Rosen & Barkin's 5-Minute Emergency Medicine Consult (609 page)

• STEMI is caused by occlusion of an epicardial coronary artery, usually as a result of a thrombotic event
  
• UA/NSTEMI is caused by a partial occlusion of coronary artery, also due to thrombus.
  

DIAGNOSIS

• Chest pain, heaviness, or pressure feeling
  
• Shortness of breath
  
• Arm, neck, or back pain
  
• Weakness or fatigue
  
• Nausea, vomiting
  
• Diaphoresis
  
• Palpitations
  
• Dizziness or syncope
  
• STEMI ECG
  

• History is critical in assessing window for use of both fibrinolytics and PCI.
  
• ECG:
  
  • Will be normal ∼50% of time
    
  • Must be compared with prior tracings if available and may evolve in short period of time, consider repeat ECGs
    
  • ST elevation in the absence of left ventricular hypertrophy or left bundle branch block (LBBB) with new ST elevation at the J point in at least 2 contiguous leads of ≥2 mm in men or ≥1.5 mm in women in leads V
    ₂
    –V
    ₃
    and/or of ≥1 mm (0.1 mV) in other contiguous chest leads or the limb leads (7)
    
  • New or presumably new LBBB has been considered a STEMI equivalent. Most cases of LBBB at time of presentation; however, are “not known to be old” because prior ECG is not available for comparison.
    
  • New or presumably new LBBB at presentation occurs infrequently, may interfere with ST-elevation analysis, and should not be considered diagnostic of acute myocardial infarction (MI) isolation without symptoms of ACS; use of Sgarbossa criteria is recommended for definitive diagnosis
    
  • Baseline ECG abnormalities other than LBBB (e.g., paced rhythm, LV hypertrophy, Brugada syndrome) may obscure interpretation
    
  • New ST-segment changes or T-wave inversions are suspicious for UA or non–Q-wave infarct
    
  • 1-mm depression of the ST segment below the baseline, 80 ms from the J point, is characteristic of UA or non–Q-wave infarct
    
• Chest radiograph: May be helpful if aortic dissection is being considered
  
• Heme stool test: Helpful in establishing baseline, especially in setting of anticipated anticoagulation
  

• Cardiac enzymes, troponin preferred
  
• Baseline creatinine, hematocrit, and coagulation profile are all appropriate in initial workup.
  

• Aortic dissection
  
• Anxiety
  
• Biliary colic
  
• Coronary aneurysm
  
• Costochondritis
  
• Esophageal spasm
  
• Esophageal reflux
  
• Herpes zoster
  
• Hiatal hernia
  
• Hyperkalemia
  
• Mitral valve prolapse
  
• Peptic ulcer disease
  
• Psychogenic symptoms
  
• Panic disorder
  
• Pericarditis
  
• Pneumonia
  
• Pulmonary embolus
  
• Ventricular aneurysm
  

TREATMENT

• IV access
  
• Oxygen
  
• Cardiac monitoring
  
• Sublingual nitroglycerin for symptom relief, unless use of phosphodiesterase inhibitor in the last 24 hr
  
• Aspirin 162 or 325 nonenteric coated
  
• Local EMS system and hospital system should preferentially transport STEMIs to PCI-capable hospital
  
• Controversies:
  
  • Whether to allow EMS activation of cardiac catheterization labs and administration of fibrinolytics.
    

• IV access
  
• Oxygen
  
• Cardiac monitoring
  
• Oxygen saturation
  
• Continuous BP monitoring and pulse oximetry
  
• Nitrates
  
• Therapeutic hypothermia if indicated post arrest
  

• Aspirin
  
• Clopidogrel
  
• Fibrinolytics for STEMI
  
  • Unless contraindicated
    
  • If PCI is not readily available within 120 min
    
• PCI is preferred for both diagnostic and therapeutic options for STEMI and UA/NSTEMI
  
• PCI and fibrinolytics therapy must be used with either UFH or an LMWH, such as enoxaparin or bivalirudin
  
• LMWH:
  
  • Kinetics more predictable
    
  • Requires no monitoring
    
  • Less potential for platelet activation
    
  • Lower bleeding rate
    
  • Is at least as effective as UFH in treatment of acute coronary syndromes
    
• Glycoprotein IIb/IIIa inhibitors
  
• Direct thrombin inhibitors—bivalirudin if history of heparin-induced thrombocytopenia
  

