Correlation between air pollution and hospitalization due to myocardial infarction

BACKGROUND: Air pollution is associated with increased risk of cardiovascular disease (CVD). This study aims to evaluate the correlation between air pollutants and hospitalization due to myocardial infarction (MI) as part of "correlation of air pollution with hospitalization and mortality of CVDs and respiratory diseases (CAPACITY) study". METHODS: This case-crossover study analyzed the data of 319 patients who were admitted with diagnosis of ST-elevation MI (STEMI) or non-ST-elevation MI (NSTEMI) in three main hospitals of Isfahan, Iran. The data of airborne pollutants including particulate matter < 10 μm (PM10), particulate matter < 2.5 μm (PM2.5), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), and ozone (O3) as well as climatic indices (temperature, wind speed, and humidity) at 24 hours, 48 hours, and one week before admission were extracted from CAPACITY study. The conditional logistic regression method was used to evaluate the correlation between air pollutants and MI hospitalization. RESULTS: 319 patients with mean age of 63.15 ± 28.14 years, including 238 men (74.6%), and 207 patients with STEMI (64.8%) were recruited. The risk of hospitalization significantly increased in patients with STEMI and 10-unit increment in PM2.5 at 48 hours before admission [odds ratio (OR) = 3.70, 95% confidence interval (CI): 1.69-7.69]. Although, majority of air pollutants had positive association with hospitalization in patients with NSTEMI, they were not statistically significant. CONCLUSION: This study showed significant association between elevated PM2.5 at 48 hours before admission and hospitalization of patients with STEMI. This finding can warn policymakers to design better care services for patients at risk of acute MI during the times of increased air pollution.