Frequency of Pathological MRI Findings in Suspected Myocarditis during the COVID-19Pandemic

ABSTRACT

Background: COVID-associated and vaccine-triggered myocarditis in young people have received much attention over the course of the pandemic due to early results of vaccination associated myocarditis. This may have led to an increase in myocarditis suspicions. In this study we wanted to examine the actual amount of COVID-associated myocarditis in ourtertiary center. Method(s) We included all cardiac MRIs performed in our institution for the indication of suspected myocarditis between 2020and 2022. We excluded patients with primary cardiomyopathy. We divided the patients into three groups Group 1 had noCOVID infection or COVID-vaccine associated with their suspected myocarditis, group 2 had received a COVID vaccination prior to developing symptoms, group 3 had had an acute COVID infection and group 4 had a clinical diagnosis of Pediatric inflammatory multisystem syndrome (PIMS). Result(s) Overall, 28 patients had MRIs for suspected myocarditis performed at our center in the investigated time frame. They were 10 to 18 years of age (mean 15.1 years). Symptoms included chest pain, fatigue, palpitations and reduction in exercise tolerance. Nineteen patients were in group one, 4 patients had symptoms associated with COVID vaccination, three had acute infection and two had a clinical diagnosis of PIMS. Late gadolinium enhancement (LGE) was found in 7 patients. None of these were in groups 2 or 3. Both patients with PIMS(n = 2) had myocarditis on biopsy but only one on MRI. Myocardial biopsy was performed in 8 patients. They showed myocarditis in 6 patients. Apart from the PIMS cases, none of them were associated with Corona infection or COVID vaccine. Three patients had parvovirus B19 on biopsy and one also had EBV. One of the PIMS patients also had HHV6. Theother four biopsies did not yield any viral DNA on PCR. Conclusion(s) Myocarditis associated with acute COVID infection or vaccination was not found in our cohort. Exercise intolerance or chest pain was not reliable indicators of cardiac causes. Even in the pandemic, coronavirus and COVID-19vaccines are unlikely causes of myocarditis. Most cases were associated with classic cardiotropic viruses. However, in cases of PIMS, cardiac involvement is likely and should be investigated accordingly.