Effect of apixaban on brain infarction and microbleeds: AVERROES-MRI assessment study.

BACKGROUND: Clinical and subclinical (covert) stroke is a cause of cognitive loss and functional impairment. In the AVERROES trial, we performed serial brain magnetic resonance imaging (MRI) scans in a subgroup to explore the effect of apixaban, compared with aspirin, on clinical and covert brain infarction and on microbleeds in patients with atrial fibrillation. METHODS: We performed brain MRI (T1, T2, fluid-attenuated inversion recovery, and T2* gradient echo sequences) in 1,180 at baseline and in 931 participants at follow-up. Mean interval from baseline to follow-up MRI scans was 1.0 year. The primary outcome was a composite of clinical ischemic stroke and covert embolic pattern infarction (defined as infarction >1.5 cm, cortical-based infarction, or new multiterritory infarction). Secondary outcomes included new MRI-detected brain infarcts and microbleeds and change in white matter hyperintensities. RESULTS: Baseline MRI scans revealed brain infarct(s) in 26.2% and microbleed(s) in 10.5%. The rate of the primary outcomes was 2.0% in the apixaban group and 3.3% in the aspirin group (hazard ratio [HR] 0.55; 0.27-1.14) from baseline to follow-up MRI scan (mean duration of follow-up: 1 year). In those who completed baseline and follow-up MRI scans, the rate of new infarction detected on MRI was 2.5% in the apixaban group and 2.2% in the aspirin group (HR 1.09; 0.47-2.52), but new infarcts were smaller in the apixaban group (P = .03). There was no difference in proportion with new microbleeds on follow-up MRI (HR 0.92; 0.53-1.60) between treatment groups. CONCLUSIONS: Apixaban treatment was associated with a nonsignificant trend toward reduction in the composite of clinical ischemic stroke and covert embolic-pattern infarction and did not increase the number of microbleeds in patients with atrial fibrillation compared with aspirin.

Addressing barriers to optimal oral anticoagulation use and persistence among patients with atrial fibrillation: Proceedings, Washington, DC, December 3-4, 2012.

Approximately half of patients with atrial fibrillation and with risk factors for stroke are not treated with oral anticoagulation (OAC), whether it be with vitamin K antagonists (VKAs) or novel OACs (NOACs); and of those treated, many discontinue treatment. Leaders from academia, government, industry, and professional societies convened in Washington, DC, on December 3-4, 2012, to identify barriers to optimal OAC use and adherence and to generate potential solutions. Participants identified a broad range of barriers, including knowledge gaps about stroke risk and the relative risks and benefits of anticoagulant therapies; lack of awareness regarding the potential use of NOAC agents for VKA-unsuitable patients; lack of recognition of expanded eligibility for OAC; lack of availability of reversal agents and the difficulty of anticoagulant effect monitoring for the NOACs; concerns with the bleeding risk of anticoagulant therapy, especially with the NOACs and particularly in the setting of dual antiplatelet therapy; suboptimal time in therapeutic range for VKA; and costs and insurance coverage. Proposed solutions were to define reasons for oral anticoagulant underuse classified in ways that can guide intervention and improve use, to increase awareness of stroke risk as well as the benefits and risks of OAC use via educational initiatives and feedback mechanisms, to better define the role of VKA in the current therapeutic era including eligibility and ineligibility for different anticoagulant therapies, to identify NOAC reversal agents and monitoring strategies and make knowledge regarding their use publicly available, to minimize the duration of dual antiplatelet therapy and concomitant OAC where possible, to improve time in therapeutic range for VKA, to leverage observational data sets to refine understanding of OAC use and outcomes in general practice, and to better align health system incentives.

Modification of outcomes with aspirin or apixaban in relation to CHADS(2) and CHA(2)DS(2)-VASc scores in patients with atrial fibrillation: a secondary analysis of the AVERROES study.

BACKGROUND: The impact of apixaban versus aspirin on ischemic stroke and major bleeding in relation to the CHADS(2) and CHA(2)DS(2)-VASc stroke risk scores in atrial fibrillation has not been investigated. METHODS AND RESULTS: In this secondary analysis of the AVERROES trial, our principal objective was to assess the effect of treatment with aspirin or apixaban on ischemic stroke and major bleeding, in relation to the CHADS(2)/CHA(2)DS(2)-VASc scores. We found no significant heterogeneity for treatment efficacy on ischemic stroke for apixaban when subdivided by stroke risk strata, based on CHADS(2)/CHA(2)DS(2)-VASc. Effects were consistent irrespective of baseline risk, and thus, absolute benefits were greatest in the high-risk groups. There was also no significant heterogeneity for apixaban versus aspirin with regard to major bleeding, when subdivided by CHADS(2)/CHA(2)DS(2)-VASc scores. In multivariable analysis, significant predictors of stroke on aspirin were age ≥75 years, prior stroke or transient ischemic attack, estimated glomerular filtration rate <60 mL/min, and nonparoxysmal atrial fibrillation. Proportions of the study cohort classified as low/moderate/high risk using the CHADS(2) and CHA(2)DS(2)-VASc scores were 0.3%/71.7%/28.1% and <0.1%/10.5%/89.5%, respectively. CONCLUSIONS: In an atrial fibrillation population, apixaban was superior to aspirin for stroke prevention, with similar rates of major bleeding, in the presence of one or more stroke risk factors, with consistency of the treatment effect by CHADS(2)/CHA(2)DS(2)-VASc scores.