Abstract Body (Do not enter title and authors here): Background: Cardiovascular disease (CVD) mortality in the U.S. younger population is on the rise. However, limited data is available on CVD-related mortality trends in this population.

Aim: This study aimed to assess the temporal trends and demographic differences in CVD-related mortality among the U.S. youth.

Methods: The CDC WONDER dataset was analyzed from 1999-2021 for CVD-related mortality in children and young adults (age <25 years). Socio-demographic data including gender, race/ethnicity, urbanization status and census region was acquired. Age adjusted mortality rates (AAMR) per 100,000 persons and annual percent changes (APCs) with 95% confidence interval (CIs) were calculated.

Results: Between 1999-2021, a total 54,283 CVD-related deaths occurred among the youth in the U.S. The overall AAMR declined from 1999-2008 (APC, -1.15 [-3.4 to 0.53]), followed by sharp decrease from 2008-2012 (APC, -3.28 [-4.68 to 0.86]). The AAMR continued to decrease steadily from 2012 to 2019 (APC: -1.20, [-3.76 to -0.06]), followed by a sharp increase in from 2019 to 2021, (APC, 3.03 [-0.66 to 5.12]). Males consistently had higher AAMRs than females from 1999 (AAMR males: 2.99 vs females: 2.3) to 2021 (AAMR males: 2.39 vs females: 1.74). Non-Hispanic (NH) Black or African Americans had the highest AAMR in 2020 (3.68), followed by NH Whites (1.71), Hispanic or Latinos (1.59), and Asian and Pacific Islanders (1.2). AAMRs also showed significant variations across different regions (overall AAMR West 1.81; Northeast 1.93; Midwest 2.3; South 2.69). Metropolitan areas (2.23) consistently had lower mortality rates than nonmetropolitan areas (2.59).

Conclusion: Our analysis revealed that CVD-related mortality in the youth declined from 1999-2019, followed by an increase in 2020 to 2021. Highest mortality rates were seen in males, Black or African Americans, Western region of the U.S, and nonmetropolitan areas. Tailored interventions are necessitated to decrease the burden of CVD-related mortality in these demographics among children and young adults in the United States.