Abstract 4369292: Sex Differences in the Association between Co-Exposure to Air Pollution and Major Adverse Cardiovascular Events among Patients with Heart Disease

Introduction: Air pollution is recognized as an important environmental risk factor for cardiovascular risk, but how combined measures of air pollution contribute to this risk and potential disparities need further investigation. Hypothesis: Patients with a recent myocardial infarction (MI) living in neighborhoods with higher rankings for a composite measure of air pollution would have a greater risk of major adverse cardiovascular events (MACE). Methods: We studied 281 patients recruited from Emory-based hospitals in the Myocardial Infarction and Mental Stress 2 (MIMS2) Study. Participants’ residential addresses were geocoded and a composite measure of air pollution at the census-tract level was calculated by the Centers for Disease Control and Prevention as part of their environmental justice index for: 1) ozone; 2) particulate matter with a diameter of 2.5 microns or less; 3) diesel particulate matter; and 4) air toxics for cancer risk. An overall score for air pollution is based on percentile ranks (0-100%) with higher values indicating greater burden of air pollution. Participants were prospectively followed for 5 years from their initial baseline visit and MACE was defined as a composite index of cardiovascular death and first/recurring events of myocardial infarction and hospitalizations for heart failure. Cox proportional hazards models were used to estimate the regression parameters accounting for clustering of recurrent events and individuals within census-tracts. Hazard ratios were estimated per 10-unit increase in percentile ranking for air pollution. Results: The mean age of the sample was 51 years (range: 26-61); 50% were women and 67% African American. During a median follow-up of 4.3 years, there were 151 adverse cardiovascular events (first and repeated). In models adjusted for sex, race, age, education, cardiovascular risk factors, and MI severity indicators, each 10-unit increase in percentile ranking for air pollution was associated with 64% greater risk of MACE (HR: 1.64, 95% CI: 1.18, 2.29; p = 0.003) among women, but not among men (HR: 1.01; 95% CI: 0.81, 1.26; p = 0.95 (sex interaction: p = 0.01). There were no significant interactions by race. Conclusions: A composite measure of air pollution is associated with cardiovascular risk only among women with heart disease. Future studies should further explore this increased risk among women and potential biological mechanisms.