Dynamic TIMI risk score for STEMI

Abstract

Background: Although there are multiple methods of risk stratification for ST-elevation myocardial infarction (STEMI), this study presents a prospectively validated method for reclassification of patients based on in-hospital events. A dynamic risk score provides an initial risk stratification and reassessment at discharge.

Methods and results: The dynamic TIMI risk score for STEMI was derived in ExTRACT-TIMI 25 and validated in TRITON-TIMI 38. Baseline variables were from the original TIMI risk score for STEMI. New variables were major clinical events occurring during the index hospitalization. Each variable was tested individually in a univariate Cox proportional hazards regression. Variables with P<0.05 were incorporated into a full multivariable Cox model to assess the risk of death at 1 year. Each variable was assigned an integer value based on the odds ratio, and the final score was the sum of these values. The dynamic score included the development of in-hospital MI, arrhythmia, major bleed, stroke, congestive heart failure, recurrent ischemia, and renal failure. The C-statistic produced by the dynamic score in the derivation database was 0.76, with a net reclassification improvement (NRI) of 0.33 (P<0.0001) from the inclusion of dynamic events to the original TIMI risk score. In the validation database, the C-statistic was 0.81, with a NRI of 0.35 (P=0.01).

Conclusions: This score is a prospectively derived, validated means of estimating 1-year mortality of STEMI at hospital discharge and can serve as a clinically useful tool. By incorporating events during the index hospitalization, it can better define risk and help to guide treatment decisions.

Figure 1.

Dynamic TIMI risk score for STEMI used to predict 1‐year mortality. Data are based on the ExTRACT‐TIMI 25 derivation set. N refers to the number of patients falling under that score category, whereas % refers to the percentage of the total population in that score category. TIMI indicates Thrombolysis In Myocardial Infarction; STEMI, ST‐elevation myocardial infarction.

Figure 2.

Dynamic TIMI risk score for STEMI for predicting 1‐year mortality in the TRITON‐TIMI 38 validation set. N refers to the number of patients falling under that score category, whereas % refers to the percentage of the total population in that score category. Risk categories were collapsed because of the low prevalence of patients assigned to certain scores. TIMI indicates Thrombolysis In Myocardial Infarction; STEMI, ST‐elevation myocardial infarction.