Built environment and cardiovascular prognosis: a study of exercise access, walkability, and mortality in HFpEF

Background Social determinants of health, including the built environment, shape cardiovascular risk and outcomes. Cardiorespiratory fitness strongly predicts cardiovascular and all-cause mortality, and neighborhood walkability and access to exercise facilities are modifiable factors that enable physical activity. Using heart failure with preserved ejection fraction (HFpEF) as a case study, we hypothesized that better neighborhood walkability and exercise access are associated with improved survival. Methods In this retrospective cohort, electronic health records of HFpEF patients living in urban California (UC Davis Health, 2014 to 2022) were linked to ZIP Code Tabulation Area (ZCTA)-level Fitness Infrastructure and Walkability Scores derived from OpenStreetMap and to U.S. Census data. Unadjusted survival was compared with Kaplan–Meier curves and log-rank tests. The association between each score (per standard deviation) and all-cause mortality was estimated with multivariable Cox proportional hazards models, adjusted sequentially for age, sex, neighborhood income, population density, urbanicity and comorbidity burden, with standard errors clustered on ZCTA. Restricted cubic splines assessed dose-response, and interaction terms tested effect modification. Results Among 4,975 patients contributing 1,660 deaths, each standard deviation increase in the fitness (12.4 points) was associated with a hazard ratio for all-cause mortality of 0.919 (95% CI 0.859–0.982; p = 0.013) in the fully adjusted model. The association was graded and monotone across the observed score range on spline analysis and was unchanged by adjustment for individual comorbidity burden (hazard ratio 0.917 before and 0.919 after). The walkability showed an association in the same direction that did not reach significance. The exposure effect did not differ before and after March 2020 (ratio of hazard ratios 1.04, 95% CI 0.92–1.18; p = 0.50) or across tertiles of neighborhood density ( p = 0.42). Conclusion In this HFpEF cohort, greater neighborhood access to exercise infrastructure was associated with lower all-cause mortality after adjustment for demographic, socioeconomic, urbanicity and comorbidity factors. Because the crude association was null and the design is observational, these findings are hypothesis-generating rather than causal. They nonetheless support treating the built environment as a measurable, potentially modifiable structural determinant that merits direct measurement in cardiovascular cohorts.