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Acute Coronary Syndrome

Unstable angina – when you have symptoms at rest, or when they arise in a non-predictable manner, but troponin is not elevated

NSTEMI, STEMI – when you have symptoms at rest, they can arise in a non-predictable manner AND troponin is elevated

2 of 3 short hand criteria required for diagnosis of ACS

  • Cardiac chest pain
  • Ischemic ECG changes
  • Elevated troponin

Universal definition of MI

  • Detection of a rise/fall of troponin where at least 1 value of troponin is higher than the 99th percentile
    • Serial troponins are required since troponins may only be detected 6 hours after MI and peak 24 hours after injury
  • One of the following:
    • Ischemia symptoms
    • ECG changes
      • New LBBB
      • Dynamic (meaning new compared to old ECG) T wave inversions
      • ST segment elevation (STEMI) or depression (NSTEMI)
    • Radiological evidence of new loss of myocardium (such as on echocardiogram)

Clinical presentation of ACS

  • Vital signs
    • Tachycardia or bradycardia
    • Tachypnea
    • Hypotension
    • Low O2 sat
  • Anginal pain – retrosternal crushing pressure
    • What isn’t anginal pain?
      • Pleuritic – pain varies based on inspiration or expiration
      • Positional – changes based on whether you are standing or sitting, leaning forward or not
      • Worse on palpation
    • It is possible while uncommon to have ACS without anginal pain
  • Diaphoresis
  • Pain radiating to left arm and jaw
  • Dyspnea
  • Nausea

Investigations

  • ECG
    • T wave peaking
    • ST segment elevations or depression
    • Prominent Q waves
  • Elevated troponin
    • Peak within 24 hours of the event
    • Troponins may still be elevated after therapy if
      • Poor renal clearance of troponin
      • Continued ischemic damage

Acute Management for STEMI

  • Immediate treatment simply based on symptoms consistent with ACS
    • ASA
      • One 162 – 325 mg tablet to chew in the acute setting
      • 81 mg daily indefinitely thereafter
    • Supplemental oxygen if hypoxic
    • Sublingual nitroglycerin (if there is no hypotension or recent use of phosphodiesterase inhibitors “viagra”)
    • Morphine for pain control
  • ECG required for immediate triage
    • ST segment elevation OR new LBBB?
      • STEMI: immediate reperfusion required
        • Percutaneous coronary intervention (PCI) – i.e. stent placement
        • Fibrinolytics
    • ST segment depression or deep T wave inversion?
      • NSTEMI
        • Early invasive management strategy
        • Dual antiplatelet therapy
        • Anticoagulation
    • Second antiplatelet agent
  • Anticoagulant
    • Initiated in the acute setting and continued for at least 48 hours or at the end of PCI
  • Cardiac Angiography
    • Using dye and x-rays to directly visualize the coronary arteries in order to identify the presence and location of a coronary artery stenosis
  • If patient refuses PCI or if there is a delay to performing it then fibrinolytics are the next option
    • Tenecteplase
  • Prior to discharge and post-ACS patients are provided with an echocardiogram in order to measure the left ventricular ejection fraction, as certain medications such as the aldosterone blockers and ACE inhibitors are more strongly recommended if they have LVEF < 40 %
  • Exercise stress testing
    • Patient is connected to ECG while exercising on treadmill in order to assess for abnormal ECG changes, HR, BP or anginal changes upon exercise
  • Clot control
    • ASA, clopidogrel or ticagrelor to prevent further clot formation
      • Can be given with anticoagulants like heparin or fondaparinux
    • High dose statins are given to stabilize plaques
  • Symptom management
    • Oxygen
    • Nitroglycerin for chest pain
    • Morphine

ticagralor over plavix if NSTEMI is high risk and they need to go to cath lab

For NSTEMI call cardiology, but usually they can take them to the cath lab in the morning

Long term management for both STEMI and NSTEMI

  • Aspirin started acutely will be continued for lifelong duration
  • Beta-blockers also show mortality benefit and reduce oxygen demands for most patients post ACS
    • Caution should be used in patients who are
      • Over the age of 70
      • Low BP and HR
      • Asthma
      • Second or third degree heart block
    • Duration is uncertain
      • If there is severe LV dysfunction, then beta-blockers must be used for lifelong duration
      • Up to 3 to 4 years, must be reassessed by cardiologist
  • Clopidogrel (anti-platelet agent in addition to aspirin)
    • Alternatives are prasugrel or ticagrelor
    • Avoid if there is allergic reaction
    • Duration
      • 12 months if
        • No stent
        • Bare metal stent
      • At least 12 months with a drug eluting stent
      • At 1 year, patient must be reassessed for bleeding risk
        • If they are at high risk for bleeding then they must only be on single anti-platelet therapy (either aspirin or clopidogrel but not both)
        • If they are at low risk for bleeding then continue DAPT for up to 3 years
  • Statins will be used indefinitely regardless of cardiovascular risk score percentage
  • ACE inhibitors or ARBs are recommended if LVEF < 40 % (systolic heart failure) for lifelong duration
  • Aldosterone angonist (like spironolactone) are recommended if LVEF < 40 % (systolic heart failure) for lifelong duration
  • Influenza vaccine should be given yearly in all ACS patients