NSTEACS Management

OVERVIEW

• NSTEACS is non-ST elevation acute coronary syndrome, and includes non-STEMI and unstable angina
• Definition and assessment of NSTEACS is described in Acute Coronary Syndromes

RISK STRATIFICATION OF PATIENTS WITH CONFIRMED ACS

Very High Risk

• Haemodynamic instability:
  • Heart failure/ cardiogenic shock
  • Mechanical complications of myocardial infarction
• Life-threatening arrhythmias or cardiac arrest
• Recurrent or ongoing ischaemia (e.g. chest pain refractory to medical treatment) or recurrent dynamic ST segment and/or T wave changes, particularly with:
  • Intermittent ST segment elevation
  • de Winter T wave changes
  • Wellens syndrome (or LMCA syndrome)
  • Widespread ST elevation in two or more coronary territories

High Risk

• Rise and/or fall in troponin level consistent with myocardial infarction
• Dynamic episode of ST segment and/or T wave changes with or without symptoms
• GRACE score >140

Intermediate Risk

• Diabetes mellitus
• Renal insufficiency (glomerular filtration rate < 60mL/min/1.73m2)
• Left ventricular ejection fraction ≤ 40 %
• Prior revascularization:
  • Percutaneous coronary intervention
  • Coronary artery bypass grafting
• GRACE score >109 and <140

Low Risk

• Patients with NSTEACS who have both of:
  • no recurrent symptoms
  • no risk criteria (as listed above)

MANAGEMENT

Initial management

• All patients must be triaged to a monitored resuscitation bay
• IV access, and blood tests taken
• Oxygen therapy
  • avoid routine use of oxygen therapy among patients with SaO2 > 93 %
  • use when the SaO2 is below this level (or if the patient is shocked) (unless COPD or other easons for a modified SaO2 target)
• Analgesia
  • Nitrates
    • These can be given sub-lingual, topical, or as an IV infusion in cases of intractable pain not responding to morphine.
    • For initial management:
      • Glyceryl trinitrate sublingual spray 400 micrograms or sublingual tablet 300 to 600 micrograms.
      • Repeat every 5 minutes as needed and if tolerated (monitor for hypotension) to a maximum of 3 doses.
  • Opiates
    • e.g. IV morphine boluses titrated to clinical effect:
    • 2.5 to 5mg IV as an initial dose, then titrated to effect every 5 to 10 minutes with further incremental doses of 2.5 to 5mg IV
    • In elderly patients or those with cardiorespiratory compromise, an initial morphine dose of less than 2.5mg IV and incremental doses of 0.5 to 1mg should be considered
    • If morphine is contraindicated, consider fentanyl at 25 to 50 micrograms IV as initial equivalent dose.
    • Note that morphine can slow the absorption of some oral medications, including ticagrelor, (and so fentanyl may be a better option), however the clinical significance of this effect is currently unknown, and morphine remains a recommended treatment.
• Anti-emetic as required:
  • IV 10 mg metoclopramide or IV 12.5 mg prochlorperazine

Further management of NSTEACS patients is guided by the risk stratification level of the patient.

• Antiplatelet therapy
  • In all patients with possible ACS and without genuine contraindications, aspirin dissolved or chewed) should be given as soon as possible after presentation.
  • Additional antiplatelet and anticoagulation therapy, or other therapies such as beta-blockers, should not be given to patients without a confirmed or probable diagnosis of ACS.
  • For all cases give:
    • Aspirin 300 mg po then 100 – 150 mg daily thereafter.
    • Aspirin is then continued indefinitely unless it is not tolerated or an indication for anticoagulation becomes apparent.
  • Note that other NSAIDs should not be given due to an increased risk of MACE (i.e major adverse cardiac event) in patients subsequently shown to have ACS.
  • Among patients with confirmed ACS at intermediate to high risk of recurrent ischaemic events, use of a P2Y₁₂ inhibitor is also recommended:

