TIMI Risk Score Calculator
An interactive implementation of the TIMI risk score for unstable angina and non-ST-elevation MI (Antman et al., JAMA 2000): seven binary variables scored 0 to 7 to estimate 30-day ischaemic risk.
Answer seven yes-or-no questions about age, coronary risk factors, known coronary disease, recent aspirin use, angina pattern, ECG changes and cardiac markers to compute the TIMI risk score from 0 to 7, with the corresponding published 30-day rate of death, myocardial infarction or urgent revascularization.
What is the TIMI risk score?
The TIMI risk score is one of the most enduring bedside tools in cardiology, and its longevity comes from radical simplicity: seven yes-or-no questions, one point each, counted on the fingers. Antman and colleagues derived it from over 7,000 patients with unstable angina or non-ST-elevation MI enrolled in the TIMI 11B and ESSENCE trials, and validated the striking stepwise relationship between the score and 30-day outcomes that the calculator reproduces. Event rates climb from under 5 percent at scores of 0 to 1 to over 40 percent at scores of 6 to 7, a gradient steep enough to change management.
The score earned its place not only by predicting risk but by predicting treatment benefit. In the derivation cohorts, the absolute benefit of low-molecular-weight heparin over unfractionated heparin, and of glycoprotein IIb/IIIa inhibitors, grew with the TIMI score, concentrating the advantage in higher-risk patients. That interaction between risk and treatment effect is the score's most clinically useful property: it identifies the patients in whom aggressive therapy buys the most, and, conversely, those in whom conservative management is reasonable.
The seven variables
Each variable captures a different facet of risk. Age 65 or older and three or more traditional coronary risk factors mark the patient's background vulnerability. Known coronary stenosis of at least 50 percent on prior angiography marks established anatomic disease. Aspirin use within the past 7 days marks breakthrough ischaemia despite therapy, a counterintuitive but powerful predictor. Two or more anginal episodes in the preceding 24 hours marks accelerating symptoms. ST-segment deviation of 0.5 mm or more on the presenting ECG and elevated cardiac markers mark objective evidence of ischaemia and necrosis.
The equal weighting is deliberate rather than naive. The investigators found that a simple count performed nearly as well as a weighted model, and simplicity is what made the score usable at 3 a.m. in a busy emergency department. The trade-off is granularity: a patient with 0.6 mm of ST depression scores the same as one with 3 mm, and the score cannot distinguish them. That is where clinical judgment and the more finely weighted GRACE score take over.
How to interpret the score
The published 30-day rates of death, myocardial infarction or urgent revascularization are: 0 to 1 points, 4.7 percent; 2 points, 8.3 percent; 3 points, 13.2 percent; 4 points, 19.9 percent; 5 points, 26.2 percent; and 6 to 7 points, 40.9 percent. In practice, scores of 0 to 2 describe lower-risk unstable angina in which selective management is often appropriate, scores of 3 to 4 describe intermediate risk warranting close observation and usually angiography, and scores of 5 or above describe high risk in which aggressive medical therapy and early invasive management are favoured.
The score also informs the intensity of antithrombotic therapy. Higher scores strengthen the case for potent P2Y12 inhibition, anticoagulation with a preferred agent, and glycoprotein IIb/IIIa blockade in selected cases, while lower scores allow a more measured approach with less bleeding risk. As always, bleeding risk must be weighed in parallel, particularly in older patients and those with renal impairment, anaemia or prior bleeding.
TIMI versus GRACE
Clinicians often ask which score to use, and the honest answer is that they answer slightly different questions. GRACE, with its weighted continuous variables, discriminates mortality better and is the guideline-preferred tool for mortality stratification and timing of angiography. TIMI is simpler, requires no laboratory values beyond troponin, and carries the unique treatment-interaction data showing greater absolute benefit of intensive therapy at higher scores. Many clinicians compute both: GRACE for prognosis and timing, TIMI as a rapid bedside cross-check and a reminder that the highest-risk patients gain the most from aggressive care.
