ACS Risk Scores TIMI and GRACE
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Direct answer
TIMI and GRACE are risk scores that estimate the short-term risk of death, myocardial infarction and need for revascularisation in non-ST elevation acute coronary syndrome. The TIMI score is a simple seven-point tally, while the GRACE score is a multivariable model using variables such as age, heart rate, systolic pressure, creatinine and Killip class, and both guide the timing of coronary angiography.
What you must remember
- TIMI score: seven binary items, each worth one point, giving a total from 0 to 7 in NSTE-ACS.
- TIMI items: age 65 or over, three or more coronary risk factors, known coronary stenosis of 50 per cent or more, aspirin use in the past week, two or more anginal episodes in 24 hours, ST deviation of 0.5 mm or more, and raised cardiac markers.
- TIMI prognosis: higher scores predict a greater risk of death, myocardial infarction or urgent revascularisation at 14 days.
- GRACE score: a multivariable model predicting in-hospital and six-month mortality, using age, heart rate, systolic pressure, creatinine, Killip class, cardiac arrest, ST deviation and troponin.
- GRACE thresholds: commonly quoted cut-offs are above 140 for high risk and 108 or below for low risk.
- Killip class: graded I to IV, from no heart failure to cardiogenic shock, and a higher class raises the GRACE score.
- Timing of angiography: high-risk patients usually undergo angiography within 24 hours, and very high-risk features need immediate invasive management.
- Pitfall: the TIMI score here is the UA/NSTEMI version (a separate TIMI STEMI score exists), and in practice both scores are applied to NSTE-ACS triage, never in place of clinical judgement or the STEMI reperfusion pathway.
How the two scores differ in use
TIMI is quick at the bedside, while GRACE carries more information and gives finer prognostic groups. The table compares the two on what matters for an exam answer.
| Feature | TIMI (NSTE-ACS) | GRACE |
|---|---|---|
| Format | Seven items, score 0 to 7 | Continuous model, total score |
| Key inputs | Age, risk factors, angina, ST deviation, markers | Age, heart rate, pressure, creatinine, Killip class |
| Outcome | 14-day death, MI or revascularisation | In-hospital and six-month death |
| Best use | Quick bedside stratification | Refined risk and timing of invasive care |
In an exam vignette, the score is applied only once NSTE-ACS is probable, and the outcome row of the table shows which endpoint the question is testing.
Renal function has a large effect in GRACE, so creatinine must be read as part of the score rather than separately. TIMI counts seven binary items, whereas GRACE combines several continuous measurements in one model. Both scores are prognostic tools that cannot exclude infarction when troponin or ECG changes are present.
Traps in risk score questions
Risk score questions test whether the score is applied to the right patient and read in the right context.
- Trap: using the NSTE-ACS scores for a patient with STEMI Correct: STEMI is managed by reperfusion, and risk scores designed for NSTE-ACS do not replace the emergency pathway.
- Trap: treating a low TIMI score as ruling out ACS Correct: risk scores stratify prognosis, and they do not exclude infarction when troponin is raised or ECG changes evolve.
- Trap: ignoring creatinine when interpreting GRACE Correct: renal impairment raises the GRACE score substantially, so a patient with reduced kidney function can move into the high-risk group.
Frequently asked questions
How many points does the TIMI score give for age?
The TIMI score gives one point for age 65 years or older in NSTE-ACS. Age is one of seven binary items, so a patient can score up to seven when every criterion is present.
What does a high GRACE score mean in NSTE-ACS?
A GRACE score above 140 indicates high risk of in-hospital death, and it is commonly used to justify an early invasive strategy with angiography within 24 hours. Scores of 108 or below are generally considered low risk.
Which ACS patients need an early invasive strategy?
Patients with high-risk features, such as a GRACE score above 140, dynamic ST changes or refractory angina, usually need an early invasive strategy. Very high-risk features such as refractory angina or cardiogenic shock call for immediate angiography.
Why does Killip class matter in the GRACE score?
Killip class grades heart failure from class I, with no signs, to class IV, with cardiogenic shock, and higher classes predict greater mortality. Because Killip class is part of the GRACE model, a patient with pulmonary oedema at presentation scores higher than a patient without it.