Background: The neutrophil-to-lymphocyte ratio (NLR) is a simple inflammatory marker that may reflect the extent of coronary atherosclerotic complexity. This study examined the relationship between NLR and angiographic disease severity in individuals presenting with non-ST-segment elevation acute coronary syndrome (NSTE-ACS), using the synergy between percutaneous coronary intervention with taxus and cardiac surgery (SYNTAX) score as an anatomical reference standard.
Methods: In this prospective observational study, 100 consecutive patients with NSTE-ACS underwent coronary angiography at two tertiary centres in Egypt between July 2020 and June 2021. Patients with persistent ST-segment elevation, active infection, chronic inflammatory diseases, malignancy, chronic obstructive pulmonary disease, or chronic steroid use were excluded. A single baseline NLR measurement was obtained at admission before angiography. Laboratory testing at both centres used the same automated analyser. SYNTAX scoring was performed independently by two interventional cardiologists who were blinded to clinical and laboratory data, with discrepancies resolved by consensus. Patients were stratified into three tertiles based on admission NLR: low NLR (≤3.65), intermediate NLR (>3.65 to ≤5.1), and high NLR (>5.1). Associations between NLR, SYNTAX score, and clinical variables were analysed using univariable methods because the number of high SYNTAX cases and 30-day mortality events did not permit reliable multivariable modelling.
Results: The mean age of the cohort was 46.5±7.4 years, and 77.0% were male. Diabetes mellitus, hypertension, and smoking were present in 66, 67, and 74 percent of patients, respectively. The mean SYNTAX score was 15.6±9.1, and the mean NLR was 4.7±1.6. A moderate positive correlation was observed between NLR and SYNTAX score (r=0.48, p<0.001). SYNTAX scores increased progressively across NLR categories, with mean values of 11.27 in the low group, 15.0 in the intermediate group, and 17.79 in the high group. Only seven patients (7.0 %) had a SYNTAX score ≥33, which limits the precision of subgroup estimates. An NLR greater than 5.5 identified patients with SYNTAX ≥33 with 100% sensitivity, 77.4% specificity, a positive predictive value (PPV) of 75%, a negative predictive value (NPV) of 100%, and an area under the ROC curve of 0.88 (95% CI: 0.78-0.95). During the 30-day follow-up, four patients died. An NLR greater than 5.4 predicted 30-day mortality with 100% sensitivity, 72.9% specificity, and an AUC of 0.86 (95% CI: 0.71-0.97). Mortality-related estimates should be interpreted cautiously because of the small number of events.
Conclusions: In NSTE-ACS, NLR correlates with the anatomical complexity of coronary artery disease and may provide useful supplementary information during early risk assessment. However, the proposed threshold should be regarded as exploratory because of the limited number of patients with very high SYNTAX scores and the small number of mortality events. NLR should be considered a complementary marker rather than a replacement for established clinical risk stratification tools. Larger, multicentre studies with external validation are needed before NLR-based thresholds can be integrated into routine clinical pathways.
Keywords: acute coronary syndrome; angiographic severity; coronary artery disease (cad); ischemic heart disease (ihd); neutrophil to lymphocyte ratio (nlr); syntax score.
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