Relation Between Neutrophil-to-Lymphocyte Ratio and Index of Microcirculatory Resistance in Patients With ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

The neutrophil-to-lymphocyte ratio (NLR) has been proved as a reliable inflammatory marker for the atherosclerotic process and as a predictor for clinical outcomes in patients with various cardiovascular diseases. A recent study reported that elevated NLR is associated with impaired myocardial perfusion in patients with ST-segment elevation myocardial infarction (STEMI). We investigated whether NLR is associated with coronary microcirculation as assessed by the index of microcirculatory resistance (IMR) in patients with STEMI who had undergone primary percutaneous coronary intervention (PCI). A total of 123 patients with STEMI who underwent successful primary PCI were enrolled in this study. NLR was obtained on admission, and patients were divided into 3 groups by NLR tertile. IMR was measured using an intracoronary thermodilution-derived method immediately after index PCI. Symptom onset-to-balloon time was significantly longer (p = 0.005), and IMR was significantly higher in the high NLR group than that in the low and intermediate groups (21.94 ± 12.87 vs 23.22 ± 12.73 vs 32.95 ± 20.60, p = 0.003). Furthermore, in multiple linear regression analysis, NLR showed an independent positive correlation with IMR (r = 0.205, p = 0.009). In conclusion, NLR has shown positive correlation with IMR, whereas negative association with infarct-related artery patency in patients with STEMI who underwent primary PCI. Therefore, NLR at admission could reflect myocardial damage and the status of coronary microcirculation in patients with STEMI (ClinicalTrials.gov number, NCT02828137).