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 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)

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 CK-MB2/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)