From the Guidelines
Warfarin should typically be discontinued 5 days before elective surgery to allow the INR to normalize. The exact timing depends on the patient's current INR and the bleeding risk of the procedure. For high bleeding risk surgeries, aim for an INR less than 1.5, while for low bleeding risk procedures, an INR up to 2.0 may be acceptable. Patients with high thrombotic risk (such as those with mechanical heart valves, recent venous thromboembolism, or atrial fibrillation with prior stroke) may require bridging therapy with low molecular weight heparin (LMWH) like enoxaparin when the INR falls below 2.0. Bridging typically starts 36-48 hours after stopping warfarin and continues until 24 hours before surgery. After surgery, warfarin can usually be resumed 12-24 hours postoperatively when hemostasis is adequate, with bridging therapy continued until the INR returns to the therapeutic range. INR should be checked the day before surgery to ensure it has decreased sufficiently, and monitored regularly after surgery until stable. This approach balances the risks of perioperative bleeding against thrombotic complications, as warfarin has a long half-life (36-42 hours) and its anticoagulant effect persists for several days after discontinuation 1.
Key Considerations
- The timing of warfarin discontinuation depends on the patient's current INR and the bleeding risk of the procedure.
- For high bleeding risk surgeries, aim for an INR less than 1.5, while for low bleeding risk procedures, an INR up to 2.0 may be acceptable.
- Patients with high thrombotic risk may require bridging therapy with LMWH.
- INR should be checked the day before surgery to ensure it has decreased sufficiently, and monitored regularly after surgery until stable.
Bridging Therapy
- Bridging therapy with LMWH may be necessary for patients with high thrombotic risk.
- Bridging typically starts 36-48 hours after stopping warfarin and continues until 24 hours before surgery.
- After surgery, bridging therapy can be continued until the INR returns to the therapeutic range.
Resuming Warfarin
- Warfarin can usually be resumed 12-24 hours postoperatively when hemostasis is adequate.
- The usual maintenance dose of warfarin can be resumed, or some clinicians may give twice the maintenance dose.
- INR should be monitored regularly after surgery until stable.
From the FDA Drug Label
The management of patients who undergo dental and surgical procedures requires close liaison between attending physicians, surgeons and dentists. In patients undergoing minimal invasive procedures who must be anticoagulated prior to, during, or immediately following these procedures, adjusting the dosage of warfarin sodium tablets to maintain the PT/INR at the low end of the therapeutic range may safely allow for continued anticoagulation Some dental or surgical procedures may necessitate the interruption of warfarin sodium tablets therapy When discontinuing warfarin sodium tablets even for a short period of time, the benefits and risks should be strongly considered.
The decision to discontinue Warfarin prior to surgery should be made on a case-by-case basis, considering the benefits and risks of interrupting anticoagulation therapy.
- The PT/INR should be determined just prior to any dental or surgical procedure.
- For minimal invasive procedures, adjusting the Warfarin dosage to maintain the PT/INR at the low end of the therapeutic range may allow for continued anticoagulation.
- For procedures that necessitate interruption of Warfarin therapy, the decision to discontinue should be made after careful consideration of the benefits and risks 2.
From the Research
Discontinuation of Warfarin Prior to Surgery
- The decision to discontinue warfarin prior to surgery depends on various factors, including the type of surgery, the patient's risk of bleeding, and the risk of thromboembolic events 3, 4, 5.
- A study published in 2014 found that simple tooth extraction can be performed safely in patients on warfarin treatment without discontinuing the medication, as long as the international normalized ratio (INR) is less than 3.5 on the day of extraction 3.
- Another study published in 1995 found that the INR decreases exponentially after discontinuation of warfarin therapy, with a half-life ranging from 0.52 to 1.2 days, and that age is a significant predictor of the rate of decrease in INR 4.
- The same study suggested that warfarin should be withheld for 96 to 115 hours (4 doses) in patients with a steady-state INR between 2.0 and 3.0 to ensure that the INR is less than 1.2 at the time of surgery 4.
- Low-dose oral vitamin K (1 mg) has been shown to be effective in normalizing the INR in patients who require temporary interruption of warfarin before surgery, with 76.6% of patients achieving a normalized INR on the day of surgery 6.
- A study published in 2007 found that active reversal of warfarin anticoagulation with intravenous vitamin K compared to withholding warfarin reduced the time to surgery by a mean of 44.5 hours, with no complications reported 7.
- A review article published in 2003 suggested that most patients on warfarin should stop taking the medication 5 days before elective surgery, and that most do not need to receive heparin in the perioperative period as a bridge to surgery 5.