What is the approach to perioperative bridge anticoagulation for a patient with a mechanical heart valve (MHV)?

From the Guidelines

Perioperative bridging anticoagulation for patients with mechanical heart valves should be limited to those with very high thrombotic risk, such as mechanical mitral valves, and should be individualized based on bleeding risk. For most patients with mechanical heart valves, warfarin should be discontinued 5 days before surgery and bridging with therapeutic-dose low molecular weight heparin (LMWH) or unfractionated heparin (UFH) may be considered, but the decision to bridge should be made on a case-by-case basis, taking into account the patient's thrombotic and bleeding risks 1. Some key points to consider when deciding on bridging anticoagulation include:

• The patient's thrombotic risk, with higher risk patients (e.g. those with mechanical mitral valves) potentially benefiting from bridging anticoagulation
• The patient's bleeding risk, with higher risk patients potentially being harmed by bridging anticoagulation
• The type of surgery being performed, with minor procedures potentially not requiring bridging anticoagulation
• The patient's overall health status and medical history, with certain conditions (e.g. previous stroke or TIA) potentially increasing the need for bridging anticoagulation. Typically, enoxaparin 1 mg/kg twice daily or UFH infusion titrated to an aPTT of 1.5-2.5 times normal may be initiated when the INR falls below 2.0, but the use of bridging anticoagulation should be carefully considered and individualized to each patient's specific situation 1. Postoperatively, bridging anticoagulation should be resumed 24-72 hours after surgery depending on bleeding risk, with therapeutic anticoagulation restarted once hemostasis is secure, and warfarin should be restarted as soon as the patient can take oral medications, typically 12-24 hours after surgery 1. Bridging therapy should continue until the INR returns to the therapeutic range (typically 2.5-3.5 for mitral valves and 2.0-3.0 for aortic valves), but the decision to continue bridging anticoagulation should be made on a case-by-case basis, taking into account the patient's thrombotic and bleeding risks 1.

From the FDA Drug Label

For all patients with mechanical prosthetic heart valves, warfarin is recommended. For patients with a St. Jude Medical (St. Paul, MN) bileaflet valve in the aortic position, a target INR of 2.5 (range, 2.0 to 3. 0) is recommended. For patients with tilting disk valves and bileaflet mechanical valves in the mitral position, the 7th ACCP recommends a target INR of 3.0 (range, 2.5 to 3.5). For patients with caged ball or caged disk valves, a target INR of 3.0 (range, 2.5 to 3. 5) in combination with aspirin, 75 to 100 mg/day is recommended.

The management of perioperative bridge anticoagulation for a mechanical heart valve is not explicitly addressed in the provided text. However, the text does provide recommendations for anticoagulation therapy in patients with mechanical heart valves.

• The recommended target INR ranges from 2.0 to 3.5, depending on the type and position of the valve.
• Aspirin may be added to warfarin therapy in certain cases, such as for patients with caged ball or caged disk valves.
• The text does not provide specific guidance on how to manage anticoagulation during the perioperative period, but it does emphasize the importance of individualizing warfarin dosing based on patient sensitivity and PT/INR results 2.

From the Research

Perioperative Bridge Anticoagulation for Mechanical Heart Valves

• The management of patients with mechanical heart valves who require temporary interruption of warfarin therapy is a common clinical problem 3.
• A standardized periprocedural anticoagulation regimen with low-molecular-weight heparin (LMWH) can be used to bridge the period when warfarin is interrupted 3, 4.
• The regimen typically involves stopping warfarin 5-6 days before the procedure and starting LMWH 3 days before the procedure 3.
• The risk of postprocedural bleeding determines the postprocedural anticoagulant management, with warfarin resumed on the evening of the procedure and LMWH resumed on the next day if hemostasis is adequate 3.

Safety and Efficacy of Bridging Anticoagulation

• Studies have shown that bridging anticoagulation with LMWH is associated with a low risk of thromboembolic and major bleeding complications 3, 4.
• The incidence of thromboembolic events and major bleeding episodes is low, ranging from 0.4% to 1.8% and 0.7% to 1.8%, respectively 3, 5.
• The use of LMWH as a bridging anticoagulant has been shown to be effective and relatively safe in patients with mechanical heart valves 4, 6.

Specific Considerations for Pacemaker Implantation

• For patients with mechanical heart valves undergoing pacemaker implantation, a minimum of 3 days cessation of warfarin prior to surgery is preferred, with LMWH bridging stopped 12 hours before surgery 7.
• Warfarin should be initiated immediately after surgery, rather than LMWH, to minimize the risk of bleeding complications 7.

Low-Molecular-Weight Heparin as a Bridging Anticoagulant

• LMWH can be used as a bridging anticoagulant early after mechanical heart valve replacement, with a mean duration of treatment of 8.3 days 6.
• The use of LMWH as a bridging anticoagulant has been shown to be feasible and safe, with a low incidence of bleeding and thromboembolic complications 6.