Low bilirubin levels are associated with coronary slow flow phenomenon.

Background And Aim: Increasing evidence suggests an inverse relationship between bilirubin levels and cardiovascular disease. The present study evaluated the effect of bilirubin level on the slow coronary flow (SCF) phenomenon.

Methods: This study was cross-sectional and observational. We enrolled 222 consecutive patients who underwent coronary angiography for suspected ischaemic heart disease and were found to have normal or near-normal coronary arteries. Then, bilirubin levels were measured and coronary flow rate was assessed using the thrombolysis in myocardial infarction (TIMI) frame count. SCF was defined as a TIMI frame count > 27 frames.

Results: SCF was observed in at least one coronary vessel in 22 of the 222 subjects, indicating a prevalence of 10%. Serum bilirubin levels were significantly decreased in the SCF group. In multivariate logistic regression analysis, total bilirubin and diabetes mellitus were independent risk factors for SCF. Furthermore, after adjusting for age, sex, and cardiovascular disease risk factors, serum bilirubin level (B = -0.34, p < 0.001) was independently associated with TIMI frame count.

Conclusions: These findings suggest that serum total bilirubin levels may be a useful marker for patients with the SCF phenomenon. We believe that further studies are needed to clarify the role of bilirubin in patients with SCF.