TIMI Risk Score Calculation
TIMI Risk Score for NSTE-ACS (Non-ST-Elevation Acute Coronary Syndromes)
The TIMI risk score for unstable angina/NSTEMI is calculated by assigning 1 point for each of 7 baseline variables present, then summing them to create a simple arithmetic score ranging from 0-7 1, 2, 3.
The 7 Variables (1 point each):
- Age ≥65 years
- ≥3 risk factors for coronary artery disease (hypertension, diabetes, hyperlipidemia, family history, current smoking)
- Prior coronary stenosis ≥50% (known CAD)
- ST-segment deviation ≥0.5 mm on presenting ECG
- ≥2 anginal events in prior 24 hours (severe anginal symptoms)
- Use of aspirin in prior 7 days
- Elevated serum cardiac biomarkers (troponin or CK-MB)
Risk Stratification and Outcomes:
The score directly correlates with 14-day risk of death, MI, or severe recurrent ischemia requiring urgent revascularization 1, 3:
- Score 0-1: 4.7% event rate
- Score 2: 8.3% event rate
- Score 3: 13.2% event rate
- Score 4: 19.9% event rate
- Score 5: 26.2% event rate
- Score 6-7: 40.9% event rate
Clinical Application:
This scoring system should be used at presentation for all patients with suspected NSTE-ACS to guide therapeutic decision-making 1. The score has been validated across multiple international trials and demonstrates that higher-risk patients (scores ≥4) derive greater benefit from aggressive therapies including low-molecular-weight heparins, glycoprotein IIb/IIIa inhibitors, and early invasive strategies 2, 3.
TIMI Risk Score for STEMI (ST-Elevation Myocardial Infarction)
For STEMI patients eligible for fibrinolysis, a different TIMI risk score exists using 10 baseline variables weighted according to their prognostic importance, creating a score that predicts 30-day mortality 4. This score shows a >40-fold graded increase in mortality from lowest to highest risk categories and captures 97% of the predictive capacity of complex multivariable models while remaining clinically practical at the bedside 4.