Abstract
We were grateful to read an interesting article by Uysal et al, 1 evaluating the association of neutrophil to lymphocyte ratio (NLR) with coronary collateral circulation (CCC) in a total of 521 consecutive patients with stable coronary artery disease (CAD). They have found that increased NLR (odds ratio [OR]: 0.70, 95% confidence interval [CI]: 0.62-0.80; P < .01) and fasting plasma glucose (OR: 0.995, 95% CI: 0.991-0.999) levels were independent predictors of CCC in multivariate regression analysis. Additionally, NLR level of >2.75 to predict poor CCC has 65% sensitivity and 68% specificity (area under the curve: 0.714, 95% CI: 0.66-0.75).
The degree of CCC is highly variable among patients with CAD. Also, the exact pathophysiological mechanisms of CCC development have not been highlighted completely yet. There were controversial data regarding the relationship between inflammatory markers (particularly C-reactive protein [CRP]) and CCC, and also no data regarding such association with NLR level. As a simple, available, and noninvasive marker, NLR is a recently emerged better reflector of inflammation and oxidative stress which has been studied widely in several cardiovascular diseases. 2 –5 So, first time in the literature, the study by Uysal et al 1 demonstrated the relationship between NLR level and CCC. However, the study should be interpreted with some drawbacks. First, the study lacks any data and correlation of NLR levels with other inflammatory markers, such as CRP. Second, as an important issue, the study by Uysal et al 1 has no data regarding the cardiovascular medications of study population. Among the various drugs, statins should be considered during interpretation of studies with inflammatory markers. It has been known that beneficial effects of statins are not only due to the improvement in plasma lipid levels but also due to the direct action on vasculature including the improvement in endothelial function, anti-inflammatory and antithrombotic actions, and attenuation of atherogenesis. 6,7 Previous animal studies have shown that statins promote angiogenesis and increase CCC development. 8,9 However, there are conflicting data in clinical trials. 10,11 In another study, Dinçer et al 12 reported that the dosage and duration of statin therapy (≥10 mg atorvastatin-equivalent dose and on therapy for >3 months) were associated with enhanced CCC. Furthermore, it has been shown that antihypertensive medications might also affect NLR levels. 13,14 In a study including 72 newly diagnosed patients with hypertension, Fici et al 13 showed that nebivolol has significantly reduced the NLR levels after 6 months of treatment period. In conclusion, the results of the study by Uysal et al 1 showed that higher levels of NLR were associated with poor CCC in stable CAD, but these results should be interpreted with some limitations, particularly statin and antihypertensive therapy among the study groups.