The Possible Role of PM2.5 Chronic Exposure on 5-Year Survival in Patients with Left Ventricular Dysfunction Following Coronary Artery Bypass Grafting.

Background: The survival benefit of surgical revascularization in multivessel coronary artery disease is well understood, though it can be modified by left ventricular dysfunction. Chronic exposure to air pollutants has gained more attention recently as a possible non-traditional morbidity and mortality cardiovascular risk factor. This study identified possible 5-year mortality risk factors related to postoperative left ventricular performance, including air pollutants.

Patients: There were 283 patients (244 (86%) males) with a median age of 65 (60-70) years enrolled in the retrospective analysis. All patients were referred for off-pump coronary artery revascularization due to chronic coronary syndrome that presented as a multivessel coronary artery disease. They were divided into three groups depending on the postoperative course of left ventricular fraction (LVEF 50% or more (169 patients), LVEF between 41 and 49% (61 patients), and LVEF 40% or less (53 patients)).

Results: The overall survival rate was 84% (237 patients) in a median follow-up time of 5.3 (4.8-6.1) years. The median (Q1-Q3) chronic air pollution exposures for the analyzed group were 19.3 (16.9-22.4) μg/m³ for fine particles such as PM_2.5, 25.8 (22.5-29.4) μg/m³ for coarse particles such as PM₁₀, and 12.2 (9.7-14.9) μg/m³ for nitric dioxide (NO₂). The mortality in the first group (LVEF at least 50%) was 23 (13.6%), in the second group (LVEF 41-49%) was 9 (15%), and in the third group (LVEF 40% or less) was 14 (26%). The multivariable regression analysis for the five-year mortality risk in the first group revealed the predictive value of dyslipidemia (HR: 3.254, 95% CI: 1.008-10.511, p = 0.049). The multivariable regression analysis for five-year mortality risk in the second group revealed the predictive value of dyslipidemia (HR: 3.391, 95% CI: 1.001-11.874, p = 0.050) and PM_2.5 (HR: 1.327, 95% CI: 1.085-1.625, p = 0.006). In the third group (severely decreased LVEF), chronic PM_2.5 exposure was found to be significant (HR: 1.518, 95% CI: 1.50-2.195, p = 0.026) for 5-year mortality prediction.

Conclusions: Traditional risk factors, such as dyslipidemia, are pivotal in the 5-year mortality risk following surgical revascularization. Chronic exposure to ambient air pollutants such as PM_2.5 may be an additional risk factor in patients with left ventricular dysfunction.