Trends in Mortality Among Decedents With Coexisting Neoplasms and Cardiac Arrhythmias in the United States, 1999–2024

Background Elderly people suffer from cardiac arrhythmias and neoplasms frequently, and they have been linked to more deaths. However, with improved survival after a neoplasm diagnosis, the burden of cardiovascular complications is continually increasing. National mortality trends, however, are not completely understood in this population. This study compares the trends in mortality in the United States from 1999 to 2024 using CDC WONDER Data. Methods A retrospective analysis of United States mortality was performed using the CDC WONDER multiple cause of death database (1999–2024) for adults aged ≥ 65 years with coexisting neoplasm and cardiac arrhythmias. ICD-10 codes(neoplasms: C00–D48; arrhythmias: I44.0–I49.9) listed on death certificates were identified. Age- adjusted mortality rates and crude mortality rates (AAMRs, CMRs) per 100,000 population were calculated. Trends were analyzed by sex, race, age group, geographic region, state, and place of death. Annual percent change. Results A total of 616,985 deaths were identified from 1999 to 2024 among adults aged 65 years and older in the United States with coexisting neoplasms and cardiac arrhythmias. Overall AAMRs increased from 43.67 in 1999 to 74.88 in 2024 (AAPC: 2.14; 95% CI: 1.71–2.58; *p* <0.001). By sex, mortality rose in both groups—females (AAPC: 2.15; 95% CI: 1.70–2.61; p<0.001) and males (AAPC: 1.88; 95% CI: 1.33–2.43; p<0.001) although absolute rates remained roughly twice as high in males (104.96 vs. 52.92 in 2024). By age, CMRs increased across all groups, with adults aged ≥85 years carrying the greatest burden (CMR: 119.62 to 233.75; AAPC: 2.67; 95% CI: 2.22–3.13; p<0.001). Among racial/ethnic groups, non-Hispanic White individuals had the highest AAMR in 2024 (81.06; AAPC: 2.36; 95% CI: 1.93–2.80; p<0.001), whereas non-Hispanic Asian or Pacific Islander individuals had the lowest (28.53; AAPC: 1.03; 95% CI: −0.12–2.20; p=0.079). Geographically, the South showed the largest increase (AAMR: 37.55 to 75.43; AAPC: 2.83; 95% CI: 2.34–3.32; p<0.001), and non-metropolitan areas exceeded metropolitan areas (82.39 vs. 63.77 per 100,000 in 2020; AAPC: 2.81 vs. 1.79; both p<0.001). The sharpest acceleration across all strata occurred between 2018 and 2021. Conclusions Mortality among older adults with coexisting neoplasms and cardiac arrhythmias increased substantially in the United States from 1999 to 2024, with the greatest burden among the oldest adults. As an ecological analysis, this study identifies associations rather than causes; the persistent demographic and geographic disparities it reveals support closer cardio-oncology surveillance and more equitable access to specialized cardiovascular care in this high-risk population.