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Heart rhythm disorders and pacemakers
Warfarin for the prevention of systemic embolism in patients with non-valvular atrial fibrillation: a meta-analysis
  1. L V Andersen1,
  2. P Vestergaard2,
  3. P Deichgraeber1,
  4. J S Lindholt3,
  5. L S Mortensen4,
  6. L Frost5,6
  1. 1
    Department of Pharmacology, Aarhus University Hospital, Aarhus, Denmark
  2. 2
    Department of Endocrinology C, Aarhus University Hospital, Aarhus, Denmark
  3. 3
    Vascular Research Unit, Department of Vascular Surgery, Viborg Hospital, Viborg, Denmark
  4. 4
    UNI-C, The Danish IT Centre for Education and Research, Aarhus, Denmark
  5. 5
    Department of Medicine, Silkeborg Hospital, Silkeborg, Denmark
  6. 6
    Clinical Institute, Aarhus University Hospital, Aarhus, Denmark
  1. Dr L V Andersen, Department of Pharmacology, Wilhelm Meyers Allé 240, Aarhus University, Aarhus University Hospital, DK-8000 Aarhus C, Denmark; ljubica.andersen{at}


Background: Warfarin for stroke prevention in patients with atrial fibrillation (AF) is well documented. However, it has not been examined in the prevention of systemic embolism.

Objectives: To evaluate the efficacy of warfarin in preventing systemic embolism (embolism to limbs or viscera) in patients with AF.

Methods and results: A combined Medline, Embase, Cochrane Library and SveMed+ search were made. Fifteen studies were included. Warfarin was better than antiplatelet agents for preventing systemic embolism with a 50% reduction of risk (odds ratio (OR) = 0.50, 95% CI 0.33 to 0.75) without increasing the risk of major bleeding (OR = 1.07; 95% CI 0.85 to 1.34). Warfarin compared with placebo resulted in a risk reduction of 71% (OR = 0.29; 95% CI 0.08 to 1.07) with higher risk of major bleeding with warfarin (OR = 3.01; 95% CI 1.31 to 6.92). Results of a comparison of warfarin with low-dose warfarin (OR = 1.52; 95% CI 0.40 to 5.81) or low-dose warfarin with aspirin (OR = 1.00; 95% CI 0.17 to 5.81) were inconclusive.

Conclusions: Warfarin not only reduces the risk of stroke but is also better than placebo and antiplatelet agents in prevention of systemic embolism in patients with non-valvular AF. Warfarin increases the risk of major bleeding compared with placebo but not compared with antiplatelet agents.

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  • Competing interests: None.