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TIMI risk score for STEMI: how the points are calculated

The TIMI risk score for ST-elevation myocardial infarction (STEMI) adds points for baseline variables at presentation: age (2 for 65 to 74, 3 for 75 or older), a history of diabetes, hypertension or angina (1), systolic pressure under 100 (3), heart rate over 100 (2), Killip class II to IV (2), weight under 67 kg (1), anterior ST elevation or left bundle branch block (1), and a delay of more than 4 hours (1). The total runs from 0 to 14.

Not a medical device. Not a diagnosis or dosing recommendation.

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What is the TIMI risk score for STEMI?

The score was published by Morrow, Antman, Charlesworth and colleagues in Circulation in 2000. The paper's title calls it "a convenient, bedside, clinical score for risk assessment at presentation." TIMI is the name of the study group. It's a separate score from the TIMI score for UA/NSTEMI.

This page explains the arithmetic. It doesn't turn a score into a mortality figure, and it doesn't say what a score means for a particular person.

The TIMI STEMI formula

TIMI STEMI = age 65–74 (2) or age ≥ 75 (3)
           + diabetes, hypertension or angina (1)
           + systolic BP < 100 (3)
           + heart rate > 100 (2)
           + Killip class II–IV (2)
           + weight < 67 kg (1)
           + anterior ST elevation or LBBB (1)
           + delay > 4 h (1)
maximum = 14

Exact expression the calculator uses:

TIMI STEMI = age 65-74 (2) or age >=75 (3) + diabetes/hypertension/angina (1) + SBP<100 (3) + HR>100 (2) + Killip II-IV (2) + weight<67 kg (1) + anterior STE or LBBB (1) + time to treatment >4 h (1); max 14

What each part means

ItemWhat earns pointsPoints
Age65 to 742
75 or older3
Diabetes, hypertension or anginaAny one of them1
Systolic blood pressureUnder 100 mm Hg3
Heart rateOver 100 beats per minute2
Killip classII, III or IV2
WeightUnder 67 kg1
Anterior ST elevation or LBBBPresent1
Time from symptom onsetMore than 4 hours1

How the score works

  1. Age. 65 to 74 adds 2; 75 or older adds 3. The two never both count.
  2. History. Diabetes, hypertension or angina adds 1 if any one is present. Having two or three still adds 1.
  3. Blood pressure and heart rate. Systolic pressure under 100 adds 3. Heart rate over 100 adds 2. A pressure of 100 or a heart rate of 100 adds nothing.
  4. Killip class. Class II to IV adds 2; class I adds nothing.
  5. Weight, ECG and time. Weight under 67 kg, anterior ST elevation or LBBB, and a delay of more than 4 hours add 1 each.
  6. Add them up. The total is 0 to 14.

Inputs come from the user

The record says the person using the calculator assigns the Killip class, the ECG finding and whether more than 4 hours have passed. Magent's calculator doesn't read an ECG or work out times. It takes age from 18 to 120, systolic pressure from 50 to 250 mm Hg, heart rate from 30 to 220, Killip class 1 to 4, and weight in kg or pounds. It returns the integer total, the maximum of 14 and a line for each item, not a mortality percentage.

Worked example

This is the worked example in Magent's record for the calculator.

Example 1: nothing scores

  1. Age 50 is under 65 → 0. No diabetes, hypertension or angina → 0.
  2. Systolic pressure 120 → 0. Heart rate 70 → 0. Killip class I → 0.
  3. Weight 80 kg → 0. No anterior ST elevation or LBBB → 0. Delay not more than 4 hours → 0.
  4. Score = 0 out of 14.

Values at the boundaries

Each line changes Example 1. All are Magent's expected values for the calculator.

  • Age 65 → 2; age 75 → 3.
  • Systolic pressure 99 with heart rate 101 → 5.
  • Killip class II, weight 66.9 kg, anterior ST elevation and a delay of more than 4 hours → 5.
  • Diabetes and hypertension together → 1.

History of the TIMI risk score for STEMI

The score comes from Morrow DA, Antman EM, Charlesworth A and colleagues, TIMI risk score for ST-elevation myocardial infarction: A convenient, bedside, clinical score for risk assessment at presentation, Circulation, 2000 (volume 102, issue 17, pages 2031–2037).

When it's used

The paper's title describes a score for use at presentation with STEMI.

Where it's used

The paper's title calls it a bedside score. Every input is a history item, a vital sign, a body weight, a Killip class or an ECG finding.

Who uses it

The person using the calculator enters the numbers and assigns the findings. The calculator does the adding.

Limits of the calculation

  • It adds up points. It returns the integer score and components, not a mortality percentage.
  • Age 65 to 74 and age 75 or older are separate bands; a person gets one or the other.
  • Diabetes, hypertension and angina together are worth 1 point, not 1 each.
  • The calculator doesn't read an ECG or compute times from timestamps.
  • This page doesn't say what to do with a score.

Clinical decisions belong to a qualified clinician who knows the patient.

  • TIMI score for UA/NSTEMI is a separate TIMI score for unstable angina and non-ST-elevation myocardial infarction, with its own items.

Glossary

  • STEMI: ST-elevation myocardial infarction, a heart attack with ST elevation on the ECG.
  • LBBB: left bundle branch block, a pattern on the ECG.
  • Killip class: a grading of heart failure signs in a heart attack, from I to IV.
  • Anterior ST elevation: ST elevation in the ECG leads that look at the front of the heart.

Common mistakes

  • Adding 2 and 3 for age. It's 2 for 65 to 74 or 3 for 75 or older.
  • Adding 1 for each of diabetes, hypertension and angina. Together they're worth 1.
  • Giving heart rate 100 points. The item needs a rate over 100.
  • Scoring weight 67 kg. The item needs weight under 67 kg.

Source

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. Circulation. 2000;102(17):2031-2037. DOI: 10.1161/01.CIR.102.17.2031

Frequently asked questions

How do you calculate the TIMI risk score for STEMI?

Add 2 for age 65 to 74 or 3 for 75 or older, 1 for diabetes, hypertension or angina, 3 for systolic pressure under 100, 2 for heart rate over 100, 2 for Killip class II to IV, and 1 each for weight under 67 kg, anterior ST elevation or LBBB, and a delay of more than 4 hours.

What does a TIMI STEMI score of 5 mean?

This page doesn't give a mortality figure by score. It adds up the points; what a score means depends on the person and the clinical context.

What is the highest TIMI STEMI score?

14.

Is this the same as the TIMI score for UA/NSTEMI?

No. They're separate scores with different items.

Who developed the TIMI risk score for STEMI?

Morrow and colleagues, in a 2000 paper in Circulation.