Background: Previous studies have shown that elevated baseline white blood cell count (WBCc) in patients undergoing percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) is associated with an increased risk of short and long-term mortality. However, there is limited data on the relationship between the different levels of WBC elevation and post-PCI mortality.
This study aims to examine the relationship between varying levels of WBC elevation and post-PCI 30-day mortality.
Methods: We used our single center registry of patients undergoing primary PCI for STEMI between 1/2001 and 7/2012.
1,877 patients for whom baseline WBCc prior to PCI was available were identified. Patients were divided into three groups; normal WBCc (<10,000, n= 642), elevated WBCc (10,000-20,000, n= 1,156), and highly elevated WBCc (>20,000, n= 79).
Clinical characteristics and 30-day outcomes were analyzed and compared according to WBCc.
Results: 30-day mortality was found to increase significantly from patients with normal, to elevated, to very elevated WBCc (0.9% vs .3.1% vs .12.7%, respectively, p= 0.001). There were no associations within 30-days between increased incidence of re-MI, stent thrombosis, coronary artery bypass graft and increasing WBCc levels. Furthermore, in a multivariate analysis elevated baseline WBCc was associated with an odds ratio of 2.1 for one year mortality (CI 1.36-3.19, p=0.0006). Anterior MI and a LVEF<40% were more common in the elevated and highly elevated WBCc groups as compared with the normal the WBCc group (57% vs 47% vs 42%, p=0.01 and 67% vs 42% vs 35%, p<0.0001 respectively).
Conclusion: Patients with an elevated baseline WBCc prior to undergoing PCI for a STEMI had double the risk of 30-day mortality. Moreover, a highly elevated baseline WBCc was associated with a significantly higher 30-day mortality rate. This study suggests that WBCc may be considered an important prognostic factor in patients with STEMI treated by PCI.
