Level 1 of 6Core
Acute coronary syndrome: ECG, antiplatelets and reperfusion
The core to-do list — diagnose and manage, at a glance
Diagnose— recognise it
- Get a 12-lead ECG within 10 minutes of first medical contact in anyone with chest discomfort, and in any elderly, diabetic or female patient with unexplained breathlessness, sweating or collapse — the ECG separates STEMI from everything else before any laboratory result exists. Repeat every 15 minutes while the patient remains in pain: a single normal tracing never excludes ACS.
- The characteristic symptom is central heaviness, pressure or squeezing — the patient places a flat hand or clenched fist over the sternum (Levine's sign); it is crescendo–decrescendo, not maximal at onset, and severe discomfort lasting over 20 minutes that does not respond to sublingual GTN may be an infarct.
- STEMI criteria: new ST elevation of 2 mm (0.2 mV) or more at the J point in V1–V3, or 1 mm or more in any other lead, in two contiguous leads — or new (or presumed new) left bundle branch block. Record V4R in every inferior infarct before any nitrate, and V7–V9 whenever there is ST depression in V1–V3 with a dominant R wave: a posterior STEMI is a STEMI.
- Exclude aortic dissection before any antithrombotic is given: pain that is sudden, tearing, maximal at onset and interscapular, with unequal pulses or an inter-arm blood pressure difference — antiplatelets and anticoagulants may be lethal in dissection, and the whole cost of asking is one question and a blood pressure in each arm.
- Troponin: treatment of STEMI is never deferred for it. Below 5 ng/L on a high-sensitivity assay has a negative predictive value of 99.4%, but a negative initial assay must be repeated at 3 hours — the rise or fall across serial samples identifies acute injury, and a raised troponin is not synonymous with type 1 infarction.Not available at your setup — Cardiac troponin.
- Assign a Killip class at the bedside and watch for red flags: SBP below 90 mmHg, new crackles or a third heart sound, a new murmur (a mechanical complication until proved otherwise), VF/VT or complete heart block, syncope with the pain, and raised JVP with clear lungs and hypotension — the signature of right ventricular infarction. Killip IV (cardiogenic shock) carries 40–60% in-hospital mortality.
Manage now— do this, in order
- Continuous cardiac monitoring with immediate access to a defibrillator — VF in the first hours is the commonest mode of death; two large-bore cannulae with all bloods drawn before anything is infused.Doctor / NurseNot available at your setup — Defibrillator.
- Aspirin 150–300 mg chewed or dispersed in water (300 mg unless already taken today), then 75–100 mg daily — give it before the opioid, since opioids delay antiplatelet absorption; a dispersible tablet per rectum if the patient cannot swallow. The highest-value single intervention.
- Add a second antiplatelet — dual therapy is standard in every ACS: clopidogrel 300 mg loading (600 mg where primary PCI is planned), then 75 mg daily — the recommended partner for thrombolysis and the safe default; ticagrelor 180 mg or prasugrel 60 mg loading are preferred where primary PCI is planned, and neither is used with planned thrombolysis.Doctor / Nurse
- Glyceryl trinitrate 500 microgram sublingual tablet or 400 microgram spray, repeated every 5 minutes to three doses; if pain persists, 2–10 mg/hour IV titrated — keep systolic BP above 90 mmHg, and withhold in right ventricular infarction, hypotension, marked brady- or tachycardia, or recent sildenafil/vardenafil (24 h) or tadalafil (48 h).Doctor / Nurse
- Morphine 2.5–5 mg by slow IV injection, titrated and repeated, with metoclopramide 10 mg IV (ondansetron instead in the young); oxygen only if saturations fall below 90%, targeting 94–98% — routine oxygen in a normoxaemic patient confers no benefit and may cause coronary vasoconstriction.Doctor / Nurse
- Antithrombin therapy alongside dual antiplatelets: enoxaparin 1 mg/kg subcutaneously twice daily (once daily if eGFR below 30 mL/min) is the usual choice; fondaparinux 2.5 mg SC daily, or unfractionated heparin 5000 units IV then 0.25 units/kg/hour with APTT at 6 hours, are alternatives.Doctor / Nurse
- STEMI — primary PCI is the preferred reperfusion, targeting 60 minutes from diagnosis to wire-crossing; thrombolysis when PCI cannot be delivered within 120 minutes, with less than 10 minutes from decision to bolus (within 6 hours it prevents 30 deaths per 1000 treated). Judge reperfusion at 60–90 minutes: less than 50% resolution of ST elevation is failed reperfusion — re-thrombolysis or, preferably, rescue angioplasty.Doctor / Nurse
- Right ventricular infarction (inferior ST elevation, hypotension, raised JVP, clear lungs, confirmed on V4R): cautious IV fluid in 250 mL increments, reassessing the chest after each — withhold nitrates, diuretics and large opioid boluses.Doctor / Nurse
- Never give aspirin to a child under 16 years (Reye's syndrome) except on explicit paediatric cardiology instruction, and never give glucocorticoids or NSAIDs (other than aspirin) after infarction — they impair healing and increase the risk of rupture.
First-line drugs
| Drug | Dose |
|---|---|
| Aspirin | 150–300 mg chewed, then 75–100 mg daily |
| Clopidogrel | 300 mg loading (600 mg pre-PCI), then 75 mg daily |
| GTN | 500 microgram SL / 400 microgram spray q5min ×3; then 2–10 mg/h IV, SBP > 90 |
| Morphine | 2.5–5 mg slow IV + metoclopramide 10 mg IV |
| Enoxaparin | 1 mg/kg SC twice daily (once daily if eGFR < 30) |
Refer / escalate
Activate the primary PCI pathway immediately on a STEMI ECG (60 minutes to wire-crossing; thrombolysis only if PCI cannot be delivered within 120 minutes); in non-ST-elevation ACS refer for angiography within 2 hours for refractory pain, heart failure, instability, shock or life-threatening arrhythmia, within 24 hours for dynamic ECG change, rising troponin or GRACE above 140 — and urgently to cardiac surgery for sudden deterioration with a new murmur between days 2 and 7.
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