Perioperative management of warfarin and antiplatelet therapy
ABSTRACT
Perioperative management of patients on warfarin or antiplatelet therapy involves assessing and balancing individual risks for thromboembolism and bleeding. Discontinuing anticoagulant and antiplatelet therapy is usually necessary for major surgery but increases the risk of thrombotic events. Bridge therapy, the temporary perioperative substitution of low-molecular-weight heparin or unfractionated heparin in place of warfarin, is an effective means of reducing the risk of thromboembolism but may increase the risk of bleeding. The timing of warfarin withdrawal and timing of the preoperative and postoperative components of bridge therapy are critical to balancing these risks. Perioperative management of antiplatelet therapy requires special care in patients with coronary stents; the timing of surgery relative to stent placement dictates management in these patients.
KEY POINTS
- Determining when and how to use bridge anticoagulation therapy depends on the patient’s risk for thromboembolism, which is in turn based on the indication for warfarin—ie, a mechanical heart valve, atrial fibrillation, or prior venous thromboembolism.
- Factor patient preference into whether and how to use bridge therapy: many patients are more concerned about stroke risk than bleeding risk, regardless of the relative frequency of these events.
- Anticoagulation with warfarin often does not need to be interrupted for patients undergoing minor surgery, such as some ophthalmic, dental, dermatologic, and gastrointestinal procedures.
- Premature discontinuation of antiplatelet therapy in surgical patients with recent coronary stent placement significantly raises the risk of catastrophic perioperative stent thrombosis.
CONCLUSIONS
Perioperative management of anticoagulant and antiplatelet therapy is complicated by the paucity of randomized clinical trial data and the risk for serious adverse events. The underlying indications for anticoagulant and antiplatelet therapy vary widely, so the best approach to perioperative management is to involve all members of the health care team—hospitalist, surgeon, cardiologist, and anesthesiologist, together with the patient—to ensure that care is individualized and all relevant considerations are accounted for. Patient and surgical risks can be identified and quantified to some extent, but patients often have greater concerns about the risk of stroke than the risk of bleeding. Ideally, nonemergency surgeries should be scheduled to allow enough time to thoroughly plan the management protocol, reducing risks for bleeding and thrombotic events as much as possible.
DISCUSSION
Question from the audience: If a patient’s INR is 1.3 or 1.4, rather than the recommended 1.2, is it necessary to cancel a planned epidural?
Dr. Jaffer: It depends on how comfortable the surgeon or anesthesiologist is with the INR level. Generally, an INR less than 1.5 is probably acceptable, but it depends on the procedure. For a craniotomy, for example, 1.2 is recommended.
Question from the audience: Is it necessary to use anti–Xa levels to guide bridge therapy when administering LMWH or UFH in a patient with a mechanical heart valve?
Dr. Jaffer: It’s not generally necessary, except for pregnant women. For most patients, doses are calculated as milligrams of LMWH per kilogram body weight or as International Units of LMWH per kilogram.
Question from the audience: You mentioned medicolegal disputes arising from adverse events associated with bridge therapy, drug discontinuation, or related issues. Who has final responsibility for making decisions about discontinuation of antiplatelet therapy, for example?
Dr. Jaffer: I don’t know if it ultimately comes down to just one person. Several physicians should be involved in the decision, and communication protocols within an institution should be very clear. It’s important to make certain everyone involved in the decision is reviewing the same literature. The final decision has to be something everyone involved can accept and support.
