Cross-Sectional Association of Ground-Level Ozone and Nitrogen Dioxide With Cardiac Mechanics Using Speckle-Tracking Echocardiography in the Cardiovascular Health Study

Purpose: Ground-level ozone (O₃) and nitrogen dioxide (NO₂) are two of the most important air pollutants, with accumulating evidence linking them to incident cardiovascular disease. The tissue-level mechanisms by which they affect myocardial function remain incompletely understood, however. Methods: We applied speckle-tracking echocardiography (STE) to explore the relationship between chronic residential gaseous air pollution exposure and cardiac mechanics in community-dwelling older adults largely free of baseline heart disease. Average annual address-specific concentrations of O₃ and NO₂ were estimated from 1990 to 1994 using validated spatiotemporal models. The association between each pollutant and STE measures of left ventricular average longitudinal strain (LVLS), simplified global longitudinal strain (sLVGLS), early diastolic strain rate (LVEDSR), left atrial reservoir strain (LALS), and STE-derived e′ and E/e′ ratio (E/STe′) was explored using multivariable linear and logistic regressions. sLVGLS was additionally modeled as a binary outcome with a cutoff of −16%. Results: One thousand five hundred and seventy-six individuals were included in the analysis. We found that each part per billion increase in O₃ exposure was associated with a 0.47 increase in E/STe′ ratio (95% CI: 0.06–0.88). O₃ exposure was not significantly associated with LV or LA strain abnormalities, including LV GLS, EDSR, or LALS. NO₂ exposure was not significantly associated with any of the STE-derived outcomes. Conclusions: Ozone exposure may be associated with subclinical markers of diastolic dysfunction, while NO₂ does not appear to be linked to echocardiographic strain abnormalities.