Saphenous Vein Graft Disease and Serum Erythropoietin Level.

Dear Editor,

We read with interest the recent report entitled ‘Saphenous vein graft disease is associated with a low serum erythropoietin level’ by Kocaoğlu et al. [1]. They mentioned that ‘SVG disease was associated with a low serum EPO level, suggesting that a low EPO level could be predictive of and contributes to the pathophysiology of SVG disease’. There are many concerns regarding this report. First, the diagnostic property of the laboratory test kit for the measurement of EPO was not discussed. Second, they forgot to deal with possible confounding factors, such as hematologic disease exemplified by thalassemia, an inherited hemoglobin disorder. A previous study has shown that cases with underlying thalassemia usually present with high EPO level [2]. Because bypass graft surgery can be seen in patients with thalassemia in clinical practice [3] SVG should be expected. Hence, the relationship between SVG and serum EPO levels should be different from the observation by Kocaoğlu et al. [1].

Dear Editor,

We would like to thank Joob and Wiwanitkit [1] for their interest in our article. First of all, we used a standardized method to determine EPO levels. Venous blood samples were drawn into a tube without anticoagulant following fasting for ≥8 h from patients undergoing coronary angiography on the same day; all the patients rested in the supine position for ≤1 h at the same time of day (13:00-14:00) to avoid diurnal variation. The EPO level was measured using ELISA. Secondly, thalassemia, an inherited hemoglobin disorder, is a childhood disease and patients usually do not survive into late adulthood [2]. Joob and Wiwanitkit cited the study of Paritpokee et al. [3], which was conducted in pediatric patients. However, we do not come across patients with thalassemia and coronary artery disease in practice since they do not reach older age, and atherosclerosis is rarely encountered in pediatric cases [4]. In our study, no patient had thalassemia. We also looked for other confounding factors and performed multivariate analysis including hemoglobin levels and found that low serum EPO levels were independently associated with saphenous vein graft disease [1].

Editor's Note

This response represents solely the opinion of the first and the second author of this article (İ.K. and U.A.).