ABSTRACT
Background: Several studies described occurrence of myocarditis after SARS-CoV-2 vaccination in pediatric patients. Weaimed to characterize the clinical course of myocarditis following SARS-CoV2 vaccination including follow-up data within the prospective German registry for suspected myocarditis in children and adolescents "MYKKE." Method: Patients younger than 18 years with suspected myocarditis and onset of symptoms within 21 days followingSARS-CoV2 vaccination were enrolled within the MYKKE registry. The suspect of myocarditis is valid in patients with clinical symptoms and diagnostic findings typically seen in myocarditis. Clinical data are monitored at initial admission and duringshort-term and long-term follow-up. Result(s): Between July 2021 and August 2022, a total of 48 patients with a median age of 16.2 years (IQR: 15.2-16.8)were enrolled by 13 centers, 88% male. Onset of symptoms occurred at a median of 3 days (IQR: 2-7) after vaccine administration, most frequently after the second dose (52%). Most common symptoms at initial admission were anginapectoris (81%), fatigue (56%), dyspnea (24%) and documented arrhythmias (17%). Initial ECG abnormalities included ST-elevation (48%) and T-wave inversion (23%). Elevated Tropon in was observed in 32 patients (67%) and in 19 cases (40%)NT-proBNP was above the normal range with a median level of 171 pg/mL (IQR: 32-501). 11 (23%) patients presentedwith mildly reduced systolic function at initial echocardiography or cardiac MRI. In 40 patients cardiac MRI and/orendomyocardial biopsy was performed (83%) and diagnosis of myocarditis could be verified in 27 cases (68%). Thirty-nine patients underwent short-term follow-up with a median of 2.8 months (IQR: 1.9-3.9) after discharge. 19 patients (49%)presented with either clinical symptoms (n = 9) and/or diagnostic abnormalities (n = 16) at follow-up. 12 patients (38%)still had medical treatment. Except for one patient with malign arrhythmias (ventricular tachycardia), no major cardiac adverse events were observed during initial admission and follow-up. Conclusion(s): Our data confirm that SARS-CoV-2 vaccine-related myocarditis is characterized by a mild disease course. However, after short-term follow-up a considerable number of patients still presented with symptoms and/or diagnostic abnormalities. Data on long-term follow-up are awaited.