Internal Medicine · Year 3 · from Internal Medicine
Case 2: Perioperative Anticoagulation Management
Patient Presentation
A 72-year-old woman with a history of atrial fibrillation, mechanical mitral valve replacement (3 years ago), and hypertension is scheduled for elective colon surgery for a recently diagnosed adenocarcinoma. She takes warfarin with an INR consistently 2.5-3.5. She has no history of stroke or TIA. Her CHA₂DS₂-VASc score is 4.
Vital Signs
- Blood Pressure: 132/78 mmHg
- Heart Rate: 72 bpm (irregularly irregular)
Physical Examination
- General: Well-appearing
- Cardiovascular: Irregularly irregular rhythm, mechanical valve click
- Abdomen: Non-tender, palpable mass in RLQ
Current Medications
- Warfarin 5 mg daily
- Lisinopril 10 mg daily
- Metoprolol 50 mg BID
Laboratory Results
- INR: 2.8
- Creatinine: 0.9 mg/dL
- Hemoglobin: 11.8 g/dL
Clinical Image
Figure 2: Algorithm for perioperative bridging anticoagulation based on thromboembolism risk.
Image Source: Educational illustration for teaching purposes.
Questions
- Does this patient require bridging anticoagulation?
- A) No, bridging is never indicated
- B) Yes, because of mechanical mitral valve (high thromboembolism risk)
- C) Only for atrial fibrillation alone
- D) Depends on bleeding risk only
- What is the appropriate bridging protocol?
- A) Stop warfarin; no bridging needed
- B) Stop warfarin 5 days before surgery; start therapeutic LMWH 3 days before; hold LMWH 24 hours before surgery
- C) Continue warfarin through surgery
- D) Switch to aspirin only
- When should anticoagulation be resumed postoperatively?
- A) Immediately after surgery
- B) Resume LMWH 24-72 hours post-op if adequate hemostasis; restart warfarin when tolerating oral intake
- C) Wait 7 days
- D) Never resume, switch to antiplatelet
- How would management differ for a patient with atrial fibrillation alone (no mechanical valve)?
- What is the role of DOACs in perioperative management?
Answers
- B) Yes, because of mechanical mitral valve (high thromboembolism risk) - Bridging indications:
- High risk (bridge indicated): Mechanical mitral valve, mechanical aortic valve with additional risk factors, recent VTE (<3 months), AF with CHA₂DS₂-VASc ≥5 or recent stroke
- Moderate risk (individualize): Mechanical aortic valve, AF with CHA₂DS₂-VASc 3-4
- Low risk (no bridging): AF with CHA₂DS₂-VASc ≤2, VTE >12 months ago
- Mechanical mitral valves have highest thromboembolism risk
- B) Stop warfarin 5 days before surgery; start therapeutic LMWH 3 days before; hold LMWH 24 hours before surgery - Protocol:
- Stop warfarin 5 days before surgery (INR should be ≤1.5)
- Start therapeutic LMWH (enoxaparin 1 mg/kg BID) 3 days before surgery
- Last dose of LMWH 24 hours before surgery
- Check INR day before surgery; give vitamin K if still elevated
- Surgery with INR ≤1.5
- B) Resume LMWH 24-72 hours post-op if adequate hemostasis; restart warfarin when tolerating oral intake - Postoperative management:
- Colon surgery is high bleeding risk - wait 48-72 hours for LMWH
- Resume warfarin when tolerating oral intake (usually post-op day 1-2)
- Continue LMWH until INR therapeutic for 24 hours
- Balance thromboembolism risk against surgical bleeding risk
- Management for AF alone (no mechanical valve):
- BRIDGE trial showed NO benefit of bridging for most AF patients
- For AF with CHA₂DS₂-VASc ≤4: No bridging recommended
- For AF with CHA₂DS₂-VASc ≥5 or recent stroke: Consider bridging
- CHA₂DS₂-VASc 4: This patient would NOT need bridging for AF alone
- The mechanical valve is the indication for bridging, not the AF
- DOAC perioperative management:
- Simpler than warfarin - predictable offset, no bridging needed
- Hold based on half-life and renal function:
- Normal renal function: Hold 24-48 hours before low bleeding risk surgery; 48-72 hours before high risk
- CrCl 30-50: Hold 36-48 hours (low risk) or 48-96 hours (high risk)
- CrCl 15-30: Hold 36-48 hours (low risk) or 96 hours (high risk)
- Resume 24-72 hours postoperatively depending on bleeding risk
- No bridging anticoagulation required for DOACs