en بیوشیمی Biochemistry پژوهشي Research <p><strong>Background and Aims: </strong>Bilirubin has been considered an antioxidant that protects against atherosclerosis. The aim of this study was to evaluate the relationship of <a name="OLE_LINK10">serum bilirubin level with the severity and complexity of coronary artery disease (CAD) and long-term outcome </a>in the patients undergoing primary percutaneous coronary intervention (PCI).</p> <p><strong>Materials and Methods:</strong> This prospective cohort study was performed on 136 patients with STEMI undergoing PCI in Heshmat Hospital, Rasht, Iran during 2 years. The complexity was calculated by using dedicated software of the syntax score and the severity of CAD was determined based on the number of vessel involvement. Also, long-term outcomes were evaluated by major adverse cardiac events (MACE ) after one year.</p> <p><strong>Results:</strong> The mean total bilirubin level was 0.95 &plusmn; 0.69 mg/dl; 60.3% of the patients were in the low range of syntax score (0-22) and 38.2 % had two vessels involved. In examining the relationship between serum bilirubin level with the severity and complexity of CAD and MACE, There was no statistically significant association (p>0.05); but, the majority of the patients with high bilirubin levels had a lower number of vessels involved and the complexity of the vessels; Also, MACE was observed in the patients with low bilirubin levels.</p> <p><strong>Conclusions:</strong><a name="OLE_LINK47"> According to the results, attention to serum bilirubin level could be important in CAD and the protective effect of bilirubin can be used for new therapeutic decisions. Further studies on a larger sample of patients have been recommended to confirm and complete these findings.</a></p> Bilirubin, CAD, Complexity, Outcomes, PCI 48 55 http://ijml.ssu.ac.ir/browse.php?a_code=A-10-1-43&slc_lang=en&sid=1 Arsalan Salari No Department of Cardiology, Guilan Interventional Cardiovascular Research Center, Heshmat Hospital, Guilan University of Medical Sciences, Rasht, Iran. Fatemeh Moaddab No Department of Nursing, Guilan Interventional Cardiovascular Research Center, Heshmat Hospital, Guilan University of Medical Sciences, Rasht, Iran. Mahsa Pourabdollah Tootkaboni No Department of Cardiology, Guilan Interventional Cardiovascular Research Center, Heshmat Hospital, Guilan University of Medical Sciences, Rasht, Iran. Maryam Shakiba No Department of Epidemiology, Guilan Interventional Cardiovascular Research Center, Heshmat Hospital, Guilan University of Medical Sciences, Rasht, Iran. Mohadeseh Poursadeghi Yes Department of Nursing, Guilan Interventional Cardiovascular Research Center, Heshmat Hospital, Guilan University of Medical Sciences, Rasht, Iran.