In the article “Prognostic Value of Total Bilirubin in Patients With ST-Segment Elevation Acute Myocardial Infarction Undergoing Primary Coronary Intervention” by Gul et al, the authors observed that in patients with ST-elevation myocardial infarction (STEMI) who undergo primary percutaneous coronary intervention (PCI), high serum total billirubin levels after primary PCI serve as an independent predictor of in-hospital cardiac mortality. The authors also reported that no association was found with long-term mortality.

Several studies have suggested that bilirubin, an antioxidant, protects against atherosclerosis and coronary heart disease under normal conditions. However, several recent studies have shown that HO-1 enzyme activity and its end-product bilirubin levels were elevated in patients with both ischemic conditions and pressure overload in the myocardium.

In a recent study by Celik et al that is similar to Gul et al’s in terms of study population and conclusions, it was determined that serum bilirubin levels were independently associated with the development of coronary no-reflow after primary PCI as well as increased in-hospital major adverse cardiac events in patients with STEMI. There are certain methodologic differences between these 2 studies. Celik et al collected samples to determine bilirubin levels on admission to the emergency department; in contrast, in Gul et al’s study, the blood samples to determine bilirubin levels were drawn after completion of PCI. Periprocedural complications such as access site or other bleeding complications are frequently seen in patients with STEMI who undergo PCI. Moreover, there was a significantly higher number of patients with cardiogenic shock (p = 0.002), who received inotrope treatment (p = 0.001), and who had advanced heart failure (p = 0.009) in the group with high bilirubin levels. It is known that overloading symptoms can occur in patients with cardiogenic shock and that heart failure can increase serum bilirubin levels.

We believe that these findings will provide useful information about the relationship between bilirubin levels and outcomes in patients with STEMI. We also believe that, in the future, the predictive effects of bilirubin levels should be included in guidelines regarding risk classifications and intensive therapy in this population.