February 17, 2022 — While cardiac imaging shows that COVID-19 vaccine–associated myocarditis has a similar pattern as that from other causes, the abnormalities are less severe and result in less functional impairment, suggests a study yesterday in Radiology.
Myocarditis (inflammation of the heart muscle) after vaccination is rare, but some cases have been reported after receipt of the Pfizer/BioNTech or Moderna mRNA COVID-19 vaccine.
University of Toronto researchers retrospectively studied the electronic health records of 92 adults diagnosed as having myocarditis with one or more T1 and T2 abnormalities on cardiac magnetic resonance imaging (MRI) from December 2019 to November 2021.
Among the 92 patients, 22% were diagnosed as having myocarditis within 14 days after COVID-19 vaccination, 11% had myocarditis after COVID-19 illness, and 66% had myocarditis from another cause (non–COVID-19 infection in 31%, autoimmune disorder in 13%, drugs in 10%, hyper-eosinophilic blood disorder in 5%, and other/unknown in 41%).
