What is the recommended dosing of enoxaparin (low molecular weight heparin) after administering tenecteplase (tissue plasminogen activator) for ST-Elevation Myocardial Infarction (STEMI)?

Enoxaparin Dosing After Tenecteplase for STEMI

For patients receiving tenecteplase for STEMI, enoxaparin should be administered as an initial 30 mg IV bolus followed by 1 mg/kg subcutaneously every 12 hours (maximum 100 mg for first two doses) until hospital discharge or up to 8 days. 1

Age-Based Dosing Adjustments

• For patients <75 years of age: 30 mg IV bolus followed by 1 mg/kg SC every 12 hours (first SC dose shortly after the IV bolus) 1
• For patients ≥75 years of age: No initial IV bolus; 0.75 mg/kg SC every 12 hours 1

Renal Function Adjustments

• For patients with impaired renal function (creatinine clearance <30 mL/min): 1 mg/kg SC once daily 1
• Alternatively, patients with known impaired renal function may be managed with unfractionated heparin (UFH) 1

Clinical Evidence Supporting Enoxaparin with Tenecteplase

• Enoxaparin is the most comprehensively studied low-molecular-weight heparin (LMWH) regimen in combination with tenecteplase 1
• The ENTIRE-TIMI 23 trial demonstrated that enoxaparin with tenecteplase is associated with similar TIMI 3 flow rates as UFH while exhibiting advantages with respect to ischemic events through 30 days 2
• In the ExTRACT-TIMI 25 trial, enoxaparin was significantly more effective than UFH in patients receiving fibrinolytic therapy in terms of reducing the 30-day combined incidence of all-cause mortality plus recurrent nonfatal myocardial infarction 3

Timing Considerations

• The first subcutaneous dose of enoxaparin should be administered within 15 minutes after the IV bolus 3
• For patients undergoing PCI after receiving subcutaneous enoxaparin, timing is important: 4
  • If angiography/PCI is performed within 8 hours of the last SC dose: No additional anticoagulation needed 1
  • If angiography/PCI is performed 8-12 hours after the last SC dose: An additional IV dose of 0.3 mg/kg enoxaparin should be administered 1, 4

Important Cautions

• Patients initially treated with enoxaparin should not be switched to UFH and vice versa because of increased risk of bleeding 1
• Platelet counts should be monitored daily in patients receiving heparin therapy 1
• Avoid using enoxaparin as an alternative to UFH in patients over 75 years who are receiving fibrinolytic therapy without appropriate dose adjustment 1

Duration of Therapy

• Anticoagulation with enoxaparin should be continued until revascularization (if performed) or for the duration of hospital stay up to 8 days 1, 3

Alternative Anticoagulants

• If enoxaparin cannot be used, UFH can be administered as a weight-adjusted IV bolus of 60 U/kg (maximum 4000 U) followed by an initial infusion of 12 U/kg per hour (maximum 1000 U/hr) adjusted to maintain aPTT at 1.5 to 2.0 times control (approximately 50 to 70 seconds) 1
• For patients with known heparin-induced thrombocytopenia, bivalirudin may be considered as an alternative 1

Following these evidence-based dosing recommendations for enoxaparin after tenecteplase administration will help optimize outcomes in STEMI patients by reducing the risk of recurrent ischemic events while minimizing bleeding complications.