Level 2: Mid-level evidence

Atrial fibrillation affects 1.5% to 2% of the general population and is associated with a fivefold increased risk of stroke (Eur Heart J. 2012;33[21]:2719). Antithrombotic therapy is consistently recommended for most patients with atrial fibrillation and until recently warfarin, a vitamin K antagonist, has been the antithrombotic of choice (J Am Coll Cardiol. 2014 March 28 online ahead of print; Eur Heart J. 2010;31[19]:2369; Can J Cardiol. 2012;28[2]:125).

Warfarin use requires monthly blood monitoring and is associated with an increased risk of bleeding. The left atrial appendage has been suggested as a major source of thromboembolism in patients with atrial fibrillation, and left atrial appendage closure without long-term antithrombotic therapy may prevent stroke (Circulation. 2002;105[16]:1887).

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The PROTECT AF trial compared percutaneous device closure of left atrial appendage versus warfarin in 707 patients with nonvalvular atrial fibrillation plus one or more risk factors for stroke including age ≥ 75 years, history of previous stroke or transient ischemic attack, hypertension, diabetes, heart failure, or left ventricular systolic dysfunction (Lancet. 2009;374[9689]:534). A four-year follow-up of the PROTECT AF trial was recently published, providing long-term efficacy and safety data (JAMA. 2014;312[19]:1988).