Cryptic late-onset myocarditis after coronavirus vaccination

Area of Science:

• Cardiology
• Immunology
• Pharmacology

Background:

• The increasing use of messenger RNA (mRNA) therapeutics necessitates understanding potential genetic and environmental factors influencing off-target side effects.
• Post-vaccination myocarditis, a rare side effect of mRNA vaccines, has been observed, with early- and late-onset cases now being recognized.

Purpose of the Study:

• To explore potential triggers for post-vaccination myocarditis, including exercise, pre-existing cardiac conditions, and immune checkpoint blockade.
• To present case studies and supporting imaging data suggesting factors that may unmask or provoke myocarditis in vaccinated individuals.

Main Methods:

• Review of three case histories detailing instances of myocarditis following mRNA vaccination.
• Comparison of cardiac scans (fluorodeoxyglucose-positron emission tomography) between vaccinated and unvaccinated subjects.

Main Results:

• Exercise may precipitate otherwise cryptic cases of early-onset postvaccination myocarditis.
• Pre-existing cardiac morbidity and immune checkpoint blockade for cancer treatment were associated with late-onset myocarditis in some cases.
• Cardiac scan data provided comparative insights into myocardial activity in vaccinated versus unvaccinated individuals.

Conclusions:

• Factors such as exercise, underlying cardiac conditions, and specific medical treatments can influence the manifestation of mRNA vaccine-related myocarditis.
• The limited pre-pandemic data on mRNA therapeutics underscored the need for rigorous post-authorization surveillance and research.