What anticoagulants should be initiated in a 64-year-old male with non-ST-segment elevation myocardial infarction (NSTEMI) and planned cardiac catheterization using radial artery access, with significant substernal chest pain and positive cardiac biomarkers?

Anticoagulation for NSTEMI with Planned Cardiac Catheterization

Initiate aspirin immediately (162-325 mg non-enteric-coated) plus a P2Y12 inhibitor (clopidogrel 600 mg or ticagrelor 180 mg loading dose) along with parenteral anticoagulation using either enoxaparin (1 mg/kg subcutaneously every 12 hours), fondaparinux (2.5 mg subcutaneously daily), bivalirudin (0.75 mg/kg IV bolus followed by 1.75 mg/kg/h infusion), or unfractionated heparin (60 IU/kg bolus, maximum 4000 IU, followed by 12 IU/kg/h infusion, maximum 1000 IU/h). 1, 2

Antiplatelet Therapy to Initiate Now

Aspirin:

• Administer 162-325 mg non-enteric-coated aspirin immediately upon presentation 1, 2
• Non-enteric-coated formulation is essential for rapid absorption 1
• Continue 81 mg daily indefinitely after the acute phase 1, 2

P2Y12 Inhibitor Selection:

• Ticagrelor 180 mg loading dose is preferred over clopidogrel for patients with planned invasive strategy, as it demonstrates superior outcomes in reducing cardiovascular death and MI 1
• Clopidogrel 600 mg loading dose is an acceptable alternative, particularly if concerns exist about bleeding risk or patient compliance with twice-daily dosing 1
• Avoid prasugrel at this time since coronary anatomy is not yet defined; prasugrel should only be given after angiography confirms anatomy suitable for PCI and excludes need for urgent CABG 1

Parenteral Anticoagulation Options

Preferred agents for patients with planned next-day catheterization:

Enoxaparin (Preferred):

• Dose: 1 mg/kg subcutaneously every 12 hours 1, 2
• Give initial 30 mg IV loading dose in selected patients 1
• Reduce to 1 mg/kg once daily if creatinine clearance <30 mL/min 1
• Continue until PCI is performed 1, 2
• Enoxaparin is preferable to unfractionated heparin for conservative strategy unless CABG planned within 24 hours 1

Fondaparinux:

• Dose: 2.5 mg subcutaneously once daily 1, 2
• Continue for duration of hospitalization or until PCI 1, 2
• Critical caveat: Must administer additional anticoagulant with anti-IIa activity (such as unfractionated heparin or bivalirudin) during PCI if patient is on fondaparinux 1, 2

Bivalirudin:

• Dose: 0.75 mg/kg IV bolus followed by 1.75 mg/kg/h infusion 1, 3
• Assess ACT 5 minutes after bolus; give additional 0.3 mg/kg bolus if needed 3
• Particularly reasonable if upstream GP IIb/IIIa inhibitor is being omitted and clopidogrel 300 mg was given at least 6 hours before planned catheterization 1
• Reduce infusion to 1 mg/kg/h if creatinine clearance <30 mL/min 3

Unfractionated Heparin:

• Dose: 60 IU/kg IV bolus (maximum 4000 IU) followed by 12 IU/kg/h infusion (maximum 1000 IU/h) 1, 4
• Adjust to therapeutic aPTT range 1
• Continue for 48 hours or until PCI is performed 1, 2
• Less preferred than enoxaparin or fondaparinux unless CABG is anticipated within 24 hours 1

GP IIb/IIIa Inhibitor Considerations

Upstream administration (before catheterization) is generally NOT recommended in this clinical scenario 1:

• This patient has positive troponin (high-risk feature) but is planned for catheterization tomorrow morning with radial access 1
• If bivalirudin is selected as anticoagulant and clopidogrel 300 mg was given at least 6 hours before catheterization, it is reasonable to omit upstream GP IIb/IIIa inhibitor 1
• Upstream GP IIb/IIIa inhibitors (eptifibatide or tirofiban) may be considered only if patient is very high-risk (elevated troponin, diabetes, significant ST-depression) AND not at high bleeding risk 1
• Abciximab should NOT be given to patients in whom PCI is not immediately planned 1

Critical Pitfalls to Avoid

Do not use enteric-coated aspirin initially - it has delayed and reduced absorption 1

Do not give prasugrel before coronary anatomy is defined - risk of bleeding complications if urgent CABG is needed 1

Do not forget additional anticoagulation during PCI if fondaparinux was used - fondaparinux alone has insufficient anti-IIa activity for PCI 1, 2

Do not routinely give upstream GP IIb/IIIa inhibitors in patients with planned next-day catheterization who are already receiving dual antiplatelet therapy and anticoagulation 1

Recommended Regimen for This Patient

For this 64-year-old male with NSTEMI and planned morning catheterization via radial access:

1. Aspirin 162-325 mg non-enteric-coated immediately 1, 2
2. Ticagrelor 180 mg loading dose (preferred) OR clopidogrel 600 mg loading dose 1
3. Enoxaparin 1 mg/kg subcutaneously every 12 hours (preferred anticoagulant for overnight management) 1, 2
4. Omit upstream GP IIb/IIIa inhibitor unless recurrent ischemia develops overnight 1

This regimen provides optimal antithrombotic protection while minimizing bleeding risk for planned next-day catheterization 1, 2.