New data show that also lower-risk AF patients benefit from oral anticoagulation

Fauchier L, Clementy N, Bisson A, et al.
Stroke. 2016;47: published online ahead of print

Background

The use of oral anticoagulation (OAC) substantially reduces the risk of stroke/systemic embolism (SSE) in patients with atrial fibrillation (AF) and is guided by risk scores [1]. The currently recommended CHA2DS2-VASc risk score is based on age, sex, and the presence of congestive heart failure, hypertension, diabetes, stroke/transient ischemic attack, and vascular disease [2]. However, different guidelines recommend different treatment approaches based on the use of the CHA2DS2-VASc risk score [3-5]:

• the AHA/ACC guidelines recommend OAC to high-risk AF patients with at least 2 nongender-related (NGR) stroke risk factors (CHA2DS2-VASc >2 in males and >3 in females),
• the ESC and NICE guidelines recommend identifying first the low-risk AF patients who do not need any antithrombotic therapy, after which effective stroke prevention is offered to those with at least 1 NGR stroke risk factor.

In this study, the adverse outcomes and the net clinical benefit of vitamin K antagonist (VKA) were evaluated in a community-based cohort of AF patients with 0 compared with 1 NGR stroke risk factor. Among 8962 AF patients with AF, 2208 (25%) had 0 or 1 NGR stroke risk factors, of which 45% were not prescribed OAC.

Main results

• The annual rate of the composite end point of SSE in non-anticoagulated AF patients with 1 NGR stroke risk factor relative to the group with 0 NGR stroke risk factor was: 2.09%; 95% CI: 1.37–3.18, which corresponded to an adjusted HR: 2.82%; 95% CI: 1.32–6.04.

• The annual rates of death and the composite end point of death/SSE were 3.78% and 5.59% respectively, in non-anticoagulated patients with 1 NGR stroke risk factor, and 0.87% and 1.42% respectively, in non-anticoagulated patients with 0 NGR stroke risk factors.

• The annual rates of bleeding events in non-anticoagulated AF patients with 0 or 1 CHA2DS2-VASc factor were: major bleeding: 0.65%; intracranial haemorrhage: 0.43%. No significant  difference was seen in patients without OACs between 0 or 1 NGR stroke risk factor.
• Net clinical benefit: When the benefit of ischaemic stroke reduction was balanced against the increased risk of intracranial haemorrhage among patients with 1 NGR stroke risk factor, the net clinical benefit was positive in favour of OAC use VS. no antithrombotic therapy or antiplatelet therapy use.
  Net clinical benefit was negative for antiplatelet therapy use vs. no antithrombotic therapy.

Conclusion

Among AF patients with 1 NGR stroke risk factor, OAC use was associated with a positive net clinical benefit for the prevention of stroke and thromboembolic events. These data support a treatment strategy focussed not only on recommending OAC to high-risk, but also to lower-risk AF patients with 1 NGR stroke risk factor.

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References

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2. Lip GY, Nieuwlaat R, Pisters R, et al. Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the euro heart survey on atrial fibrillation. Chest. 2010;137:263–272.
3. Camm AJ, Lip GY, De Caterina R, et al; ESC Committee for Practice Guidelines (CPG). 2012 focused update of the ESC Guidelines for the management of atrial fibrillation: an update of the 2010 ESC Guidelines for the management of atrial fibrillation. Developed with the special contribution of the European Heart Rhythm Association. Eur Heart J. 2012;33:2719–2747.
4. January CT, Wann LS, Alpert JS, et al; American College of Cardiology/American Heart Association Task Force on Practice Guidelines. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2014;64:e1–76.
5. National Clinical Guideline Centre (UK). Atrial Fibrillation: The Management of Atrial Fibrillation [Internet]. London, United Kingdom: National Institute for Health and Care Excellence (UK); 2014.