c_nsteacs_mx

Mx of possible acute coronary syndrome without ST elevation (NSTEACS)

introduction

initial Mx in ED

  • triage 2 to a cardiac monitored cubicle
  • oxygen if SaO2 < 93% or if in shock (oxygen is no longer advised to be given routinely!)
  • cardiac monitor as risk of cardiac arrhythmias, basic set of observations
  • early 12 lead ECG
  • IV access & send bloods for FBE, U&E, glucose, cardiac enzymes (usually CK, troponin), (plus clotting profile if thrombolysis likely or patient is on warfarin)
  • if severe pain radiating to back in patient with PH hypertension then exclude aortic dissection ASAP
    • check BP in each arm, early CXR, consider D-Dimer, if likely then urgent CT Angiogram.
  • aspirin (acetylsalicylic acid) 300mg o crushed if not already had aspirin that day and not allergic (in which case consider alternatives)
  • treat chest pain as appropriate eg GTN, morphine +/- proton pump inhibitors (PPIs) if suspect gastro-oesophageal reflux
  • CXR when available preferably whilst on cardiac monitor
  • serial ECG's and troponins (4hr and 6hr post most severe pain) whilst cardiac monitoring.
  • contact cardiology if either:
    • dynamic ECG changes
    • rise in troponin
    • episode of VF or sustained VT
    • high risk patient (see below)
      • National Heart Foundation of Australia high risk category
      • TIMI risk score > 2
  • if low risk after serial troponins then:
    • consider alternative diagnoses
    • if very low risk for IHD then follow up by LMO
    • if pain is consistent with angina then commence daily aspirin, advise against exertion until further testing:

initial risk stratification

  • a subgroup of these patients can be regarded as sufficiently high risk even with normal initial ECG and troponin, that they warrant EARLY referral to cardiology with additional medical Mx and early coronary angiography rather than observation in an ED short stay observation unit and stress testing.
  • diagnosis and short term risk stratification should be based on a combination of clinical history, symptoms, ECG, biomarkers, and risk score results.

the HEART score

  • perhaps the best tool for ED patients as of 2014 as it outperforms the TIMI and GRACE scores1)
parameter score 0 score 1 score 2
*History slightly suspicious mod. suspicious highly suspicious
*ECG normal non-specific repolarisation disturbance significant ST depression
*Age ≤ 45 years 45 – 65 years ≥ 65 years
*Risk factors no known factors 1-2 risk factors > 2 risk factors
*Troponin normal 1-3x normal limit ≥ 3x normal limit
  • probability of having a cardiac event:
    • score 1-3: 1.7%
    • score 4-6: 17%
    • score >6: 50% chance of infarct, PTCA, CABG or death within 6 wks

additional Mx according to risk stratification

  • coronary angiography with view to revascularisation appears to be appropriate for those patients with a risk of death or AMI at 1 yr of >10% and at 5 yrs of > 20%. Patients at lower risk do not appear to have benefit2).

high risk group

  • eg. HEART score > 6
  • EARLY consultation with cardiology team as should be considered for early coronary angiography
  • medical therapy in addition to aspirin:
      • grade B recommendation
      • 300mg o load then 75mg daily
      • AVOID if:
        • likely to require early CABG surgery eg. severe widespread ST depression or haemodynamic instability
        • immediate coronary angiography anticipated (but should be given if > 6hrs delay for angiography)
        • risk of bleeding such as recent head injury or trauma, age > 75 years, etc.
      • clopidogrel should be ceased 5 days prior to CABG surgery
      • there is evidence for benefit of clopidogrel use for up to 12 months after ACS, and in those whom aspirin is C/I, especially if they have recurrent ischaemic events.
    • consider stopping warfarin Rx and replacing with heparin or enoxaparin (grade D recommendation)
    • additional antithrombotic Rx:
      • option 1:
        • s/c enoxaparin Rx until angiography or for 48-72hrs (level I evidence, grade A recommendation), PLUS:
        • consider GPIIb/IIIa inhibitors:
          • iv tirofiban or eptifibatide is recommended for:
            • high risk patients when invasive strategy is planned and started ASAP (level I evidence, grade A recommendation)
            • high risk patients with persistent ischaemia on enoxaparin (level III evidence, grade B recommendation)
            • high risk patients with diabetes (level I evidence, grade A recommendation)
      • option 2:
        • fondaparinux and bivalirudin
          • not currently available in Australia but may be the preferable option, particularly where there is risk of bleeding.3)
      • option 3:
        • in lab administration of iv GPIIb/IIIa inhibitors (particularly abciximab) may be preferable to short term upstream administration in high risk patients undergoing PCI. Pre-treatment with high-dose clopidogrel is not an adequate alternative to abciximab in patients undergoing PCI who have raised troponin levels.4)
    • consider oral beta adrenergic blockers (NOT iv unless severe HT or arrhythmia!!) in the 1st 24 hours (no hurry) unless C/I
      • (level I evidence, grade A recommendation)
      • contra-indications to beta blockers in acute coronary syndromes:
        • risk of cardiogenic shock or heart block:
          • age > 70, systolic BP < 120, HR < 60, HR > 110 (as evidence of decreased cardiac reserve), 1st degree heart block with PR > 240msec or 2nd/3rd degree HB.
        • acute asthma or reactive airways disease
    • iv GTN for refractory pain (grade D recommendation)
    • ensure good glycaemic control for diabetics - consider insulin Rx whilst in hospital and for 3 or more months in selected patients (grade B recommendation)
    • statins Rx should be commenced for all patients with coronary heart disease (level II evidence, grade B recommendation)
    • ACE inhibitors should be commenced early after an ACS, and its use reviewed later (level II evidence, grade B recommendation)
  • usually warrant transfer to a coronary care unit (CCU) although cardiology team may elect to Mx some of these as for intermediate risk group (eg TIMI risk score < 3)
  • invasive Mx:
    • early coronary angiography (within 48hrs) and revascularisation unless severe comorbidities (grade A recommendation), particularly for those with TIMI risk scores > 3

