For people with atrial fibrillation, new “blood thinners” (factor Xa inhibitors) reduce strokes and clots more than warfarin

Bruins Slot KMH, Berge E. Factor Xa inhibitors versus vitamin K antagonists for preventing cerebral or systemic embolism in patients with atrial fibrillation. Cochrane Database Syst Rev. 2013;8:CD008980.

Review question

How effective and safe are factor Xa inhibitors for the prevention of cerebral embolism (strokes) or systemic embolic events in people with atrial fibrillation?

Background

Atrial fibrillation is a common type of irregular heartbeat. It can lead to small clots forming in the heart. Clots can then flow from the heart to block an artery in the brain (cerebral embolism causing a stroke) or other organ (systemic embolism of the heart—causing a heart attack—or the legs—causing gangrene).

Management of atrial fibrillation aims at reducing symptoms and preventing blood clotting. An adverse effect of preventing clots is abnormal bleeding.

For decades, anticoagulant treatment with vitamin K antagonists such as warfarin (Coumadin) has been the therapy of choice for most people with atrial fibrillation.

Factor Xa inhibitors—a new class of anticoagulants—seem to have some advantages over vitamin K antagonists.

How the review was done

This summary is based on a systematic review of 10 randomized controlled trials directly comparing warfarin with factor Xa inhibitors. Publication period was 2008 to 2013.

Studies involved 42,084 people. Age ranged from 18 to 75 years. At least 50% of participants were followed up for between 12 weeks and 1.9 years

Factor Xa inhibitors assessed were apixaban, betrixaban, darexaban, edoxaban, idraparinux, and rivaroxaban.

Outcomes included strokes, embolism in other organs, major bleeding, intracranial hemorrhage, and death from all causes.

What the researchers found

Compared with warfarin, factor Xa inhibitors

• reduced the number of strokes and systemic embolic events by 22% (7 fewer events per 1,000 people treated).
• reduced the number of strokes by 26% (7 fewer events per 1,000 people treated).
• reduced the number of major bleeds by 15% (7 fewer events per 1,000 people treated). This evidence is less strong due to variation of effect across trials.
• reduced the number of intracranial hemorrhages by 45% (6 fewer events per 1,000 people treated).
• reduced the number of deaths from any cause by 18% (6 fewer events per 1,000 people treated).

Conclusion

For people with atrial fibrillation, anticoagulant treatment with factor Xa inhibitors reduces strokes and systemic embolic events compared with warfarin and also reduces the risk of bleeding.