Interleukin-18: a strong predictor of the extent of coronary artery disease in patients with unstable angina

The aim of this study was to confirm that plasma interleukin (IL)-18 level is associated with the extent of coronary artery disease in unstable angina patients. Previous studies have shown that patients with unstable angina have significantly higher plasma IL-18 levels than healthy volunteers. However, the association between IL-18 and the extent of coronary artery atherosclerosis in patients with unstable angina remains unclear. Plasma concentrations of IL-18 and high-sensitivity C-reactive protein (hs-CRP) were measured in 166 consecutive patients admitted for coronary arteriography. One hundred and eighteen patients with unstable angina had coronary artery disease (coronary artery disease group; severity score: 2.32 +/- 1.47; Gensini score: 31.3 +/- 25.9), and 48 patients with coronary risk factors and without coronary artery lesions served as the risk control group. Plasma levels of IL-18 were higher in the coronary artery disease group than in the risk control group (P = 0.062). Additionally, plasma levels of IL-18 were significantly higher in 77 coronary artery disease patients with severity score >= 2 than in the risk control group (242.3 +/- 110.6 vs 209.8 +/- 120.3 pg/ml, P = 0.016). By univariate analysis, log-transformed plasma IL-18 concentration was positively correlated with coronary artery disease severity score (r = 0.244, P = 0.009). By multiple regression analyses, the association between coronary artery disease severity score and IL-18 remained significant (beta = 0.733, P = 0.017) when controlling for age, diabetes mellitus and left ventricular ejection fraction. Additionally, coronary artery disease severity score was greater in the highest tertile (> 246 pg/ml) of plasma IL-18 levels than in the middle (176-246 pg/ml) and the lowest (< 176 pg/ml) tertiles (2.79 +/- 1.52 vs 2.05 +/- 1.08 vs 2.13 +/- 1.66, P = 0.028). Of note, plasma hs-CRP level had no significant correlation with coronary artery severity. Plasma IL-18 level is associated with the extent of coronary artery disease in unstable angina patients, suggesting the link between IL-18 and coronary artery atherosclerosis in these patients.