Warfarin for the prevention of systemic embolism in patients with non-valvular atrial fibrillation: a meta-analysis.
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.


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


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.
Andersen
L V
LV
Department of Pharmacology, Wilhelm Meyers Allé 240, Aarhus University, Aarhus University Hospital, Aarhus C, Denmark. ljubica.andersen@farm.au.dk
Vestergaard
P
P
Deichgraeber
P
P
Lindholt
J S
JS
Mortensen
L S
LS
Frost
L
L
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000150:complications*; D004617:Embolism / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D014859:Warfarin / Q000627:therapeutic use*; D055815:Young Adult
D000925:Anticoagulants; D010975:Platelet Aggregation Inhibitors; D014859:Warfarin; D001241:Aspirin