Antiplatelet therapy reduces the risk of myocardial infarction, stroke, and vascular death in patients who have symptomatic peripheral artery disease. However, a subset of patients who take aspirin continues to have recurrent cardiovascular events. There are few data on cardiovascular outcomes in patients with peripheral artery disease who manifest aspirin resistance. Patients with peripheral artery disease on long-term aspirin therapy (≥4 wk) were tested for aspirin responsiveness by means of the VerifyNow Aspirin Assay. The mean follow-up duration was 22.6 ± 8.3 months. The primary endpoint was a composite of death, myocardial infarction, or ischemic stroke. Secondary endpoints were the incidence of vascular interventions (surgical or percutaneous), or of amputation or gangrene caused by vascular disease. Of the 120 patients enrolled in the study, 31 (25.8%) were aspirin-resistant and 89 (74.2%) were aspirin-responsive. The primary endpoint occurred in 10 (32.3%) patients in the aspirin-resistant group and in 13 (14.6%) patients in the aspirin-responsive group (hazard ratio=2.48; 95% confidence interval, 1.08-5.66; P=0.03). There was no significant difference in the secondary outcome of revascularization or tissue loss. By multivariate analysis, aspirin resistance and history of chronic kidney disease were the only independent predictors of long-term adverse cardiovascular events. Aspirin resistance is highly prevalent in patients with symptomatic peripheral artery disease and is an independent predictor of adverse cardiovascular risk. Whether intervening in these patients with additional antiplatelet therapies would improve outcomes needs to be explored.
Keywords: Aspirin/therapeutic use; blood platelets/drug effects; lower extremity/blood supply; peripheral vascular diseases; platelet aggregation inhibitors/therapeutic use.