Neutrophil to platelet ratio predicts in-hospital mortality in patients with acute myocardial infarction.

Acute myocardial infarction (AMI) is a critical medical emergency worldwide and a leading cause of mortality. This study aims to investigate the predictive utility of the neutrophil-to-platelet ratio (NPR) in identifying AMI patients at an increased risk of in-hospital mortality. We enrolled 664 patients, including 421 with ST-elevation myocardial infarction (STEMI) and 243 with non-ST-elevation myocardial infarction (NSTEMI), at Zhongshan Hospital, Fudan University, from January 2020 to September 2023. NPR was calculated as the neutrophil count divided by the platelet count. The primary outcome was defined as in-hospital mortality. The overall in-hospital mortality among AMI patients was 6.78%. Mortality was notably higher in the high NPR group compared to the low NPR group. Univariate analysis identified several variables significantly associated with in-hospital mortality, including age, left ventricular ejection fraction (LVEF), neutrophil-to-lymphocyte ratio (NLR), and NPR. NPR demonstrated a strong independent association with in-hospital mortality following adjustment for potential confounders. Receiver operating characteristic (ROC) curve analyses were performed to assess the discriminative power of NPR and NLR in predicting in-hospital mortality. NPR exhibited an area under the curve (AUC) of 0.755 (95% CI, 0.682-0.829, p < 0.001), indicating good discriminative ability. Similarly, NLR showed a discriminative AUC of 0.674 (95% CI, 0.586-0.762, p < 0.001). The optimal cutoff values for predicting mortality were determined as 0.042 for NPR (sensitivity 80%, specificity 62.2%) and 8.02 for NLR (sensitivity 62.2%, specificity 67.5%). Bootstrap validation with 1000 iterations confirmed the robustness of these findings, with validated AUCs of 0.755 (95% CI, 0.681-0.826) for NPR and 0.674 (95% CI, 0.587-0.766) for NLR. This study identifies NPR as an independent and valuable predictor of in-hospital mortality among AMI patients, The findings underscore NPR's potential utility in clinical practice for risk stratification and early intervention strategies aimed at reducing mortality rates in this high-risk patient population.