OBJECTIVE: The purpose of this systematic review is to evaluate the original peer-reviewed studies on athletes who developed myocarditis after coronavirus disease (COVID-19) infection or after COVID-19 mRNA vaccination. Both entities likely have an immunologic component. We discuss elite, professional, college, and adolescent athletes. The athletes are generally young and healthy, representing a distinctive population group that differs from the general population. This review includes diagnosis of myocarditis, incidence, complications, prognosis, and return-to-play guidance for sports medicine clinicians and coaches. DATA SOURCES: We surveyed the PUBMED, Embase, and Web of Science databases for the relevant peer-reviewed articles in the English language published from the onset of the pandemic until April 2023. Included were original observational studies and case series. Excluded were individual case reports and a small series with incomplete data. The resulting search yielded 30 original articles. MAIN RESULTS: Reported myocardial abnormalities in athletes were rare after COVID-19 infection and even less frequent after COVID-19 mRNA vaccination. True incidence, however, may be higher because of under-reporting and frequent asymptomatic presentation. Male gender was prevalent for both manifestations
postvaccination myocarditis occurrence was the highest after the second vaccine dose. Diagnostic and return-to-play algorithms were developed and should be adopted and followed. CONCLUSIONS: The risk of myocarditis from COVID-19 infection and COVID-19 mRNA vaccination is very low. The long-term prognosis and evolution of the observed cardiac magnetic resonance abnormalities are currently unknown. Although inferences can be made from the published data, COVID-19 and postvaccine myocarditis in athletes may represent only a small fraction of the true incidence of those who have been affected worldwide and not evaluated.