A meta-analysis of myocarditis post-mRNA vaccine administration

ABSTRACT

INTRODUCTION: Myocarditis is increasingly being reported after mRNA COVID-19 vaccination especially in young individuals. We aim to compile the clinical, laboratory, and investigational data on reported cases of post-COVID-19 vaccination in adults and assess the clinical features, investigational findings, and prognosis in this meta-analysis. METHODS: PubMed database was searched using keywords for post-COVID-19 vaccination myocarditis for articles published before July 6th, 2021. 37 unique studies were identified. Case reports and case series published in English which reported individual patient data on adults aged 18 years or older that were hospitalized for presumed post mRNA vaccination myocarditis are included in our study. Pre-prints were included if they had individual patient data. Editorials, correspondence, reviews, perspectives, original articles were excluded. 13 articles met our criteria for inclusion. Individual participant data was tabulated on a spreadsheet. Age, time of presentation, and length of stay are expressed as Median. The rest of the findings are mentioned as frequency (n). RESULTS: Post mRNA vaccination myocarditis is predominantly seen in males with a mean age of 27.5 years and more after their second dose of vaccination. It is reported after both Pfizer-BioNTech and Moderna vaccine use. The median time of hospital presentation was 3 days after vaccination. The main presenting symptom is chest pain in 96.7% of the patients. Troponin was elevated and cardiac MRI showed late gadolinium enhancement in all the patients. The mean hospital length of stay was 5.5 days. All the patients made a good recovery. CONCLUSION: Post COVID-19 myocarditis is possibly a hypersensitivity reaction to mRNA vaccines. It is predominantly seen in young males and is characterized by chest pain, elevated troponin, and abnormal cardiac MRI. The condition carries a good prognosis. Further investigations are necessary to understand the underlying pathogenesis.