Stroke-bleeding risk score pairings within individuals in the outcomes registry for better informed treatment of atrial fibrillation (ORBIT-AF) registry

Background: Decisions about stroke prevention strategies in atrial fibrillation (AF) typically balance thromboembolism reduction against increased bleeding from oral anticoagulation therapy (OAC). When determining eligibility for OAC, guidelines recommend calculation of thromboembolic event rates using a validated score such as CHA2DS2-VASc. In contrast, routine calculation of bleeding scores is not recommended, in part because many patient factors associated with an increased risk of bleeding are associated with an even larger increased risk of ischemic stroke. We set out to characterize patients by paired stroke and bleeding risk scores to understand the level of concordance. Methods: Between 2010 and 2016, we identified 20,451 AF patients in the Outcomes Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF) I and II Registries. We grouped patients by stroke and bleeding risk pairings: low and high stroke risk (CHA2DS2-VASc < and >= 2), low and high bleeding risk (ORBIT < and >= 4) and described treatment rates with OAC and antiplatelet (AP) therapy. Results: Most patients (68.6 %) were at high stroke and low bleeding risk. Patients at high bleeding risk (19.4 %) had high stroke risk (98.5 %). Treatment rates differed with combined OAC + AP therapy highest for patients at high stroke and bleeding risks. Ischemic and bleeding events were also highest in this group. Conclusions: Nearly all AF patients in this cohort with high bleeding risk (ORBIT score >= 4) had high stroke risk (CHA2DS2-VASc >= 2), supporting that bleeding risk should not obviate the need for stroke prevention. In contrast, most at high stroke risk were at low bleeding risk (ORBIT <4), supporting OAC for the majority. Bleeding scores, in combination with factors that specifically indicate a higher risk of bleeding, may identify patients who might be candidates for alternative stroke prevention such as left atrial appendage occlusion devices or bleeding mitigation strategies such as de-escalation of antiplatelet therapy.