see also:

• cardiology
• ischaemic heart disease (IHD)
• the adult patient with chest pain in the ED
• Mx of possible acute coronary syndrome without ST elevation (NSTEACS)
• cardiac stress testing
• acute myocardial infarction (AMI/STEMI/NSTEMI)
• EBM for interventions in acute coronary syndromes
• historical perspectives and timelines on ischaemic heart disease including the major research trials
• AFTB Lecture Notes - ACS I
• ACS in the Elderly: Where the Guidelines Fall Short - Amal Mattu - ICEM 2012 presentation (pdf)
• GRACE score for predicting medium term mortality post ACS
• new Australian guidelines on ACS 2025

• acute coronary syndrome (ACS) is an rather abitrary clinical entity with variable definitions used to describe an acute cardiac event caused by insufficient coronary blood flow and which includes the diagnoses of:
  • non-ST elevation ACS (NSTEACS):
    • unstable angina
      • “normal” troponin levels AND chest pain consistent with ischaemic cardiac pain, WITH increased frequency, new onset or new pain at rest
      • 30 day mortality ~4.5%
      • 6 month mortality ~8.6%
    • non-ST-elevation infarct (NSTEMI)
      • raised troponin +/- raised CK but no ST elevation on ECG nor new LBBB
      • depending on the definition, this may require a level of troponin above a certain cut-off value
      • 30 day mortality ~10.4-12.9%
      • 6 month mortality ~18.7-19.2%
  • ST-elevation myocardial infarct (STEMI)
    • chest pain with ST elevation or new Left Bundle Branch Block (LBBB) consistent with infarct and supported by raised troponin +/- raised CK
    • some definitions add new Right Bundle Branch Block (RBBB) with ischaemic chest pain into this category (eg. Fibrinolytic Therapy Trialists' Group FTTG) as there is evidence that new RBBB is as common as, and has a higher mortality than new LBBB in AMI. However, the majority of these patients with new RBBB do have ST elevation, and it is unknown whether patients with new RBBB but without ST elevation benefit from reperfusion therapy.

• oxygen to give SaO2 > 92%
• aspirin 300mg if not already had aspirin that day
• pain relief such as GTN, morphine
• cardiac monitoring
• 12 lead ECG where possible
  • if there is new LBBB or ST elevation then:
    • the patient should ideally be transferred to a hospital with emergency angioplasty facilities ASAP, preferably with the cardiology and ED teams being fore-warned of the imminent arrival.
    • if there would be delay in reaching such a facility > 30min, and there are no C/I, then pre-hospital fibrinolysis should be considered if available.

• see the adult patient with chest pain in the ED
• a high quality systematic review of 21 studies examined the usefulness of 16 different clinical signs and symptoms in the diagnosis of acute coronary syndromes ¹⁾.
  • taken in isolation no clinical symptom or sign was useful in ruling in or ruling out ACS, however, presence of pleuritic pain (LR+ 0.19 95% CI 0.14-0.25) and tenderness on palpation (LR+ 0.23 95% CI 0.08-0.30) were the most useful in ruling out ACS.
• ECG diagnosis:
  • whilst acute ST elevation is a relatively specific marker for acute myocardial infarction (AMI/STEMI/NSTEMI), it's sensitivity for AMI is only about 58% and is not present in unstable angina or NSTEMI.
• biochemical markers:
  • troponin:
    • there is still debate as to the appropriate timing of troponin levels
      • refer to your local policy on serial troponins
    • a normal troponin DOES NOT necessarily mean the patient is not at risk of cardiac mortality within 30 days, particularly if the patient has high risk factors, but in the absence of these risk factors (ie. TIMI score 0), it is generally assumed the patient will be safe for discharge and early outpatient cardiac stress testing and follow up.
    • see Mx of possible acute coronary syndrome without ST elevation (NSTEACS) and cardiac markers (troponin)
    • unfortunately, elevated troponin levels may occur in conditions other than ACS but in these cases are general associated with severity of illness:
      • congestive cardiac failure
      • pulmonary embolism (PE)
      • chronic renal failure
      • sepsis / septicaemia
      • persistent tachycardias such as atrial fibrillation

• Aust. Heart Foundation - Mx acute coronary syndromes
• Scottish Intercollegiate Guidelines Network (SIGN) - Acute coronary syndromes, a national clinical guideline Feb 2007 (pdf)