fully abated along with all of his inflammatory and cardiac markers. He had a cardiac magnetic resonance (CMR) study 8 weeks later (from the date of his vaccine dose) that showed prominent mid to epicardial lateral wall fibrosis with normal T1 and T2 mapping. A repeat CMR was performed 3 months later, which is almost 22 weeks since the vaccine administration. It showed persistent, though partially resolving fibrosis, despite full resolution of symptoms and biomarkers, demonstrating an insidious recovery. Conclusion: This case demonstrates myocarditis following the second dose of the mRNA covid-19 vaccination with evidence of myocardial fibrosis on CMR and on follow-up CMR scan nearly 5 and a ½ months from administration. Furthermore, it shows remaining evidence of myocardial fibrosis despite the normalization of symptoms and traditional screening methods such as echocardiography and the use of cardiac and inflammatory biomarkers in disease surveillance. It provides insight into its natural course and insidious recovery as well as the utility of CMR in clinical management.