Abstract Body (Do not enter title and authors here): Background/Aim: We previously reported that late gadolinium enhancement (LGE) on cardiac MRI (CMR) was as high as 82% in pediatric patients with COVID-19 vaccine-associated myocarditis (C-VAM) despite mild clinical symptoms and normal left ventricular function. As LGE can be a harbinger for future adverse events including arrhythmias, heart failure or sudden cardiac death, we sought to identify predictors for LGE in C-VAM, specifically assessing troponin as a screening marker for C-VAM patients at risk for myocardial scarring who could then be referred for a confirmatory CMR with LGE.

Methods: In this longitudinal multicenter retrospective observational study across 38 U.S. member institutions of the Myocarditis After COVID Vaccination (MACiV) study network, 333 patients with C-VAM based on CDC criteria were included from April 2021 to November 2022. Data collected included demographics, laboratory values, clinical and cardiac imaging characteristics and outcomes. Using logistic regression, troponin levels at presentation were assessed as a log transformed continuous variable and categorized into tertiles.

Results: The C-VAM patients were predominantly white (67%) adolescent males (91%, 15.7± 2.8 years). There were 216/333 (65%) patients who had both a reported troponin value and had a CMR. On univariate analysis, elevated troponin increased the probability of having LGE (OR=1.29, 95% CI: 1.06, 1.58, p=0.012). Even after controlling for age, race, sex, number of vaccine doses and left ventricular ejection fraction (OR=1.32, 95% CI: 1.06, 1.65, p=0.013). Patients >15 years compared to those ≤15 years of age were 2.94 (95% CI: 1.28, 6.75, p=0.011) times more likely to have LGE at presentation. Patients with troponin levels in the highest tertile compared to lowest tertile were 2.66 times (95% CI: 1.04, 6.83, p=0.042) more likely to have LGE along with a greater involvement > 4 AHA myocardial segments with LGE (p=0.004)

Conclusions: Higher troponin values are associated with presence of late gadolinium enhancement on cardiac MRI in patients with COVID-19 vaccine-associated myocarditis. Troponin levels at presentation may facilitate risk stratification and function as a screening tool to identify those C-VAM patients with the greatest likelihood of myocardial scarring, who may benefit from undergoing CMR for tissue characterization.