The Acute Coronary Syndromes, Including Acute MI

1
The Acute Coronary Syndromes, Including Acute MI

• 2000 ACLS Text
• Consensus Guidelines

2
Acute Coronary Syndromes

• Unstable angina
• Non-Q-wave MI
• Q-wave MI

3
Acute Coronary Syndromes

• Are a continuum initiated by
• rupture of an unstable, lipid-rich atheromatous
  plaque in epicardial artery activating platelet
  adhesion, fibrin clot formation and coronary
  thrombosis

4
Suspicious Chest Pains

• Classic angina - dull, pressure, substernal arm
  or neck radiation SOB, palpitations, sweating,
  nausea or vomiting
• Angina Equivalent - no pain but sudden
  ventricular failure or ventricular dysrhythmias
• Atypical chest pain - precordial area but with
  musculoskeletal, positional, or pleuritic features

5
CAD Risk Stratification

• High Risk (?1 of the following features)
• Prior MI, VT or VF or known CAD
• Definite clinical angina
• Dynamic ST changes
• Marked anterior T-wave changes

6
CAD Risk Stratification

• Intermediate Risk (no high-risk features plus 1
  of the following)
• Definite angina (young age)
• Probable angina (older age)
• Possible angina (DM or 3 other risk factors)
• ST depression ? 1 mm or T inversion ? 1 mm

7
CAD Risk Stratification

• Low Risk (no high- or intermediate-risk
  features plus 1 of the following)
• Possible angina
• One risk factor (not DM)
• T-wave inversion lt 1mm
• Normal ECG

8
Short-Term Risk of Death

• High Risk (?1 of the following)
• Prolonged continuing pain not relieved by rest
  (gt20 min)
• Pulmonary edema, S3 or rales
• Hypotension with angina
• Dynamic ST changes gt 1 mm
• Elevated serum troponin T or I

9
Short-Term Risk of Death

• Intermediate risk (no high-risk features plus 1
  of the following)
• Prolonged (gt 20 min) but resolved or stuttering
  angina
• Rest angina gt 20 min or relieved with NTG
• Age gt 65
• Dynamic T-wave changes and angina
• Q waves or ST depression lt 1mm multiple-lead
  groups

10
Short-Term Risk of Death

• Low Risk (no high- or intermediate-risk features
  plus 1 of the following)
• Angina increased in frequency, severity, or
  duration
• Lower activity threshold before angina
• 1 risk factor, no DM
• New-onset angina gt 2 wk to 2 mo
• Normal or unchanged ECG

11
Primary goals of therapy for ACS

• Reduction of myocardial necrosis in patients with
  ongoing infarction
• Prevention of major adverse cardiac events
• Death
• Nonfatal MI
• Need for urgent revascularization
• Rapid defibrillation when VF occurs

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Out-of-Hospital Management

• Early defibrillation
• Prehospital death 52
• Primary VF 4-18 of patients with MI
• In-hospital VF 5
• EMS system for immediate defibrillation is
  mandatory
• Early access to AED through out the community

13
Out-of-Hospital Management (contd)

• Delays in therapy
• From onset of symptoms to patient recognition
• Median time ? 2 hrs
• During out-of-hospital transport 5
• During in-hospital evaluation door to data, to
  decision and to drug (4 Ds) 25-33
• Patient education is important to minimize the
  delay

14
Out-of-Hospital Management (contd)

• Out-of-hospital fibrinolysis
• Appears to reduce mortality when transport times
  are long
• Recommended when a physician is present or
  out-of-hospital transport time is ? 60min (Class
  IIa)

15
Out-of-Hospital Management (contd)

• Out-of-hospital ECGs
• Increases the time spent at the scene by 0 to 4
  min
• Diagnosis of AMI can be made sooner
• Recommended in urban and suburban paramedic
  systems (Class I)

16
Out-of-Hospital Management (contd)

• Cardiogenic shock and out-of-hospital facility
  triage
• Transfer patients at high risk (shock, HR gt 100,
  SBP lt 100, age lt 75) to facility capable of PCI
  or CABG (Class I)
• Transfer patients with contraindications to
  fibrinolytic therapy to interventional facilities
  (Class IIa)

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ER Patient Care

• Initial assessment (lt 10 min)
• Measure vital signs
• Measure SpO2
• Obtain IV access
• Obtain 12-lead ECG
• Perform brief, targeted history and PE)

• Obtain initial cardiac marker levels
• Evaluate initial electrolyte and coagulation
  studies
• Request, review portable chest x-ray (lt30 min

18
ER patient care

• Initial general treatment (memory aid MONA
  greets all patients
• Morphine, 2-4 mg repeated q 5-10 min
• Oxygen, 4 L/min continue if SaO2 lt 90
• NTG, SL or spray, followed by IV for persistent
  or recurrent discomfort
• Aspirin, 160 to 325 mg (chew and swallow)

19
Triage by ECG

• ST elevation or new LBBB
• ST elevation ?1 mm in 2 or more contiguous leads
• ST depression or dynamic T-wave inversion
• ST depression gt 1 mm
• Marked symmetrical T-wave inversion in multiple
  precordial leads
• Dynamic ST-T changes with pain
• Nondiagnostic ECG or normal ECG

