The TIMI Risk Score for STEMI (ST-Elevation Myocardial Infarction) was developed by the Thrombolysis in Myocardial Infarction study group to rapidly stratify the mortality risk of patients suffering a massive heart attack.
The Variables
The score is built upon easily obtainable clinical variables available within minutes of the patient arriving at the hospital:
- Age: The heaviest weighted factor. (65-74 gets 2 points, ≥ 75 gets 3 points).
- Vitals: Systolic BP < 100 mmHg (3 points) and Heart Rate > 100 bpm (2 points) indicate cardiogenic shock and heavily spike the score.
- Killip Class: Presence of heart failure (rales, pulmonary edema, shock) adds 2 points.
- History: Diabetes, hypertension, or prior angina adds 1 point.
- ECG: Anterior STEMI or new LBBB adds 1 point.
- Time/Weight: Delayed treatment (>4 hours) and low body weight (<67 kg) add 1 point each.
TIMI Score = Sum of points derived from patient age, historical factors, and presentation vital signs/ECG.
Mortality Prediction
The resulting score (0 to 14) corresponds to a historically validated 30-day mortality rate. A score of 0 has a mortality of <1%, while a score >8 predicts a mortality rate exceeding 35%. This objective quantification is crucial for guiding aggressive therapies (like IABP placement) and having realistic discussions with families.