Limitations
The TIMI risk score was derived from clinical trial populations, which tend to be younger and less comorbid than unselected emergency department cohorts, so absolute event rates may differ in contemporary practice. Its binary variables discard information, and its discrimination is modest compared with GRACE. It applies only to unstable angina and non-ST-elevation MI; a different TIMI score exists for ST-elevation MI, and neither should delay reperfusion when ST-elevation MI is diagnosed. High-sensitivity troponin assays have also shifted the boundary between unstable angina and NSTEMI since the derivation era, moving some patients between categories without changing their underlying risk.
References
- Antman EM, Cohen M, Bernink PJLM, et al. The TIMI risk score for unstable angina/non-ST elevation MI: a method for prognostication and therapeutic decision making. JAMA. 2000;284(7):835-842.
- Collet JP, Thiele H, Barbato E, et al. 2020 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation. Eur Heart J. 2021;42(14):1289-1367.
- Amsterdam EA, Wenger NK, Brindis RG, et al. 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes. Circulation. 2014;130(25):e344-e426.
Key takeaways
- The TIMI risk score sums seven binary variables, age 65 or older, three or more CAD risk factors, known stenosis of 50 percent or more, aspirin in the past 7 days, two or more anginal episodes in 24 hours, ST deviation of 0.5 mm or more, and elevated cardiac markers, into a score from 0 to 7.
- Published 30-day rates of death, MI or urgent revascularization run from 4.7 percent at 0 to 1 points to 40.9 percent at 6 to 7 points.
- Higher scores identify patients who gain the greatest absolute benefit from aggressive antithrombotic therapy and early invasive management.
- The score applies to unstable angina and non-ST-elevation MI only; use the separate TIMI STEMI score, or GRACE, for ST-elevation presentations.
- Prior aspirin use scores a point because breakthrough ischaemia on therapy marks aggressive disease, not because aspirin is harmful.
- Weigh bleeding risk alongside the score, and consider GRACE for finer mortality stratification.
Frequently asked questions
What is the TIMI risk score used for?
The TIMI risk score estimates the 30-day risk of death, myocardial infarction or urgent revascularization in patients presenting with unstable angina or non-ST-elevation myocardial infarction. It sums seven binary variables, each worth one point: age 65 or older, three or more coronary artery disease risk factors, known coronary stenosis of at least 50 percent, aspirin use in the prior 7 days, two or more anginal episodes in the preceding 24 hours, ST-segment deviation of 0.5 mm or more, and elevated cardiac markers.
What do the TIMI risk score values mean?
The published 30-day event rates are 4.7 percent for scores of 0 to 1, 8.3 percent for 2, 13.2 percent for 3, 19.9 percent for 4, 26.2 percent for 5, and 40.9 percent for 6 to 7. Higher scores identify patients more likely to benefit from aggressive antiplatelet and anticoagulant therapy and from an early invasive strategy.
Can the TIMI risk score be used in ST-elevation MI?
No. This version of the TIMI risk score was derived and validated in unstable angina and non-ST-elevation MI. A separate TIMI risk score exists for ST-elevation MI with different variables. In ST-elevation MI, emergency reperfusion takes priority regardless of any score.
Why does prior aspirin use add a point?
Aspirin use in the 7 days before presentation marks a patient whose ischaemia broke through antiplatelet therapy, which signals more aggressive underlying disease and a higher risk of recurrent events. It is a marker of treatment failure rather than a harmful effect of aspirin itself.
What is the difference between the TIMI and GRACE scores?
The TIMI risk score uses seven equally weighted yes-or-no variables and predicts a 30-day composite of death, MI or urgent revascularization, while GRACE uses eight weighted variables including continuous measurements and is better calibrated for predicting mortality at hospital discharge and at 6 months. Guidelines favour GRACE for mortality stratification, but TIMI remains useful for its simplicity and its treatment interaction data.
Does a low TIMI score rule out ACS?
No. The score stratifies risk among patients already diagnosed with unstable angina or NSTEMI; it is not a diagnostic test for chest pain. A patient with a score of 0 still has a 4.7 percent 30-day event rate in the derivation data, and the diagnosis of ACS rests on the history, ECG and troponin, not on the score.