intermediate risk group

  • eg. HEART score 4-6
  • these patients can usually be transferred to an ED short stay observation unit or a chest pain unit for re-classification into either high risk or low risk group with:
    • cardiac monitoring
    • serial ECG's
    • serial troponins - usually a sample taken at least 6-8 hrs after onset of the most severe pain is regarded as sufficient
  • if any features arise that place the patient in the high risk group, then Mx as for high risk group.
  • patients with normal serial troponins and no dynamic ECG changes can usually be Mx as for low risk group, although should be referred for timely cardiac stress testing - preferably stress echo, or if this is C/I or not available, then a stress MIBI
  • there are still dilemmas in the risk stratification and evaluation of this group of patients5)

a normal ECG and troponin does not exclude ACS in higher risk patients

  • normal ECG, negative troponin, thus “low risk” - well not quite - you could still have a 10% risk of cardiac death or AMI in next 30days:
  • A Spanish study published in 2007 confirmed that non-specific ECG changes or raised troponin in the absence of ECG or CK evidence of infarct, do not add much to clinical risk of 30 day or long term risk of cardiac death or AMI if you clinically suspect their chest pain is due to IHD.
    • used a scoring tool giving:
      • 1 point if typical cardiac chest pain
      • 1 point if two or more episodes of this typical chest pain occurred in past 24hrs
      • 1 point if PH PTCA
      • 1 point if age > 66yrs
      • 2 points if IDDM
    • 30 day risk of cardiac death or AMI was (26 month risk in brackets):
      • 1.7% (9%) if score < 3 and no ST depression on ECG and normal troponin
      • 10.8% (26%) if score 3 or more and no ST depression on ECG and normal troponin
      • 6.6% (30%) if ST depression on ECG but normal troponin
      • 9.4% (25%) if no ST depression but troponin elevated
    • note these patients received aspirin and beta blockers and early stress testing. I'm guessing that their 30day risk would be even higher if they did not receive these interventions.
  • this is again highlighted with the HEART score - with normal ECG and normal troponin, you can still score 7 = 50% risk of cardiac event

low risk group

  • eg. HEART score < 4
  • “appropriate period of observation” with serial ECGs and troponins as for intermediate risk group if you feel the pain may be cardiac in nature.
  • depending on probability of ACS, either:
    • refer for stress testing:
      • discharge on aspirin +/- beta adrenergic blockers if no C/I
      • consider outpatient stress MIBI or stress ECHO within 7 days (preferably within 72 hours but after 12-24 hours of no pain and stable ECG) if not already performed.
    • no referral for stress testing
      • ie. likelihood of ACS is too low and stress testing is only likely to give false positive results or true negative results
      • patients with a HEART score < 4 may not need stress testing (this needs further validation)
      • patients with a low pre-test probability of ACS under age 75yrs and without PH CAD probably should NOT have stress testing:
        • in a 2013 Chest Pain Unit study, of 377 low pretest probability patients, NO patients were subsequently diagnosed with ACS or had a true-positive stress test. Even in those with “intermediate” pre-test probability, ACS was detected in only 1.7% 6)

references and resources

c_nsteacs_mx.txt · Last modified: 2014/06/04 07:44 by gary1