Enoxaparin Anticoagulation for PCI
For patients undergoing PCI without prior anticoagulation, administer enoxaparin 0.5-0.75 mg/kg IV bolus at the time of the procedure, with 0.5 mg/kg being the preferred dose due to significantly lower bleeding rates while maintaining adequate anticoagulation. 1, 2
Dosing Algorithm Based on Prior Enoxaparin Exposure
No Prior Anticoagulation (De Novo PCI)
- Administer 0.5-0.75 mg/kg IV bolus immediately before PCI 1, 2
- The 0.5 mg/kg dose is preferred as it reduces non-CABG-related bleeding by 2.6% absolute risk reduction compared to UFH (5.9% vs 8.5%, p=0.01), while the 0.75 mg/kg dose shows no significant bleeding benefit 3
- This single bolus achieves anti-Xa levels >0.5 IU/mL in nearly 100% of patients, providing adequate anticoagulation for 2-4 hours 3, 4, 5
Prior Subcutaneous Enoxaparin Administration
Last dose within 8 hours:
- Give NO additional enoxaparin - adequate anticoagulation persists 1, 2, 6
- Proceed directly to PCI without supplemental anticoagulation 6
Last dose 8-12 hours prior OR fewer than 2 therapeutic SC doses:
- Administer 0.3 mg/kg IV enoxaparin (Class I recommendation) 1, 2
- This supplemental dose restores therapeutic anticoagulation as the effect from subcutaneous dosing diminishes 1
Last dose >12 hours prior:
- Treat as de novo anticoagulation with full-dose regimen (0.5-0.75 mg/kg IV enoxaparin OR switch to UFH/bivalirudin) 1, 2, 6
- Standard UFH dosing: 70-100 U/kg IV bolus without GP IIb/IIIa inhibitor, or 50-70 U/kg with GP IIb/IIIa inhibitor 1, 6
Critical Safety Considerations
Avoid "Stacking" (Class III: Harm)
- Never administer UFH to patients who received subcutaneous enoxaparin within 12 hours 1, 6
- This combination significantly increases bleeding risk, as demonstrated in the SYNERGY trial where bleeding complications were attributed to inappropriate UFH administration on top of enoxaparin 1
Monitoring
- ACT monitoring is NOT required or reliable with enoxaparin - it has minimal effect on ACT measurements despite adequate anticoagulation 6
- Anti-Xa level monitoring is not routinely necessary due to predictable pharmacokinetics 2, 4
- Target anti-Xa levels (>0.5 IU/mL) are achieved in 79% with 0.5 mg/kg and 92% with 0.75 mg/kg, compared to only 20% achieving target ACT with UFH 3
Prolonged Procedures
- For procedures exceeding 90-120 minutes, administer an additional 0.3 mg/kg IV bolus 7
- The 0.5 mg/kg dose maintains anti-Xa >0.5 IU/mL for approximately 2.7 hours, while 0.75 mg/kg extends this to 3.4 hours 4, 7
Evidence Quality and Guideline Strength
The ACC/AHA guidelines classify enoxaparin use in PCI as Class IIb (Level of Evidence: B), indicating it "may be reasonable" but is not the preferred first-line agent 1. This contrasts with bivalirudin and UFH, which both carry Class I recommendations 1. However, the 0.3 mg/kg supplemental dose for patients on upstream subcutaneous enoxaparin carries a Class I recommendation 1.
Despite the moderate guideline recommendation, research evidence demonstrates enoxaparin's safety profile. In primary PCI for STEMI, enoxaparin was associated with lower major bleeding (2.6% vs 4.4%, adjusted OR 0.55, p=0.045) and reduced 30-day composite ischemic outcomes (5.3% vs 8.0%, adjusted OR 0.47, p=0.0005) compared to UFH 8. The STEEPLE trial in elective PCI confirmed that 0.5 mg/kg enoxaparin significantly reduces bleeding while maintaining predictable anticoagulation 3.
Common Pitfalls
- Do not rely on ACT values to guide enoxaparin dosing or assess adequacy of anticoagulation 6
- Do not give additional UFH within 8-12 hours of the last enoxaparin dose - this creates dangerous over-anticoagulation 1, 6
- Do not use higher doses (>0.75 mg/kg) as they markedly increase the proportion of patients with excessive anti-Xa levels (>1.5 IU/mL) to 48-79% without improving efficacy 4
- Watch for catheter thrombosis - one study reported increased sheath catheter thrombosis with 0.75 mg/kg enoxaparin (26.6% vs 10% with UFH), though this did not translate to clinical events 7