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(Stroke. 2008;39:1482.)
© 2008 American Heart Association, Inc.

Original Contributions

Risks and Benefits of Oral Anticoagulation Compared With Clopidogrel Plus Aspirin in Patients With Atrial Fibrillation According to Stroke Risk

The Atrial Fibrillation Clopidogrel Trial With Irbesartan for Prevention of Vascular Events (ACTIVE-W)

Jeff S. Healey, MD, MSc; Robert G. Hart, MD; Janice Pogue, MSc; Marc A. Pfeffer, MD, PhD; Stefan H. Hohnloser, MD; Raffaele De Caterina, MD; Greg Flaker, MD; Salim Yusuf, MD, DPhil Stuart J. Connolly, MD

From the Population Health Research Institute (J.S.H., J.P., S.Y., S.J.C.), McMaster University, Hamilton, Canada; the University of Texas at San Antonio (R.G.H.), San Antonio, Tex; Brigham and Women’s Hospital (M.A.P.), Harvard University, Boston, Mass; J.W. Goethe University (S.H.H.), Frankfurt, Germany; G. D’Annunzio University (R.D.C.), Chieta, Italy; and the University of Missouri (G.F.), Columbia, Mo.

Correspondence to Jeff Healey, McMaster University, 237 Barton St E, Hamilton, Ontario, Canada, L8L 2X2. E-mail healeyj{at}hhsc.ca

Background and Purpose— In ACTIVE-W, oral anticoagulation (OAC) was more efficacious than combined clopidogrel plus aspirin (C+A) in preventing vascular events in patients with atrial fibrillation. However, because OAC carries important bleeding complications, risk stratification schemes have been devised to identify patients for whom the absolute benefits of OAC exceed its risks.

Methods— Participants were risk-stratified with the widely-used CHADS₂ scheme. Treatment-specific rates of stroke and major bleeding were calculated for patients with a CHADS₂=1 and compared to those with a CHADS₂>1.

Results— Observed stroke rates for those with a CHADS₂=1 were 1.25% per year on C+A and 0.43% per year on OAC (RR=2.96, 95% CI: 1.26 to 6.98, P=0.01). Among patients with a CHADS₂>1, the stroke rates were 3.15% per year on C+A and 2.01% per year on OAC (RR=1.58, 95% CI: 1.11 to 2.24, P=0.01) (P for interaction between stroke risk category and efficacy of OAC=0.19). The risk of major bleeding during OAC was significantly lower among patients with CHADS₂=1 (1.36% per year) compared with CHADS₂>1 (2.75% per year) (RR=0.49, 95% CI 0.30 to 0.79, P=0.003).

Conclusions— In this clinical trial, patients with a CHADS₂=1 had a low risk of stroke, yet still derived a modest (<1% per year) but statistically significant absolute reduction in stroke with OAC and had low rates of major hemorrhage on OAC.

Key Words: atrial fibrillation • stroke • risk stratification • anticoagulation

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The Balance Between Stroke Prevention and Bleeding Risk in Atrial Fibrillation: A Delicate Balance Revisited

Gregory Y.H. Lip
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