White blood cell count adds prognostic information to the thrombolysis in myocardial infarction risk index in patients following primary percutaneous coronary intervention (ANIN Myocardial Infarction Registry)

Aims To determine the relationship between baseline white blood cell (WBC) count, Thrombolysis in Myocardial Infarction (TIMI) risk index, and 30-day mortality in unselected patients with ST-elevation myocardial infarction (STEMI) treated with primary mechanical reperfusion (PCI). Methods and results 903 patients from prospective registry admitted for primary PCI to a tertiary cardiological center. Both baseline WBC count and TIMI risk index data were dichotomized about the respective medians. Overall 30-day mortality was 4.3%. Higher WBC count was associated with adverse clinical outcome (6.3% vs. 2.4%; Kaplan–Meier p = 0.004) as were higher TIMI risk index values (7.2% vs. 1.4%; Kaplan–Meier p < 0.00001). In addition, median WBC count stratified patients within TIMI risk index strata into very low risk (0%), intermediate risk (3.3%) and high risk (11%) (Kaplan–Meier p = 0.023 and p = 0.005 for comparison of lower and higher WBC count within TIMI risk index stratas). In multivariate analysis WBC count provided independent and additional to TIMI risk index predictive information (Hosmer–Lemeshow p = 0.57 and p = 0.88 respectively for predictive value of TIMI risk index alone and combined with WBC count). Other independent predictors of death were current smoking (RR 0.33; 95% CI: 0.13–0.87) and previous MI (RR 3.13; 95% CI: 1.28–7.69). Conclusions WBC count may be a simple and useful tool for risk stratification in STEMI patients, providing additional to established risk index prognostic information. Our findings stress the strong correlation of inflammation and poor outcome in STEMI patients, which may indicate directions of development of new therapies.