Abstract Body (Do not enter title and authors here): Background: Long QT Syndrome (LQTS) is an inherited arrhythmia syndrome that predisposes patients to sudden death. Prior studies on racial disparities in LQTS have shown similar number of cardiac events, but longer QTc in Black patients compared to non-Hispanic Whites (NHW). There is limited data on cardiac events in Hispanic children with LQTS. We hypothesized that Hispanic children with LQTS have worse outcomes compared to NHW children.

Methods: This retrospective cohort study of the Pediatric Health Information System (PHIS) database included children ages 0 - 17 years hospitalized from 2013-2024 with an International Classification of Disease 9^th or 10^th edition code for LQTS listed in the first five admission diagnoses. Patients with congenital heart disease and chromosomal abnormalities were excluded. The primary predictor variable was race/ethnicity, with covariables including age, sex, and insurance type. Our primary outcome variable was a documented lethal arrhythmia, and secondary outcomes included pacemaker and/or implantable cardioverter defibrillator (ICD) placement. Chi-square was used to assess patient characteristics. Univariable mixed-effect log-binomial regression was used to assess risk of outcomes by characteristics using hospital as a random effect with multivariable models generated via backward elimination.

Results: We identified 6,476 children (24% Hispanic, 76% NHW). Compared to NHW children, Hispanic children were more often male and presented earlier (median age 11y vs 13y, 25-75 IQR 6-15; p<0.0001) (Table 1). Hispanics had a higher use of public insurance and a longer length of stay (LOS) than NHW (Table 1). Both groups had similar numbers of cardiac arrest and mortality (Table 1). On multivariable analyses, there was no increased risk of lethal arrhythmias (p= 0.76) or pacemaker/ICD placement (p=0.56) for Hispanics compared to NHW.

Conclusion: This is the first national descriptive study assessing outcomes in Hispanic children with LQTS. Hispanics with LQTS were hospitalized at an earlier age, had a longer LOS, and higher rates of public insurance. Further studies are warranted to determine knowledge of family history of LQTS, medication adherence, and long-term ability for follow up.