What are the indications for bridging warfarin (anticoagulant) with Low Molecular Weight Heparin (LMWH)?

From the Guidelines

Bridging warfarin with low molecular weight heparin (LMWH) is only indicated for patients with a very high thromboembolic risk who require temporary interruption of warfarin therapy for procedures. According to the most recent and highest quality study, the 2022 American College of Chest Physicians clinical practice guideline 1, bridging therapy should be considered for high thrombotic risk populations. The guideline suggests using full-dose, subcutaneous LMWH (e.g., enoxaparin, 1 mg/kg bid or 1.5 mg/kg daily or dalteparin, 100 IU/kg bid or 200 IU/kg daily), with the last dose given the morning of the day prior to the procedure at half the total daily dose.

Key Points to Consider

• The decision to bridge warfarin with LMWH should be based on the patient's thromboembolic risk, with high-risk patients being those with mechanical heart valves, recent venous thromboembolism, atrial fibrillation with high CHADS2 score, or recent stroke/TIA.
• The BRIDGE study 1 found that absence of bridging was noninferior to bridging with LMWH for prevention of arterial thromboembolism and decreased the risk of bleeding, suggesting that bridging may not be necessary for all patients.
• The typical bridging protocol involves stopping warfarin 5 days before the procedure, starting LMWH when the INR falls below 2.0, stopping LMWH 24 hours before the procedure, and resuming both LMWH and warfarin after the procedure when hemostasis is adequate.
• Patients with low bleeding risk can resume full-dose LMWH 24 hours post-procedure, while those with high bleeding risk should wait 48-72 hours.
• Warfarin can be resumed on the evening of the procedure (D0) for most patients, or the day after the procedure (i.e., D1) at the patient’s usual maintenance dose 1.

Management of Antithrombotic Therapy

• Low-dose LMWH (e.g., enoxaparin, 40 mg daily or dalteparin 5,000 IU daily) can be used for VTE prophylaxis for the first 24-72 hours post-procedure, with full-dose LMWH resumed 2-3 days post-procedure 1.
• The goal of bridging therapy is to minimize the time patients are without effective anticoagulation during the perioperative period, balancing the risks of thromboembolism from stopping anticoagulation against the risks of perioperative bleeding.

From the FDA Drug Label

INDICATIONS AND USAGE FRAGMIN is a low molecular weight heparin (LMWH) indicated for • Prophylaxis of ischemic complications of unstable angina and non-Q-wave myocardial infarction (1. 1) • Prophylaxis of deep vein thrombosis (DVT) in abdominal surgery, hip replacement surgery or medical patients with severely restricted mobility during acute illness (1. 2) • Extended treatment of symptomatic venous thromboembolism (VTE) to reduce the recurrence in adult patients with cancer. In these patients, the FRAGMIN therapy begins with the initial VTE treatment and continues for six months (1.3) • Treatment of symptomatic venous thromboembolism (VTE) to reduce the recurrence in pediatric patients from birth (gestational age at least 35 weeks) (1. 4)

The indications to bridge warfarin with low molecular weight heparin are not explicitly stated in the provided drug label. However, bridging therapy is often considered in clinical practice for patients who require temporary interruption of warfarin, such as those undergoing surgery or invasive procedures.

• Key considerations for bridging therapy include the patient's risk of thromboembolism and bleeding.
• Low molecular weight heparin (LMWH), such as dalteparin, may be used for bridging therapy in certain clinical situations, but the specific indications and dosing regimens should be individualized based on patient-specific factors 2.

From the Research

Indications for Bridging Warfarin with Low Molecular Weight Heparin

The decision to bridge warfarin with low molecular weight heparin (LMWH) is based on the patient's risk of thromboembolism and bleeding. The following are indications for bridging warfarin with LMWH:

• Patients with mechanical heart valves, chronic atrial fibrillation, or embolic stroke who require temporary interruption of warfarin therapy due to an invasive procedure 3
• Patients at increased risk for arterial thromboembolism who require temporary interruption of warfarin therapy 3, 4
• Patients with mechanical heart valves (MHVs) who are at high risk of thromboembolic complications 5, 6

Patient Selection

The selection of patients for bridging warfarin with LMWH depends on their individual risk factors, including:

• Thromboembolic risk: patients with a high risk of thromboembolism, such as those with mechanical heart valves or a history of embolic stroke, may benefit from bridging with LMWH 3, 5
• Bleeding risk: patients with a high risk of bleeding, such as those undergoing high-bleeding-risk procedures, may not require bridging with LMWH 3, 7
• Type of procedure: the type of procedure prompting bridging, such as cardiac or non-cardiac surgery, may influence the decision to bridge with LMWH 6

Bridging Regimens

Different bridging regimens have been studied, including:

• Standardized periprocedural anticoagulation regimen with LMWH, which involves stopping warfarin 5-6 days before the procedure and starting LMWH 3 days before the procedure 3
• Individualized bridging protocol, which involves tailoring the bridging regimen to the patient's thromboembolic risk 4
• Comparison of LMWH and unfractionated heparin (UFH) for bridging anticoagulation, which suggests that LMWH may be safer and more effective than UFH in patients with MHVs 6