Abstract

Objectives To evaluate efficacy of warfarin in preventing systemic embolism (embolism to limbs or viscera) in patients with atrial fibrillation (AF). Warfarin for stroke prevention in patients with AF is well documented. However, it has not been examined in the prevention of systemic embolism.

Methods and Results A combined MEDLINE, EMBASE, Cochrane Library and SveMed+ search were made. Fifteen studies were included. Warfarin was superior to antiplatelets with a 50 % reduction of risk of systemic embolism (odds ratio [OR], 0.50, 95% confidence interval [CI], 0.33-0.75) without increasing the risk of major bleeding (OR, 1.07; 95% CI, 0.85-1.34). Warfarin compared with placebo resulted in a risk reduction of 71 % (OR, 0.29; 95% CI 0.08-1.07) with higher risk of major bleeding on warfarin (OR, 3.01; 95% CI, 1.31-6.92). Warfarin compared with low-dose warfarin (OR, 1.52; 95% CI, 0.40-5.81) or low-dose warfarin and aspirin (OR, 1.00; 95% CI, 0.17-5.81) shows inconclusive evidence.

Conclusions Warfarin not only reduces the risk of stroke, but is also superior to placebo as well as antiplatelets in prevention of systemic embolism in patients with nonvalvular atrial fibrillation. Warfarin increase risk of major bleeding compared with placebo but not compared with antiplatelets.