Background: Bilirubin is a strong antioxidant under physiological conditions and suppresses the oxidation of lipids and low density lipoproteins and prevents free radical injury. Lesser serum bilirubin levels are associated with Protein Kinase C activation, inflammation, and oxidative stress, which are known mediators of endothelial and microvascular dysfunction. The aim of the study was to assess the serum bilirubin levels and coronary artery disease in comparison with controls without coronary artery disease and its relation with ACS sub types such as STEMI, NSTEMI and unstable angina.

Methods: A hospital based analytical study was conducted for a period of two years in our medical college hospital. Patients attending casualty with STEMI, NSTEMI and Unstable Angina confirmed by ECG, ECHO and cardiac markers were taken as cases. Controls were selected and matched with age, gender and other co-morbid conditions. Total of 110 subjects were included in the study with 55 cases and 55 controls. General and systemic examination was conducted on all study subjects including laboratory investigations like complete blood count, renal function test, lipid profile, CKMB, Troponin I, HBsAg, HCVIgM, SGOT, SGPT, total bilirubin, direct bilirubin, in direct bilirubin, albumin and globulin levels. A 12 lead ECG and a trans thoracic echocardiogram was performed for all patients.

Results: Risk factors like diabetes mellitus, hypertension, smoking history, family history, fasting lipid profile and liver function tests were compared between the cases and controls and it was found that the serum bilirubin levels which includes total bilirubin, direct bilirubin and indirect bilirubin were found to be lower among the case group compared to the control group and this difference was found to be statistically significant (p<0.05). Bilirubin levels in people with STEMI were lower than NSTEMI and bilirubin levels in people with NSTEMI were lower than people with Unstable angina but the difference was not statistically significant.

Conclusions: This study confirmed a significant inverse association between the reduced serum bilirubin levels and the occurrence of Coronary artery disease. Thus total bilirubin may serve as a protective biomarker of CAD.

Keywords: Coronary artery disease, Risk factor, Serum bilirubin, STEMI, NSTEMI, unstable angina.

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Prof Dr M. Senthilvelan

Professor & HOD, Department of General Medicine, Rajah Muthiah Medical College, Annamalai University, Chidambaram, Tamilnadu, India