Aspirin Therapy in Peripheral Arterial Disease
Aspirin is indicated for both asymptomatic and symptomatic peripheral arterial disease (PAD) to reduce the risk of myocardial infarction, stroke, and vascular death. 1
Recommendations Based on PAD Status
Asymptomatic PAD
- Aspirin 75-100 mg daily is recommended (Grade 2B) 1
- Benefits include:
- Prevention of 19-31 nonfatal MIs per 1,000 patients treated (moderate to high-risk)
- Reduction in total mortality (6 fewer deaths per 1,000 patients over 10 years)
- Potential reduction in cancer mortality with long-term use
Symptomatic PAD
- Aspirin 75-325 mg daily is strongly recommended (Class I, Level A) 1
- Benefits demonstrated in meta-analyses:
- 22-23% reduction in adverse cardiovascular events
- Significant reduction in vascular events across PAD subgroups:
- 23% reduction in patients with intermittent claudication
- 22% reduction in patients with peripheral arterial grafts
- 29% reduction in patients undergoing peripheral angioplasty
Optimal Dosing
- 75-150 mg daily provides 32% reduction in vascular events
- 160-325 mg daily provides 26% reduction in vascular events
- Higher doses (500-1500 mg) provide less benefit (19% reduction) with increased bleeding risk 1
- Doses below 75 mg daily show significantly reduced efficacy (only 13% reduction) 1
Risk-Benefit Considerations
- Bleeding risk increases with aspirin therapy:
- 1.5-fold increased risk of major extracranial bleeding with 75-150 mg daily
- 1.4-fold increased risk with 160-325 mg daily 1
- The number of vascular events and deaths prevented significantly outweighs bleeding events in symptomatic PAD 1
- For asymptomatic PAD, the balance is closer but still favors treatment 1
Alternative Antiplatelet Options
- Clopidogrel (75 mg daily) may be more effective than aspirin in PAD patients:
- 23.8% greater reduction in MI, stroke, or vascular death compared to aspirin in PAD subgroup analysis 1
- Consider as an alternative in aspirin-intolerant patients
Oral Anticoagulation
- Warfarin is NOT indicated to reduce cardiovascular events in PAD patients (Class III) 1
- Combination therapy of warfarin plus aspirin increases bleeding risk approximately 2-fold without significant benefit in graft patency 1
Implementation Considerations
- Monitor for aspirin nonsensitivity, which affects approximately 24% of vascular disease patients 2
- Medication adherence is critical - noncompliance is common and associated with worse outcomes 2
- The benefit of aspirin appears consistent across PAD subgroups, though some recent studies suggest it may be less effective in PAD than in coronary artery disease 3
In conclusion, aspirin therapy represents a cornerstone of PAD management for both asymptomatic and symptomatic disease, with strong evidence supporting its use for reducing cardiovascular morbidity and mortality.