Unstable angina – risk stratification

Unstable angina – risk stratification

Unstable angina can be classified into low risk, intermediate risk and high risk depending on certain clinical, electrocardiographic and biochemical parameters. The management schedule is different for each risk category.

Low risk unstable angina

Features of low risk unstable angina are:
New-onset exertional angina
Minor chest pain during exercise
Pain relieved promptly by nitroglycerine

Management f low risk unstable angina

Low risk unstable angina can be managed safely as an outpatient (assuming close follow-up and rapid investigation).

Intermediate risk unstable angina

Features of intermediate risk unstable angina are:
Prolonged chest pain
Diagnosis of myocardial infarction ruled-out

Management of intermediate risk unstable angina

Observe in the emergency room / ward
Monitor clinical status and ECG
Obtain cardiac enzyme (troponin) every 8 to 12 hours

High risk unstable angina

Features of high risk unstable angina are:
Recurrent chest pain
ST-segment change
Hemodynamic compromise
Elevation in cardiac enzyme

Management of high risk unstable angina

Monitor in the Coronary Care Unit and consider early invasive strategy.

Risk stratification of unstable angina by ECG

The risk of death or myocardial infarction at 30 days strongly related to ECG during pain:
ST depression 10 %
T-wave inversion 5 %
No ECG changes 1~2 %

TIMI risk score for unstable angina

In TIMI risk score for unstable angina, 1 point each is assigned for presence of :
Age more than 65 years
Documented prior coronary artery stenosis more than 50%
Three or more conventional cardiac risk factors (e.g. age, sex, family history, hyperlipidemia, diabetes, smoking, obesity)
Use of aspirin in the preceding 7 days
Two or more anginal events in the preceding 24 hours
ST-segment deviation (transient elevation or persistent depression)
Increased cardiac biomarkers
If the score is between 5 – 7, it comes under the high risk group.
If the score is between 3 – 4, it comes under the intermediate risk group.
If the score is 0 – 2, it is low risk unstable angina.

Noninvasive testing in unstable angina

Noninvasive testing in unstable angina is recommended for those in intermediate and low risk groups. High risk group needs invasive investigation and management. Noninvasive investigations are used to assess ischemia in patients with a low likelihood of coronary artery disease (CAD) and also to estimate prognosis.
Modalities for noninvasive evaluation are:
Exercise ECG stress test
Exercise test imaging (nuclear)
Pharmacological stress test with imaging (nuclear or echo)
Choice of test based on:
Resting ECG
Ability of patient to exercise
Expertise/availability

Noninvasive testing in unstable angina is recommended in low risk patients who are free of chest pain and heart failure for a minimum of 12-24 hours. It is recommended in intermediate risk patients free of chest pain and heart failure for a minimum of 2-3 days. High risk group needs early invasive strategy.