Junior Doctor Notes 🩺

Acute Coronary Syndromes

8 min read

Risk factors

  • Increased risk of ACS with central obesity, autoimmune conditions, chronic renal disease, diabetes and HIV

Symptoms

  • Pain or tightness in chest, jaw, neck, left arm, right arm or epigastrium associated with symptoms of dyspnoea, diaphoresis or fatigue
  • Atypical symptoms of myocardial ischaemia occur in women, people with diabetes and the elderly

Classification

  • Other classification
    • Type 1 spontaneous myocardial infarction = atherothrombotic coronary occlusion compromises myocardial blood flow (i.e. heart attack due to coronary plaque rupture)
    • Type 2 myocardial infarction = secondary to ischaemic imbalance between myocardial oxygen suply and/or demand. Can happen due to coronary artery spasm, tachyarrhythmias, bradyarrhythmias, anaemia etc
  • Troponins
    • For high sensitivity troponins, considered positive if1:
      • Increase of ≥20% if first Tn elevated, or
      • Increase of ≥50% in patients with small initial Tn elevations
    • Can consider a third troponin

Clinical Features

  • Some groups of people (females, diabetics, CKD and the elderly) are more likely to present with atypical or less-specific symptoms such as breathlessness and the pain is absent

Unstable Angina

  • Defined by ≥1 of:
    • Angina on exertion, occurring with increasing frequency over a few days, provoked by progressively less exertion (also known as crescendo angina)
    • Episodes of angina like pain occurring recurrently and unpredictably, without specific provocation by exercise. These episodes may be relatively short-lived (e.g. a few minutes) and may settle spontaneously or be relieved temporarily by sublingual glyceryl trinitrate, before recurring
    • An unprovoked and prolonged episode of chest pain, raising suspicion of AMI, but, without definite ECG changes or laboratory evidence of AMI
  • In unstable angina the ECG may be:
    • Be normal
    • Show evidence of acute myocardial ischaemia (usually ST segment depression)
    • Show non-specific abnormalities (e.g. T-wave inversion)
  • In unstable angina, by definition, troponins are negative

STEMI

ECG STEMI Criteria

  • Ongoing chest pain and any of the following:
    • ST elevation of 1mm or more in 2 or more adjacent leads except V2 and V3 which require ST elevation of:
      • 2.5mm or more in men under 40 years
      • 2.0mm or more in men aged 40 years or over
      • 1.5mm or more in women
    • Left bundle branch block and haemodynamically unstable
    • Left bundle branch block and haemodynamically stable with positive modified Sgarbossa criteria
    • Posterior infarct (ST depression V1-V3); needs a posterior ECG to confirm
    • de Winter T waves V2-V5

As from: PASCA ACS Flowchart and PASCA STEMI Flowchart

Other STEMI

  • In patients with inferior STEMI, RV infarction is suggested by:
    • ST elevation in V1
    • ST elevation in V1 and ST depression in V2 (highly specific for RV infarction)
    • Isoelectric ST segment in V1 with marked ST depression in V2
    • ST elevation in III > II
  • Diagnosis is confirmed by the presence of ST elevation in the right-sided leads (V3R-V6R)

