Bridging anticoagulation for interruption of warfarin in a patient with atrial fibrillation

Should this patient’s anticoagulation be interrupted for surgery?

Both the procedural bleeding risk and anesthetic plan affect the decision of whether to interrupt anticoagulation. Prospective observational studies and randomized trials have shown that continuing anticoagulants for most skin, dental and cataract procedures is safe.3 Patients undergoing pacemaker or defibrillator insertion experience less bleeding when warfarin is continued perioperatively than when bridging with heparin is used.4 However, procedures with a major bleeding risk, including abdominal, thoracic, orthopedic and urologic surgeries, require anticoagulant interruption.3 As such, temporary warfarin cessation is appropriate for this patient.

Should bridging anticoagulation be used?

Guidelines suggest warfarin be stopped about five days before a major procedure.3 Anticoagulation is resumed when the postoperative bleeding risk is diminished, with full therapeutic effect delayed five to seven days. Bridging anticoagulation is the use of heparin (typically low-molecular-weight heparin [LMWH]) to minimize time off anticoagulation and reduce the risk of thrombosis.

Guidelines suggest that patients at high risk of thromboembolism receive bridging anticoagulation.3 This group includes patients with a CHADS₂ score of 5 or 6, most patients with mechanical heart valves, and those with recent ischemic stroke or TIA, or recent deep vein thrombosis or pulmonary embolism (Box 2).3 However, a meta-analysis involving more than 12 000 patients suggested that bridging is associated with an increased risk of overall and major bleeding, with no improvement in stroke risk.5 Data from a prospective observational registry of more than 7000 US outpatients with atrial fibrillation also showed that patients undergoing anticoagulation bridging had more bleeding events, with a higher risk of arterial thromboembolism, hospital admission and death.6

These observations were confirmed in the BRIDGE trial, where patients with atrial fibrillation undergoing elective invasive procedures or surgeries were randomly assigned to bridging with therapeutic LMWH or placebo during warfarin interruption.7 The incidence of major bleeding was three times higher in the bridged group (3.2% v. 1.3%, p = 0.005 for superiority), and bridging was not associated with a reduction in the incidence of arterial thromboembolism (0.3% v. 0.4%, p = 0.01 for noninferiority).7 These results suggest that bridging is associated with increased bleeding without reduction in perioperative stroke in most patients, and it would not be recommended for this patient.

In the BRIDGE trial, however, patient groups at high risk of stroke were either excluded or underrepresented (e.g., 97% of patients had a CHADS₂ score of 4 or less).7 Until more data are available in these higher-risk groups, one could consider bridging anticoagulation in these patients, although deciding to forego bridging would also be reasonable.

In patients at moderate thrombotic risk, guidelines have suggested that decisions of whether to use bridging be made in consideration of individual patient factors and procedure-specific thrombotic risk.3 Results from the BRIDGE trial suggest that most patients at moderate risk, such as this patient, do not benefit from bridging. The Canadian Hematology Society suggests that bridging not be offered unless the thrombotic risk exceeds the bleeding risk (Box 3).8

What if this patient had been taking a direct oral anticoagulant?

The periprocedural management of patients taking direct oral anticoagulants has been reviewed elsewhere.9 Although bridging studies did not include patients taking direct oral anticoagulants, similar principles around decisions to withhold anticoagulation may be used. Given the rapid onset and shorter half-life of direct oral anticoagulants, bridging with heparin (or LMWH) is unnecessary and may lead to postoperative bleeding if reinstituted prematurely following a procedure.10

Case revisited

The patient’s warfarin was held five days before his procedure without bridging anticoagulation. The surgery was uncomplicated with minimal blood loss, and his warfarin was restarted the next day with no bridging anticoagulation.