This study examined variation in county-level cardiovascular disease (CVD) death rates among adults aged 35-64 years using four measures of rural-urban status: Urban Influence Codes, Rural-Urban Continuum Codes (RUCC), National Center for Health Statistics Urban-Rural Classification Scheme, and Core-Based Statistical Areas. We estimated 2021 CVD death rates and used Poisson regression models to calculate rate ratios (RR) for full and dichotomized rural-urban measures. All measures identified the largest RR in the middle of the rural-urban spectrum. RUCC demonstrated patterns by population size and adjacency. RR magnitude varied across dichotomization methods. These findings demonstrate complexity underlying rural-urban differences and can guide public health practice.

Amid the COVID-19 pandemic, national cardiovascular disease (CVD) death rates increased, especially among younger adults. County-level variation has not been documented. Using county-level CVD deaths (ICD-10 codes: I00-I99) from the US National Vital Statistics System, we developed a Bayesian multivariate spatiotemporal model to estimate excess CVD death rates in 2020 based on trends from 2010-2019 for adults aged 35-64 and ≥65 years. Among adults aged 35-64 years, 64.7% of counties experienced significant excess CVD death rates. The median county-level CVD death rate in 2020 was 150 per 100,000 persons, which exceeded the predicted rate for 2020 (median excess death rate: 11 per 100,000; median excess rate ratio: 1.08). Among adults aged ≥65 years, 15.2% of counties experienced significant excess CVD death rates. The median county-level CVD death rate was 1,546 per 100,000 in 2020, which exceeded the predicted rate in 2020 (median excess death rate: 48 per 100,000, median excess rate ratio: 1.03). Counties with significant excess death rates in 2020 were geographically dispersed. In 2020, disruptions of county-level CVD death rates were widespread, especially among younger adults, suggesting the continued importance of CVD prevention and treatment in younger adults in communities across the country.