Post-mRNA COVID-19 vaccines myocarditis: Not so rare in cardiology practice

INTRODUCTION: In the context of large-scale anti-SARS-Cov-2 vaccination campaign by new mRNA vaccines, post-vaccination associated myocarditis (PVM) appeared as rare but potentially serious side effects. Few data are currently available on its prevalence in practice in intensive cardiac care unit (ICCU). OBJECTIVE: We carried out an exhaustive epidemiological multicentric collection of acute myocarditis managed in ICCU in Western Europe to describe PVM prevalence and acute prognosis. METHOD: Patients managed for an acute myocarditis (AM) in 4 tertiary ICCU in France between May and September 2021 were included. Myocarditis was defined according to ESC guidelines and Lake Louise CMR criteria. PVM diagnosis was retained in case of compatible vaccination-myocarditis diagnosis delay (usually between 2 and 9 days) (5), with a negative etiologic assessment for other AM causes. Baselines characteristics and in-hospital complications were compared between PVM and others AM. RESULTS: Patients managed for an acute myocarditis (AM) in 4 tertiary ICCU in France between May and September 2021 were included. Myocarditis was defined according to ESC guidelines and Lake Louise CMR criteria. PVM diagnosis was retained in case of compatible vaccination-myocarditis diagnosis delay (usually between 2 and 9 days) (5), with a negative etiologic assessment for other AM causes. Baselines characteristics and in-hospital complications were compared between PVM and others AM. CONCLUSION: Post-vaccination myocarditis is a rare, and most often benign, side effects of mRNA anti-COVID19 vaccine. However, healthcare professionals should be aware of it due to its higher prevalence in expert referrals centers especially in the context of mass vaccination campaign.