• Aspirin: 162–325 mg PO nonenteric coated
  
• Enoxaparin (Lovenox): 1 mg/kg SC q12h
  
• Clopidogrel (Plavix): 300–600 mg PO load, 75 mg PO per day
  
• Prasugrel 60 mg PO load, 10 mg PO per day
  
• Not to be used in patients with history of stroke
  
• Ticagrelor 180 mg PO load, 90 mg PO BID
  
• Glycoprotein IIb/IIIa inhibitor:
  
  • Abciximab (ReoPro): For use before PCI only; 0.25 mg/kg IV bolus; 0.125 μg/kg/min to a max. of 10 μg/min for 12 hr
    
  • Eptifibatide (Integrilin): 180 μg/kg IV over 1–2 min, followed by continuous IV infusion of 2 μg/kg/min up to 72 hr
    
  • Tirofiban (Aggrastat): 0.4 μg/kg/min for 30 min, then 0.1 μg/kg/min for 48–108 hr
    
• Heparin 60 U/kg IV bolus (max. 4,000 U), then 12 U/kg/h (max. 1,000 U/h)
  
• Bivalirudin 0.1 mg/kg bolus, followed by 0.25 mg/kg/h for UA/NSTEMI and 0.75 mg/kg bolus, followed by 1.75 mg/kg/h in STEMI
  
• Metoprolol: 5 mg IV q2min for 3 doses followed by 25–50 mg PO starting dose as tolerated (note: β-blockers contraindicated in cocaine chest pain)
  
• Fibrinolytics:
  
  • Recombinant tissue plasminogen activator (Reteplase): 10 U IV bolus, repeat dose after 30 min; patients should also receive heparin 5,000 IU IV bolus, then infuse 1,000 IU/h for 48 hr, keeping activated partial thromboplastin time (aPTT) 1.5–2.5.
    
  • Streptokinase: 1.5 million U over 60 min; patients should also receive methylprednisolone 250 mg IV.
    
  • Tissue plasminogen activator: 15 mg IV bolus, then 0.75 mg/kg (max. 50 mg) over 30 min, then 0.5 mg/kg (max. 35 mg) over 60 min; patients should also receive heparin 5,000 IU IV bolus, then infuse 1,000 IU/h for 48 hr keeping a PTT 1.5–2.5
    
  • Tenecteplase: Weight-based dosing with max. single dose of 30–50 mg given over 5 sec; IV bolus over 5 sec
    
  • Contraindications:
    
    • Active internal bleeding
      
    • History of cerebrovascular accident in last 6 mo
      
    • History of a hemorrhagic cerebrovascular accident
      
    • Recent (within 2 mo) intracranial or intraspinal surgery or trauma
      
    • Intracranial neoplasm, arteriovenous malformation, or aneurysm
      
    • Known bleeding diathesis
      
    • Severe, uncontrolled hypertension
      
    • Pregnancy
      
    • Head trauma within last month
      
    • Trauma or surgery within last 2 wk that may result in closed-space bleed
      

FOLLOW-UP

All patients being considered for reperfusion therapy should be admitted to a cath lab or transferred to a PCI center or admitted to tele bed or an ICU setting

No patient being considered for reperfusion therapy should be discharged home from ED

• Goal of reperfusion therapy is primary PCI within 90 min of 1st medical contact. Transfer to a PCI-capable facility when this window can be accomplished or assess for fibrinolytics if >120 min for transfer
  
• Goal of fibrinolytics therapy is a 30 min door-to-needle time if PCI not possible or will be delayed
  
• Goal of reperfusion in STEMI patients by either fibrinolytics or PCI is the major goal
  
• PCI should be considered in all post arrest patients along with hypothermia
  

• American College of Emergency Physicians; Society for Cardiovascular Angiography and Interventions, O’Gara PT, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines.
  J Am Coll Cardiol.
  2013;61:e78–e140. doi:10.1016/j.jacc.2012.11.019.
  
• Wright RS, Anderson JL, Adams CD, et al. 2011 ACCF/AHA focused update of the Guidelines for the Management of Patients with UA/Non-ST-Elevation Myocardial Infarction (updating the 2007 guideline): A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines developed in collaboration with the American College of Emergency Physicians, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons.
  J Am Coll Cardiol
  . 2011;57(19):1920–1959. doi:10.1016/j.jacc.2011.02.009.
  

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