What is the protocol for Warfarin (Coumadin) bridging therapy?

From the Guidelines

Warfarin bridging therapy should be individualized, considering the patient's inherent thrombotic risk and the bleeding risk of the specific procedure, and is generally recommended for patients at high thrombotic risk, including those with mechanical heart valves, recent venous thromboembolism, or atrial fibrillation with high CHADS2 score. When interruption of oral VKA therapy is deemed necessary, the agent is usually stopped 3 to 4 days before the procedure and is restarted postoperatively as soon as bleeding risk allows, typically 12 to 24 hours after surgery 1. Bridging anticoagulation with intravenous unfractionated heparin or subcutaneous low-molecular-weight heparin is started when the INR falls below the therapeutic threshold, usually 36 to 48 hours before surgery, and is stopped 4 to 6 hours (for intravenous unfractionated heparin) or 12 hours (for subcutaneous low-molecular-weight heparin) before the procedure 1. Some key points to consider when deciding on bridging therapy include:

• The patient's thrombotic risk, including the presence of mechanical heart valves, recent venous thromboembolism, or atrial fibrillation with high CHADS2 score
• The bleeding risk of the specific procedure
• The use of fresh frozen plasma or prothrombin complex concentrate in patients with mechanical valves receiving VKA therapy who require emergency noncardiac surgery or invasive procedures 1
• The lack of randomized comparative-effectiveness trials evaluating a strategy of bridging versus no bridging in adequate numbers of patients with prosthetic heart valves needing temporary interruption of oral anticoagulant therapy 1 In general, bridging therapy should be avoided in patients with low thrombotic risk, as it may expose them to higher bleeding risks without reducing the risk of thromboembolism. For patients who require bridging therapy, the following protocol can be used:
• Stop warfarin 3 to 4 days before the procedure
• Start bridging anticoagulation with intravenous unfractionated heparin or subcutaneous low-molecular-weight heparin when the INR falls below the therapeutic threshold
• Stop bridging anticoagulation 4 to 6 hours (for intravenous unfractionated heparin) or 12 hours (for subcutaneous low-molecular-weight heparin) before the procedure
• Restart warfarin as soon as bleeding risk allows, typically 12 to 24 hours after surgery 1.

From the Research

Warfarin Bridging Therapy Protocol

The protocol for Warfarin (Coumadin) bridging therapy involves the use of low-molecular-weight heparin (LMWH) to bridge the gap in anticoagulation when warfarin is temporarily interrupted for surgical or invasive procedures. The following are key points to consider:

• LMWH is usually started 3 to 4 days before surgery and continued for 6 days after surgery at a dose of 70 anti-factor Xa U/kg twice daily in high-thromboembolic-risk patients and prophylactic once-daily doses in moderate- to low-risk patients 2
• Oral anticoagulation with warfarin is resumed the day after the procedure with a boost dose of 50% for 2 days and maintenance doses afterward 2
• The choice of LMWH and dosing regimen may depend on the patient's renal function and body weight, with some studies suggesting that enoxaparin should be limited to patients with a creatinine clearance greater than 30 ml/minute 3
• The use of LMWH bridging therapy has been associated with a higher risk of thrombotic events in some studies, although the overall risk of complications does not differ significantly from non-bridging therapy 4

Patient-Specific Considerations

When considering bridging therapy for patients on warfarin, the following patient-specific factors should be taken into account:

• Thromboembolic risk: patients with high thromboembolic risk may require more intensive bridging therapy, such as twice-daily LMWH 2
• Renal function: patients with renal dysfunction may require adjusted dosing of LMWH, such as enoxaparin, to avoid accumulation and increased risk of bleeding 3
• Body weight: obese patients may require dosing of LMWH based on total body weight, although unfractionated heparin may be recommended for patients weighing more than 150 kg 3
• Age: increasing age has been identified as a predictor of a residual anticoagulant effect from LMWH, which may increase the risk of bleeding 5

Clinical Evidence

Several studies have investigated the safety and efficacy of LMWH bridging therapy in patients on warfarin, including:

• A prospective inception cohort management study that found a bridging protocol tailored to patients' thromboembolic risk to be feasible, effective, and safe for many patients 2
• A randomized, double-blind, placebo-controlled trial that found forgoing bridging anticoagulation to be noninferior to bridging with LMWH for the prevention of perioperative arterial thromboembolism and superior with respect to major bleeding in patients with atrial fibrillation 6
• A register-based cohort study that found no benefit from LMWH bridging therapy in patients with mechanical heart valves, although the results may have been influenced by the type of procedure prompting bridging 4