How risky is it to stop Coumadin prior to elective foot surgery?
Anticoagulation therapy is used for a number of conditions including atrial fibrillation, history of deep vein thrombosis, cardiac and vascular implants and in cases of clotting disorders that result in thrombocytosis (elevated platelets that lead to clotting). Invariably, some of these patients who are on anticoagulation therapy will need to undergo elective surgery. As a podiatrist, how do I manage the transition away from Coumadin (warfarin) so that I can perform a surgery without excessive blood loss?
Is bridging with heparin necessary in elective foot surgery?
Salynn Boyles wrote a great article in MedPageToday on June 22, 2015 that drills down into the topic of anticoagulation therapy, elective surgery and bridging with heparin. Coumadin and heparin both work to delay clotting. Coumadin has a long half-life while heparin is short-acting. Classically, Coumadin is stopped five days prior to a surgery and heparin is used as a bridge to inhibit clotting. According to James Douketis, MD of McMaster University, Hamilton Ontario, bridging is no longer necessary. Dr. Douketis states,
“The rationale for the use of bridging anticoagulation therapy has been anchored on the premise that the associated higher bleeding risk was clinically acceptable because it would be off-set by a lower risk of peri-operative arterial thromboembolism. The findings from our trial as well as from randomized studies suggest that the peri-operative risk of arterial thromboembolism in patients with atrial fibrillation during interruption of warfarin treatment may have been overstated and may not be mitigated by bridging anticoagulation.”
The McMaster study was a double-blind, randomized trial that included 950 patients who received no bridging and 934 who did bridge with a low molecular weight heparin (dalteparin). Patients were followed for 30 days post-surgery. Thromboembolism was found in 0.4% of the no bridge and 0.3% of the bridged patients.
In the article, hematologist Stephan Moll, MD of the University of North Carolina commented;
“It has increasingly become clear that the patients at low or moderate risk for thromboembolism, either atrial fibrillation or DVT or PE patients on warfarin do not need low molecular weight heparin bridging when warfarin if temporarily interrupted for surgical interventions. It leads to more bleeding yet no benefit.”
What is the new protocol for cessation of anticoagulation therapy for foot and ankle surgery patients?
Although the study suggests a low risk to patients undergoing foot and ankle surgery who are on Coumadin who undergo elective surgery without bridging, I still have concerns about three issues.
- Co-morbidities – patients who have co-morbidities that increase the chance of VTE (venous thromboembolism) would not be considered low risk. Co-morbidities would include;
- BMI greater than 40
- Hx of past or present smoking
- Current use of birth control pills
- Patients currently using hormone replacement therapy
2. Tourniquet use in surgery – tourniquets are frequently used in lower extremity surgery. Compression of the vein by a tourniquet during surgery may contribute to a VTE.
3. Ambulatory or non-ambulatory post-op – the make-up of the patient and the surgery that the patient undergoes results in either early ambulation, delayed ambulation or complete non-weight bearing post-op. I would consider a patient who is actively anticoagulated to be high risk if the outcome of the surgery resulted in delayed weight-bearing or complete weight-bearing.
But the bottom line for foot and ankle surgeons is the fact that we can feel a bit more comfortable with our choice to temporarily discontinue anticoagulation therapy without bridging with LMWH. Our primary job is to ensure the safety of the patient. And without bridging, surgery can often be performed more safely and easily without excessive bleeding.