Dalteparin bridging does not prevent arterial thromboembolism in AF patients: Study

Canada: A recent study found no benefit of postoperative dalteparin bridging for preventing major thromboembolism in patients with atrial fibrillation or mechanical heart valves who had warfarin interrupted for a procedure. The study findings are published in The BMJ. 

Whether patients with atrial fibrillation or mechanical heart valves who require interruption of vitamin K antagonists for invasive procedures benefit from bridging with low molecular weight heparin (LMWH) after the procedure remains uncertain.

Previous studies have sought to address this common clinical problem, however, there has been concern that these patients are at high risk of thrombotic complications caused by a procoagulable state while off vitamin K antagonists, noted the authors.

Against the above background, Michael J Kovacs, Department of Medicine, Dalteparin Bridging Western University, London, ON, Canada, and colleagues aimed to determine the safety and efficacy of dalteparin postoperative bridging treatment versus placebo for patients with atrial fibrillation or mechanical heart valves when warfarin is temporarily interrupted for a planned procedure.

For this purpose, the researchers conducted a prospective, double-blind, randomized controlled trial. The trial included 1471 patients aged 18 years or older with atrial fibrillation or mechanical heart valves who required temporary interruption of warfarin for a procedure from 10 thrombosis research sites in Canada and India between February 2007 and March 2016. 

The participants were randomly assigned to receive dalteparin (n=821; one patient withdrew consent immediately after randomization) or a placebo (n=650) after the procedure.

The main outcome measure was major thromboembolism (stroke, transient ischaemic attack, proximal deep vein thrombosis, pulmonary embolism, myocardial infarction, peripheral embolism, or vascular death) and major bleeding within 90 days of the procedure. 

"In patients with atrial fibrillation or mechanical heart valves who had warfarin interrupted for a procedure, no significant benefit was found for postoperative dalteparin bridging to prevent major thromboembolism," wrote the authors. 

"Further studies are needed to determine the need for bridging before procedures in patients with mechanical heart valves," they concluded. 

Reference:

The study titled, "Postoperative low molecular weight heparin bridging treatment for patients at high risk of arterial thromboembolism (PERIOP2): double blind randomised controlled trial," is published in The BMJ.

DOI: https://www.bmj.com/content/373/bmj.n1205