To the Editor,We have read the paper written by Akyüz et al. (1) titled “Relationship of serum salusin beta levels with coronary slow flow” with great interest. In this research, the authors compared serum salusin-β levels between two patient groups, those with normal coronary arteries and those with coronary slow flow (CSF) pattern in the absence of significant coronary artery disease. They concluded that serum salusin-β levels could play a role as a biomarker for the evaluation of CSF. In previous studies, salusin-β has been reported to be related to the development and progression of atherosclerosis, and it has been shown that the circulating levels are high in patients with documented atherosclerosis (2,3).On the other hand, atherosclerotic plaques are also abundant for consistent salusin-β release. In a previous intravascular ultrasound study, Cin et al. (4) have demonstrated the association of subclinical atherosclerosis with CSF. Therefore, we believe that the increased serum salusin-β levels in patients with CSF may be the effect of subclinical atherosclerosis and can not be evaluated as a biomarker for CSF. Morever, in the study group, patients with nonsignificant atherosclerosis have not been excluded, and this might be a factor for the increased serum salusin-β levels observed in this group.The hypothesis regarding the role of serum salusin-β levels in CSF should be tested between patient groups with similar atherosclerotic plaque burden.