Fondaparinux Dosing for STEMI
Fondaparinux is NOT recommended as the sole anticoagulant for STEMI patients undergoing primary PCI due to increased risk of catheter thrombosis, but for STEMI patients receiving fibrinolytic therapy or no reperfusion, the dose is 2.5 mg IV initially, followed by 2.5 mg subcutaneously once daily. 1
Critical Context: When Fondaparinux Should NOT Be Used
Fondaparinux carries a Class III: Harm recommendation (meaning it should NOT be used) as the sole anticoagulant to support primary PCI in STEMI patients. 1 This is because of documented increased risk of catheter thrombosis during the procedure. 1 If fondaparinux has already been given and PCI is planned, you must add an anticoagulant with anti-IIa activity (such as unfractionated heparin 50-100 U/kg bolus) to prevent catheter-related thrombotic complications. 1
Appropriate Use: Fibrinolytic Therapy or No Reperfusion
Standard Dosing Regimen
For STEMI patients receiving fibrinolytic therapy (specifically non-fibrin-specific agents like streptokinase) or no reperfusion therapy:
- Initial dose: 2.5 mg IV bolus 1
- Maintenance dose: 2.5 mg subcutaneously once daily 1, 2, 3, 4
- Duration: Up to 8 days or until hospital discharge 2, 3, 4
Renal Dosing Adjustments
Critical renal function assessment is mandatory before administering fondaparinux:
- Creatinine clearance ≥30 mL/min: Standard dose of 2.5 mg once daily 1
- Creatinine clearance <30 mL/min: Fondaparinux is contraindicated and should be avoided 1
The American Heart Association guidelines specifically state that fondaparinux should be avoided when creatinine clearance is below 30 mL/min. 1 Unlike enoxaparin, there is no reduced-dose option for severe renal impairment—you must choose an alternative anticoagulant. 1
Age Considerations
Unlike enoxaparin, fondaparinux does not require dose reduction based on age alone. 1 The 2.5 mg once-daily dose remains standard regardless of whether the patient is above or below 75 years of age. 1
Evidence Supporting This Approach
The OASIS-6 trial (n=12,092) demonstrated that fondaparinux 2.5 mg daily significantly reduced death and reinfarction at 30 days compared to usual care (9.7% vs 11.2%, p=0.008) without increasing major bleeding (1.0% vs 1.3%, p=0.13). 3, 4 However, this benefit was seen predominantly in patients receiving fibrinolysis or no reperfusion therapy. 3, 4
In the subgroup of 2,867 STEMI patients not receiving any reperfusion therapy, fondaparinux reduced death or reinfarction from 15.1% to 12.2% (HR 0.80,95% CI 0.65-0.98) without increasing severe bleeding. 5
Common Pitfalls to Avoid
- Using fondaparinux as sole anticoagulant during primary PCI: This is explicitly contraindicated (Class III: Harm) due to catheter thrombosis risk. 1
- Failing to add UFH during PCI if patient already on fondaparinux: If PCI becomes necessary, add 50-100 U/kg UFH bolus to prevent catheter thrombosis. 1
- Administering to patients with severe renal impairment: Fondaparinux is contraindicated when creatinine clearance is <30 mL/min. 1
- Confusing fondaparinux dosing with enoxaparin: Fondaparinux is always 2.5 mg once daily regardless of weight or age (unless contraindicated by renal function), whereas enoxaparin requires weight-based and age-based adjustments. 1, 6, 7