A case of mRNA COVID-19 vaccine-associated myocarditis in a child

ABSTRACT

Background and Aim: Accumulation of cases is needed to determine whether vaccines should be recommended for children because of their potential to cause myocarditis in healthy children. Method(s) We report a case in which changes in laboratory data, electrocardiogram (ECG), and magnetic resonance imaging (MRI) were tracked at our hospital. Result(s) A 12-year-old girl developed fever a day after receiving the second dose of the COVID-19 vaccine. Three days after vaccina-tion, she also developed chest pain and went to a hospital. ECG showed ST-T segment elevation. However, the symptoms were mild, and she was treated with antipyretics and analgesics. The next day, she visited the hospital again because she had mild chest pain. ECG showed a negative T-wave, and she was referred to our hos-pital. Her real-time reverse-transcription polymerase chain reac-tion tests for COVID-19 yielded negative results. Computed tomography revealed no anatomical abnormalities of the coronary arteries. The serum concentration of troponin T was elevated by 131 ng/L. Echocardiography showed the left ventricular ejection fraction to be 64%. MRI showed a normal T2 value on T2-weighted imaging;however, extracellular volume increased by 33%. Although the Lake Louise criteria was not met, we diagnosed the condition as myocarditis. She was hospitalized for 2 days and discharged without the need for steroids or gamma globulin treat-ment to relieve her symptoms. Although these findings improved 17 days after vaccination, late gadolinium enhancement was noticed on MRI. Conclusion(s) The COVID-19 vaccine-related myocarditis (C-VAM) in this case was mild and like as cases in Europe and the United States. The risk of COVID-19 associated myocarditis is more than three times the risk of C-VAM. In addition, the mor-tality rate for COVID-19 associated myocarditis is higher than that for C-VAM. The need for a vaccine to protect populations from COVID-19 should be properly recognized. However, because the symptoms of C-VAM are mild, there may be many potential patients with C-VAM. Therefore, it may be advisable to avoid strenuous exercise for approximately 1 week after vaccination. Further research is needed to determine the long-term outcomes of C-VAM because of the late enhancement identified on MRI.