How do you bridge warfarin (Coumadin) and heparin (unfractionated heparin) therapy?

From the Guidelines

Bridging warfarin and heparin involves temporarily stopping warfarin before procedures and using heparin for anticoagulation during the perioperative period, with the goal of minimizing the risk of thromboembolism and bleeding complications, as recommended by the American College of Chest Physicians clinical practice guideline 1, 2.

Key Considerations

• Discontinue warfarin 5 days before the procedure to allow the INR to normalize (below 1.5) 1.
• Start therapeutic-dose low molecular weight heparin (LMWH) such as enoxaparin 1 mg/kg twice daily or 1.5 mg/kg once daily when the INR falls below 2.0, typically 2-3 days before the procedure 1, 2.
• Stop LMWH 24 hours before the procedure (or 12 hours if using prophylactic dosing) to minimize the risk of bleeding complications 2.
• After the procedure, resume LMWH 24-72 hours post-procedure depending on bleeding risk, and restart warfarin within 24 hours when hemostasis is adequate 2.
• Continue LMWH until the INR returns to the therapeutic range (typically 2.0-3.0) for two consecutive days, as this approach allows for better control of anticoagulation during the perioperative period 1.

Patient Selection

• Patients with high thrombotic risk (mechanical heart valves, recent venous thromboembolism, atrial fibrillation with prior stroke) typically require bridging, while those with lower risk may not 1, 2.
• The decision to bridge should be individualized based on the patient's risk of thromboembolism and bleeding, as well as the type of procedure being performed 2.

Monitoring and Management

• Monitor patients closely for signs of bleeding or thromboembolism during the perioperative period, and adjust the anticoagulation regimen as needed 2.
• Consider using intermediate-dose LMWH regimens or full-dose unfractionated heparin in patients with severe renal insufficiency or those who are dialysis-dependent 2.

From the FDA Drug Label

CONVERSION FROM HEPARIN THERAPY Since the anticoagulant effect of warfarin sodium tablets is delayed, heparin is preferred initially for rapid anticoagulation Conversion to warfarin sodium tablets may begin concomitantly with heparin therapy or may be delayed 3 to 6 days. To ensure continuous anticoagulation, it is advisable to continue full dose heparin therapy and that warfarin sodium tablets therapy be overlapped with heparin for 4 to 5 days, until warfarin sodium tablets have produced the desired therapeutic response as determined by PT/INR When warfarin sodium tablets have produced the desired PT/INR or prothrombin activity, heparin may be discontinued.

To bridge warfarin and heparin, the following steps should be taken:

• Heparin is preferred initially for rapid anticoagulation
• Warfarin therapy may begin concomitantly with heparin therapy or may be delayed 3 to 6 days
• Heparin therapy should be overlapped with warfarin for 4 to 5 days
• Heparin may be discontinued when warfarin has produced the desired PT/INR or prothrombin activity 3

From the Research

Bridging Warfarin and Heparin

To bridge warfarin and heparin, the following steps can be taken:

• Transitioning from argatroban to warfarin therapy in patients with heparin-induced thrombocytopenia (HIT) can be done with acceptably low complication rates 4.
• The transition typically involves overlapping argatroban and warfarin for a median of 4 days, with monitoring of international normalized ratio (INR) and activated partial thromboplastin time (aPTT) 4.
• In patients with elevated INR (> 4) during argatroban and warfarin cotherapy, the risk of thrombosis exceeds the risk of bleeding 5.
• Intravenous warfarin can be used as an alternative to oral warfarin in patients with HIT who have malabsorption issues or are unable to take enteral medications 6.
• The management of patients with HIT requires a multidisciplinary approach, including discontinuation of heparin, initiation of a non-heparin anticoagulant, and transition to warfarin 6, 7.

Key Considerations

• Monitoring of INR and aPTT is crucial during the transition from argatroban to warfarin 4, 5.
• The risk of thrombosis and bleeding should be carefully assessed in patients with HIT 5.
• A multidisciplinary team approach is essential for optimal management of patients with HIT 6, 7.
• There is no relevant information available from the study 8 as it discusses the functional role of parvalbumins in regulating Ca2+ in vertebrate skeletal muscles, which is not related to bridging warfarin and heparin.