Myocarditis after COVID-19 mRNA vaccines

Koizumi, Takahiro; Awaya, Toru; Yoshioka, Keitaro; Kitano, Shoma; Hayama, Hiromasa; Amemiya, Katsushi; Enomoto, Yoshinari; Yazaki, Yoshiyuki; Moroi, Masao; Nakamura, Masato

COVID-19 vaccinations have been deployed to mitigate the effects of the COVID-19 pandemic. However, vaccine-associated myocarditis has been reported. Two typical cases in terms of young age and after the second vaccination were admitted to our hospital with symptoms of worsening chest pain, ST elevation on the electrocardiogram (ECG) and creatine kinase elevation. Emergency coronary angiography revealed no coronary arteries, and an endomyocardial biopsy showed no remarkable findings. Their symptoms were resolved within a few days of sufficient rest and non-steroidal anti-inflammatory drug. The ECG of Patient 1 showed typical change; therefore, the diagnosis of myocarditis was easy. However, the ECG of Patient 2 did not show typical change for myocarditis, and there was no abnormality in the wall motion on echocardiography. Cardiac magnetic resonance imaging (MRI), strain analysis by speckle-tracking echocardiography and serial ECG were useful for the diagnosis of myocarditis. This work shows that conducting early examinations with multimodality imaging and sufficient rest are needed to prevent the worsening of vaccine-associated myocarditis. Although the benefits of the vaccines outweigh the risks, we should be aware that myocarditis can occur after COVID-19 mRNA vaccination regardless of race, especially in young males.