Clinical course and follow-up of pediatric patients with COVID-19 vaccine-associated myocarditis compared to non–vaccine-associated myocarditis within the prospective multicenter registry—“MYKKE”

• DOI: 10.1016/j.ahj.2023.11.006
• Publication Date: 2023-11-11T16:24:34Z
• Authors: Nele Rolfs; Cynthia Huber; Eicke Schwarzkopf; Dirk Mentzer; Brigitte Keller-S...; Bernd Opgen-Rhein; Wiebke Frede; Axel Rentzsch; Tobias Hecht; Martin Boehne; Maria Grafmann; Daniela Kiski; Iva Graumann; Rudi Foth; Inga Voges; Ulrich Schweigmann; Bettina Ruf; Marcus Fischer; Gesa Wiegand; Karin Klingel; Thomas Pickardt; Tim Friede; Daniel Messroghli; Stephan Schubert; Franziska Seidel
• Keywords: 610; 600; 3. Good health

Since the onset of widespread COVID-19 vaccination, increased incidence of COVID-19 vaccine-associated myocarditis (VA-myocarditis) has been noted, particularly in male adolescents.Patients <18 years with suspected myocarditis following COVID-19 vaccination within 21 days were enrolled in the PedMYCVAC cohort, a substudy within the prospective multicenter registry for pediatric myocarditis "MYKKE." Clinical data at initial admission, 3- and 9-months follow-up were monitored and compared to pediatric patients with confirmed non-vaccine-associated myocarditis (NVA-myocarditis) adjusting for various baseline characteristics.From July 2021 to December 2022, 56 patients with VA-myocarditis across 15 centers were enrolled (median age 16.3 years, 91% male). Initially, 11 patients (20%) had mildly reduced left ventricular ejection fraction (LVEF; 45%-54%). No incidents of severe heart failure, transplantation or death were observed. Of 49 patients at 3-months follow-up (median (IQR) 94 (63-118) days), residual symptoms were registered in 14 patients (29%), most commonly atypical intermittent chest pain and fatigue. Diagnostic abnormalities remained in 23 patients (47%). Of 21 patients at 9-months follow-up (259 (218-319) days), all were free of symptoms and diagnostic abnormalities remained in 9 patients (43%). These residuals were mostly residual late gadolinium enhancement in magnetic resonance imaging. Patients with NVA-myocarditis (n=108) more often had symptoms of heart failure (P = .003), arrhythmias (P = .031), left ventricular dilatation (P = .045), lower LVEF (P < .001) and major cardiac adverse events (P = .102).Course of COVID-19 vaccine-associated myocarditis in pediatric patients seems to be mild and differs from non-vaccine-associated myocarditis. Due to a considerable number of residual symptoms and diagnostic abnormalities at follow-up, further studies are needed to define its long-term implications.