High admission levels of Interleukin-1 receptor antagonist (IL-1RA) in acute MI patients are associated with increased rates of all-cause mortality and cardiac death at 5 years follow-up

Background Inflammation is involved in the pathogenesis of coronary heart disease. Interleukin-1 (IL-1) inflammatory activity is inhibited by IL-1 receptor antagonist (IL-1RA). Based on its relatively high levels in plasma/serum as compared with IL-1b/a, IL-1RA is also considered as a reliable marker of activity in the IL-1 system. While an early increase of IL-1RA has been noted in patients with an acute myocardial infarction (MI), reports relating this biomarker to prognosis following an MI are scarce. Aim To assess the utility of IL-1RA as a prognostic marker of all-cause and cardiac mortality at 5 years follow-up in patients hospitalized with an acute MI. Methods We measured IL-1RA levels in platelet-poor plasma by enzyme immunoassay in 363 consecutive Argentinean patients. Stepwise Cox regression models, applying quartiles (Q), were fitted for the biomarker with mortality within 5 years follow-up as the dependent variable. The hazard ratio (HR) (95% CI) was assessed in a univariate and multivariable model, adjusting for traditional clinical cardiovascular risk factors, which also included B-type natriuretic peptide, high sensitivity C-reactive protein, and troponin-T. Results Death was recorded in 91 (25.1%) patients with a quartile distribution of 21.3% in Q1, 24.7% in Q2, 25.9% in Q3 and 40.7% in Q4. Log Rank Test p=0.019. Cardiac death was recorded in 49 (13.5%) patients. In univariate analysis, IL1RA was significantly associated with all-cause mortality restricted to Q4 as compared to Q1 with a hazard ratio (HR) of 2.32 (95%CI 1.24-3.99), p=0.008, which remained significant after adjusting for confounders [HR 2.22 (1.15-4.29), p=0.018]. The risk of cardiac death showed a similar pattern; HR 2.26 (1.02-5.04), p=0.045 and HR 2.87 (1.21-6.77), p=0.016, respectively. Conclusion In this Argentinean population, high admission levels of IL1RA were independently associated with increased 5 years mortality in patients with an acute MI.