When to initiate anticoagulation (anticoagulant) therapy post-operatively?

From the Guidelines

Anticoagulation after surgery should be started as early as 6 hours postoperatively for direct oral anticoagulants (DOACs) if hemostasis has occurred, while vitamin K antagonists (VKAs) can be restarted 12 to 24 hours postoperatively. The decision on when to start anticoagulation depends on the type of surgery, the patient's thrombotic risk, and the specific anticoagulant used.

Key Considerations

• For patients undergoing low bleeding risk surgery, DOACs like apixaban, rivaroxaban, or dabigatran can be resumed as early as 6 hours postoperatively, as peak levels and therapeutic anticoagulation effect are achieved in ∼2 to 3 hours 1.
• For high bleeding risk procedures, DOACs can be resumed 48 to 72 hours after surgery, as seen in the PAUSE trial, which reported overall low bleeding and thrombotic events 1.
• VKAs, such as warfarin, can be restarted 12 to 24 hours postoperatively, at the previous therapeutic dose, with additional monitoring required due to potential interactions with concomitant medications and altered nutrition or drug clearance during the perioperative period 1.

Specific Anticoagulants

• Dabigatran: can be resumed on the day after surgery (24 hours postoperative) for low bleeding risk surgery, and 2-3 days after surgery (48-72 hours postoperative) for high bleeding risk surgery, at a dose of 150 mg twice daily 1.
• Rivaroxaban: can be resumed on the day after surgery (24 hours postoperative) for low bleeding risk surgery, and 2-3 days after surgery (48-72 hours postoperative) for high bleeding risk surgery, at a dose of 20 mg once daily 1.
• Apixaban: can be resumed on the day after surgery (24 hours postoperative) for low bleeding risk surgery, and 2-3 days after surgery (48-72 hours postoperative) for high bleeding risk surgery, at a dose of 5 mg twice daily 1.

Additional Measures

• Early mobilization and mechanical prophylaxis with compression stockings or intermittent pneumatic compression devices can be used immediately after surgery before pharmacological anticoagulation is initiated.
• Patients with mechanical heart valves or recent venous thromboembolism may require bridging therapy with low molecular weight heparin (LMWH) until oral anticoagulants reach therapeutic levels.

From the FDA Drug Label

For prophylaxis of deep vein thrombosis: Fondaparinux sodium 2.5 mg subcutaneously once daily after hemostasis has been established. The initial dose should be given no earlier than 6 to 8 hours after surgery and continued for 5 to 9 days.

Table 1: Recommended Dosage in Adults ... 10 mg once daily for 35 days, 6–10 hours after surgery once hemostasis has been established

• Timing of anticoagulant initiation: The initial dose of fondaparinux sodium should be given no earlier than 6 to 8 hours after surgery 2, while rivaroxaban should be initiated 6-10 hours after surgery 3.
• Key consideration: Anticoagulant therapy should only be started after hemostasis has been established 2 3.

From the Research

Timing of Anticoagulant Therapy After Surgery

The optimal timing for starting anticoagulant therapy after surgery is a critical consideration to balance the risk of thromboembolic complications against the risk of bleeding. Several studies have investigated this issue:

• A study published in 2022 4 compared the efficacy and safety of low-molecular-weight heparin (LMWH) and unfractionated heparin (UH) in patients with mechanical prosthetic heart valves undergoing non-cardiac surgery, finding that LMWH was more effective and had a better safety profile.
• Another study from 1996 5 demonstrated that extending the duration of anticoagulant therapy with LMWH (enoxaparin) to one month after total hip replacement reduced the incidence of venous thromboembolism compared to a shorter duration of therapy.
• A review of clinical trials published in 2015 6 suggested that delaying the first postoperative dose of anticoagulants for at least 6 hours after surgery may improve safety and efficacy.
• A registry study from 2006 7 compared the use of UH and LMWH as bridging therapy in patients on long-term oral anticoagulants undergoing elective surgery or invasive procedures, finding similar rates of adverse events between the two groups.
• An earlier study from 1993 8 introduced enoxaparin as a low-molecular-weight heparin for prevention of postoperative thromboembolic complications, highlighting its pharmacology, efficacy, and safety profile.

Key Findings

Key findings from these studies include:

• The importance of delaying the first postoperative dose of anticoagulants to minimize bleeding risk while maintaining efficacy in preventing thromboembolic complications 6.
• The potential benefits of using LMWH (such as enoxaparin) over UH in certain patient populations, including those with mechanical prosthetic heart valves 4 or undergoing total hip replacement 5.
• The need for careful consideration of patient-specific factors, such as comorbidities and type of surgery, when selecting anticoagulant therapy and determining the optimal timing of initiation 7.