Abstract Body (Do not enter title and authors here): Background: The US population has seen a dramatic increase in the burden of heart failure (HF) and sudden cardiac death (SCD) mortality. SCD is one of the prominent causes of mortality in HF patients. However, HF-associated SCD-related mortality trends have not been established yet.

Aims: This study aims to highlight the annual trends and demographic differences in HF-associated SCD mortality among adults in the U.S from 1999-2020.

Methods: The CDC WONDER multiple-cause of death database was examined from 1999 to 2020 for HF-associated SCD mortality in adults over the age of 25. Age-adjusted mortality rates (AAMRs) per 1,000,000 persons was calculated. Trends and annual percent changes (APCs) were assessed overall and stratified by sex, race/ethnicity, urbanization status, and census region.

Results: Between 1999 and 2020, 39,660 HF-associated SCD-related deaths occurred among US populations. Following a reduction from 10.9 in 1999 to 6.8 in 2018 (APC, -2.5 [-2.8 to -2.3]), AAMR increased to 8.2 in 2020 (APC, 10.3 [3.6 to 13.7]) in the overall population. Men had consistently higher AAMRs than women from 1999 (AAMR men: 15.1 vs women: 7.9) to 2020 (AAMR men: 11.3 vs women: 5.6). Non-Hispanic (NH) Black or African Americans had the highest AAMR (14.0), followed by NH Whites (8.3), and Hispanics or Latinos (3.4). Southern region had the highest AAMR (10.4), followed by Midwest (9.6), West (5.8), and Northeast (5.8). Moreover, rural areas had consistently higher AAMR (14.6) than urban areas (6.9).

Conclusion: Following a steady decline until 2018, HF-associated SCD mortality in adults increased between 2018 and 2020. The highest AAMRs were observed among Black or African American adults and men, and patients living in the Southern and non-metropolitan areas. Tailored strategies focusing specifically on arrhythmic events and related mortality in HF patients are needed to address the recent surge in mortality rates among these demographics.