Abstract 15128: Are We Underestimating the Incidence of Significant Ventricular Ectopy in Pediatric Patients With Post-Covid Vaccine Myocarditis?

Abstract

Background: The development of mRNA vaccines was essential in combatting the COVID-19 pandemic. Emergency use authorization for COVID-19 vaccine was granted to adolescents aged 12 and older in May 2021. Subsequently, an increase in myocarditis was observed related to the mRNA vaccine. Previous reports estimate a 5% incidence of ventricular arrhythmias in patients with vaccine-associated myocarditis. Hypothesis: The incidence of ventricular ectopy in patients with post-COVID vaccine myocarditis is higher than previously described. Methods: We analyzed data retrospectively for patients admitted to our cardiac center with clinically suspected myocarditis who received COVID-19 vaccine within 30-days prior to onset of symptoms and had no other clinical cause for myocarditis. We separated this cohort into 3 groups based on the presence of rhythm monitoring post discharge: normal monitor post discharge (Lown grade 0 or 1), abnormal monitor post discharge (Lown grade ≥ 2), and no monitor post discharge. Data are shown as mean ± standard deviation. Results: We included 16 patients with a mean age of 14.9 ± 3.1 years. 12 patients were discharged with ambulatory monitoring and 3 were categorized as abnormal (25%). Abnormal findings included non-sustained ventricular tachycardia, ventricular ectopy with bigeminy and trigeminy patterns, and sustained monomorphic ventricular tachycardia. 1 patient was readmitted for sustained ventricular tachycardia. Mean troponin levels were higher in the arrhythmia group (17.3 ±4) compared to the non-arrhythmia group (4.3 ±4.3). 2 of the 3 patients in the arrhythmia group had myocardial edema on cMRI. Only one patient had LGE. Conclusion: At our center, 25% of patients with post-COVID vaccine myocarditis experienced ventricular arrhythmias, and these patients had higher troponin levels during acute illness. Awareness of this increased rate of arrhythmia is necessary to safely monitor patients with post-COVID vaccine myocarditis.