Abstract Body: Introduction:
Sudden cardiac death (SCD) and heart failure (HF) are major contributors to cardiovascular mortality in the United States, particularly among aging populations. HF is associated with structural and electrical remodeling of the heart, which substantially increases the risk of SCD. However, national trends and demographic disparities in mortality due to concurrent SCD and HF remain poorly characterized.

Methods:
We analyzed CDC WONDER mortality data (1999–2020) to identify deaths among U.S. middle-aged (55–74 years) and older adults (≥75 years) in which both SCD and HF were listed as causes of death on death certificates. Causes of death were identified using ICD-10 codes. Age-adjusted mortality rates (AAMRs) per 100,000 population were calculated overall and stratified by sex, age group, race/ethnicity, place of death, and Census region. Temporal trends were assessed using annual percent changes (APCs) with 95% confidence intervals. A p-value <0.05 was considered statistically significant.

Results:
From 1999 to 2020, a total of 26,030 deaths were attributed to coexisting SCD and HF. Although the overall AAMR declined slightly from 0.73 per 100,000 in 1999 to 0.65 in 2020, a significant decrease was observed until 2018 (APC: −1.66%, p < 0.05). Males had higher mortality rates than females, with nearly twice the AAMR (0.81 vs 0.44). Older adults had substantially higher AAMRs (2.49; 95% CI, 2.46–2.52) compared with middle-aged adults (0.32; 95% CI, 0.31–0.33). By race, non-Hispanic (NH) Blacks had the highest mortality rate (1.0), followed by NH American Indians (0.59), NH Whites (0.58), Hispanics (0.25), and NH Asians (0.19). Rural areas had higher mortality rates than urban areas; however, urban areas experienced a steeper increase in mortality (APC: +14.0%, p < 0.05) compared with rural areas (APC: +1.92%, p < 0.05). Regionally, AAMRs were highest in the South (0.78) and Midwest (0.69). The Northeast had relatively lower AAMRs (0.40), while the West maintained the lowest rates overall (0.38). Additionally, 39% of deaths occurred at the decedent’s home, whereas 36% occurred in medical facilities.

Conclusion:
Mortality due to coexisting SCD and HF showed a modest overall decline from 1999 to 2020, with higher mortality observed among males, older adults, non hispanic black individuals, and residents of rural regions. These findings highlight populations that may benefit from targeted cardiovascular prevention strategies and improved access to care.