In an adult with acute ST‑elevation myocardial infarction (STEMI), what intravenous drip therapies should be initiated during the initial management while arranging reperfusion?

STEMI Intravenous Drip Therapies During Initial Management

For adults with acute STEMI, the essential IV drip therapies during initial management while arranging reperfusion are: unfractionated heparin (UFH) as the primary anticoagulant, and aspirin (which can be given IV if oral route unavailable), with consideration of IV beta-blockers only in hemodynamically stable patients without contraindications. 1, 2

Mandatory Anticoagulation

Unfractionated heparin (UFH) is the preferred IV anticoagulant for primary PCI, administered as a weight-adjusted bolus (typically 70 U/kg without maximum dose) with subsequent infusion. 3, 1 This should be initiated immediately upon STEMI diagnosis while arranging catheterization. 1

For patients receiving fibrinolysis (when PCI cannot be achieved within 120 minutes), enoxaparin is preferred over UFH, given as an IV bolus followed by subcutaneous administration. 1 However, if enoxaparin is started, do not switch to UFH during the acute phase as this increases bleeding risk. 1

Antiplatelet Therapy

Aspirin 162-325 mg should be administered immediately upon first medical contact, preferably chewed for rapid absorption. 2, 4 While oral administration is standard, IV aspirin (250 mg) can be used if the patient cannot take oral medications. 3

Ticagrelor 180 mg loading dose should be given orally as soon as possible, ideally in the EMS vehicle or emergency department before catheterization. 1 This is not typically given as an IV drip but is critical initial therapy.

Beta-Blocker Considerations

IV beta-blockers should NOT be routinely administered in the acute STEMI setting. 1 They are contraindicated in patients with:

• Hypotension or hemodynamic instability 1
• Acute heart failure 1
• AV block or marked bradycardia 1
• Cardiogenic shock 3

Oral beta-blockers should be initiated within 24 hours in stable patients and continued indefinitely. 2, 1

Glycoprotein IIb/IIIa Inhibitors

GP IIb/IIIa inhibitors (abciximab or eptifibatide) may be considered as IV infusions during primary PCI, particularly in high-risk patients. 3 These were used in 70% of cases in organized STEMI networks, typically initiated in the catheterization laboratory. 3 However, they are not mandatory for all patients and should be used at the interventionist's discretion. 3

Critical Timing and Pitfalls

Do not delay reperfusion therapy to start additional drips. The priority is achieving:

• Primary PCI within 90 minutes of first medical contact if at a PCI-capable facility 3
• Primary PCI within 120 minutes if transfer is required 3
• Fibrinolysis within 30 minutes if PCI cannot be achieved within these timeframes 3

Avoid fondaparinux as the sole anticoagulant during PCI as it increases catheter thrombosis risk and requires additional UFH. 1

Do not use routine oxygen unless oxygen saturation is <90%. 3 Routine supplemental oxygen in non-hypoxemic patients is not recommended. 3

What NOT to Give as Routine Drips

• Morphine or opioids: While not contraindicated, there is ongoing debate about their safety in STEMI, and they should be used judiciously only for severe pain not relieved by nitrates. 3
• Routine IV nitroglycerin: Not a mandatory drip for all STEMI patients; reserve for ongoing chest pain, hypertension, or pulmonary edema without hypotension
• IV beta-blockers: As noted above, contraindicated in unstable patients 1

Algorithm Summary

1. Immediate (within 10 minutes of diagnosis): 3

   • IV access established
   • Aspirin 162-325 mg (oral preferred, IV if necessary) 2
   • UFH bolus and infusion (if primary PCI planned) 1
   • OR Enoxaparin IV/SC (if fibrinolysis planned) 1

2. While arranging reperfusion:

   • Continue UFH infusion 1
   • Ticagrelor 180 mg orally 1
   • Consider GP IIb/IIIa inhibitor (decision typically made in cath lab) 3

3. Avoid delays: Every minute counts—door-to-balloon or door-to-needle times are critical quality metrics. 3