Neutrophil–Lymphocyte Ratio is a Predictor of Saphenous Vein Graft Patency in Patients Undergoing Coronary Artery Bypass Surgery

We read the article “Preoperative Neutrophil–Lymphocyte Ratio and Saphenous Vein Graft Patency After Coronary Artery Bypass Grafting” by Tasoglu et al. ¹ They aimed to investigate the predictive value of preoperative neutrophil–lymphocyte (N/L) ratio in postoperative saphenous vein graft (SVG) patency in patients undergoing coronary artery bypass grafting (CABG) surgery. They showed that the N/L ratio is a powerful and independent predictor of further SVG failure after CABG. Patients in the highest tertile of N/L ratio were at greater risk. The study is successful in planning and presenting the results. We believe that these findings will enlighten further studies about the postoperative SVG patency and the N/L ratio. Thanks to the authors for their contribution

Coronary lesion severity should be examined using both anatomical and physiological myocardial ischemia methods. Although coronary angiography is the conventional gold standard anatomical evaluation method, intravascular ultrasound and optical coherence tomography give useful information about the severity of coronary artery stenosis. Additionally, fractional flow reserve value has also become a necessary tool for the functional severity of coronary artery stenosis recently. All of these methods should be used together to evaluate the severity of coronary artery stenosis. ²

Routine peripheral blood counts may be helpful in patients with postoperative SVG patency undergoing CABG surgery. White blood cell (WBC) count is one of the useful inflammatory biomarkers in clinical practice. Although WBC is in the normal range, subtypes of WBC like N/L ratio may predict cardiovascular mortality. The N/L ratio is a readily measurable laboratory marker used to evaluate systemic inflammation. Because of uncontrolled hypertension, uncontrolled diabetes mellitus, metabolic syndrome ³ , left ventricular dysfunction or hypertrophy, acute coronary syndromes, valvular heart disease, congenital heart disease, abnormal thyroid function tests, renal or hepatic dysfunction, known malignancy, local or systemic infection, previous history of infection (<3 months), inflammatory diseases, and any medication related to inflammatory condition of patients, the measurement of N/L ratio can be potentially affected in all of the above conditions. For these reasons, it would be better if the authors had mentioned these factors.

Finally, not only the N/L ratio but also the mean platelet volume ⁴ , red cell distribution width, uric acid, a γ-glutamyl transferase, ⁵ and carotid intima–media thickness ⁶ are easy methods to assess the SVG patency in patients with CABG. These markers might be useful in clinical practice. ⁷ In conclusion, we strongly believe that those findings obtained from the current study will lead to further large-scale studies examining the relationship between the N/L ratio and the SVG patency in patients with CABG. However, one should keep in mind that the N/L ratio alone without other inflammatory markers may not give exact information to clinicians about the inflammatory status and SVG patency of the patients. So, from that point of view we think that it should be evaluated accompanied with other serum inflammatory markers. ⁸