Abstract Body: Background
Septicemia often results in cardiovascular collapse and cardiac arrest (ICD-10 I46); however, national mortality trends within this population are not yet thoroughly analyzed.

Hypothesis
We postulated that the age-adjusted mortality rates (AAMR) for cardiac arrest in adults aged 25 years and older with septicemia have significantly altered from 1999 to 2024 and that disparities are present based on demographic and geographic factors
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Methods
CDC WONDER multiple cause-of-death data (1999–2024) were analyzed for U.S. decedents aged ≥25 years with both ICD-10 A41 and I46 codes. Total deaths and proportions by place of death (medical facility, home, nursing home, hospice, other) were tabulated. Annual AAMRs per 100,000 population were calculated. Joinpoint regression estimated average annual percent change (AAPC) in AAMR. Analyses were stratified by sex, race/ethnicity, U.S. Census region, and urban versus rural residence.

Results
A total of 669,989 fatalities were recorded among adults aged ≥25 years due to septicemia and cardiac arrest (330,729 men; 339,260 women). The overall AAMR remained stable from 1999 to 2018, increased sharply from 2018 to 2021 (AAPC +7.2%, p < 0.001), and subsequently declined from 2021 to 2024 (AAPC –8.4%, p < 0.001). Men consistently exhibited higher rates than women, peaking at 17.2 per 100,000 compared to 12.4. When analyzed by race and ethnicity, non-Hispanic Black adults had the highest AAMR at 21.8, followed by Hispanic at 17.0. Hispanic adults experienced the steepest increase from 2018 to 2021 (AAPC +10.8%, p < 0.05) as well as the most significant decline thereafter (AAPC –11.0%, p < 0.05). Regionally, the Northeast exhibited the highest average AAMR at 16.3, whereas the Midwest reported the lowest average AAMR of 5.7. Urban areas surpassed rural areas in mortality rates (2020: 13.5 vs. 11.9). State AAMRs varied significantly, ranging from 27.7 in Nevada to 2.0 in Minnesota/Wisconsin. Most deaths occurred in medical facilities (90.2%), followed by nursing homes (5.4%).

Conclusions
Cardiac arrest mortality in adults with septicemia was flat until 2018, surged during 2018–2021, then declined through 2024. Persistent disparities by sex, race/ethnicity, region, and urbanization highlight the need for targeted clinical and public health interventions to prevent and manage sepsis-related cardiac arrest during infectious disease surges.