New risk score for patients with acute chest pain, non-ST-segment deviation, and normal troponin concentrations: a comparison with the TIMI risk score.

OBJECTIVES: The purpose of this research was to develop a risk score for patients with chest pain, non-ST-segment deviation electrocardiogram (ECG), and normal troponin levels.
BACKGROUND: Prognosis assessment in this population remains a challenge.
METHODS: A total of 646 consecutive patients were evaluated by clinical history (risk factors and chest pain score according to pain characteristics), ECG, and early exercise testing. ST-segment deviation and troponin elevation were exclusion criteria. The primary end point was mortality or myocardial infarction at one year. The secondary end point was mortality, myocardial infarction, or urgent revascularization at 14 days (similar to the Thrombolysis In Myocardial Infarction [TIMI] risk score).
RESULTS: Primary and secondary end point rates were 6.7% and 5.4%. A risk score was constructed using the variables related to the primary end point: chest pain score > or =10 points (hazard ratio [HR] = 2.5; 1 point), > or =2 pain episodes in last 24 h (HR = 2.2; 1 point), age > or =67 years (HR = 2.3; 1 point), insulin-dependent diabetes mellitus (HR = 4.2; 2 points), and prior percutaneous transluminal coronary angioplasty (HR = 2.2; 1 point). Patients were classified into five categories of risk (p = 0.0001): 0 points, 0% event rate; 1 point, 3.1%; 2 points, 5.4%; 3 points, 17.6%; > or =4 points, 29.6%. The accuracy of the score was greater than that of the TIMI risk score for the primary (C index of 0.78 vs. 0.66, p = 0.0002) and secondary (C index of 0.70 vs. 0.66, p = 0.1) end points.
CONCLUSIONS: Patients presenting with chest pain despite no ST-segment deviation or troponin elevation show a non-negligible rate of events at one year. A risk score derived from this specific population allows more accurate stratification than when using the TIMI risk score.