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c_acs

acute coronary syndromes

introduction

  • 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.

pre-hospital Mx of suspected ACS

  • 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.

clinical assessment

  • 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:
  • biochemical markers:

resources

c_acs.txt · Last modified: 2018/09/14 06:01 by wh