Acute Management

  • Determine if alternate cause of ST elevation (i.e. type 2 MI) and manage that cause accordingly
  • Call senior doctor and obtain an urgent cardiology consult
  • Move to resuscitation bay and apply defibrillator pads
  • Indications for reperfusion therapy for STEMI:
    • Presented to hospital within 12 hours of chest pain/AMI symptoms
    • Or if >12 hours since symptom onset any of:
      • Ongoing ischaemia (e.g. persistent pain and dynamic ECG changes)
      • Viable myocardiam (preservation of R waves in infarct-related ECG leads)
      • Major complications (e.g. cardiogenic shock, heart failure, malignant arrhthymias)
    • Consider advanced care directive and other factors affecting the patient’s overall survival (e.g. advanced age, frailty)
  • PCI available in <60 minutes2:
    • Request urgent transfer for PCI
    • Anticoagulation before PCI:
      • Aspirin 300mg if not already given as part of [[Chest Pain#Assessment#Initial Assessment (if not done on the phone)|chest pain initial assessment & management]]
      • Heparin 5000 units IV
      • Ticagrelor 180mg PO or Prasugrel 60mg PO preferred otherwise alternatively
        • Clopidogrel 300-600mg PO
        • Note that ticagrelor is contraindicated in 2nd or 3rd degree AV block
      • Ask cardiologist if glycoprotein IIb/IIIa inhibitor is indicated (e.g. eptifibatide, tirofiban)
    • Transfer for PCI
  • PCI not available:
    • Check for contraindications to thrombolysis:
      • Symptoms present for more than 12 hours
      • BP >180/110 → treat hypertension (see Hypertension) and reassess
      • Major trauma or surgery or internal bleeding within one month
      • Ischaemic stroke within 3 months
      • Intracerebral bleed at any time
      • Allergy to tenecteplase
    • Request senior review if relative contraindication to thrombolysis present:
      • Ischaemic stroke >3 months
      • INR >1.8
      • On anticoagulation
      • Bleeding disorder
    • Antiplatelet before thrombolysis
      • Aspirin 300mg if not already given as part of [[Chest Pain#Assessment#Initial Assessment (if not done on the phone)|chest pain initial assessment & management]]
      • Clopidogrel 300mg if <74 years or 75mg if ≥75 years
        • Clopidogrel is preferred for thrombolysis
    • Thrombolysis with tenecteplase, dosage based on weight
    • Anticoagulation after thrombolysis
    • Thrombolysis successful if all: - ECG >50% reduction in ST elevation - Symptoms largely resolved - Haemodynamically stable
    • Admit or transfer for PCI depending on local protocols
      • Failed thrombolysis → immediate transfer to PCI hospital for rescue PCI
      • Sccuessful thrombolysis → Angiography ± PCI during same admission
  • Also organise echocardiogram

  • Cardiogenic shock management
    • In most cases IV fluid bolus is the mainstay of management; involve your senior early if hypotension is not fluid responsive
    • Cardiogenic shock
      • Clinically manifested by hypotension, elevated JVP and pulmonary oedema
      • Treat ACS-related causes (see ACS)
        • After giving aspirin, heparin and clopidogrel or prasugrel refer for immediate PCI
        • Fibrinolytic therapy does not substantially improve the outcome in cardiogenic shock1
        • Exclude other causes of hypotension with raised JVP using urgent echocardiogram
        • Also perform urgent echocardiogram in patients with a new murmur as valve repair my be required
      • Inferior STEMI
        • Confirm RV infarction by placing right sided chest leads (usually just V4R but sometimes also with V5R and V6R)
        • STE indicates RV infarction
        • These patients are dependent on preload for their cardiac output so avoid dropping preload with GTN, morphine or diuretics
        • Less likely to develop pulmonary oedema → try small aliquots of normal saline at 2 mL/kg
      • Exclude aortic dissection causing shock from tamponade or severe aortic incompetence
        • Arrange CT scan with IV contrast (CT angiography) or TOE to best distinguish Aortic Dissection from ACS
      • General measures of shock
        • Give maximal oxygenation, careful fluid management and consider inotrope infusions such as noradrenaline with or without dobutamine in the ICU.
        • If these measures are unsuccessful, intra-aortic balloon pump, left ventricular assist device (LVAD) or circulatory bypass are required if a reversible pathological feature is present and it is available
    Link to original

Basic level (MONASH)

