About the TIMI Risk Score for STEMI
The TIMI Risk Score for ST-elevation myocardial infarction (STEMI) is a bedside scoring system published by Morrow and colleagues in 2000, derived from the InTIME-II trial of fibrinolysis-treated STEMI patients. It combines eight variables available at presentation — age, cardiovascular history, systolic blood pressure, heart rate, Killip class, body weight, ECG findings, and treatment delay — into a single 0 to 14 point score that tracks with 30-day mortality risk.
How the score is built
Each variable contributes a fixed number of points once its threshold is met:
- Age: 0 points under 65, 2 points for 65-74, 3 points for 75 and older.
- History of diabetes, hypertension, or angina: 1 point if any is present.
- Systolic blood pressure under 100 mmHg: 3 points.
- Heart rate over 100 beats per minute: 2 points.
- Killip class II-IV (rales, third heart sound, or cardiogenic shock) at presentation: 2 points.
- Weight under 67 kg: 1 point.
- Anterior ST elevation or new left bundle branch block: 1 point.
- Time from symptom onset to treatment over 4 hours: 1 point.
Adding the eight components gives a total from 0 to 14. Because systolic blood pressure, heart rate, and Killip class describe hemodynamic status at presentation and carry the largest weights, the calculator also reports that three-item subtotal (out of 7 points) separately from the full score.
Interpreting the result
In the original derivation cohort, 30-day mortality rose steeply with the score: roughly 0.8% at a score of 0, climbing to the mid-single digits at scores of 3-4, into the teens and low twenties at scores of 5-7, and to roughly a quarter to a third of patients at scores of 8 or higher. A higher score summarizes risk factors already visible to the treating team — it does not by itself choose a treatment.
When to consult a professional
This tool performs the published TIMI STEMI arithmetic for education and reference. It is not a diagnosis and does not replace clinical judgment. Treatment decisions for a person experiencing a heart attack must be made immediately by emergency medical personnel, not derived from this calculator.