TIMI Score for UA/NSTEMI Calculator

Understanding the TIMI Score

The TIMI score emerged from two pivotal international trials conducted in the late 1990s and published in 2000. It addresses a fundamental clinical challenge: not all patients with acute coronary syndrome face equal risk. Some may experience recurrent ischaemia or infarction within days, whilst others remain stable. The TIMI framework enables rapid, objective risk assessment at the bedside to inform treatment decisions.

The score applies specifically to patients meeting criteria for UA or NSTEMI—those with symptoms of acute coronary syndrome but without persistent ST elevation. A separate TIMI score exists for STEMI, which uses different risk variables. The UA/NSTEMI version focuses on clinical history, medication use, and acute findings rather than imaging or enzyme dynamics alone.

Each positive risk factor adds one point, creating a scale from 0 to 7. Higher scores correlate sharply with 14-day event rates, ranging from under 5% for low-risk patients to over 40% for those scoring 6–7 points.

TIMI Score Calculation

The TIMI score is the sum of seven binary (yes/no) risk factors. Each factor present contributes 1 point to the total score.

• Age ≥65 — Patient age of 65 years or older at presentation
• CAD Risk Factors ≥3 — Three or more of: diabetes, hypercholesterolemia, family history of CAD, hypertension, or current smoking status
• Known CAD — Prior angiography documenting coronary stenosis ≥50%, or history of myocardial infarction or revascularization
• ASA Use — Acetylsalicylic acid (aspirin) taken within the 7 days prior to admission
• Severe Angina — Two or more anginal episodes within the 24 hours before presentation
• EKG Changes — ST-segment deviation ≥0.5 mm on 12-lead electrocardiogram at rest
• Positive Marker — Elevated cardiac troponin T, troponin I, or CK-MB on blood test

Clinical Pearls and Limitations

Apply the TIMI score thoughtfully within the broader clinical picture.

1. Risk factors must meet specific definitions — Smoking status requires current active smoking; prior smokers do not count. CAD risk factor thresholds (≥3, stenosis ≥50%) are precise cutoffs. Ensure documentation supports each criterion before assigning points.
2. EKG deviations warrant careful measurement — ST changes must be ≥0.5 mm in amplitude and documented at baseline. Dynamic changes or repolarisation abnormalities from prior infarction may complicate interpretation; consider serial EKGs to distinguish acute from chronic findings.
3. Troponin timing affects sensitivity — Early troponin (within 3 hours of symptom onset) may be falsely negative. Serial troponin at 3 and 6 hours improves sensitivity for myocardial necrosis; do not base risk assignment on a single negative troponin in the hyperacute phase.
4. Score informs but does not dictate therapy — TIMI stratification guides intensity of anticoagulation and timing of angiography, but clinical judgment remains essential. Haemodynamic instability, ongoing ischaemia, or contraindications to antithrombotic agents may override score-based recommendations.

Interpreting Your TIMI Score Result

A TIMI score of 0–1 identifies very-low-risk patients with approximately 5% 14-day event rate; these individuals may safely receive conservative management. Scores of 2–3 represent intermediate risk (10–15% event rate) warranting standard dual antiplatelet therapy and anticoagulation, with angiography considered based on symptoms or stress testing. Scores of 4–5 identify high-risk patients (20–30% event rate) who benefit from early invasive angiography and aggressive antithrombotic regimens.

Patients scoring 6–7 face the greatest peril, with event rates exceeding 40%. These individuals warrant urgent angiography, often within hours, combined with maximal antiplatelet and anticoagulant therapy. However, the score serves as one input alongside clinical presentation, comorbidities, and institutional protocols. A borderline TIMI score coupled with high clinical suspicion or haemodynamic compromise may justify more aggressive intervention than the score alone suggests.

TIMI Score in Clinical Practice

The TIMI score integrates readily available information—age, medical history, current medications, anginal pattern, EKG findings, and troponin—without requiring advanced imaging or invasive testing. This accessibility makes it ideal for emergency department triage and early risk stratification. Countless hospitals use TIMI-based algorithms to guide decision-making pathways, from admission to intensive care monitoring and catheterisation lab scheduling.

The score has been validated in diverse populations and healthcare systems, demonstrating robust predictive power across different patient demographics. Nevertheless, regional variations in access to catheterisation and institutional treatment algorithms mean the same TIMI score may translate to different management approaches in different centres. Integration of TIMI scoring with troponin kinetics, echocardiography, and stress testing further refines risk assessment and guides intensity of intervention for individual patients.