Prognostic impact of neutrophil-to-lymphocyte ratio in patients with and without diabetes mellitus undergoing percutaneous coronary intervention

Background The neutrophil-to-lymphocyte ratio (NLR) is a marker of systemic inflammation associated with adverse cardiovascular outcomes. However, limited evidence exists regarding its prognostic role in patients with diabetes mellitus (DM) undergoing percutaneous coronary intervention (PCI), which we sought to explore in this analysis. Methods We retrospectively evaluated all patients undergoing PCI at a large tertiary centre between 2012 and 2022. Patients were stratified according to the presence of DM, and NLR quartiles were derived in each subgroup. The primary endpoint was major adverse cardiovascular events (MACE), consisting of all-cause mortality, spontaneous myocardial infarction (MI) or stroke. Secondary endpoints were each single MACE component, target vessel revascularisation, bleeding and postprocedural acute kidney injury. A multivariable Cox regression model, adjusted for relevant baseline characteristics, was computed. Results A total of 9427 patients were included (48.5% with DM). DM patients had more comorbidities and higher baseline high-sensitivity C reactive protein levels, while patients with elevated NLR in both subgroups exhibited multivessel disease with moderate/severe calcification. DM patients in the upper NLR quartile had the highest rates of MACE (15.7%) than any other subgroup. An independent association of elevated NLR with MACE was observed in both patients with and without DM, and was confirmed after multivariable adjustment. This was primarily driven by all-cause mortality rates in both subgroups and by MI incidence in DM patients only. Conclusions Patients undergoing PCI with a higher NLR had worse clinical outcomes, regardless of DM status. The combination of DM and elevated NLR revealed the most unfavourable prognosis.