Background: The presence of good coronary collateral circulation (CCC) can protect and preserve myocardium from ischemia, increase myocardial contractility, and reduce adverse clinical events. However, its impact on mortality is still a topic of debate, particularly in acute coronary syndrome (ACS). The aim of this study was to investigate the association of CCC with cardiac risk factors and in-hospital mortality in patients hospitalized with a diagnosis of ACS.
 Methods: The study population included 200 patients with ST – elevation myocardial infrarction who underwent coronary angiography and were found to have TIMI flow coronary 0 or 1. The CCC was graded according to the Rentrop classification. The patients were classified into a poor CCC group (Rentrop grades 0-1, n=161) or a good CCC group (Rentrop grades 2-3, n=39). Following of major adverse cardiac events about 30day after PCI.
 RESULTS: Patients with good CCC had time onset chest pains (p = 0,001), higher rate of Killip class of at least 2 at admission (p = 0,031), peak troponin T (p = 0,037), lacticemia lower (p = 0,03), multivessel lesion upper (p = 0,03) with the patients with poor CCC. MACE of patients with good CCC nosignificant with the patient with poor CCC (OR=3,9, 95%CI[0,5- to 30,5], mortality (HR 2,5, 95%CI[0,31-19,2], p=0,45), unplanned target vessel revascularisation (TVR) (HR 28,8 (0.006 to 1.4), p=0.44), comelack in-hospital by cardiovascular causes (HR 1,06, 95%CI[0,29 to 3,7]. P=0,93). Increase left ventricular ejection fraction after 30day in patients with good CCC upper patients with poor CCC (p=0,004).
 CONCLUSION: In contrast to previous studies, our study did not confirm a beneficial role of good CCC in patients with ST – elevation myocardial infarction. The presence of good CCC was even independently associated NYHA grades, Killip grades, peak troponin T, lacticemia and left ventricular ejection fraction.