What is the management of ST-Elevation Myocardial Infarction (STEMI) in the emergency department, including medications administered before Percutaneous Coronary Intervention (PCI)?

Emergency Department Management of STEMI Before PCI

Administer aspirin 162-325 mg (chewable, non-enteric coated) immediately upon STEMI diagnosis, followed by a P2Y12 inhibitor loading dose (clopidogrel 600 mg, prasugrel 60 mg, or ticagrelor 180 mg) as early as possible, along with anticoagulation (unfractionated heparin or bivalirudin) to support primary PCI. 1

Immediate Actions Upon STEMI Diagnosis

ECG and Monitoring

• Obtain 12-lead ECG within 10 minutes of first medical contact 2
• Initiate continuous ECG monitoring with defibrillator capacity immediately 2
• Activate the cardiac catheterization laboratory for primary PCI (goal: door-to-balloon time ≤120 minutes) 1, 2

Oxygen and Hemodynamic Support

• Do not administer routine supplemental oxygen if oxygen saturation is ≥90% 2
• Only provide oxygen therapy for hypoxemic patients (SpO2 <90%) 2

Antiplatelet Therapy (Class I Recommendations)

Aspirin

• Loading dose: 162-325 mg orally (chewable, non-enteric coated preferred for faster absorption) 1
• Alternative: 250-500 mg IV if patient unable to swallow 2
• This should be given before primary PCI 1

P2Y12 Inhibitor (Choose One)

All three options below are Class I recommendations and should be given as early as possible or at time of PCI 1:

• Clopidogrel: 600 mg loading dose 1, 3
• Prasugrel: 60 mg loading dose 1
  • Contraindication: Do NOT use in patients with prior stroke or TIA 1
• Ticagrelor: 180 mg loading dose 1

Important caveat: While guidelines support pre-catheterization laboratory administration of P2Y12 inhibitors, some evidence suggests potential interaction between morphine and oral P2Y12 inhibitors that may delay drug absorption 4. However, this does not change the Class I recommendation to administer these agents early 1.

Anticoagulation Therapy (Class I Recommendations)

Choose one of the following regimens 1:

Unfractionated Heparin (UFH)

• Bolus: 100 units/kg IV (or 60 units/kg if GP IIb/IIIa inhibitor planned) 1
• Additional boluses administered as needed to maintain therapeutic activated clotting time during PCI 1

Bivalirudin

• Administer with or without prior UFH treatment 1
• Preferred in patients at high risk of bleeding (Class IIa) 1

What NOT to Use

• Fondaparinux should NOT be used as sole anticoagulant for primary PCI due to risk of catheter thrombosis 1

GP IIb/IIIa Inhibitors (Class IIa/IIb)

At Time of PCI (Class IIa - Reasonable)

In selected patients receiving UFH, consider 1:

• Abciximab (Level of Evidence: A) 1
• High-bolus-dose tirofiban (Level of Evidence: B) 1
• Double-bolus eptifibatide (Level of Evidence: B) 1

Pre-Catheterization Laboratory (Class IIb - May Be Reasonable)

• Administration in the emergency department or ambulance is optional and not strongly recommended 1

Pain Management

Morphine

• Use for relief of chest pain and anxiety 5
• Caution: May delay absorption of oral P2Y12 inhibitors 4
• Despite this interaction, morphine remains appropriate for symptom relief when needed 4

Nitroglycerin

• Sublingual or IV for ongoing chest pain 5
• Avoid in right ventricular infarction or hypotension 5

Medications to Avoid or Defer Until After PCI

Beta-Blockers

• Do NOT routinely administer IV beta-blockers in the emergency department 4
• Oral beta-blockers should be started after PCI in stable patients with heart failure or LVEF <40% 2
• Early beta-blocker treatment has shown conflicting results and is not part of immediate pre-PCI management 4

Statins

• High-intensity statin therapy should be initiated, but this is not time-critical before PCI 2
• Can be started in ED but does not delay transfer to catheterization laboratory 2

Special Populations

Patients with Elevated Transaminases

• Aspirin and clopidogrel are NOT contraindicated in patients with elevated liver enzymes 6
• Elevated ALT/AST alone does not equal hepatic dysfunction—assess synthetic function (albumin, INR, bilirubin) 6
• Administer antiplatelet therapy per standard protocols without delay 6

Patients with Prior Stroke/TIA

• Avoid prasugrel (Class III: Harm) 1
• Use clopidogrel or ticagrelor instead 1

Patients with High Bleeding Risk

• Consider bivalirudin monotherapy over UFH plus GP IIb/IIIa inhibitor 1
• Still administer aspirin and P2Y12 inhibitor as these are Class I recommendations 1

Transfer Protocol

Direct to Catheterization Laboratory

• Bypass the emergency department when possible and transfer directly to catheterization laboratory 2
• All medications listed above should be administered during transport or immediately upon arrival 2
• Goal: first medical contact to device time ≤120 minutes 1, 2

If PCI Delayed >120 Minutes

• Consider fibrinolytic therapy (tenecteplase, alteplase, or reteplase) 2, 7
• Full dose for patients <75 years; half dose for patients ≥75 years 2
• Still administer aspirin, clopidogrel, and anticoagulation with fibrinolytics 2

Common Pitfalls to Avoid

• Do not delay aspirin or P2Y12 inhibitor administration for laboratory results or imaging 1
• Do not use fondaparinux as sole anticoagulant for primary PCI 1
• Do not give prasugrel to patients with prior stroke/TIA 1
• Do not routinely administer IV beta-blockers in the acute phase 4
• Do not provide supplemental oxygen to non-hypoxemic patients 2
• Do not withhold antiplatelet therapy due to elevated transaminases alone 6