The relationship between serum levels of total bilirubin and coronary plaque vulnerability.

Previous studies have reported that serum total bilirubin provides some protection against coronary artery disease (CAD); however, the relationship between serum levels of total bilirubin and culprit/target plaque vulnerability in patients with CAD remains unclear. In this study, we investigated the association between total bilirubin and tissue characterization of coronary plaque in patients with CAD.We enrolled 85 consecutive patients with CAD who underwent coronary angiography and intravascular ultrasound analyses [45 with acute coronary syndrome (ACS); 40 with stable angina pectoris (SAP)], and 45 age-matched participants served as the control group. Serum levels of total bilirubin in all participants were measured. The stability of the coronary plaque was compared between the ACS group and the SAP group, and the relationship between serum levels of total bilirubin and the features of coronary plaque was analyzed.Serum levels of total bilirubin in the ACS group were significantly lower than those in the SAP and control groups (P<0.01). Serum levels of total bilirubin were positively associated with fibrous plaques (r=0.386, P<0.001), whereas they were negatively associated with plaque burden (r=-0.413, P<0.001), lipid plaque (r=-0.419, P<0.001), and remodeling index (r=-0.275, P<0.05). Furthermore, an independent association between serum levels of total bilirubin and lipid-rich plaques (odds ratio, 0.78; 95% confidence interval, 0.64-0.95) was observed.Serum total bilirubin levels were found to be inversely associated with coronary plaque vulnerability, and decreased serum levels of total bilirubin may be an important factor for coronary lipid plaque formation, which contributes to the pathogenesis of CAD.