This study evaluated the benefit of dual therapy in reducing ischemic events in atrial fibrillation (AF) patients presenting with acute coronary syndrome (ACS) or undergoing percutaneous coronary intervention (PCI). We searched PubMed, Cochrane Library, and ClinicalTrials.gov for randomized controlled trials (RCTs) comparing dual and triple therapies (oral anticoagulation plus aspirin and P2Y12 inhibitor) for AF patients with ACS or those undergoing PCI. The composite primary outcome included all-cause death, myocardial infarction (MI), stent thrombosis (ST), or stroke. Relative risk (RR) and the corresponding 95% confidence interval (CI) was used as the measure of effect size. Four RCTs with 10,969 patients were included. Dual therapy had a higher event rate of primary outcome than triple therapy (RR, 1.15; 95%CI, 1.03–1.28; P<0.0001). Dual therapy was associated with significantly higher MI risk, insignificantly higher ST risk, and significantly lower major bleeding risk than triple therapy (RR1.23, 95%CI 1.01–1.49, P = 0.036; RR 1.43, 95 %CI 0.98–2.09, P = 0.064; and RR0.58, 95%CI 0.45–0.76, P<0.0001, respectively). Dual antithrombotic therapy was associated with higher ischemic risk but lower major bleeding risk than triple therapy. The data suggest that antithrombotic regimens should be based on tradeoffs between ischemia and bleeding risk.