What is the recommended anticoagulation management prior to surgery for patients on warfarin (Low Molecular Weight Heparin), novel oral anticoagulants (NOACs) such as apixaban (Apixaban) or rivaroxaban (Rivaroxaban), and aspirin?

Anticoagulation Management Prior to Surgery

Warfarin Management

For patients on warfarin, discontinue therapy 5 days before elective surgery to allow the INR to fall to ≤1.5, and determine whether bridging with LMWH is needed based on thromboembolic risk stratification. 1, 2

Preoperative Warfarin Protocol

• Stop warfarin 5 days (or 5-6 doses) before the planned procedure to allow adequate washout time for INR normalization 1
• Check INR on the day before surgery to confirm it is ≤1.5 before proceeding 1
• If INR is 1.5-1.8 on the day before surgery, administer low-dose oral vitamin K (1-2.5 mg) for reversal 1
• For elderly patients, those with high-intensity INR targets (3.0-4.0), or those on longer-acting coumarins, extend the washout period beyond 5 days 1

Bridging Anticoagulation Decision

High thromboembolic risk patients (requiring bridging) include 1, 2:

• Mechanical heart valves (especially mitral position)
• Recent VTE within 3 months
• Atrial fibrillation with CHADS₂ score ≥5 or prior stroke
• Antiphospholipid syndrome with recurrent thrombosis

Low to moderate thromboembolic risk patients (no bridging needed) include 1, 3:

• Atrial fibrillation with CHADS₂ <5 without prior stroke
• VTE >3 months ago
• The landmark BRIDGE trial demonstrated that forgoing bridging in atrial fibrillation patients was noninferior for preventing thromboembolism (0.4% vs 0.3%) but superior for reducing major bleeding (1.3% vs 3.2%, P=0.005) 3

LMWH Bridging Protocol (When Indicated)

For high-risk patients requiring bridging 1, 2:

• Start therapeutic-dose LMWH 36 hours after the last warfarin dose (approximately 3 days before surgery) when INR falls below 2.0 1
• Administer the last preoperative LMWH dose 24 hours before surgery at half the normal daily dose to minimize residual anticoagulant effect 1
• Therapeutic LMWH dosing: enoxaparin 1 mg/kg twice daily or 1.5 mg/kg once daily; dalteparin 100-200 IU/kg daily 1

Critical caveat: Studies show that 16-30% of patients have residual anticoagulant effect (anti-Xa ≥0.10 IU/mL) at the time of surgery despite following standard protocols, with therapeutic-dose LMWH being the strongest predictor 4, 5

Postoperative Warfarin Resumption

• Resume warfarin at the usual maintenance dose on the evening of surgery or the next morning once adequate hemostasis is achieved 1, 2
• For low bleeding risk procedures: restart therapeutic-dose LMWH within 24 hours postoperatively and continue until INR ≥2.0 for 2 consecutive days 1
• For high bleeding risk procedures: delay therapeutic LMWH for 48-72 hours postoperatively, or use prophylactic-dose LMWH initially 1, 2
• Major bleeding rates as high as 20% occur when therapeutic LMWH is resumed too soon after high-risk surgery 1

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Novel Oral Anticoagulants (NOACs) Management

For patients on NOACs (apixaban, rivaroxaban, dabigatran), the timing of discontinuation depends on bleeding risk of the procedure and renal function, with no bridging anticoagulation required. 1, 6

Low Bleeding Risk Procedures

Discontinue NOACs the night before the procedure (last dose on the morning of the day before surgery for twice-daily regimens or morning-dosed once-daily regimens) 1

• For apixaban and rivaroxaban: last dose should be at least 24 hours before low-risk procedures 1, 6
• For dabigatran: last dose 24 hours before procedure if CrCl >50 mL/min 1
• Resume NOACs at least 6 hours after the procedure once hemostasis is achieved 1, 6

High Bleeding Risk Procedures

For apixaban, rivaroxaban, and edoxaban 1:

• Discontinue 3 days (≥48 hours) before high bleeding risk procedures 1
• The FDA-approved apixaban label specifically states discontinuation at least 48 hours prior to elective surgery with moderate-to-high bleeding risk 6

For dabigatran (renal elimination requires longer washout) 1:

• CrCl >50 mL/min: discontinue 4 days before surgery
• CrCl 30-50 mL/min: discontinue 5 days (72 hours minimum) before surgery 1
• For rapidly deteriorating renal function, consult hematology 1

Very High Bleeding Risk Procedures

For intracranial neurosurgery or neuraxial anesthesia, extend the discontinuation period beyond standard high-risk timing 1, 2

Key Differences from Warfarin Management

• No bridging anticoagulation is recommended for NOACs due to their rapid onset/offset and evidence showing increased bleeding without thrombotic benefit 1
• No routine measurement of NOAC concentrations is needed before procedures 1
• Switching from warfarin to NOACs: discontinue warfarin and start NOAC when INR <2.0 6

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Aspirin Management

Continue aspirin perioperatively for most patients, as the cardiovascular risk of discontinuation typically outweighs bleeding risk, except for specific high bleeding risk procedures. 1

When to Continue Aspirin

• Patients with coronary stents (bare-metal <6 weeks or drug-eluting <6-12 months) should continue aspirin perioperatively if at all possible 2
• High thrombotic risk patients undergoing high-risk endoscopic procedures should continue aspirin with cardiology consultation regarding dual antiplatelet therapy 1
• Most surgical procedures can be safely performed on aspirin monotherapy 1

When to Discontinue Aspirin

• Stop aspirin 7 days before surgery for procedures where even minor bleeding could have catastrophic consequences (intracranial surgery, spinal surgery with neuraxial anesthesia) 1
• For elective coronary artery bypass grafting in low-risk patients, discontinue aspirin 7 days preoperatively 7

Dual Antiplatelet Therapy (Aspirin + P2Y12 Inhibitor)

• Stop clopidogrel, prasugrel, or ticagrelor 5-7 days before high bleeding risk procedures while continuing aspirin if possible 1, 2
• Resume P2Y12 inhibitors as soon as hemostasis is achieved, ideally within 24 hours 2
• For patients with recent coronary stents requiring urgent surgery, delaying surgery even 12 hours can reduce bleeding risk if clinically feasible 7

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Common Pitfalls and Critical Safety Points

Major Bleeding Risks

• Administering therapeutic LMWH too soon postoperatively increases major bleeding to 20% after high-risk procedures 1, 2
• Residual LMWH effect at surgery time occurs in 16-30% of bridged patients, particularly with therapeutic dosing, advanced age, and higher BMI 4, 5
• Never perform neuraxial procedures with residual NOAC effect, especially dabigatran in elderly or renally impaired patients 2

Thrombotic Risks

• Inadequate warfarin washout period in elderly or high-intensity INR patients can lead to bleeding 1
• Bridging low-risk atrial fibrillation patients increases bleeding without reducing thromboembolism 3
• Stopping antiplatelet therapy in recent stent patients can cause catastrophic stent thrombosis 2

Monitoring Requirements

• Check INR the day before surgery for all warfarin patients to confirm ≤1.5 1, 2
• Reassess renal function postoperatively as it affects LMWH and NOAC dosing 2
• Monitor hemoglobin, platelet count, and creatinine at baseline and as clinically indicated 2
• Check INR daily after warfarin resumption until therapeutic range (2.0-3.0) is achieved 2