The perioperative management of patients who require interruption of a vitamin K antagonist (VKA) because of surgery or another non-invasive procedure is a common and sometimes challenging clinical problem. Bridging anticoagulation refers to the use of a short-acting anticoagulant,which is usually therapeutic-dose subcutaneous low-molecular-weight heparin (LMWH) such as enoxaparin 1 mg/kg twice-daily, administered during the time when a VKA is interrupted and there is no therapeutic anticoagulation. However, there is no standardized definition of ’bridging anticoagulation’ and other treatment regimens, including low-dose (enoxaparin 40 mg once-daily) or intermediate-dose (eg, enoxaparin 40 mg twice-daily) LMWH regimens, have been used, particularly in selected patients at high risk for bleeding complications.
Although perioperative anticoagulant management may be straightforward in many cases, requiring simple interruption and postoperative resumption of VKA therapy, there are also many instances where management decisions may affect clinical outcomes, whether thromboembolic or bleeding. In all cases management decisions are anchored on weighing perioperative risks for thromboembolism and bleeding.
The objectives of this chapter are: 1) to stratify patients according to their risk for arterial or venous thromboembolism if VKA therapy is stopped and the risk for bleeding associated with surgery or procedure; 2) to provide a practical approach to the perioperative interruption and resumption of VKA therapy; 3) to provide a practical protocol for the administration of bridging anticoagulation when required.
A 54-year-old woman with rheumatic valvular heart disease requires hysterectomy (uterine fibroids). She has a St. Jude mechanical prosthetic valve in the mitral position and she is on warfarin. The perioperative management of anticoagulant therapy should start with the assessment of her thromboembolic risk, which should be considered high in the presence of any mitral valve prosthesis.
The second step is represented by the assessment of bleeding risk, which can be considered nonhigh because the type and location of surgery do not involve critical sites or major tissue injury or highly vascularized organ.
A preoperative bridging regimen is suggested here:
- Day –5: stop warfarin (may stop on day –6 if INR range is 2.5 –3.5)
- Day –3: start therapeutic-dose heparin (SC LMWH or IV UFH)
- Day –1:
- check INR if possible (if INR > 1.5, vitamin K 1 –2 mg orally can be administered)
- if SC LMWH was chosen, give the last dose in the morning (this dose must be reduced by 50% in case of once-daily dosing regimen)
- if IV UFH was chosen, stop infusion 4 hours before surgery
A post-operative bridging regimen is suggested here:
- Day 0: after assessing surgical site hemostasis, warfarin can be resumed on the evening after surgery, if feasible
- Day +1 to +3: resume therapeutic-dose LMWH or UFH when hemostasis is secure, and in no case before 12 hours after surgery (typically on the morning afterwards)
- Day +5 to +6: stop LMWH or UFH when INR is therapeutic
A cautionary note: there are no randomized controlled trials that definitively ...