Definition/Introduction
Patients who initially present with signs and symptoms of unstable angina or non-ST elevated myocardial infarction require risk stratification. The need for this stratification is two-fold. Primarily, it helps in making decisions about patient management. Additionally, it helps predict the likelihood of adverse cardiac events.
The thrombolysis in myocardial infarction (TIMI) score is considered a tool for early risk stratification. According to several trials, notably TIMI 11B and ESSENCE, seven factors help assess the mortality risk and risk of other adverse cardiac events, as listed below.[1]
- Age of 65 years or older
- Presence of at least three risk factors for coronary artery disease (i.e., diabetes mellitus, hypertension, hyperlipidemia, smoking, family history)
- Previous history of coronary stenosis of 50% or more
- Presence of greater than or equal to 2 episodes of angina 24 hours before the presentation
- Aspirin use in the past seven days
- ST-segment deviations greater than or equal to 0.05 mV on initial ECG at admission
- Elevated serum cardiac markers of necrosis
If present, each factor contributes a value of one point toward the TIMI risk score, making it a simple tool that does not require differential weights for each factor. A higher score implies a higher likelihood of adverse cardiac events and/or risk of mortality. The following represents scores paired with the percent risk of mortality, new/recurrent MI, or severe ischemia requiring further invasive cardiac intervention.
- 4.7% for a score of 0/1
- 8.3% for a score of 2
- 13.2% for a score of 3
- 19.9% for a score of 4
- 26.2% for a score of 5
- 40.9% for a score of 6/7
Scores ranging from 0-2 constitute a low risk. Scores from 3-5 are considered intermediate risk. A score of 6 or 7 indicates high risk.[2]
Studies have shown that the TIMI risk score is far superior in providing diagnostic evidence for acute coronary syndrome (ACS) compared to history, physical examination, EKG’s, or biomolecular cardiac markers alone.[3][4]