NSTEMI and Unstable Angina
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Direct answer
NSTEMI and unstable angina together form non-ST-elevation acute coronary syndrome, separated by a troponin rise in NSTEMI and by a normal troponin in unstable angina. Management is risk-stratified: GRACE and TIMI scores set the timing of coronary angiography, while dual antiplatelet therapy, parenteral anticoagulation and high-intensity statin therapy begin early in almost every patient without a contraindication.
What you must remember
- Diagnosis: ischaemic pain at rest or new severe angina with dynamic ST depression or T-wave inversion; ST elevation is absent by definition, and a rise and fall of high-sensitivity troponin above the 99th centile defines NSTEMI.
- GRACE score: predicts in-hospital and six-month mortality from age, heart rate, systolic pressure, creatinine, Killip class, cardiac arrest on arrival, ST deviation and troponin status.
- TIMI score: one point each for age 65 or above, three or more risk factors, known coronary stenosis of 50 per cent or more, aspirin in the past seven days, two or more anginal episodes in 24 hours, ST deviation of 0.5 mm or more and a positive marker.
- Immediate angiography: within two hours for haemodynamic instability, refractory pain, life-threatening arrhythmia, mechanical complications, acute heart failure or recurrent dynamic ST changes.
- Early invasive strategy: within 24 hours for a GRACE score above 140 or any high-risk feature; lower-risk patients may follow a selective, stress-test guided approach.
- Antiplatelets: aspirin 150 to 300 mg loading then 75 to 100 mg daily, plus a P2Y12 inhibitor (ticagrelor, prasugrel or clopidogrel) usually for twelve months; prasugrel is contraindicated after stroke or transient ischaemic attack.
- Anticoagulation: unfractionated heparin or enoxaparin in the acute phase, with fondaparinux an alternative where bleeding risk is high; NSAIDs are avoided throughout.
A worked decision for rest pain at night
A 64-year-old man with hypertension and a smoking history wakes with forty minutes of central pressure. His ECG shows 1 mm horizontal ST depression in V4 to V6, and high-sensitivity troponin is raised at zero and two hours.
- Give medical therapy at once: Aspirin is given immediately, with heparin, a high-intensity statin and intravenous glyceryl trinitrate for ongoing pain. A P2Y12 inhibitor is started per local protocol, since routine pretreatment is not advised when angiography is planned early.
- Decide on very high-risk features: If pain persists, or pulmonary oedema or ventricular arrhythmia develops, angiography is needed within two hours.
- Calculate the GRACE score once stable: A value above 140 places him in the early invasive group, with angiography inside 24 hours.
- Choose antithrombotics for the procedure: Heparin continues through the catheter laboratory, and bivalirudin is an option where bleeding risk is high.
- Continue treatment after revascularisation: Dual antiplatelet therapy continues, a beta blocker starts once haemodynamically stable, and cardiac rehabilitation is arranged.
The lesson is that the score guides timing, not whether to treat: antithrombotic therapy starts whatever the risk estimate says.
Where the exam tries to catch you
Examiners return to a few traps here.
- Trap: reading a single normal troponin at presentation as excluding infarction. Correct: serial measurement is required, because a normal value at presentation does not exclude infarction.
- Trap: choosing prasugrel by default. Correct: it is contraindicated after prior stroke or transient ischaemic attack, and in patients under 60 kilograms a reduced maintenance dose of 5 mg is used, with clopidogrel or ticagrelor as the substitute.
- Trap: using GRACE and TIMI interchangeably. Correct: TIMI is a simple bedside tool for unstable angina and NSTEMI, whereas GRACE predicts mortality and guides timing.
- Trap: holding a very high-risk patient for medical stabilisation alone. Correct: in many Indian district hospitals without an invasive laboratory the question becomes transfer, and the patient should move immediately because the time window closes.
Frequently asked questions
Which score predicts in-hospital mortality in NSTEMI?
The GRACE score predicts in-hospital and six-month mortality in NSTEMI and unstable angina, using age, heart rate, systolic pressure, creatinine, Killip class, cardiac arrest at admission, ST deviation and troponin status. It also guides whether angiography should be early or delayed.
When is immediate coronary angiography required in NSTEMI?
Angiography within two hours is required for very high-risk features: haemodynamic instability, refractory or recurrent chest pain, life-threatening arrhythmia, mechanical complications, acute heart failure or recurrent dynamic ST changes. These patients should not be held back for further medical stabilisation.
Why is prasugrel avoided in some patients with NSTEMI?
Prasugrel carries a higher bleeding risk, so it is contraindicated in patients with prior stroke or transient ischaemic attack, and a reduced maintenance dose is used under 60 kilograms. Clopidogrel or ticagrelor is preferred after stroke.
How long should dual antiplatelet therapy continue after an acute coronary syndrome?
Aspirin combined with a P2Y12 inhibitor is usually continued for twelve months after an acute coronary syndrome. The duration is shortened or extended according to individual bleeding and ischaemic risk, as judged by the treating cardiologist.