Author's reply.

To the Editor,

We would like to thank the authors of the letter for their interest and criticism about our study entitled “Could plasma asymmetric dimethylarginine level be a novel predictor beyond the classic predictors of stent restenosis?” published in September issue of The Anatolian Journal of Cardiology 2014; 14: 491-7. (1). We agree with the authors that the glomerular filtration rate (GFR) provides more accurate knowledge about renal function than the serum creatinine level (2). But, we excluded the patients with chronic renal disease, and also, the average age of the study population was 59 years, and creatinine levels were in the normal range. So, we thought that the difference between the groups would be small and could be neglected and that serum creatinine might be enough to assess the renal functions of both groups.

Comparative studies revealed that the ELISA method produces considerably higher asymmetric dimethylarginine concentrations in plasma or serum in healthy humans in the basal state than mass spectrometry and high-performance liquid chromatography methods and runs varyingly in different laboratories (3). As stated by the authors, HPLC coupled to mass spectrometric detection (LC-MS/MS) is not widely available, and the equipment is comparatively expensive (4). So, HPLC was the preferable method for us to detect ADMA.

Intravascular ultrasonography is a validated and superior method when compared with coronary angiography to determine neointimal tissue burden, assessment of lesion significance, and stent restenosis (5). But, in our country conditions, it is not feasible to evaluate stent restenosis for every patient because of its cost and low availability.

There are so many relevant biomarkers known for stent restenosis (6), but it is not feasible to evaluate all of them in one study protocol. Our aim was to evaluate if ADMA predicts stent restenosis beyond classic predictors or not. In our study, we concluded that plasma ADMA level may be used as a novel marker for stent restenosis beyond the classic stent restenosis markers. However, as we stated in our study, this result should be confirmed by larger, prospective, and controlled studies.