TIMI Risk Score Calculator for UA/NSTEMI
The TIMI Risk Score for unstable angina (UA) and non-ST-elevation MI (NSTEMI) is a validated 7-point clinical prediction tool developed by Antman et al. (JAMA 2000). Check each criterion that applies to your patient to get the total score, the corresponding 14-day event rate (all-cause death, new MI, or urgent revascularization), and the risk tier that guides management intensity. The result updates instantly as you check boxes.
Formula
Worked example
A 68-year-old patient (age 65+: +1) with hypertension, diabetes, and a family history of CAD (3+ risk factors: +1), known 60% LAD stenosis (+1), who took aspirin daily (+1), had 3 chest pain episodes in the past 24 hours (+1), has 1 mm ST depression on ECG (+1), and a troponin above normal (+1) scores 7/7, placing them in the high-risk tier with a ~40.9% 14-day composite event rate.
What is the TIMI Risk Score for UA/NSTEMI?
The TIMI (Thrombolysis in Myocardial Infarction) Risk Score for unstable angina and non-ST-elevation MI is a validated clinical decision tool created by Dr. Elliott Antman and colleagues at Harvard Medical School and published in JAMA in 2000. It assigns one point each for seven binary clinical variables, producing a score from 0 to 7. The score was derived and validated using data from the TIMI 11B and ESSENCE randomized trials (approximately 1,960 patients each) and has since been externally validated in many other patient populations. It estimates the probability that a patient will experience a major adverse cardiac event - defined as all-cause death, new or recurrent myocardial infarction, or severe recurrent ischemia requiring urgent revascularization - within 14 days of presentation.
The seven criteria and why each matters
Each criterion contributes equally (1 point) regardless of how strongly it is present. Age 65 or older reflects the higher baseline cardiovascular risk with advancing age. Three or more CAD risk factors (family history, hypertension, hypercholesterolemia, diabetes, or current smoking) indicates a higher underlying atherosclerotic burden. Known coronary artery disease with at least 50% stenosis on prior angiography confirms established obstructive disease. Aspirin use within the past 7 days is paradoxical: its presence suggests symptoms despite therapy, pointing to more severe or progressing plaque rupture rather than protective benefit. Two or more anginal episodes in the past 24 hours reflects recurrent ischemia and an unstable coronary lesion. ST-segment deviation of 0.5 mm or greater on the presenting ECG signals active transmural ischemia. Elevated cardiac biomarkers (troponin I, troponin T, or CK-MB) indicate actual myocardial necrosis and are considered the single most prognostic of the seven criteria.
Risk stratification and management implications
Scores of 0-2 are generally classified as low risk, with a 14-day event rate of roughly 4.7-8.3%. These patients are candidates for a conservative (non-invasive) management strategy, including early stress testing or coronary imaging within 72 hours before discharge. Scores of 3-4 represent intermediate risk (13-20% event rate) and typically warrant consideration of an early invasive strategy with coronary angiography within 24-72 hours, along with intensified antiplatelet and anticoagulant therapy. Scores of 5-7 indicate high risk (26-41% event rate) and are associated with clear benefit from an early invasive approach within 2-24 hours, intensive dual antiplatelet therapy, and close monitoring. The 2014 ACC/AHA NSTEMI guidelines and 2020 ESC NSTE-ACS guidelines cite the TIMI score as one of several validated risk tools appropriate for this initial triage, alongside the HEART score and GRACE score.
Limitations and context for clinical use
The TIMI score is a useful and widely used triage tool, but it has well-recognized limitations. It was derived in 2000, before high-sensitivity troponin assays were available; contemporary biomarker measurement may shift classification for some patients. The score weights each criterion equally despite varying prognostic strength: for example, an elevated troponin and ST changes individually carry more prognostic weight than age alone, yet each contributes only one point. The score also does not incorporate hemodynamic parameters such as heart rate, blood pressure, or Killip class, which are captured by the GRACE score. Because of these differences, the GRACE score generally shows better discrimination (higher C-statistic) in most validation studies. The TIMI UA/NSTEMI score is specifically validated for patients who already have a diagnosis of UA or NSTEMI; the HEART score is preferred for undifferentiated chest pain in the emergency department where the diagnosis is not yet established.
