Background and purpose: Long-term anticoagulation is routinely used for secondary stroke prevention in atrial fibrillation, often regardless of stroke subtype. Although the role of warfarin in cardioembolic stroke is established, it may not prevent recurrence in other stroke subtypes, even in the presence of atrial fibrillation.
Methods: This was a 2-year, prospective, intervention study conducted in a district general hospital. Participants included 386 acute stroke patients with atrial fibrillation. Subjects were characterized for stroke subtype on clinical, neuroimaging, carotid ultrasonographic, and echocardiographic criteria. Eligible patients were treated with adjusted-dose warfarin (international normalized ratio, 2.0 to 3.0). Aspirin (75 to 300 mg/d) was used in patients with contraindications or those who refused anticoagulation. The main outcome measures were rate of recurrent stroke by subtype and major and minor bleeding complications.
Results: The aspirin group (n=172) was comparable to the warfarin group (n=214) in terms of age, sex, risk factors, and initial stroke subtype. The rate of recurrent stroke was higher (9.5% versus 4.9%, P<0.02) but that of major bleeding was lower (0.6% versus 2.5%, P<0.05) with aspirin. The increased stroke rate with aspirin was due predominantly to cardioembolic recurrence in patients presenting initially with cardioembolic stroke (8.4% versus 1.9%, P<0.01). The recurrence rate in aspirin-treated patients who presented with lacunar stroke and atrial fibrillation was similar to that seen in patients receiving warfarin (8.8% versus 8.9%).
Conclusions: In this cohort of stroke patients with atrial fibrillation, anticoagulation was superior to aspirin in preventing cardioembolic but not lacunar recurrence. Determination of stroke subtype may be important in anticoagulation decisions for secondary prevention, and further studies are required.