Patients with atrial fibrillation (AF) who underwent percutaneous coronary intervention (PCI) are at elevated risk for bleeding and thromboembolic ischemic events. Currently, guidelines on antithrombotic treatment for these patients are based on weak consensus. We describe patterns and determinants of antithrombotic prescriptions in this population. The Antithrombotic Strategy Variability in Atrial Fibrillation and Obstructive Coronary Disease Revascularized with PCI Registry was an international observational study of 859 consecutive patients with AF who underwent PCI from 2009 to 2011. Patients were stratified by treatment at discharge with either dual antiplatelet therapy (DAPT; aspirin plus clopidogrel) or triple therapy (TT; warfarin plus DAPT). Bleeding and thromboembolism risks were assessed by the HAS-BLED and CHADS2 scores, respectively, and predictors of TT prescription at discharge were identified. Major adverse cardiovascular events and clinically relevant bleeding (Bleeding Academic Research Consortium score ≥2) at 1-year follow-up were compared across antithrombotic regimens. Compared with patients on DAPT (n = 488; 57%), those given TT (n = 371; 43%) were older, with higher CHADS2 scores, lower left ventricular ejection fraction, and more often had permanent AF, single-vessel coronary artery disease, and bare-metal stents. In multivariate analysis, increasing thromboembolic risk (CHADS2 ) was associated with a higher rate of TT prescription at discharge (intermediate vs low CHADS2 : odds ratio 2.2, 95% confidence interval CI 2.0 to 3.3, p <0.01; high vs low CHADS2 : odds ratio 1.6, 95% CI 2.6 to 4.3, p <0.01 for TT). However, there was no significant association between bleeding risk and TT prescription in the overall cohort or within each CHADS2 risk stratum. The rates of major adverse cardiovascular events were similar for patients discharged on TT or DAPT (20% vs 17%, adjusted hazard ratio 0.8, 95% CI 0.5 to 1.1, p = 0.19), whereas the rate of Bleeding Academic Research Consortium ≥2 bleeding was higher in patients discharged on TT (11.5% vs 6.4%, adjusted hazard ratio 1.8, 95% CI 1.1 to 2.9, p = 0.02). In conclusion, the choice of the intensity of antithrombotic therapy correlated more closely with the risk of ischemic rather than bleeding events in this cohort of patients with AF who underwent PCI.