Neutrophil percentage-to-albumin ratio and medium-term major adverse cardiovascular events in patients with ST-elevation myocardial infarction undergoing percutaneous coronary intervention: a retrospective cohort study

<title>Abstract</title> <p> <bold>Background:</bold> The neutrophil percentage-to-albumin ratio (NPAR) has been proposed as a novel prognostic biomarker in cardiovascular diseases. However, most evidence derives from studies evaluating short-term outcomes, and its association with medium-term major adverse cardiovascular events (MACE) in patients with ST-elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI) remains unclear. <bold>Objective:</bold> To evaluate the association between admission NPAR and medium-term MACE in STEMI patients who underwent successful primary PCI. <bold>Methods:</bold> This retrospective cohort study analyzed data from 461 consecutive STEMI patients who underwent primary PCI at a single center (2010–2014), with 30 months of follow-up. NPAR was calculated as neutrophil percentage (%) divided by serum albumin (g/dL). The primary outcome was MACE, defined as the composite of cardiac death, recurrent myocardial infarction, target lesion revascularization, cardiogenic shock, or congestive heart failure. Cox proportional hazards models with progressive covariate adjustment, quartile-based dose–response analysis, nonlinearity assessment, subgroup analyses, and evaluation of incremental predictive value (ΔC-index, net reclassification improvement [NRI], and integrated discrimination improvement [IDI]) were performed. <bold>Results:</bold> During follow-up, 118 patients (25.6%) experienced MACE. In the fully adjusted Cox model, NPAR was not independently associated with MACE (hazard ratio [HR] = 1.008 per unit increase, 95% confidence interval [CI]: 0.960–1.059, P = 0.736). No linear or nonlinear dose–response relationship was observed (P for trend = 0.621; P for nonlinearity = 0.056). Kaplan–Meier analysis showed no significant difference between groups (log-rank P = 0.386). The addition of NPAR yielded negligible improvements in discrimination (ΔC-index = 0.0008, P = 0.644), reclassification (NRI = −0.117, P = 0.422), and integrated discrimination (IDI = 0.000022, P = 0.994). Age (HR = 1.029, P = 0.002), hemoglobin (HR = 0.987, P = 0.016), Gensini score (HR = 1.008, P = 0.011), and eGFR (HR = 0.992, P = 0.024) were identified as independent predictors of MACE. <bold>Conclusions:</bold> In this cohort of STEMI patients undergoing primary PCI, admission NPAR was not independently associated with medium-term MACE and provided no incremental predictive value beyond established clinical risk factors. These findings do not support the routine use of NPAR for medium-term risk stratification in this population. </p>