Usefulness of the delta neutrophil index to predict 30-day mortality in patients with ST segment elevation myocardial infarction

Abstract

This study aimed to evaluate the association between the delta neutrophil index (DNI), which reflects immature granulocytes, and the severity of ST-elevation myocardial infarction (STEMI), as well as to determine the significance of the DNI as a prognostic marker for early mortality and other clinical outcomes in patients with STEMI who underwent reperfusion. This retrospective, observational cohort study was conducted using patients prospectively integrated in a critical pathway program for STEMI. We included 842 patients diagnosed with STEMI who underwent primary percutaneous coronary intervention (pPCI). Higher DNI values at time-I (within 2 h of pPCI; hazard ratio [HR], 1.075; 95% confidence interval [CI]: 1.046-1.108; p < 0.001) and time-24 (24 h after admission; HR, 1.066; 95% CI: 1.045-1.086; p < 0.001) were significant independent risk factors for 30-day mortality. Specifically, DNI values >2.5% at time-I (HR, 13.643; 95% CI: 8.13-22.897; p < 0.001) and > 2.9% at time-24 (HR, 12.752; 95% CI: 7.308-22.252; p < 0.001) associated with increased risks of 30-day mortality. In conclusion, an increased DNI value, which reflects the proportion of circulating immature granulocytes in the blood, was found to be an independent predictor of 30-day mortality and poor clinical outcomes in patients with acute STEMI post-pPCI.

Figure 1

Flow diagram of patient enrolment. ECG, electrocardiogram; FIRST, Fast Interrogation Rule for ST-elevation Myocardial Infarction; DNAR, do not attempt resuscitation; PCI, percutaneous coronary intervention; STEMI, ST segment elevation myocardial infarction.

Figure 2

(A) Comparison of the performance of the survival models with and without the delta neutrophil index (DNI) by Harrell’s C-index, integrated discrimination improvement (IDI), and continuous net reclassification improvement (NRI). (B) Comparison of Harrell’s C-index for biomarkers at the time of emergency department admission, immediately after reperfusion, and 24 h after admission. Harrell’s C-index showed discriminative abilities for the risk stratification of 30-day mortality (statistical information in Supplement 3). CI, confidence interval; PCI, percutaneous coronary intervention; DNI, delta neutrophil index; WBC, white blood cell count; Neu(#), number of neutrophils; Neu(%), proportion of neutrophils; NT-proBNP, N-terminal pro-brain natriuretic peptide; Tn-T; Troponin-T; CK-MB, Creatinine kinase-MB.

Figure 3

The delta neutrophil index (DNI) as a predictor of 30-day mortality. Higher DNI values within 2 h post-primary percutaneous coronary intervention (pPCI) (A) and 24 hours after emergency department admission (B) were significantly associated with increased 30-day mortality risk among patients with ST segment elevation myocardial infarction (STEMI) who underwent pPCI. When the same cut-offs were applied to the validation cohort, external validation demonstrated that higher DNI values within 2 h post-pPCI (C) and 24 hours after emergency department admission (D) remained significantly associated with increased risks of 30-day mortality. HR, hazard ratio; CI, confidence interval.