Interleukin-6, but not C-reactive protein, predicts the occurrence of cardiovascular events after drug-eluting stent for unstable angina

Background: Evidences concerning the predictive value of baseline inflammatory biomarkers after drug-eluting stent (DES) placement are controversial, mainly because the use of statin was not precisely defined.

Objectives: The aim was to compare the differences between interleukin (IL)-6 and high-sensitivity C-reactive protein (hs-CRP) in predicting cardiovascular events 2 years after stenting in patients with unstable angina (UA) who had not received statin pretreatment.

Methods: There were 1,896 patients included in this study. The primary end-point was the occurrence of cardiac death or myocardial infarction (MI). Secondary endpoints included all-cause death, stent thrombosis (ST), target lesion revascularization (TLR), target vessel revascularization (TVR), or a composite of major adverse cardiac events (MACE) at 2 years after the procedure.

Results: During the median follow-up of 2.77 years, 96 patients experienced cardiac death (n = 37, 1.95%) or MIs (n = 70, 3.69%), 94 TLRs, 123 TVRs, 215 MACEs, and 21 definite or probable STs. In multivariable Cox proportional-hazards models and discrimination analysis, elevated IL-6 levels were superior to hs-CRP in predicting the occurrence not only of cardiac death or MI (HR 1.337, 95% CI 1.234-1.449, P < 0.001), but also of MACE and late-occurring definite/probable ST. Incorporation of IL-6 into conventional variables resulted in significantly increased c statistic for the prediction of end-points, with the exception of TLR and TVR.

Conclusion: Elevated IL-6 levels were independent predictors of cardiac death or MI, MACE, and late ST in patients with UA who had not received statin pretreatment, suggesting a role for IL-6 in the inflammatory risk assessment. Pathological studies have confirmed that atherosclerosis is a chronic inflammatory disease. Serum levels of high-sensitivity C-reactive protein (hs-CRP), matrix metalloproteinase, plasminogen activator inhibitor-1, the complement components C3a or C5a, and interleukin(IL)-6 were reported to provide strong and independent indications of the risk for future cardiovascular (CV) events, even among individuals who are thought to be free of vascular disease.