Air pollution and recurrence of cardiovascular events after ST-segment elevation myocardial infarction

The effects of air pollution on discharged patients after ST-segment elevation myocardial infarction (STEMI) still remain uncertain. We examined the association between air pollutants and recurrent cardiovascular events in STEMI survivors.

A retrospective cohort of 1641 discharged patients after STEMI was established in 2013 and followed until the end of 2019. Concentrations of air pollutants including fine particles <2.5 μm aerodynamic diameter (PM_2.5), inhalable particles <10 μm aerodynamic diameter (PM₁₀), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO) and ozone (O₃) measured by fixed ambient air monitoring stations were collected for exposure assessment. Multivariate-adjusted Cox proportional hazards models were used to estimate the increased risks of recurrent cardiovascular events.

Compared with the first exposure quartile, for short-term exposure, hazard ratios (HRs) of recurrent cardiovascular events associated with the fourth exposure quartiles of PM_2.5, PM₁₀, NO₂, SO₂, CO, and O₃ were 4.06 (95% CI: 2.62-6.30), 3.79 (95% CI: 2.57-5.58), 2.22 (95% CI: 1.67-2.94), 4.47 (95% CI: 3.08-6.48), 3.73 (95% CI: 2.54-5.48), and 5.35 (95% CI: 3.12-9.20), respectively. For long-term exposure, HRs associated with the fourth exposure quartiles of PM_2.5, PM₁₀, NO₂, SO₂, CO, and O₃ were 6.43 (95% CI: 3.60-11.47), 4.77 (95% CI: 2.85-7.99), 3.22 (95% CI: 2.00-5.19), 3.20 (95% CI: 2.05-5.01), 4.44 (95% CI: 2.65-7.45), and 1.07 (95% CI: 0.80-1.42), respectively. The risks of recurrent cardiovascular events brought by air pollutants mostly increased nonlinearly.

Short- and long-term exposure to air pollutants except ozone increases the risks of recurrent cardiovascular events in STEMI survivors. Better environmental policies and secondary prevention strategies should be developed to protect STEMI survivors as a susceptible population.