Transcript The Acute Coronary Syndromes, Including Acute MI

The Acute Coronary Syndromes,
Including Acute MI
2000 ACLS Text
Consensus Guidelines
Acute Coronary Syndromes
• Unstable angina
• Non-Q-wave MI
• Q-wave MI
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
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
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
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
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 < 1mm
– Normal ECG
Short-Term Risk of Death
• High Risk (≧1 of the following)
– Prolonged continuing pain not relieved by rest
(>20 min)
– Pulmonary edema, S3 or rales
– Hypotension with angina
– Dynamic ST changes > 1 mm
– Elevated serum troponin T or I
Short-Term Risk of Death
• Intermediate risk (no high-risk features
plus 1 of the following)
– Prolonged (> 20 min) but resolved or “stuttering”
angina
– Rest angina > 20 min or relieved with NTG
– Age > 65
– Dynamic T-wave changes and angina
– Q waves or ST depression < 1mm multiple-lead
groups
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 > 2 wk to 2 mo
– Normal or unchanged ECG
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
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
Out-of-Hospital Management (cont’d)
• 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 D’s): 25-33%
• Patient education is important to minimize the
delay
Out-of-Hospital Management (cont’d)
• 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)
Out-of-Hospital Management (cont’d)
• 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)
Out-of-Hospital Management (cont’d)
• Cardiogenic shock and out-of-hospital facility
triage
– Transfer patients at high risk (shock, HR > 100,
SBP < 100, age < 75) to facility capable of PCI or
CABG (Class I)
– Transfer patients with contraindications to
fibrinolytic therapy to interventional facilities
(Class IIa)
ER Patient Care
Initial assessment (< 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
(<30 min
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 < 90%
– NTG, SL or spray, followed by IV for persistent or
recurrent discomfort
– Aspirin, 160 to 325 mg (chew and swallow)
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 > 1 mm
– Marked symmetrical T-wave inversion in multiple
precordial leads
– Dynamic ST-T changes with pain
• Nondiagnostic ECG or normal ECG
ST elevation or new LBBB
Start adjunctive treatment
• If time < 12 hr
– Select a reperfusion strategy based on local
resources
• If time > 12 hr
– Assess clinical status, either high-risk or clinically
stable
ST elevation or new LBBB
Adjunctive treatments
– β-blockers
– NTG IV
– Heparin IV
– ACE inhibitors (after 6 hours or when stable)
ST elevation or new LBBB, time < 12 hr
Reperfusion strategy based on local resources
– Thrombolytics (< 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
ST elevation or new LBBB, time > 12 hr
• Perform cardiac
catheterization for highrisk 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)
Benefit of Thrombolytics
Time Lives saved/1000
< 1h
65
1-2 h
37
2-3 h
29
3-6 h
26
6-12
18
12-24
9
Thrombolytics and Stroke
• Risk factors:
– > 65 years
– BW < 70 Kg
– BP > 180/110
– on anticoagulants
• Strokes
– no risks = 0.25%
– 3 risks = 2.5%
Contraindications to Thrombolytics
• Absolute
–Previous hemorrhagic stroke
–CVA within past 1 year
–Brain neoplasm
–Active internal bleeding
–Suspected aortic dissection
Contraindications to Thrombolytics
• Relative:
– BP > 180/110 or
chronic severe
hypertension
– On anticoagulants
– Trauma or internal
bleeding < 2-4 wks
– Traumatic CPR (>10 min)
– Major surgery < 3 wks
– Previous SK
– Active ulcer
– Pregnancy
– Hidden puncture
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
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)
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)
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
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 < 70 kg)
• Optimal aPTT: 50-70 sec
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
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
Cardiac Markers
• CK-MB Isoforms
– Improved sensitivity
compared with CK-MB
– Only one form in the
myocardium
– CK-MB2 > 1U/L or CKMB2/CK-MB1 > 1.5
• Troponins
– Troponin I/Troponin T
– Increased sensitivity
compared with CK-MB
– Detect minimal
myocardial damage
– Useful in risk
stratification
– Biphasic release kinetics
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)