Is aspirin (acetylsalicylic acid) 81mg suitable for stroke prevention in a 92-year-old patient with atrial fibrillation (afib)?

Aspirin 81mg is Not Suitable for Stroke Prevention in a 92-year-old with Atrial Fibrillation

Aspirin 81mg alone is not recommended for stroke prevention in a 92-year-old patient with atrial fibrillation as it offers only modest protection against stroke with a risk reduction of just 19% compared to placebo, and is particularly ineffective in patients over 75 years of age. 1

Risk Assessment in Elderly AF Patients

• Age over 75 years is considered a high-risk factor for stroke in patients with atrial fibrillation according to the CHADS2 scoring system 1
• A 92-year-old patient would automatically have at least 1 point on the CHADS2 score for age ≥75 years, placing them at increased stroke risk 1
• The adjusted annual stroke rate for patients with a CHADS2 score of 1 is 2.8%, increasing significantly with additional risk factors 1
• Aspirin appears to prevent non-disabling strokes more than disabling strokes, making it less effective for preventing the more severe cardioembolic strokes common in AF 1

Evidence Against Aspirin in Elderly AF Patients

• Aspirin was shown to be ineffective in preventing strokes specifically in those >75 years of age in clinical trials 1
• Meta-analysis of 5 randomized trials showed aspirin provides only a modest 19% reduction in stroke risk (95% CI: 2% to 34%) compared to placebo, with the 95% confidence interval nearly encompassing zero 1
• The Birmingham Atrial Fibrillation Treatment of the Aged Study (BAFTA) specifically evaluated warfarin versus aspirin in patients aged 75 years or older (mean age 81.5 years) and found warfarin significantly superior with a yearly stroke risk of 1.8% versus 3.8% with aspirin 2
• The AVERROES study demonstrated that apixaban was significantly superior to aspirin for stroke prevention in AF patients deemed unsuitable for warfarin therapy, with similar major bleeding risks 1

Appropriate Antithrombotic Therapy Based on Risk

• According to the 2012 American College of Chest Physicians guidelines, patients with a CHADS2 score of ≥2 (which would include a 92-year-old with any additional risk factor) should receive oral anticoagulation rather than aspirin 1
• Even for patients with a CHADS2 score of 1 (which would be the minimum for a 92-year-old with AF), oral anticoagulation is recommended rather than aspirin 1
• The 2014 AHA/ACC/HRS guidelines emphasize that aspirin has not been shown to be effective in preventing strokes in elderly patients with AF 1

Special Considerations for Very Elderly Patients

• For frail elderly patients with low weight, the American Geriatrics Society recommends particular caution when initiating anticoagulation therapy due to increased bleeding risk 3
• If oral anticoagulation is chosen, a target INR of 2.0 (range 1.6 to 2.5) may be appropriate for elderly patients with nonvalvular AF to reduce bleeding risk while maintaining approximately 80% of the efficacy 3
• Novel oral anticoagulants (NOACs) may be suitable alternatives to warfarin for stroke prevention in older patients due to fewer drug interactions and no requirement for regular monitoring 4
• Dose adjustments may be required for certain NOACs in elderly patients with renal impairment 4

Conclusion for Clinical Practice

• For a 92-year-old patient with AF, aspirin 81mg alone is inadequate for stroke prevention 1, 2
• If the patient has no contraindications to anticoagulation, an oral anticoagulant (either warfarin with careful monitoring or an appropriately dosed NOAC) would be the preferred option 1, 4
• If anticoagulation is absolutely contraindicated, the combination of aspirin and clopidogrel provides better stroke prevention than aspirin alone, but with increased bleeding risk 5
• The AVERROES trial showed that apixaban was superior to aspirin with similar bleeding risk in patients deemed unsuitable for warfarin, making it a potential alternative to aspirin in this elderly population 6