Feature

High Risk

(At least 1 of the following features present)

Intermediate Risk

(No high risk feature but at least 1 of the following features)

Low Risk

No high or intermediate risk features but may have any of features below

History

Accelerating tempo of ischaemic symptoms in preceding 48 hours

Prior MI, peripheral or cerebrovascular disease, or CABG; prior aspirin use

Character of pain

Prolonged ongoing (>20min) rest pain

Prolonged (>20mins) rest angina now resolved, with moderate or high likelihood of CAD

Rest angina (<20 min or relieved with rest or sublingual GTN)

New onset or progressive CCS Class III or IV angina in the past weeks with moderate or high likelihood of CAD

Clinical findings

Pulmonary oedema, most likely related to ischaemia

New or worsening MR

S3 or new or worsening rales

Hypotension, bradycardia, tachycardia

Age >75 years

Age > 70 years

ECG findings

Angina at rest with transient ST-segment changes >0.05mV

Bundle branch block, new or presumed new sustained VT

T-wave inversions > 0.2 mV

Pathological Q waves

Normal or unchanged ECG during an episode of chest discomfort

Cardiac markers

Elevated (eg TnT or TnI > 0.01ng/ml)

Slightly elevated (eg TnT > 0.01 but < 0.1 ng/ml)

  Normal