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High neutrophil to lymphocyte (N/L) ratio has been reported to have a strong predictive value for worse clinical outcomes in patients with ST elevation myocardial infarction. However, the clinical significance of high N/L ratio in the setting of non-ST elevation myocardial infarction (NSTEMI) has not been fully elucidated.
We performed a retrospective analysis of 481 consecutive patients with NSTEMI who underwent coronary angiography within five days after presentation. Patients with suspected infection, chronic steroid use and active malignancy were excluded. White blood cell, neutrophil and lymphocyte count were obtained from the initial blood sample. Patients were categorized into a high N/L ratio group and control group. Baseline and angiographic characteristics, in-hospital revascularization procedures, heart failure as well as in-hospital major adverse cardiac event (MACE) including death, recurrent myocardial infarction, and target vessel revascularization were compared between the two groups.
Among 456 patients included in the final analysis, the median N/L ratio was 3.47 (interquartile range; [2.16-5.57]). The optimal cutoff value in predicting in-hospital MACE was 5.44 by receiver operating characteristic curve analysis (area under the curve was 0.84). As a result, 118 patients (25.9%) were categorized into the high N/L ratio group. Patients with high N/L ratio were older (70[61-80] years vs. 65[56-74] years, p=0.003) and had higher white blood cell count (10.1[8.0-12.4] x109/L vs. 7.9 [6.4-9.7] x109/L, p<0.001) and peak troponin I value (2.22[0.30-11.8] ng/mL vs. 0.39[0.08-3.95] ng/mL, p<0.001). Other baseline characteristics were comparable between the two groups. Patients with high N/L ratio had a higher rate of three-vessel disease (including left main disease) (36.4% vs. 23.7%, p=0.007). There was no significant difference in the rate of impaired coronary flow and in-hospital revascularization. Patients with high N/L ratio had a higher rate of in-hospital MACE (5.9% vs. 0.3%, p<0.001) and in-hospital heart failure (23.7% vs. 11.5%, p=0.001) compared with the control group. In contrast, the absolute white blood cell count was not associated with in-hospital MACE or in-hospital heart failure.
High N/L ratio was significantly associated with a larger infarct size indicated by peak troponin I value, and a higher rate of three-vessel disease and in-hospital MACE in patients with NSTEMI.