Background Extreme heat is a well‐established environmental hazard linked to elevated cardiovascular disease (CVD) morbidity and mortality, yet few studies evaluate temperature effects across multiple temporal scales or identify community‐specific vulnerability. Methods We analyzed neighborhood‐level CVD deaths and emergency department visits linked to sociodemographic characteristics and high‐resolution temperature and humidity estimates. Generalized additive models with smooth splines for temperature, humidity, age, and time estimated excess heat‐related rates across temporal scales. Principal component analysis and k‐means clustering classified Chicago community areas by multidimensional heat vulnerability. Results Higher temperatures were significantly associated with increased CVD and coronary heart disease mortality across warm‐season, monthly, and daily scales but were not associated with cardiovascular emergency department visits. Peak warm‐season thresholds for all CVD mortality occurred at 25.6 °C, corresponding to 20.7 excess deaths per 100 000 (SD 20.3; P <0.001). Daily peaks occurred at 39.5 °C with 0.048 excess deaths per 100 000 per day (SD 0.068; P <0.001), and a 0 to 3‐day lag peak at 38 °C produced 0.049 excess deaths per 100 000 (SD 0.133; P <0.001). Coronary heart disease mortality showed similar patterns, with warm‐season peaks at 27.8 °C (9.19 per 100 000; P =0.004). No statistically significant associations were observed for myocardial infarction or stroke mortality. Principal component analysis and clustering identified 3 vulnerability profiles driven by socioeconomic disadvantage, racial and ethnic composition, heat exposure, and humidity. Conclusions Temperature thresholds for cardiovascular mortality vary across temporal scales and CVD subtypes, with strongest associations for all CVD and coronary heart disease mortality. Integrating temperature–mortality relationships with community vulnerability profiles may support targeted heat warning systems and neighborhood‐specific adaptation strategies.
Graffy et al. (Wed,) studied this question.