To explore the relationship between the neutrophil-to-lymphocyte ratio (NLR) and microcirculatory disturbance in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) based on the index of microcirculatory resistance (IMR).

Fifty patients with acute STEMI from January 2016 to December 2018 were selected from Northern Jiangsu People's Hospital and divided into a low NLR group (NLR ≤ 6.17, n = 25) and a high NLR group (NLR > 6.17, n = 25). The clinical data, coronary artery disease, interventional treatment and IMR after primary PCI were compared between the two groups. Meanwhile, the correlation between the NLR and IMR after primary PCI was analyzed by Pearson correlation analysis.

The diabetes history (7/25 vs. 15/25, χ² = 5.195, P = 0.023), hyperlipidemia history (7/25 vs. 14/25, χ² = 4.023, P = 0.045), neutrophil count [6.33 (4.04, 6.66) × 10⁹/L vs. 7.90 (7.23, 12.09) × 10⁹/L, H = 18 716.000, P < 0.001], lymphocyte count [1.85 (1.37, 2.56) × 10⁹/L vs. 0.87 (0.78, 1.03) × 10⁹/L, H = 29 710.000, P < 0.001], onset-balloon dilation time [227.00 (180.00, 390.00) min vs. 360.00 (270.00, 435.00) min, H = 25 199.500, P < 0.001] and IMR after primary PCI [(29.9 ± 2.7) vs. (40.4 ± 1.7), t = 16.307, P < 0.001] were statistically significantly different between the low NLR group and high NLR group. Pearson correlation analysis showed a positive correlation between the NLR and IMR (r = 0.676, P < 0.001). Further simple linear regression analysis showed that the NLR was associated with the occurrence of microcirculatory disturbance after primary PCI (R² = 0.457, P < 0.001).

The higher NLR of STEMI patients at admission is closely related to their severe microcirculatory disturbance after primary PCI, and it has certain reference value for predicting their microcirculation status.