  • Morphine
  • Oxygen
  • Nitrates
  • Antiplatelets
  • Save tissue
  • Heparin

NSTEACS

Assessment

As from PASCA ACS Checklist

Acute Management

  • Perform serial ECGs immediately and after 6-8 hours or every 15 minutes if the pain is continuing. Also perform ECG each time a troponin is taken
  • Perform high sensitivity troponin at 0 and 2 hours
  • Perform standard sensitivity troponin at 6 and 8 hours
  • Aspirin 300 mg orally chewed or dissolved before swallowing if not given already
    • 100-150 mg orally daily aspirin
  • High clinical risk:
    • Criteria: Any of the following
      • Typical or ongoing symptoms
        • On call makes mention of repetitive or prolonged (>10 min) ongoing chest pain or typical chest pain in patients with diabetes or chronic renal impairment (eGFR <60)
      • Syncope at presentation or SBP <90mmHg
      • Acute onset left ventricular failure
      • Significant arrhythmia (2nd or 3rd degree AV block or VT)
      • AMI, PCI or CABG in last 6 months
      • Dynamic ECG: ST (>0.5mm up or down) or new T wave inversion
      • Initial and repeat troponin positive with no non-ischaemic cause of troponin elevation
    • Management
      • If STEMI changes follow [[Acute Coronary Syndromes#STEMI#Management|STEMI Management as above]]
      • Commence high-flow oxygen if shocked or hypoxic
      • Give aspirin 300mg PO if not done so already
      • Contact senior doctor immediately, then the cardiology registrar
        • Give prasugrel 60mg PO (then 10mg OD), ticagrelor 180mg PO (then 90mg BD) or clopidogrel 300mg PO (then 75mg OD) as indicated by senior/reg
        • Cardiology team will advise heparin anticoagulation; suitable options include
          • LMWH if renal function allows
          • UFH; ask senior for advice
        • Cardiology will advise of use of glycoprotein IIb/IIIa inhibitors (e.g. eptifibatide or tirofiban) if immediate access to cath lab is not available
      • Admit with cardiac monitoring (preferably to CCU) for consideration of angiography within next 48 hours3
      • Admitting team will advise:
        • Anticoagulation
        • Antiplatelet therapy
        • Beta blockers
          • Or diltiazem if beta blockers are contraindicated
          • Avoid dihydropyridine calcium channel blockers (e.g. nifedipine)
        • Statins
  • Intermediate risk
    • Criteria: Doesn’t meet high or low risk criteria
    • Management
      • Give aspirin 300mg PO if not done so already
      • Call senior doctor and refer to inpatient medical registrar
      • Repeat ECG and troponin at 6-8 hours
      • Admit without cardiac monitoring or discharge after senior review with follow up with GP/Cardiologist in one week
      • Usually require exercise stress testing ideally within 72 hours to further categorise into EST-positive and EST-negative
  • Low risk
    • Criteria: Symptom free with non-ischaemic ECGs and ALL of the following:
      • Age <45
      • Symptoms atypical for angina
      • no known coronary artery disease
    • Management
      • Treat other diagnoses
      • Give aspirin 300mg PO if not done so already
      • Review precipitating cause of angina (e.g. anaemia, aortic stenosis, thyrotoxicosis and HCM) and ECG
      • If known diagnosis of angina
        • Determine if threshold for angina has decreased or the severity of pain increased
        • Consult with senior for adjustment to antianginal medication
        • If episode was prolonged or worse with no easily fixable precipitant repeat troponin and ECG at 6-8 hours
      • Follow up with GP or cardiology outpatient
      • Exercise stress testing, echo, cardiac perfusion and CTA NOT usually indicated4 As from: PASCA ACS Flowchart

Other Management

Recurrent Pain

  • Recurrent episodes of ischaemic chest pain may require GTN infusion for a short period of time; prolonged infusion rapidly induces tolerance
    • GTN 10 micrograms/minute by IV infusion increasing by 10 micrograms/minute every 3 minutes until pain is controlled provided systolic blood pressure ≥95 mmHg

Long Term Management

  • Aspirin and a P2Y-12 inhibitor (DAPT)
  • Statin
  • Beta-blocker
  • ACE-inhibitor
    • Should be started within 24-48 hours of acute myocardial infarciton
    • Contraindications include haemodynamic instability and hypotension

Sources

Footnotes

  1. As from https://www.aliem.com/high-sensitivity-troponin-testing/ ↩

  2. eTG says if PCI is available within 120 minutes ↩

  3. eTG says within 2 hours for very high risk and within 24 hours for high risk ↩

  4. eTG says for patients with unstable angina considered low risk non-invasive investigations such as stress testing are usually appropriate ↩

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