What are the perioperative guidelines for managing anticoagulant (blood thinner) and antiplatelet agents in patients undergoing surgery?

Perioperative Management of Anticoagulant and Antiplatelet Agents

For patients on warfarin requiring elective surgery, stop warfarin 5 days before surgery, resume 12-24 hours postoperatively when hemostasis is adequate, and use bridging anticoagulation only in high-risk patients (mechanical heart valves, atrial fibrillation with high stroke risk, or recent VTE). 1

Warfarin Management

Preoperative Discontinuation

• Stop warfarin approximately 5 days before surgery to allow INR normalization (target INR <1.5 for major surgery) 1
• For minor procedures where bleeding risk is lower, a shorter interruption (2-3 days) targeting INR 1.5-1.8 may be sufficient 1
• Check INR the day before surgery when feasible to identify elevated values requiring oral vitamin K (1.0-2.5 mg) 1

Postoperative Resumption

• Resume warfarin 12-24 hours after surgery (evening of surgery or next morning) when adequate hemostasis is achieved 1
• No tapering is required when resuming therapy 2

Bridging Anticoagulation Decision

High-Risk Patients (USE bridging): 1

• Mechanical heart valves (especially mitral position or older valve types)
• Atrial fibrillation with CHADS₂ score ≥5 or recent stroke/TIA (<3 months)
• Recent VTE (<3 months) or recurrent VTE

Low-Risk Patients (NO bridging): 1

• Atrial fibrillation with CHADS₂ score ≤2
• Remote VTE (>12 months) without recurrence
• Bileaflet aortic valve without other risk factors

The evidence shows that bridging increases bleeding risk without clear thrombotic benefit in low-risk patients 3, with one large observational study demonstrating only 0.7% thromboembolism rate with brief warfarin interruption without bridging 3.

Bridging Protocol (When Indicated)

Low-Molecular-Weight Heparin (LMWH) Bridging: 1

• Last preoperative dose: 24 hours before surgery (not 12 hours) to minimize bleeding risk 1
• Postoperative resumption timing:
  • High bleeding risk surgery: Resume therapeutic LMWH 48-72 hours after surgery 1
  • Low-moderate bleeding risk surgery: Resume therapeutic LMWH 24 hours after surgery 1

Unfractionated Heparin (UFH) Bridging: 1

• Stop IV UFH 4-6 hours before surgery 1

Minor Procedures (Dental, Dermatologic, Cataract Surgery)

Continue warfarin without interruption for these low-bleeding-risk procedures: 1

• Dental procedures: Continue warfarin with oral prohemostatic agent OR stop 2-3 days before 1
• Dermatologic procedures: Continue warfarin and optimize local hemostasis 1
• Cataract surgery: Continue warfarin perioperatively 1

This approach avoids the thrombotic risk of warfarin interruption while maintaining acceptable bleeding rates with local hemostatic measures 1.

Aspirin (ASA) Management

Risk-Stratified Approach

Continue ASA perioperatively: 1

• Moderate-to-high cardiovascular risk patients undergoing noncardiac surgery 1
• All patients undergoing CABG surgery 1
• Minor dental, dermatologic, or cataract procedures 1

Stop ASA 7-10 days before surgery: 1

• Low cardiovascular risk patients undergoing elective surgery 1

The decision balances the 1-2% risk of perioperative myocardial ischemia against increased surgical bleeding 1.

Dual Antiplatelet Therapy (DAPT) and Coronary Stents

Critical Timing Recommendations

Defer elective surgery: 1

• ≥6 weeks after bare-metal stent placement 1
• ≥6 months after drug-eluting stent placement 1

This strong recommendation (Grade 1C) reflects the catastrophic consequences of stent thrombosis, which carries 20-45% mortality 1.

Urgent Surgery Within Critical Window

If surgery cannot be deferred: 1

• Continue dual antiplatelet therapy perioperatively rather than stopping both agents 7-10 days before surgery 1
• Accept increased bleeding risk to prevent stent thrombosis 1
• This represents a Grade 2C recommendation acknowledging the difficult risk-benefit balance 1

CABG-Specific Management

For patients on DAPT requiring CABG: 1

• Continue aspirin perioperatively 1
• Stop clopidogrel/prasugrel 5 days before surgery 1, 4
• Stop ticagrelor 3-5 days before surgery 5, 4
• Stop prasugrel 7 days before surgery 5, 4

Postoperative Resumption

• Resume antiplatelet therapy within 24 hours after surgery when hemostasis is adequate 5, 4
• Consider clopidogrel loading dose (300 mg) for patients with drug-eluting stents 5

P2Y12 Inhibitor Management (Clopidogrel, Prasugrel, Ticagrelor)

Discontinuation timing for elective noncardiac surgery: 5, 4

• Clopidogrel: 5 days before surgery 5, 4
• Prasugrel: 7 days before surgery 5, 4
• Ticagrelor: 3-5 days before surgery 5, 4

These intervals allow approximately 10-14% platelet function recovery per day after clopidogrel discontinuation 4.

Common Pitfalls and Caveats

Medication Reconciliation

• Patients may not report over-the-counter NSAIDs with antiplatelet effects, requiring thorough medication history 5
• Multiple antiplatelet or anticoagulant agents significantly increase bleeding risk 5

High-Bleeding-Risk Procedures

Specific procedures warrant particular caution with antithrombotic continuation: 1

• Transurethral prostate resection and urologic procedures (endogenous urokinase release)
• Pacemaker/ICD implantation (pocket hematoma risk)
• Large colonic polyp resection
• Cardiac, intracranial, or spinal surgery (small bleeds have serious consequences)
• Major cancer surgery or joint arthroplasty

Laboratory Monitoring

• Check INR day before surgery when stopping warfarin to identify patients needing vitamin K 1
• Routine platelet function testing is not recommended for guiding perioperative antiplatelet management 4

Standardized Protocols

Institutions should implement standardized perioperative protocols including: 1

• Assessment at least 7 days before surgery
• Patient calendar outlining medication timing
• Patient education on LMWH injection technique for outpatient bridging
• Postoperative hemostasis assessment before resuming anticoagulation