AIM: To study the relation between development of coronary collaterals and clinical outcome in patients with acute coronary syndrome(ACS).METHODS:251 patients with clinical diagnosed ACS were consecutively enrolled into the present study and divided into two groups according to the presence of coronary collaterals by quantitative coronary angiography(QCA).Serial venous blood samples were collected at admission for determining of high-sensitive C-reactive protein(hs-CRP),brain natriuretic peptide(BNP),and cardiac troponin I(cTnI).Baseline left ventricular ejection fraction(LVEF)was determined by cardiac echo.RESTULTS: Coronary collaterals were detected in 38 patients(as CC group),another 213 patients without coronary collaterals were served as control group.Serum levels of cTnI in patients in CC group was significantly higher than in control group((0.91)?(1.13) vs(0.29)?(0.23)(ng?ml~(-1)),P(0.05)).Serum levels of cTnI in patiemets of CC group was significantly lower than those of control group((0.29)?(0.23) vs(0.91)?(1.13)(ng?ml~(-1)),P