TIMI Risk Score STEMI Calculator

TIMI Risk Score STEMI Calculator for Cardiology. The score behaves as a continuous risk gradient rather than fixed cut-points, spanning more than a 40-fold range in 30-day mortality. In the derivation cohort a score of 0 carried under 1% mortality, roughly 3-5% in the mid range (scores 3-4), and above 20-30% at scores of 8 or more. Low scores (0-2) identify patients who may be candidates for early step-down or transfer, while high scores (>=5) mark those needing intensive monitoring, prompt reperfusion, and early consideration of mechanical support. It informs prognosis and disposition; it does not choose the reperfusion strategy itself.

How this calculator works

The score is a weighted integer sum of ten baseline clinical variables that were the strongest independent predictors of 30-day death in a logistic model, collapsed so that each carries preset points. Age contributes most (2 points for 65-74 years, 3 points for 75 or older), followed by systolic BP below 100 mmHg (3), heart rate above 100 (2), and Killip class II-IV (2). One point each is added for anterior ST-elevation or LBBB, diabetes/hypertension/angina history, weight under 67 kg, and time to treatment beyond 4 hours. The total runs from 0 to 14 and maps directly to a predicted 30-day mortality.

When to use this calculator

Use it at first presentation for a fibrinolytic-eligible STEMI patient to quantify 30-day mortality and triage intensity of monitoring and transfer. It was derived and validated in reperfusion-treated cohorts, and in NRMI 3 it discriminated equally well for fibrinolysis (c=0.79) and primary PCI (c=0.80). Do not rely on it in patients who receive no reperfusion, where it underestimates mortality and discrimination falls to c=0.65, nor apply it to NSTEMI/unstable angina, which use the separate TIMI UA/NSTEMI score.

Inputs used

  • Age
  • Systolic blood pressure
  • Heart rate
  • Killip class
  • Weight
  • ECG territory
  • Time to treatment
  • Clinical history

Clinical interpretation

The score behaves as a continuous risk gradient rather than fixed cut-points, spanning more than a 40-fold range in 30-day mortality. In the derivation cohort a score of 0 carried under 1% mortality, roughly 3-5% in the mid range (scores 3-4), and above 20-30% at scores of 8 or more. Low scores (0-2) identify patients who may be candidates for early step-down or transfer, while high scores (>=5) mark those needing intensive monitoring, prompt reperfusion, and early consideration of mechanical support. It informs prognosis and disposition; it does not choose the reperfusion strategy itself.

Worked example

A 78-year-old woman (3 points, age >=75) with anterior STEMI (1), heart rate 108 (2), systolic BP 92 mmHg (3), Killip II crackles (2), diabetic and hypertensive (1), weight 60 kg (1), presenting 5 hours after symptom onset (1) scores 14. This places her in the highest band, where derivation-cohort 30-day mortality exceeded 35%, flagging her for aggressive reperfusion and ICU-level care.

Limitations and safety notes

Because it was built in fibrinolytic-eligible trial populations, it excludes cardiogenic shock at presentation and non-reperfused patients, and it systematically under-predicts death in the latter group. Weighting reflects late-1990s pharmacological reperfusion, so absolute mortality estimates run higher than modern primary-PCI outcomes and should be read as relative stratification. It captures no biomarker (troponin, BNP), renal function, or bleeding risk, and treats the heterogeneous history variable (diabetes, hypertension, or prior angina) as a single point.

Frequently asked questions

How is TIMI STEMI different from the TIMI score for UA/NSTEMI?

They are separate instruments. The STEMI score predicts 30-day all-cause mortality in ST-elevation patients using ten weighted variables (max 14), while the 7-point UA/NSTEMI score predicts a 14-day composite of death, MI, or urgent revascularization. Do not interchange them.

Does the score tell me whether to give fibrinolysis or send for primary PCI?

No. It quantifies mortality risk, not the reperfusion strategy. In NRMI 3 it discriminated similarly for both fibrinolysis and primary PCI. Use it for prognosis, triage, and level-of-care decisions alongside the reperfusion pathway your system already follows.

Why does age carry so much weight?

Age was the single strongest independent predictor in the derivation model, so it is the only variable scored on a graded scale: 2 points at 65-74 years and 3 points at 75 or older. A patient can reach a high-risk total on age plus one or two hemodynamic findings alone.

Can I use it in a patient who is not getting reperfusion?

It performs poorly there. Among non-reperfused NRMI 3 patients it underestimated mortality and discrimination dropped to c=0.65, versus about 0.79-0.80 in reperfused patients. Treat any estimate in that setting as unreliable.

How does Killip class factor in?

Killip class II, III, or IV (any sign of heart failure, pulmonary edema, or shock) adds 2 points as a single threshold; Killip I adds nothing. It is one of the higher-weighted hemodynamic terms and often distinguishes an intermediate from a high-risk total.

References

  • Morrow DA, Antman EM, Charlesworth A, Cairns R, Murphy SA, de Lemos JA, Giugliano RP, McCabe CH, Braunwald E. TIMI risk score for ST-elevation myocardial infarction: A convenient, bedside, clinical score for risk assessment at presentation: An intravenous nPA for treatment of infarcting myocardium early II trial substudy. Circulation. 2000. PMID: 11044416.
  • Morrow DA, Antman EM, Parsons L, de Lemos JA, Cannon CP, Giugliano RP, McCabe CH, Barron HV, Braunwald E. Application of the TIMI risk score for ST-elevation MI in the National Registry of Myocardial Infarction 3. JAMA. 2001. PMID: 11560541.

Editorial review and citation methodology

Reviewed by the Quick Medical Calculator Editorial Team. Last reviewed: April 4, 2026. The review checks calculator inputs, intended population, interpretation, limitations, and source alignment.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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