Impact of air pollution exposure on short and long-term outcomes in patients with ST-elevation myocardial infarction

Background Air pollution has emerged as a novel risk factor for atherosclerosis and coronary artery disease (CAD). Both acute and chronic exposure to air pollutants have been associated with adverse cardiovascular events; however, their prognostic impact in patients following ST-elevation myocardial infarction (STEMI) remains insufficiently studied. Methods Observational registry including consecutive patients admitted with STEMI between 2020 and 2023, with air pollution exposure data available on the day of the index invasive procedure (acute exposure) and over the preceding two years (chronic exposure). Patients were stratified according to chronic exposure to fine particulate matter (PM₂.₅) using the World Health Organization-recommended cutoff of 15 μg/m³ (>15 μg/m³ vs ≤15 μg/m³). The primary endpoint was the occurrence of major adverse cardiovascular events (MACE), defined as a composite of all-cause death, recurrent acute myocardial infarction (AMI), and hospitalization for heart failure (HF), assessed over a median follow-up of 3 years. Secondary endpoints included: i) in-hospital cardiovascular death, recurrent AMI, and arrhythmias; ii) long-term cardiovascular death, recurrent AMI, and HF hospitalization. Results A total of 312 patients (median age, 64 [IQR:57-74] years, 250 [80.1%] males) were included. Baseline clinical characteristics, cardiovascular risk factors, clinical presentation, in-hospital management, and discharge medical therapy were comparable between groups. Patients with higher PM₂.₅ levels exhibited more often multivessel disease (p=0.015), higher inflammatory markers at admission (p=0.013), and consistently greater exposure to air pollutants both acutely (day of the index event: PM2.5, PM10, O3, NO2, C6H6 p<0.010 for all) and chronically (PM2.5, PM10, NO2, C6H6 p<0.001 for all). In-hospital outcomes did not differ significantly between groups. At 3-year follow-up, Kaplan–Meier analysis showed that patients exposed to PM₂.₅ levels>15 μg/m³ had a significantly lower rate of MACE (Log rank 6.95, p=0.008) and recurrence of myocardial infarction (Log rank 9.62, p=0.002). No differences were observed for all-cause death, cardiovascular death and HF hospitalization. At multivariable Cox regression analysis, chronic PM₂.₅ exposure was independently associated with an increased risk of MACE after adjustment for confounding factors (HR 1.13, 95% CI 1.03-1.23; p=0.008). Conclusions Chronic exposure to fine particulate air pollution is independently associated with worse long-term outcomes after STEMI. These results support air pollution reduction as a public health priority to improve long-term cardiovascular outcomes in patients following STEMI.KM figures