Anti-Platelet Therapy

• In all patients with possible ACS and without genuine contraindications, aspirin dissolved or chewed) should be given as soon as possible after presentation
• Additional antiplatelet and anticoagulation therapy, or other therapies such as beta-blockers, should not be given to patients without a confirmed or probable diagnosis of ACS.
• For all cases give:
  • Aspirin 300 mg po then 100 – 150 mg daily thereafter.
  • Aspirin is then continued indefinitely unless it is not tolerated or an indication for anticoagulation becomes apparent.
  • Note that other NSAIDs should not be given due to an increased risk of MACE (i.e major adverse cardiac event) in patients subsequently shown to have ACS.
• Among patients with confirmed ACS at intermediate to high risk of recurrent ischaemic events, use of a P2Y₁₂ inhibitor is also recommended:
  • Ticagrelor loading dose, 180 mg followed by 90 mg B.D
  • Careful assessment of bleeding risk should be undertaken before using these agents.
  • Avoid if emergency coronary artery bypass grafting may be required, (e.g. ongoing ischaemia, extensive ECG changes, hemodynamic instability).
  • Dual antiplatelet therapy (i.e. with aspirin and a P2Y12 inhibitor (clopidogrel or ticagrelor) should be prescribed for up to 12 months in patients with confirmed ACS, regardless of whether coronary revascularisation was performed. The use of Prasugrel for up to 12 months should be confined to patients receiving PCI.
  • Consider continuation of dual antiplatelet therapy beyond 12 months if ischaemic risks outweigh the bleeding risk of P2Y12 inhibitor therapy; conversely, consider discontinuation if bleeding risk outweighs ischaemic risks.
  • Clopidogrel if there are specific CI to ticagrelor or prasugrel
    • Avoid if emergency coronary artery bypass grafting is likely
    • Give loading dose, 300-600 mg orally, then 75 mg daily
• Anticoagulation
  • Either unfractionated heparin or enoxaparin is recommended in patients with ACS at intermediate to high risk of ischaemic events.
  • Enoxaparin may be preferred over unfractionated heparin as it does not require monitoring of partial thromboplastin time and is simpler to administer.
  • Swapping between enoxaparin and unfractionated heparin has been shown to increase bleeding risk and is not recommended.
  • Give:
    • Enoxaparin, 1 mg/kg SC (or a reduced dose, 0.75 mg/kg SC in the elderly or those with renal impairment)
    • Heparin (loading dose followed by infusion) should be given if the patient is to receive an urgent PCI
  • Heparin or enoxaparin is not required in patients with successful revascularization and without other indication for anticoagulation
• Glycoprotein IIb/IIIa Inhibitors
  • An IV glycoprotein IIb/IIIa inhibitor in combination with heparin is recommended at the time of PCI among patients:
    • With high risk clinical and angiographic characteristics.
    • Who continue to have ischemia despite other treatments.
  • Agents available include:
    • Abciximab, (Trade name Reopro)
    • Eptifibatide (Trade name Integrilin)
    • Tirofiban, (Trade name Aggrastat)
  • The need for, and the specific agent to be used, will be determined by the treating cardiologist.
• Bivalirudin (direct thrombin inhibitor)
  • Bivalirudin (0.75 mg/kg intravenously with 1.75 mg/kg/h infusion) may be considered as an alternative to glycoprotein IIb/IIIa inhibition and heparin among patients with ACS undergoing PCI with clinical features associated with an increased risk of bleeding events

Reperfusion therapy

• Patients with confirmed (i.e elevated troponin levels) intermediate, high and very high risk NSTEACS (except patients with type 2 MI) should have angiography with coronary revascularization (i.e PCI or coronary artery bypass grafting – where appropriate).
• Recommended intervention times vary according to the level of risk:
  • Very High Risk NSTEACS: within 2h
  • High Risk NSTEACS: within 24h
  • Intermediate Risk NSTEACS: within 72h
  • Low Risk NSTEACS (no recurrent symptoms and no risk criteria): selective invasive strategy guided by provocative testing for inducible ischaemia

Further Secondary Prevention medications:

• Statin
  • Initiate and continue indefinitely, the highest tolerated dose of an HMG-CoA (3-hydroxy-3- methylglutaryl-coenzyme A) reductase inhibitor (statin) for a patient following hospitalization with ACS, unless contraindicated or there is a history of intolerance.
  • There is additional benefit from progressive lowering of cholesterol levels, with no apparent lower limit. Within the context of an individualized care plan, a target low density lipoprotein cholesterol level of less than 1.8 mmol/L is suggested in the first instance.
• Beta Blocker
  • Initiate treatment with vasodilatory b-blockers in patients with reduced left ventricular systolic function (left ventricular ejection fraction < 40%) unless contraindicated
• ACEI/ Sartan
  • Initiate and continue angiotensin-converting enzyme inhibitors (or angiotensin receptor blockers) in patients with evidence of heart failure, left ventricular systolic dysfunction, diabetes, anterior MI or co-existent hypertension.

Disposition

• High Risk Patients
  • All will clearly require hospital admission and most of these patients will require admission to coronary care admission
  • Coronary care admission criteria includes:
    • Significantly elevated serum troponin
    • Recurrent chest pain, whilst in the ED
    • ECG changes
    • Hemodynamic instability
    • Arrhythmias
  • High risk patients require further objective testing during the index admission
• Intermediate Risk Patients
  • Non-invasive objective testing is recommended in intermediate risk patients, as defined by a validated Suspected ACS-AP, with normal serial troponin and ECG testing and who remain symptom free
  • Intermediate risk patients may be safely accelerated for early inpatient testing or discharged for outpatient testing, ideally within 7 days but acceptable up to 14 days after presentation
  • Investigation before discharge from the emergency department is desirable among patients with characteristics associated with significant failure to re-attend for medical review, given the higher rates of MACE in such patients.
• Low Risk Patients
  • Patients in whom no further objective testing for coronary artery disease (CAD) is recommended are those at low risk (see above).
  • Following discharge, attendance at cardiac rehabilitation or undertaking a structured secondary prevention service is recommended for all patients hospitalized with ACS.

References and links

LITFL

• Percutaneous Coronary Intervention (PCI) (CCC)
• Acute Coronary Syndromes (CCC)

Journal articles

• Chew DP, Scott IA, Cullen L, et al. National Heart Foundation of Australia and Cardiac Society of Australia and New Zealand: Australian clinical guidelines for the management of acute coronary syndromes 2016. The Medical journal of Australia. 205(3):128-33. 2016. [pubmed]
• Chew DP, Scott IA, Cullen L, et al. National Heart Foundation of Australia & Cardiac Society of Australia and New Zealand: Australian Clinical Guidelines for the Management of Acute Coronary Syndromes 2016. Heart, lung & circulation. 25(9):895-951. 2016. [pubmed] [free full text]
• Delewi R, Zijlstra F, Piek JJ. Left ventricular thrombus formation after acute myocardial infarction. Heart. 2012 Dec;98(23):1743-9. doi: 10.1136/heartjnl-2012-301962. Review. PubMed PMID: 23151669; PubMed Central PMCID: PMC3505867.
• Thygesen K, Alpert JS, Jaffe AS. Third universal definition of myocardial infarction. Circulation. 126(16):2020-35. 2012. [pubmed]