Clinical question: In patients with atrial fibrillation (AF) or flutter, is heparin bridging needed during interruption of warfarin therapy for surgery or invasive procedures?
Background: Bridging is intended to decrease the risk of stroke or other arterial thromboembolism by minimizing time off anticoagulation. Bridging may increase the risk of serious bleeding, offsetting any benefit. Guidelines have provided weak and inconsistent recommendations due to a lack of randomized trials.
Study design: Randomized, double blind, placebo-controlled trial.
Setting: More than 100 centers in the U.S. and Canada, from 2009-2014.
Synopsis: Investigators randomized 1,884 patients on warfarin with a CHADS2 risk factor of one or higher undergoing elective surgery or procedure to dalteparin or placebo, from three days to 24 hours before the procedure and for five to 10 days after. Mean CHADS2 score was 2.3; 3% of patients had scores of five to six. Approximately one-third of patients were on aspirin, and most procedures (89%) were classified as minor. Patients with mechanical heart valves, stroke/transient ischemic attack (TIA)/systemic embolization within 12 weeks, major bleeding within six weeks, renal insufficiency, thrombocytopenia or planned cardiac, intracranial, or intraspinal surgery were excluded.
Thirty-day incidence of arterial thromboembolism (stroke, TIA, systemic embolization) was 0.4% in the non-bridging group and 0.3% in the bridging group (P=0.01 for noninferiority). Patients suffering arterial thromboembolism had mean CHADS2 scores of 2.6; most events occurred after minor procedures. Major bleeding was less common with no bridge (1.3% vs. 3.2%, relative risk 0.41, P=0.005 for superiority).
In this trial, most patients underwent minor procedures and few CHADS2 5-6 patients were enrolled; however, this well-designed, randomized trial adds important evidence to existing observational data.
Bottom line: Bridging is not warranted for most AF patients with CHADS2 scores of four or lower, at least for low-risk procedures.
Citation: Douketis JD, Spyropoulos AC, Kaatz S, et al. Perioperative bridging anticoagulation in patients with atrial fibrillation. N Engl J Med. 2015;373(9):823-833.