20
ST elevation or new LBBB

• Start adjunctive treatment
• If time lt 12 hr
• Select a reperfusion strategy based on local
  resources
• If time gt 12 hr
• Assess clinical status, either high-risk or
  clinically stable

21
ST elevation or new LBBB

• Adjunctive treatments
• ß-blockers
• NTG IV
• Heparin IV
• ACE inhibitors (after 6 hours or when stable)

22
ST elevation or new LBBB, time lt 12 hr

• Reperfusion strategy based on local resources
• Thrombolytics (lt 30 min)
• TPA 15 mg bolus 0.75 mg/Kg over 30 min 0.5
  mg/Kg over 60 min or
• SK 1.5 million IU over 1 h
• Primary percutaneous coronary intervention (PCI,
  angioplasty stent) (90 ? 30 min)
• Cardiothoracic surgery backup

23
ST elevation or new LBBB, time gt 12 hr

• Perform cardiac catheterization for high-risk
  patients
• Persistent symptoms
• Depressed LV function
• Widespread ECG changes
• Prior AMI, PCI, CABG

• Admit to CCU/ monitored bed if clinically stable
• Continue or start adjunctive treatments
• Serial serum markers
• Serial ECG
• Consider imaging study (2D echocardiography or
  radionuclide)

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Benefit of Thrombolytics
25
Thrombolytics and Stroke

• Risk factors
• gt 65 years
• BW lt 70 Kg
• BP gt 180/110
• on anticoagulants

• Strokes
• no risks 0.25
• 3 risks 2.5

26
Contraindications to Thrombolytics

• Absolute
• Previous hemorrhagic stroke
• CVA within past 1 year
• Brain neoplasm
• Active internal bleeding
• Suspected aortic dissection

27
Contraindications to Thrombolytics

• Relative
• BP gt 180/110 or chronic severe hypertension
• On anticoagulants
• Trauma or internal bleeding lt 2-4 wks

• Traumatic CPR (gt10 min)
• Major surgery lt 3 wks
• Previous SK
• Active ulcer
• Pregnancy
• Hidden puncture

28
ST depression or dynamic T-wave inversion

• Thrombolytics contraindicated
• Adjunctive therapy
• Heparin (UFH/LMWH)
• Aspirin 160-325 mg qd
• Glycoprotein IIb/IIIa receptor inhibitors
• NTG IV
• ?-blockers
• Cardiac catheterization for high-risk patients or
  monitoring for clinically stable patients

29
Glycoprotein IIb/IIIa receptor inhibitors

• Inhibits the GP IIb/IIIa receptor in the membrane
  of platelets
• Inhibits final common pathway activation of
  platelet aggregation
• Available approved agents
• Abciximab (ReoPro)
• Eptifibitide (Integrilin)
• Tirofiban (Aggrastat)

30
Low Molecular Weight Heparin

• Not neutralized by heparin-binding proteins
• More predictable effects
• Measurement of aPTT not required
• Administered subcutaneously, avoiding difficulty
  with continuous IV administration
• Available agents
• Enoxaparin (Loxinox), dalteparin (Fragmin),
  nadroparin (Fraxiparine)

31
Low Molecular Weight Heparin

• Inhibits thrombin indirectly through complex,
  with antithrombin III
• Compared with unfractionated heparin, has more
  inhibition of factor Xa
• Each molecule of Xa inhibited have led to many
  molecules of thrombin

32
Lower dose of heparin

• To reduce the incidence of ICH
• Bolus dose 60 U/kg (maximum 4000U)
• Maintenance dose 12 U/kg/hr (maximum 1000 U/hr
  for patients weighing lt 70 kg)
• Optimal aPTT 50-70 sec

33
Nondiagnostic ECG or normal ECG

• Meets criteria for unstable or new-onset angina?
  Or troponin positive?
• Yes, start adjunctive treatments and assess
  clinical status
• Cardiac catheterization for high-risk patients or
  monitoring for clinically stable patients
• No, admit to ER chest pain unit for monitoring
• If no evidence of ischemia or infarction
• Discharge and arrange follow-up

34
Cardiac Markers

• Myoglobin
• Nonspecific
• Rapid-release kinetics
• Useful for its negative predictive accuracy in
  the early hours after symptom onset
• Useful marker for reperfusion

• Inflammatory Markers
• Can indicate plaque or systemic inflammation
  associated with ACS
• CRP identifies a subgroup of patients with
  unstable angina at high risk for adverse
  cardiac events

35
Cardiac Markers

• CK-MB Isoforms
• Improved sensitivity compared with CK-MB
• Only one form in the myocardium
• CK-MB2 gt 1U/L or CK-MB2/CK-MB1 gt 1.5

• Troponins
• Troponin I/Troponin T
• Increased sensitivity compared with CK-MB
• Detect minimal myocardial damage
• Useful in risk stratification
• Biphasic release kinetics

36
Acute stroke

• Major guidelines changes
• IV administration of tPA for ischemic stroke
• within 3 hrs of onset of stroke symptoms (Class
  I)
• Between 3-6 hrs of onset of stoke symptoms (class
  indeterminate)
• IA fibrinolysis within 3-6 hrs may be beneficial
  in patients with occlusion of MCA (Class IIb)