Giraldez, R. R., Sabatine, M. S., Morrow, D. A., Mohanavelu, S., McCabe, C. H., Antman, E. M., Braunwald, E. Baseline hemoglobin concentration and creatinine clearance composite laboratory index improves risk stratification in ST-elevation myocardial infarction American heart journal. 2009;157(3):517-24.

BACKGROUND: Hemoglobin (Hgb) and creatinine clearance (CrCl) are readily-available, routinely-obtained laboratory parameters that predict acute coronary syndrome outcomes. We sought to develop a laboratory index (LI) to predict early mortality in ST-elevation myocardial infarction (STEMI) and determine the additional risk stratification offered by adding the LI to the TIMI Risk Score (TRS) for STEMI.

METHODS AND RESULTS: The association between Hgb and CrCl values obtained at hospitalization and 30-day mortality was evaluated in 14,373 STEMI patients undergoing fibrinolysis in Intravenous NPA for the Treatment of Infarcting Myocardium Early II-Thrombolysis In Myocardial Infarction-17 (InTIME II-TIMI 17). Logistic regression models determined the optimal combination of laboratory variables into a LI. Prognostic utility of the LI was validated in 18,427 STEMI patients from Enoxaparin and Thrombolysis Reperfusion for Acute Myocardial Infarction Treatment (ExTRACT)-TIMI 25. In InTIME II, Hgb levels <15.0 g/dL and CrCl <100 mL/min were significantly and independently associated with increased risk of death (OR(adj) 1.22, 95% CI 1.15-1.29 for each 1 g/dL decrease in Hgb, P < .001, and OR(adj) 1.23, 95% CI 1.17-1.29 for each 10 mL/min decrease in CrCl, P < .001, respectively). In multivariable analysis, the optimal weighting of Hgb and CrCl to form an LI to predict mortality was (15-Hgb) + (100-CrCl)/8. The LI revealed a 10-fold increase in death across prespecified groups (P < .001). The LI offered additional risk stratification across all TRS groups and improved the discriminatory ability of the TRS (c-statistic from 0.755 to 0.789, P < .001). External validation in ExTRACT showed similar enhancement of the prognostic capacity of the TRS (c-statistic from 0.747 to 0.777, P < .001).

CONCLUSIONS: The LI is a simple, powerful tool to predict death in STEMI, either separately or with the TRS.