NSTEMI

• A Non-ST elevation MI is defined as
  • • Elevated biomarkers
      • • Dynamic troponin (ie significant change), with at least one elevated value (>99^th centile). Exact numbers depend on assay.
    • And evidence of myocardial ischaemia
      • • ECG suggestive
          • • New horizontal or downsloping ST depression of >0.5mm in 2 contiguous leads or
            • Dynamic T wave changes in 2 contiguous leads
        • Or ischaemic sounding chest pain
        • Or imaging suggestive of new ischaemia
• The ECG
  • • ST depression of >1mm is more specific and worse prognostically
    • Upsloping ST depression is non-specific for myocardial ischaemia (often seen in tachyarrhymias)
    • The ST depression and TWI of NSTEMI are less clearly related to the site of myocardial damage than in STEMI
    • ECG may be normal in 30%

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Assessing risk

• Do the GRACE score
  • • Gives in-hospital and 6-month risk of mortality in NSTEMI
    • 5-3% is low, 3-6% is intermediate, 6-9% is high, >9% is highest
• Assess for high risk features (urgent PCI may be indicated if present)
  • TWI V1-V4 ie LAD syndrome
  • Trop+++
  • Unstable patient
  • Arrhythmia
  • Shock
  • Ongoing chest pain (ie. patient currently infarcting)

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Management strategy

• 300mg loading aspirin, and then continue at 75mg OD
• GTN spray if pain ongoing
• Anticoagulation
  • • Fondaparinux 2.5mg OD
      • • Used if no high bleeding risk, and not undergoing angiography in the next 24 hours
        • Mainly used in NSTEMI whilst awaiting angiography (not used in STEMI patients a/w PCI)
    • Unfractionated heparin
      • • Alternative to fondaparinux if creat >265
        • Also give in cath lab if having PCI (whether or not received fondaparinux)
        • Also indicated in NSTEMI if anticipating early PCI (ie in next 24 hours) – start at time of MI diagnosis
    • Consider contraindications
      • • Absolute: anticoagulated, severe renal impairment, active bleeding, recent intracranial haemorrhage, major surgery in last 2 months, IE
        • Relative: bleeding disorder, severe HTN, severe liver failure, CVA in last 2 years, low platelets, low BMI
    • Usually stop anticoagulants after PCI (except if LV aneurysm with thrombus, or AF)
• Consider a second antiplatelet
  • • Depends on trust policy and how long until angiogram – any delay, probably give DAPT (if bleeding risk not high), but guidelines suggest not giving if PCI planned within 24 hours
    • If having PCI, offer aspirin with prasugrel or ticagrelor (if not anticoagulated) at the time of PCI
    • If not having PCI, offer aspirin and ticagrelor (unless high bleeding risk – in which case consider clopidogrel)
    • No renal dose adjustments required unless eGFR <15 (then probably need heparin infusion)
    • Options – see Acute Coronary Syndrome
• GTN infusion – if ongoing pain (50mg in 50ml saline, run at 2-10ml/hour)
• Betablocker
  • • Often commenced unless contraindicated – best is metoprolol 25mg
    • Not in acute heart failure, asthma, hypotension, bradycardia
    • Reduces myocardial O2 demand
    • If contraindicated, consider diltiazem, but avoid nifedipine / other CCBs

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• Percutaneous Coronary Intervention (PCI)
  • • Emergency PCI (treat as STEMI) if high risk features (see above) or patient unstable (or consider emergency CABG)
    • If out of hospital arrest, ROSC and stable – best to delay PCI and exclude non-cardiac causes
    • Consider PCI within 72 hours if intermediate or high risk on GRACE score (6/12 risk >3%) and no contraindications to angiography (eg active bleeding, a comorbidity)
    • Consider PCI within 24 hours if GRACE score > 140
    • Consider PCI if low risk on GRACE if ischaemia subsequently experienced or demonstrated by testing, esp if younger (who have lower expected mortality)
    • Benefits of PCI include – reduced mortality from all causes at 6, 12 and 24 months. Reduced incidence of MI and stroke. Reduces risk of readmission
    • Risks include – procedural (incl major bleeding and MI)

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• Later
  • • • Consider early discharge if aged <70, good LV function, successful PCI, one or two vessel disease and no persistent arrythmias
      • Bystander disease – make a plan whether to treat later if present (and as inpatient or outpatient)
      • Consider ischaemia-testing before discharge if no angiogram done
      • Echo
        • • Usually non-urgent but done during same admission
          • If LV function <40%, repeat in 6-12 weeks
      • Lifestyle advice – diet, exercise, weight, smoking, ETOH