Acute Coronary Syndromes

STEMI & NSTEACS, plus ACOMI (acute coronary occlusion MI) — ECG patterns beyond classic ST-elevation (e.g. posterior MI, De Winter T waves) that also warrant emergency reperfusion.

History and examination

Retrosternal chest pain radiating to jaw/arm, with diaphoresis, nausea, and shortness of breath; a pressure/heaviness/tightness quality (Levine sign — clenched fist on chest). Patients may be pale, grey, clammy, and diaphoretic.

Beware silent infarcts in diabetics, hypertensives, women, and the elderly — these groups may also present atypically. The 2025 guideline adds explicit practice points for priority populations (women, older adults, First Nations peoples, and people in regional/remote areas), given these groups are more likely to be under-recognised or under-treated.

May rapidly progress to cardiogenic shock — consider haemodynamic support devices/LVAD if refractory.

Investigations

• ECG (see ECG Interpretation for the systematic reading approach): ST elevation in 2 contiguous leads (>2mm chest leads, >1mm limb leads) with reciprocal changes, or an ACOMI pattern (posterior MI, De Winter T waves) without classic ST-elevation. NSTEMI shows dynamic T-wave inversion or ST depression.
• High-sensitivity troponin decision pathways now enable efficient rule-in/rule-out in ED — don’t delay transfer waiting on a troponin result in the outpatient/GP setting.
• Coronary occlusion can be atherosclerotic or non-atherosclerotic in origin (previously the 2016 guideline’s “type 1” vs “type 2” MI) — SCAD, coronary embolism, and coronary spasm/microvascular dysfunction can present identically to atherosclerotic AMI and are now formally classified under the ACOMI umbrella, requiring urgent angiography to distinguish and guide treatment.

Management

Transfer to hospital ASAP for reperfusion.

STEMI: primary PCI within 60 minutes of first medical contact at PCI-capable centres, 90 minutes at non-PCI-capable centres — otherwise fibrinolytic therapy within 30 minutes of hospital arrival. Give aspirin 300mg + clopidogrel 600mg if undergoing PCI (or 300mg if fibrinolysis planned) — P2Y12 inhibitor choice and timing (clopidogrel/ticagrelor/prasugrel) and anticoagulation are now guided by new treatment algorithms; confirm current choice with cardiology/eTG rather than defaulting to clopidogrel. Nitrates for pain (400mcg SL every 5 min, max 3 doses), oxygen if SpO2 <94%, morphine 2.5mg if pain persists despite max nitrates.

NSTEACS: also treated in hospital and may progress to STEMI. Early angiography and revascularisation are of clinical benefit; recurrent pain refractory to medical treatment warrants reperfusion therapy. Consider SCAD, coronary embolism, or coronary spasm if the presentation is atypical for atherosclerotic disease — these can present identically to AMI and may need a more conservative/selective revascularisation approach. Intravascular imaging (IVUS/OCT)-guided PCI now has supporting evidence specifically for NSTEACS. For multivessel disease, new recommendations specify the timing of staged PCI to non-infarct-related arteries and when to use invasive physiology assessment (e.g. FFR), rather than treating the culprit vessel alone.

Long-term management — see Atherosclerotic CVD. Use a high-intensity statin. Start beta-blockers within 12 hours (new recommendations revisit routine long-term use — the 2024 REDUCE-AMI trial found no mortality/reinfarction benefit from long-term beta-blockade post-MI with preserved ejection fraction on modern therapy), ACEi within 24 hours, and aspirin + clopidogrel (P2Y12 choice as above). A PCSK9 inhibitor is now explicitly recommended if the LDL-C target below isn’t met on maximally tolerated statin + ezetimibe.

Targets: BP <140/90, total cholesterol <4, LDL <1.4mmol/L, ≥50% reduction from baseline, triglycerides <2.

Post-discharge care: medicines/adherence review, vaccinations, and screening for mental health conditions are now explicitly recommended.

Complications

LV failure (manage as per CCF), LV aneurysm, pericarditis (first few days). Dressler Syndrome - 6 weeks later, autoimmune pericarditids with effusion/fever.