#1	(atrial fibrillation OR atrial flutter):ti,ab,kw
#2	warfarin:ti,ab,kw OR coumadin:ti,ab,kw
#3	MeSH descriptor Antithrombins explode all trees OR antithrombins:ti,ab,kw OR (direct:ti,ab,kw AND thrombin:ti,ab,kw AND inhibitors:ti,ab,kw) OR "direct thrombin inhibitors":ti,ab,kw OR "direct thrombin inhibitor":ti,ab,kw
#4	MeSH descriptor Anticoagulants explode all trees OR anticoagulant:ti,ab,kw OR anticoagulants:ti,ab,kw OR vitamin k:ti,ab,kw OR enoxaparin:ti,ab,kw OR lovenox:ti,ab,kw OR rivaroxaban:ti,ab,kw OR xarelto:ti,ab,kw OR dabigatran:ti,ab,kw OR pradaxa:ti,ab,kw OR heparin:ti,ab,kw OR apixaban:ti,ab,kw OR eliquis:ti,ab,kw OR edoxaban:ti,ab,kw OR lixiana:ti,ab,kw
#5	#1 AND #2 AND (#3 OR #4)
#6	#5, Limits: Cochrane Reviews, 2000 to 2012