Association Of Serum Bilirubin Concentration With Severity Of Coronary Artery Disease

Objective: To study the association of serum bilirubin concentration with severity of coronary artery disease, and to explore new idea for prevention and therapy of coronary heart disease.Methods: 116 patients who underwent coronary angiography (CAG)to determine their severity degree of coronary artery disease. According to the results of CAG, All the cases were classified as CHD group and non-CHD group, observe the differences of serum bilirubin between the two groups. In one week before CAG, all the cases provided blood samples after 12 hours fasting, then all the samples were test for fasting total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL), high density lipoprotein (HDL), apolipoprotein A (APOA), apolipoprotein B (APOB), total bilirubin (TBIL), conjugated bilirubin (DBIL), and unconjugated bilirubin (IBIL). Fast blood glucose (FBG) was tested by Sure Step TM Plus BLOOD GLUECOSE METER made by Lifescan Incorporated Company of America, the average values of three times test results were adopted. Blood pressure was examined by fixed person at fixed time in the morning, the average values of the results of three times were adopted. All the cases were measured body height and weight, then BMI was calculated. according to these date. Based on smoking history of all cases, smoking index was calculated to estimate smoking status. All cases were asked age, and gender was set as two-divided value, male=1, femal=2. According to the result of CAG, coronary severity scores(CCS) was applied to estimate severity of coronary artery disease. The association of bilirubin and CCS was analyzed by two–sample test for independent samples, linear correlation and multiple liner stepwise regression. The association of bilirubin and other risk factors of CHD was analyzed by multiple liner stepwise regression.Results: The two–sample test for independent samples showed that The level of TBIL and DBIL in non-CHD group are higher than those in CHD group(P＜0.01), whereas there was no difference of IBIL between two groups(P＞0.05). Linear correlation reveal that both TBIL and DBIL have negative correlation with LNCCS, r=–0.450 (P＜0.01) and r=–0.774(P＜0.01) respectively. Multiple linear stepwise regression analysis showed DBIL, LDL, GENDER, SQRTSMOKING enter regression equation. The regression equation is:LNCCS=1.376-0.445DBIL+0.402LDL+0.483GENDER+0.011SQRTSMOKINGR=0.852, R2=0.725, R2adj=0.715DBIL is related to LDL, GENDER and AGE. The regression equation is:DBIL=6.381-0.501LDL-0.927GENDER-0.031AGE R=0.584, R2=0.341, R2adj=0.323IBIL is related to both HDL and LDL. The regression equation is:IBIL=6.910+1.952HDL-0.649LDL R=0.293, R2=0.086, R2adj=0.070Conclusion: Serum bilirubin has an inverse association with severity of coronary artery disease, low serum bilirubin concentration is an independent risk factor of CHD. Bilirubin is a potent physiological antioxidant. By inhibiting lipids oxidation, oxygen radical formation, immune reaction and inflammatory processes, scavenging peroxyl radicals, bilirubin may provide important protection against atherosclerosis, coronary artery disease, and inflammation. The protection of bilirubin against atherosclerosis, coronary artery disease establish theory base and pioneer a new way for precaution and therapy of CHD. The association of bilirubin and severity of coronary artery disease also has a certain value in clinic, by analyzing bilirubin concentration and other risk factors of CHD, it is helpful to estimate the severity of coronary artery disease and make more reasonable therapy plan. As for which circulating form of bilirubin has more powerful antioxidant capacity needs further study. Bilirubin might be a new focus for prevention and therapy of CHD.