When should therapeutic heparin be stopped in a patient with acute coronary syndrome (ACS) who has been transitioned to a long-term anticoagulant regimen, such as aspirin and a P2Y12 inhibitor (e.g. clopidogrel)?

When to Stop Therapeutic Heparin in ACS Patients

Therapeutic heparin should be discontinued immediately after completion of percutaneous coronary intervention (PCI) or diagnostic angiography, or after 48 hours if managed medically without intervention. 1

Timing Based on Management Strategy

For Patients Undergoing PCI or Angiography

• Stop parenteral anticoagulation (including UFH, enoxaparin, fondaparinux, or bivalirudin) immediately after the invasive procedure is completed 1
• If using unfractionated heparin, continue for a maximum of 48 hours or until PCI is performed, whichever comes first 1
• Enoxaparin should be continued only until PCI is performed or for the duration of hospitalization if no intervention occurs 1

For Medically Managed Patients (No Intervention)

• Continue parenteral anticoagulation for the duration of hospitalization if managed conservatively 1
• Maximum duration should not exceed 48 hours for UFH in the absence of ongoing ischemia 1

Critical Transition to Oral Antiplatelet Therapy

The key is NOT to stop all antithrombotic therapy—you must transition to dual antiplatelet therapy (DAPT) before or concurrent with stopping heparin:

• Initiate aspirin plus a P2Y12 inhibitor (clopidogrel, ticagrelor, or prasugrel) before discontinuing parenteral anticoagulation 2, 3
• DAPT should continue for at least 12 months in patients not at high bleeding risk 2, 3
• Loading doses of P2Y12 inhibitors should be given early (clopidogrel 300-600 mg, ticagrelor 180 mg, or prasugrel 60 mg) 4

Special Circumstance: Patients Requiring Long-Term Oral Anticoagulation

If the patient requires ongoing anticoagulation (e.g., atrial fibrillation, mechanical valve, venous thromboembolism):

• Stop parenteral anticoagulation after PCI and transition to oral anticoagulant (preferably a DOAC like apixaban) 2, 5
• Use triple therapy (aspirin + P2Y12 inhibitor + oral anticoagulant) for only 1-4 weeks maximum 2, 5
• After 1-4 weeks, discontinue aspirin and continue only P2Y12 inhibitor (preferably clopidogrel) plus oral anticoagulant to reduce bleeding risk 2, 5
• Triple therapy beyond 30 days significantly increases bleeding risk without proportional ischemic benefit 5

Common Pitfalls to Avoid

• Never stop heparin without ensuring adequate oral antiplatelet coverage is established—this creates a dangerous prothrombotic window 1, 3
• Do not continue parenteral anticoagulation beyond the acute phase (48 hours or post-procedure) as this increases bleeding risk without additional benefit 1
• For patients on long-term anticoagulation, the most common error is continuing triple therapy beyond 4 weeks—this dramatically increases major bleeding events 2
• If fondaparinux is used, remember to add a UFH bolus at the time of PCI to prevent catheter thrombosis 1

Bleeding Risk Mitigation

• Prescribe a proton pump inhibitor to all patients receiving DAPT or combination antithrombotic therapy to reduce gastrointestinal bleeding 2, 5, 3
• For high bleeding risk patients (≥75 years, prior bleeding, CKD, low body weight), consider shorter DAPT duration (3-6 months) after the initial transition from heparin 2, 4