White blood cell count to mean platelet volume ratio as a novel non-invasive marker predicting long-term outcomes in patients with non-ST elevation acute coronary syndrome.

BACKGROUND Total white blood cell (WBC) count and mean platelet volume have previously been shown to predict outcomes in acute coronary syndrome (ACS) patients. In this prospective study, we sought to determine the prognostic value of baseline WBC count to mean platelet volume ratio (WMR) in patients with non-ST elevation acute coronary syndrome (NSTE-ACS). METHODS A total of 490 patients with NSTE-ACS were prospectively enrolled. The relationship between baseline WMR and major adverse cardiovascular events (MACE) incidence was assessed during a mean follow-up of 330.8 ± 38 days. RESULTS The patients' mean age was 60.4 ± 12.9 year, 59% of them were male. The patients were categorized into two groups based on WMR values, high- and low-WMR groups (< 755 vs. ≥ 755). The incidence of MACE was significantly higher in high-WMR compared with that of low-WMR group (22.4% vs. 10.7%, p < 0.001). Total WBC counts (median 7.9 vs. 6.9 ×103/μL, p = 0.004), neutrophil count (median 4.6 vs. 4.2 ×103/μL, p = 0.021), and WMR (median 863.2 vs. 731.5, p = 0.001) were significantly higher in the MACE-positive than MACE-negative group. The high-WMR was found to be significantly associated with the MACE-free survival rate (p < 0.001). In an adjusted cox regression model, the elevated WMR was independently predicted the incidence of MACE (hazard ratio 2.419, 95% CI 1.515-3.862, p < 0.001). CONCLUSIONS The elevated baseline WMR independently predicted the MACE incidence in patients with NSTE-ACS during long-term follow-up.