From the Guidelines
Aspirin alone is not sufficient for stroke prevention in most patients with paroxysmal atrial fibrillation. Oral anticoagulants such as direct oral anticoagulants (DOACs) like apixaban, rivaroxaban, dabigatran, or edoxaban, or warfarin, are generally recommended instead, as stated in the 2024 ESC guidelines for the management of atrial fibrillation 1. The choice of anticoagulation should be based on the patient's stroke risk, typically assessed using the CHA₂DS₂-VASc score. For patients with a score of 2 or higher in men or 3 or higher in women, oral anticoagulation is strongly recommended. Aspirin provides only modest stroke risk reduction (approximately 20%) compared to oral anticoagulants (60-70% reduction) 1.
Some key points to consider:
- The efficacy of stroke prevention with aspirin is weak, with a potential for harm, since the risk of major bleeding (and ICH) with aspirin is not significantly different to that of OAC, especially in the elderly 1.
- The use of antiplatelet therapy (as aspirin–clopidogrel combination therapy or—less effectively—aspirin monotherapy for those who cannot tolerate aspirin–clopidogrel combination therapy) for stroke prevention in AF should be limited to the few patients who refuse any form of OAC 1.
- The CHA2DS2-VASc score is better at identifying ‘truly low-risk’ patients with AF and is as good as—and possibly better than—scores such as CHADS2 in identifying patients who develop stroke and thromboembolism 1.
In patients with AF, antiplatelet therapy alone (monotherapy or aspirin in combination with clopidogrel) is not recommended for stroke prevention alone, regardless of stroke risk, according to the 2018 Chest guideline and expert panel report 1. Instead, NOACs are recommended over VKA for patients eligible for OAC, considering patient and caregiver preferences, cost, formulary considerations, anticipated medication adherence or compliance with INR testing and dose adjustment 1.
Overall, the current evidence suggests that aspirin alone is not sufficient for stroke prevention in most patients with paroxysmal atrial fibrillation, and oral anticoagulants are generally recommended instead, with the choice of anticoagulation based on the patient's stroke risk.
From the Research
Aspirin and Paroxysmal Atrial Fibrillation
- Aspirin has a limited role in stroke prevention for patients with atrial fibrillation, including those with paroxysmal atrial fibrillation, as it is an inferior strategy compared to anticoagulants like warfarin 2.
- The annual risk of stroke in patients with atrial fibrillation is approximately 5%, with a wide range depending on additional risk factors, and aspirin therapy results in a 20 to 30% risk reduction 3.
- For patients with paroxysmal atrial fibrillation, the risks of stroke or systemic embolism and major bleeding are considered similar to those with sustained atrial fibrillation, and warfarin has demonstrated superior efficacy to aspirin 4.
- Novel oral anticoagulants (NOACs) have shown superior efficacy over warfarin and trended to show reduced major bleeding irrespective of the atrial fibrillation type, including paroxysmal atrial fibrillation 4.
- Aspirin may be used in patients with paroxysmal atrial fibrillation who have contraindications to anticoagulant therapy or who are not at high risk for developing thromboembolic stroke, but its use should be carefully considered based on individual patient risk factors 5.
Stroke Prevention Strategies
- Anticoagulation therapy, such as warfarin or NOACs, is recommended for patients with atrial fibrillation at moderate to high risk of stroke, including those with paroxysmal atrial fibrillation 6, 4.
- Aspirin may be used in combination with clopidogrel in patients with atrial fibrillation who refuse oral anticoagulant drugs or have difficulties with anticoagulation monitoring, but this combination shows only modest benefit in stroke prevention compared to aspirin monotherapy 2.
- The choice of antithrombotic therapy for patients with paroxysmal atrial fibrillation should be based on individual patient risk factors, including the risk of stroke and bleeding, and should take into account the latest clinical trial evidence and guidelines 3, 4.