Bayer Pharma AG

Essence of this Article

Antiplatelet agents have demonstrated some efficacy in the prevention of stroke in patients with atrial fibrillation (AF); however, they are far less efficacious than vitamin K antagonist (VKA) therapy, and their use is becoming increasingly limited as guidelines recommend antiplatelet therapy for only a small population of patients. The two antiplatelet agents used for stroke prophylaxis in patients with AF are acetylsalicylic acid (ASA; aspirin) and clopidogrel. ASA has previously been used in patients with a low risk of stroke, but its role has been diminishing owing to limited evidence of efficacy in comparison with oral anticoagulants (OACs).

Atrial fibrillation-related stroke: a major healthcare burden

Antiplatelet agents have demonstrated efficacy in the prevention of stroke in patients with AF,198, 199 although to a far lesser extent than VKA therapy.200 The use of antiplatelet therapy for stroke prevention in patients with AF is becoming increasingly limited, because current guidelines only recommend antiplatelet therapy for a small population of patients, such as those who are unwilling to take OACs, or for whom oral anticoagulation is contraindicated.

International guidelines have previously recommended that patients with AF receive ASA if they were at a low risk of stroke,201, 202 and as a treatment option (with VKA therapy as the other option) for patients who have AF and a moderate risk of stroke.201 However, the role of ASA for stroke prevention has diminished in recent guidelines given the limited evidence for efficacy and potential for causing serious bleeding events.187, 200, 203

Current American College of Chest Physicians (ACCP) 2012 guidelines now limit the recommendation for ASA to an option for patients with AF with a low risk of stroke (although oral anticoagulation is preferred), or patients with AF and no stroke risk factors (with no antithrombotic therapy preferred over ASA therapy).190 The latest European Society of Cardiology (ESC) 2012 guideline update only recommends ASA in combination with clopidogrel for patients who refuse OACs, and ASA alone in any of the latter group who cannot tolerate combined antiplatelet therapy.187 However, the most recent American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS) 2014 guidelines for the management of patients with AF still include ASA as an option for patients with a moderate risk of stroke.534

Antiplatelet agents used for stroke prophylaxis in patients with AF

Drug Target Dose/regimen Supporting study/ substudies
ASA Irreversibly inhibits the COX­1 enzyme 75–325 mg oda,b ACTIVE-W198
ACTIVE-A199
Meta-analysis200
Clopidogrel Thienopyridine – irreversibly binds to the ADP receptor P2Y186 75 mg od, administered in combination with ASA 75–100 mg dailyb
aMay be considered for stroke prevention in patients with AF who refuse oral anticoagulant therapy but cannot tolerate ASA plus clopidogrel; bmay be considered in patients who refuse oral anticoagulant therapy.187
ADP, adenosine diphosphate; AF, atrial fibrillation; ASA, acetylsalicylic acid; od, once daily.

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