What medications should be administered immediately in the emergency department to an adult with suspected ST‑segment‑elevation myocardial infarction?

Immediate Medications for STEMI in the Emergency Department

All STEMI patients should receive aspirin (162-325 mg oral or IV if unable to swallow) immediately upon arrival, followed by a potent P2Y12 inhibitor (prasugrel 60 mg or ticagrelor 180 mg loading dose) before or at the time of PCI, plus anticoagulation with unfractionated heparin as a weight-adjusted IV bolus. 1, 2, 3

Core Immediate Medications (Within Minutes of Diagnosis)

Antiplatelet Therapy

• Aspirin 162-325 mg (oral or IV if patient cannot swallow) given immediately without delay 1, 2, 4
• P2Y12 inhibitor loading dose administered before or at the time of PCI 1, 2, 3:
  • Prasugrel 60 mg (preferred) 1, 2, 3
  • Ticagrelor 180 mg (preferred alternative) 1, 2, 3
  • Clopidogrel 600 mg only if prasugrel and ticagrelor are contraindicated or unavailable 1, 2
  • Avoid prasugrel in patients with prior stroke/TIA 1

Anticoagulation

• Unfractionated heparin (UFH): weight-adjusted IV bolus followed by continuous infusion 1, 2, 4
• Enoxaparin: acceptable alternative with IV bolus followed by subcutaneous dosing 1
• Bivalirudin: acceptable alternative anticoagulant 2
• Do NOT use fondaparinux as sole anticoagulant for primary PCI (Class III: Harm) 1, 4

Fibrinolytic Strategy Medications (If PCI Cannot Be Performed Within 120 Minutes)

When primary PCI cannot be achieved within 120 minutes of diagnosis, initiate the following within 10 minutes 1, 2:

• Fibrin-specific thrombolytic agent (tenecteplase, alteplase, or reteplase) 1, 2
• Aspirin (oral or IV) 1, 2
• Clopidogrel loading dose in addition to aspirin 1, 2
• Enoxaparin (IV bolus followed by subcutaneous) preferred over UFH 1, 2
• UFH as weight-adjusted IV bolus followed by infusion if enoxaparin unavailable 1

Adjunctive Medications

Pain Management

• Morphine 4-8 mg IV for chest pain relief, though use with caution as it may affect blood pressure and potentially reduce effectiveness of oral P2Y12 inhibitors 4
• Sublingual nitroglycerin up to three doses at 5-minute intervals if systolic BP ≥90 mmHg and heart rate 50-100 bpm 2
• IV nitroglycerin can be continued for 24-48 hours in hemodynamically stable patients 2

Oxygen

• Supplemental oxygen only if oxygen saturation <90% 1, 2, 4
• Routine oxygen administration is NOT recommended (Class III) 1

Early Secondary Prevention (Within 24 Hours)

• High-intensity statin initiated as soon as possible 1, 3
• Oral beta-blocker within 24 hours after successful reperfusion if no contraindications (heart failure, cardiogenic shock, bradycardia) 3, 4
• ACE inhibitor within first 24 hours, particularly important in anterior STEMI 3

Critical Pitfalls to Avoid

• Never delay reperfusion while waiting for cardiac biomarkers; treat based on ECG and clinical presentation 4
• Avoid IV beta-blockers in the acute STEMI setting (Class III recommendation) 4, 5
• Do not use NSAIDs for pain relief due to increased mortality and reinfarction risk 4
• Do not use fondaparinux for primary PCI 1, 4
• Avoid clopidogrel as first-line P2Y12 inhibitor when prasugrel or ticagrelor are available, as they provide more prompt and potent antiplatelet effects 1, 2, 3

Timing Targets

• Aspirin and P2Y12 inhibitor: immediately, without waiting for laboratory results 2, 4
• Primary PCI: door-to-balloon ≤90 minutes (≤60 minutes for early presenters) 2
• Fibrinolytic therapy: door-to-needle ≤30 minutes if PCI cannot be performed within 120 minutes 1, 2
• ECG: obtain and interpret within 10 minutes of first medical contact 2