The purpose of this study was to perform a meta-analysis comparing the effectiveness and safety of anticoagulation to antiplatelet
therapy for the prevention of thromboembolic events in patients with
atrial fibrillation (AF). MEDLINE, Cochrane, EMBASE, and Google Scholar databases were searched for studies published through May 31, 2014. Randomized controlled trials comparing
anticoagulants (
warfarin) and antiplatelet
therapy in patients with AF were included. The primary outcomes were the rates of
stroke and systemic
embolism. Secondary outcomes included the rates of
hemorrhage/major
bleeding and death. Pooled odds ratios (
ORs) and 95% confidence intervals (CIs) were calculated. Nine reports of 8 trials that enrolled 4363 patients (2169 patients received anticoagulation and 2194 antiplatelet
therapy) were included. All of the studies compared adjusted-dose
warfarin or with
aspirin, and the majority of the patients were >70 years of age.
Anticoagulants were titrated to an international normalized ratio (INR) of 2.0 to 4.5, and
aspirin was administered at a dosage of 75 to 325 mg/d. Death occurred in 206 participants treated with an
anticoagulant and 229 participants treated with antiplatelet
therapy. There was no significant difference in the overall
stroke rate between the groups (OR = 0.667, 95% CI 0.426-1.045, P = 0.08); however, patients with nonrheumatic AF (NRAF) treated with an
anticoagulant had a lower risk of
stroke (OR = 0.557, 95% CI 0.411-0.753, P < 0.001).
Anticoagulants were associated with a lower risk of
embolism (OR = 0.616, 95% CI = 0.392-0.966, P = 0.04), and this finding persisted in patients with NRAF (OR = 0.581, 95% CI 0.359-0.941, P = 0.03). No significant difference in the rate of
hemorrhage/major
bleeding was noted (OR = 1.497, 95% CI 0.730-3.070, P = 0.27), and this finding persisted on subgroup analysis.
Anticoagulants appear to be more effective than
aspirin in preventing
embolisms in patients with AF, as the risk of
bleeding is not increased.