PRACTICE CHANGER
Stop using low molecular weight heparin (LMWH) for surgical procedures to “bridge” low- to moderate-risk patients with atrial fibrillation (CHADS2 score ≤4) who are receiving warfarin. The risks outweigh the benefits.1
Strength of recommendation
B: Based on a single good-quality randomized control trial.
Douketis JD, Spyropoulos AC, Kaatz S, et al. Perioperative bridging anticoagulation in patients with atrial fibrillation. N Engl J Med. 2015;373:823-833.
Illustrative case
A 75-year-old man comes to your office for surgical clearance before right knee replacement surgery. He has diabetes and high blood pressure, and is taking warfarin for atrial fibrillation. He is scheduled for surgery in a week. What is the safest way to manage his warfarin in the perioperative period?
More than 2 million people are being treated with oral anticoagulation in North America to prevent stroke, or to prevent or treat venous thromboembolism.2 Since 2010, several new oral anticoagulants have been approved, including dabigatran, apixaban, and rivaroxaban. These new medications have a shorter half-life than older anticoagulants, which enables them to be stopped 1 to 2 days before surgery.
On the other hand, warfarin—which remains a common choice for anticoagulation—has a 3- to 7-day onset and elimination.3,4 This long clinical half-life presents a special challenge during the perioperative period. To reduce the risk of operative bleeding, the warfarin must be stopped days prior to the procedure, but physicians often worry that this will increase the risk of arterial or venous thromboembolism, including stroke.
An estimated 250,000 patients need perioperative management of their anticoagulation each year.5 As the US population continues to age and the incidence of conditions requiring anticoagulation (particularly atrial fibrillation) increases, this number is only going to rise.6
Current guidelines on bridging. American College of Chest Physicians (ACCP) guidelines recommend transition to “a short-acting anticoagulant, consisting of subcutaneous low molecular weight heparin (LMWH) or intravenous unfractionated heparin, for a 10- to 12-day period during interruption of vitamin K antagonist (VKA) therapy.”5 Furthermore, for an appropriate bridging regimen, the ACCP guidelines recommend stopping VKA therapy 5 days prior to the procedure and utilizing LMWH from within 24 to 48 hours of stopping VKA therapy until up to 24 hours before surgery.5 Postoperatively, VKA or LMWH therapy should be reinitiated within 24 hours and 24 to 72 hours, respectively, depending on the patient’s risk of bleeding during surgery.5
These guidelines recommend using CHADS2 scoring (TABLE3) to determine arterial thromboembolism (ATE) risk in atrial fibrillation.3,5 Patients at low risk for ATE (CHADS2 score 0-2) should not be bridged, and patients at high risk (CHADS2 score of 5-6) should always be bridged.5 These guidelines are less clear about bridging recommendations for moderate-risk patients (CHADS2 score 3-4).
Previous evidence on bridging. A 2012 meta-analysis of 34 studies evaluated the safety and efficacy of perioperative bridging with heparin in patients receiving VKA.7 Researchers found no difference in ATE events in 8 studies that compared groups that received bridging vs groups that simply stopped anticoagulation (odds ratio [OR]=0.80; 95% confidence interval [CI], 0.42–1.54).7 The group that received bridging had an increased risk of overall bleeding in 13 studies, and of major bleeding in 5 studies.7 This meta-analysis was limited by poor study quality and variation in the indication for VKA therapy.
A 2015 subgroup analysis of a larger cohort study of patients receiving anticoagulants for atrial fibrillation found an increased risk of bleeding when their anticoagulation was interrupted for procedures (OR for major bleeding=3.84; 95% CI, 2.07-7.14; P<.0001).8
Douketis et al1 conducted a randomized trial to clarify the need for and safety of bridging anticoagulation for ATE in patients with atrial fibrillation who were receiving warfarin.
STUDY SUMMARY: When it comes to stroke/TIA, there’s no advantage to bridging
This double blind, placebo-controlled trial compared bridging with dalteparin, a form of LMWH, to placebo among 1884 patients with atrial fibrillation on warfarin whose anticoagulation therapy needed to be interrupted for an elective procedure. Patients were included if they were receiving warfarin to prevent stroke, and had been on warfarin for at least 12 weeks, with a goal international normalized ratio (INR) of 2.0 to 3.0. Exclusion criteria included having a mechanical heart valve or having a stroke/transient ischemic attack (TIA; 12 weeks prior) or major bleeding (6 weeks prior). Cardiac, intracranial, and intraspinal surgeries were also excluded from the study.
The patients’ mean CHADS2 score was 2.3; 38.3% of patients had a CHADS2 score ≥3, and 9.4% of patients had a history of stroke. Forty-four percent of patients underwent a gastrointestinal procedure, 17.2% underwent a cardiothoracic procedure, and 9.2% underwent an orthopedic procedure.
