Neutrophil to lymphocyte ratio and systemic immune inflammation index are correlated with coronary microvascular disease assessed by caIMR

Background The inflammatory response serves as a core driving factor for coronary microvascular disease (CMVD).The neutrophil-to-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII) are emerging inflammatory markers. This study aims to explore the correlation and predictive efficacy of NLR and SII with CMVD by assessing coronary microvascular function in patients with obstructive coronary artery disease using caIMR. Methods This study retrospectively analyzed coronary heart disease patients who underwent coronary angiography and caIMR measurement in the Third Affiliated Hospital of Sun Yat-sen University from July 2023 to January 2025. A total of 118 patients were included, Patients were divided into CMVD Group (caIMR ≥ 25) and non-CMVD Group (caIMR < 25) according to the critical value of caIMR at 25U. Pearson correlation analysis and multifactor linear regression model were used to explore the relationship between NLR, SII and caIMR. Results A total of 118 patients were included (66.2 ± 10.76 years, 69.5% male).The CMVD group had higher levels of neutrophil count, NLR, and SII, with statistically significant differences between the groups.The results of the Pearson correlation analysis indicate that NLR and SII are positively correlated with caIMR values(NLR: r = 0.335; SII: r = 0.279). After adjusting for confounding factors, NLR and SII remain independently positively correlated with caIMR. NLR and SII are independent predictors of CMVD. Conclusion In patients with coronary heart disease and concurrent CMVD, NLR and SII may be independent predictors of CMVD, possibly providing valuable predictive insights.