TIMI Score for STEMI Calculator

Free Timiscore stemicalculator Calculator with medically-sourced formulas. Enter your measurements for personalized, accurate health insights.

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Formula

TIMI STEMI Score = Age points + Clinical factors (0-14 points)

Weighted scoring: Age 65-74 (+2) or >= 75 (+3), SBP < 100 (+3), HR > 100 (+2), Killip II-IV (+2), weight < 67 kg (+1), anterior STE/LBBB (+1), time to treatment > 4h (+1), DM/HTN/angina history (+1). Maximum 14 points, with higher scores indicating greater 30-day mortality risk.

Worked Examples

Example 1: Low-Risk STEMI Assessment

Problem: A 55-year-old male, weight 80 kg, presents with inferior STEMI within 2 hours of symptom onset. BP 135/85, HR 78, Killip class I. No history of diabetes, hypertension, or angina.

Solution: TIMI STEMI Score calculation:\nAge < 65: 0 points\nDiabetes/HTN/Angina: No (0 points)\nSystolic BP 135 (>= 100): 0 points\nHR 78 (<= 100): 0 points\nKillip Class I: 0 points\nWeight 80 kg (>= 67): 0 points\nAnterior STE or LBBB: No, inferior (0 points)\nTime to treatment 2h (<= 4h): 0 points\nTotal TIMI STEMI Score = 0

Result: TIMI Score: 0/14 | 30-day mortality: 0.8% | Low Risk | Standard primary PCI

Example 2: High-Risk STEMI Assessment

Problem: A 78-year-old female, weight 55 kg, presents with anterior STEMI 6 hours after symptom onset. BP 88/60, HR 110, Killip class III with pulmonary edema. History of diabetes and hypertension.

Solution: TIMI STEMI Score calculation:\nAge >= 75: 3 points\nDiabetes/HTN/Angina: Yes (+1 point)\nSystolic BP 88 (< 100): +3 points\nHR 110 (> 100): +2 points\nKillip Class III: +2 points\nWeight 55 kg (< 67): +1 point\nAnterior STE: Yes (+1 point)\nTime to treatment 6h (> 4h): +1 point\nTotal TIMI STEMI Score = 14

Result: TIMI Score: 14/14 | 30-day mortality: 35.9% | Very High Risk | Urgent PCI with MCS consideration

Frequently Asked Questions

What is the TIMI Risk Score for STEMI and how does it differ from the UA/NSTEMI version?

The TIMI Risk Score for STEMI is a bedside clinical tool specifically designed to predict 30-day mortality in patients presenting with ST-Elevation Myocardial Infarction. Unlike the TIMI score for UA/NSTEMI, which uses seven binary variables to predict a composite endpoint, the STEMI version uses a weighted scoring system with different variables that can generate scores from 0 to 14 points. The STEMI score incorporates hemodynamic parameters like systolic blood pressure and heart rate, which reflect the acute severity of the infarction. It was derived from the InTIME II trial involving over 15,000 STEMI patients receiving thrombolytic therapy. The score helps identify patients at highest risk who may benefit from more aggressive interventions including mechanical circulatory support and is particularly useful for rapid triage in the emergency department setting.

What clinical variables are included in the TIMI STEMI score and how are they weighted?

The TIMI STEMI score includes eight clinical variables with different point assignments reflecting their relative prognostic importance. Age is the most heavily weighted variable, contributing 0 points for age under 65, 2 points for age 65 to 74, and 3 points for age 75 or older. Systolic blood pressure below 100 mmHg receives 3 points, reflecting the significance of hemodynamic compromise. Heart rate above 100 beats per minute adds 2 points. Killip class II through IV (signs of heart failure) adds 2 points. Body weight under 67 kilograms adds 1 point. Anterior ST elevation or left bundle branch block adds 1 point. Time from symptom onset to treatment exceeding 4 hours adds 1 point. History of diabetes, hypertension, or angina adds 1 point. The maximum possible score is 14 points.

How does the Killip classification affect the TIMI STEMI score interpretation?

The Killip classification assesses the degree of heart failure in acute myocardial infarction and is an important component of the TIMI STEMI score, contributing 2 points for Killip class II through IV. Killip Class I indicates no clinical signs of heart failure and is associated with approximately 6 percent mortality. Class II involves crackles in the lungs, an S3 gallop, or elevated jugular venous pressure, with mortality around 17 percent. Class III represents frank pulmonary edema with mortality approaching 38 percent. Class IV indicates cardiogenic shock with hypotension and signs of end-organ hypoperfusion, carrying mortality exceeding 80 percent without intervention. The presence of any heart failure signs significantly worsens the prognosis and may indicate need for mechanical circulatory support devices such as intra-aortic balloon pump or Impella.

Why is time to treatment an important variable in the TIMI STEMI score?

Time from symptom onset to reperfusion treatment is a critical variable because in STEMI, every minute of coronary occlusion results in progressive myocardial cell death. The concept of time is muscle reflects the direct relationship between ischemic duration and infarct size. The TIMI STEMI score adds one point when the time to treatment exceeds 4 hours because patients treated later have larger infarcts, more complications, and higher mortality. Studies have shown that each 30-minute delay in reperfusion is associated with a 7.5 percent relative increase in one-year mortality. Current guidelines recommend a door-to-balloon time of less than 90 minutes for primary percutaneous coronary intervention and a door-to-needle time of less than 30 minutes for fibrinolytic therapy. The time variable underscores the importance of rapid recognition, emergency medical services activation, and streamlined hospital protocols.

What is the significance of anterior ST elevation in STEMI prognosis?

Anterior ST elevation in STEMI indicates occlusion of the left anterior descending coronary artery, which supplies the largest territory of myocardium including the anterior wall, septum, and apex of the left ventricle. This territory represents approximately 40 to 50 percent of the left ventricular mass, making anterior STEMI the most hemodynamically consequential location for acute infarction. Compared to inferior or lateral STEMI, anterior STEMI is associated with larger infarct size, greater reduction in ejection fraction, higher incidence of left ventricular aneurysm formation, increased risk of cardiogenic shock, and higher short-term and long-term mortality. Left bundle branch block is included alongside anterior ST elevation because new LBBB in the setting of acute chest pain is considered a STEMI equivalent, often masking the underlying anterior wall ischemia on ECG.

How does body weight below 67 kg affect the TIMI STEMI score?

Low body weight (below 67 kilograms or approximately 148 pounds) is included as a risk factor in the TIMI STEMI score because it has been consistently associated with worse outcomes after myocardial infarction. Several mechanisms explain this relationship. Lower body weight is associated with smaller coronary artery caliber, which can lead to more complete occlusion and difficulty with percutaneous intervention. Underweight patients may have underlying frailty, malnutrition, or chronic illness that impairs recovery. In the era of thrombolytic therapy (when the score was developed), lower weight patients were at increased risk of bleeding complications, including intracranial hemorrhage, because dosing was not always adequately adjusted. Additionally, low body weight is often a marker for advanced age, female sex, and comorbid conditions. The one-point weighting reflects its independent but modest contribution to overall mortality risk.