TIMI Score: 14-Day Event Rates by Score
| TIMI Score | Risk Category | 14-Day Event Rate | Management Approach |
|---|---|---|---|
| 0-1 | Low | ~4.7% | Conservative / early stress testing |
| 2 | Low | ~8.3% | Conservative / early stress testing |
| 3 | Intermediate | ~13.2% | Consider early invasive strategy |
| 4 | Intermediate | ~19.9% | Consider early invasive strategy |
| 5 | High | ~26.2% | Early invasive strategy favored |
| 6-7 | High | ~40.9% | Urgent invasive strategy |
Data from Antman et al., JAMA 2000. Event = all-cause death, new or recurrent MI, or severe recurrent ischemia requiring urgent revascularization within 14 days.
Frequently asked questions
What does a TIMI score of 0 mean?
A score of 0 means none of the seven criteria are positive. This places the patient in the low-risk tier, but it does not mean zero risk. The original TIMI 11B data show approximately 4.7% of patients with a score of 0-1 still experienced a major adverse cardiac event within 14 days. A score of 0 supports a conservative management strategy, but close observation and serial biomarkers remain important.
Why does aspirin use in the past 7 days add a point if aspirin is protective?
The aspirin criterion is a marker of disease severity, not a treatment variable. A patient who is already on regular aspirin and still develops an acute coronary syndrome has experienced a coronary event despite antiplatelet protection, which implies a more complex, unstable, or progressing plaque rupture. That clinical picture carries a higher short-term risk than a de-novo event in a patient not on aspirin, which is why its presence adds one point.
How is the TIMI UA/NSTEMI score different from the TIMI STEMI score?
These are two entirely separate scoring systems that share the TIMI name. The TIMI Risk Score for UA/NSTEMI (this calculator) uses 7 binary criteria to estimate 14-day risk of death, MI, or urgent revascularization in patients without ST elevation. The TIMI Risk Score for STEMI uses 11 criteria and a different scale to predict 30-day mortality in ST-elevation MI patients who are treated with thrombolytic therapy. The two scores should not be confused or interchanged.
Is the TIMI score better or worse than the GRACE score?
Both are validated, guideline-endorsed tools, but they have different strengths. The GRACE score incorporates continuous variables such as heart rate, systolic blood pressure, creatinine, and Killip class, giving it a higher C-statistic (better discriminatory ability) in most head-to-head validation studies. The TIMI score is quicker to calculate at bedside because all seven variables are binary. Many clinicians use both: TIMI for rapid initial triage and GRACE for more precise risk quantification when data are available. ACC/AHA guidelines recommend using at least one validated risk score and mention both as acceptable options.
What is a "positive cardiac biomarker" in the context of the TIMI score?
In the original 2000 study, a positive cardiac marker was defined as elevated CK-MB or troponin above the upper limit of normal at the time of presentation. In modern practice, this criterion is considered met when high-sensitivity troponin I or troponin T exceeds the 99th-percentile upper reference limit. Troponin elevation is the single most prognostic of the seven criteria, and Antman et al. noted that its prognostic importance was independent of the other six variables.
Can I use the TIMI score for undifferentiated chest pain in the ED?
The TIMI UA/NSTEMI score is validated for patients who already carry a working diagnosis of UA or NSTEMI. For undifferentiated chest pain where the diagnosis is not yet confirmed, the HEART score (History, ECG, Age, Risk factors, Troponin) is generally preferred because it was specifically designed and validated in the undifferentiated ED chest pain population. Once UA or NSTEMI is established, the TIMI or GRACE score is appropriate for risk stratification.