Choosing hearts to treat
A TIMI prognostication scheme is clinically useful in cardiac patients.
LONDON, August 17 (SPIS MedWire). Given the heterogeneous nature of unstable angina and non-ST-segment elevation myocardial infarction (UA/NSTEMI), patients have a wide spectrum of risk for death and cardiac ischemic events. A paper in this week's JAMA concludes that the TIMI (Thrombolysis in Myocardial Infarction) risk score accurately predicts outcomes in these patients and can assist therapeutic decision-making. Antman at Brigham and Women's Hospital, Boston, and multicenter colleagues collected data on patients enrolled in two phase III international, randomised, double-blind trials: TIMI 11B and ESSENCE (Efficacy and Safety of Subcutaneous Enoxaparin in Unstable Angina and non-Q-wave MI trial). A total of 1,957 patients with UA/NSTEMI were randomised to receive unfractionated heparin (test cohort) and 1,953 to receive enoxaparin in TIMI 11B, while 1,564 and 1,607 were assigned to heparin and anoxaparin, respectively, in ESSENCE. Antman et al then used multivariate logistic regression to select independent prognostic variables, assigning a score of 1 when the factor was present and 0 when it was absent. The seven variables were: age ≥65 years; ≥3 risk factors for coronary artery disease; prior coronary stenosis ≥50%; ST-segment deviations on presenting ECG; ≥2 anginal events in the prior 24 hours; and elevated serum cardiac markers. The group found that event rates increased significantly as the TIMI risk score increased: in the TIMI 11B cohort a score of 0/1 the event rate was 4.7%, rising to 40.9% for a score of 6/7 (p<0.001 for trend). The slope of the increase in event rates with increasing numbers of risk factors was significantly lower in the enoxaparin groups in both TIMI 11B (p= 0.01) and ESSENCE (p =0.03) and there was a significant interaction between TIMI risk score and treatment (p=0.02). Antman's group concludes: 'TIMI offers a simple prognostication scheme that categorises a patient's risk of death and ischemic events' and note that a promising clinical application of the score is the identification of a patient "for whom new antithrombic therapies would be especially effective." In an accompanying editorial, Magnus Ohman and colleagues from Duke University Medical Center, North Carolina, suggest that the TIMI risk score may allow comparisons of the cost-effectiveness of other drugs, as well as of early invasive versus early conservative strategies.