How to manage elevated International Normalized Ratio (INR) in a pre-operative patient due to vitamin K antagonist therapy?

Management of Elevated INR in Pre-operative Patients on Vitamin K Antagonists

For pre-operative patients with elevated INR due to vitamin K antagonist therapy, vitamin K administration is not routinely recommended unless the INR is >1.5 within 1-2 days of surgery, in which case 1 mg of oral vitamin K can be administered to normalize the INR for surgery. 1

Initial Assessment and Management

• For patients on vitamin K antagonists (VKAs) requiring elective surgery, VKAs should be stopped 5 days before surgery (for warfarin) or 3 days (for acenocoumarol) to allow INR to fall to ≤1.5 1
• INR should be checked the day before or day of surgery to ensure it's appropriate for the procedure 1
• If INR remains >1.5 within 1-2 days before surgery, management depends on bleeding risk and thrombotic risk 1

Management Algorithm Based on INR and Risk Factors

For INR >1.5 within 1-2 days before elective surgery:

• Low thrombotic risk patients (e.g., bileaflet mechanical aortic valve without risk factors):

  • Consider postponing the procedure if INR >1.5 1
  • If surgery cannot be postponed, 1 mg oral vitamin K can normalize INR in 76.6% of patients within 24 hours 1

• High thrombotic risk patients (mechanical mitral valve, older-generation mechanical valves, or mechanical valve with any risk factor):

  • Bridging anticoagulation with therapeutic-dose LMWH or UFH is recommended during the time when INR is subtherapeutic 1
  • For urgent procedures with elevated INR, 1-2 mg of oral vitamin K may be given 1, 2

Vitamin K Administration for Pre-operative INR Correction

• For INR >1.5 before surgery, 1 mg oral vitamin K can normalize INR (≤1.3) in 76.6% of patients within 24 hours 1
• Intravenous vitamin K (1 mg) given approximately 27 hours pre-operatively can achieve normalized INR in 54.9% of patients 1
• For emergency surgery with elevated INR, fresh frozen plasma or prothrombin complex concentrate with low-dose (1-2 mg) oral vitamin K may be administered 1, 2

Special Considerations for Different Patient Groups

• Mechanical heart valve patients:

  • Require more careful management due to higher thrombotic risk 1
  • May need hospitalization and treatment with IV UFH until 4 hours before surgery 1
  • Higher doses of vitamin K should be avoided to prevent difficulty in re-anticoagulation 1, 2

• Low bleeding risk procedures:

  • For procedures with minimal bleeding risk (skin surgery, dental cleaning, cataract surgery), VKA may be continued without interruption 1

Post-operative Management

• Resume VKA at the usual dose (not double dose) 12-24 hours after surgery when bleeding risk allows 1
• Continue bridging anticoagulation with LMWH or UFH until INR returns to therapeutic range in high-risk patients 1

Common Pitfalls to Avoid

• Administering high-dose vitamin K (>5 mg), which can lead to warfarin resistance for days to weeks 2, 3
• Routine use of pre-operative vitamin K in all patients with elevated INR, which may cause difficulty in post-operative re-anticoagulation 1, 2
• Inadequate bridging therapy in high thrombotic risk patients, increasing risk of thromboembolism 1
• Failing to consider the type of surgical procedure and its associated bleeding risk when planning anticoagulation management 1