Impaired responsiveness to clopidogrel and aspirin in patients with recurrent stent thrombosis following percutaneous intervention for peripheral artery disease

Patients with peripheral artery disease (PAD) following peripheral percutaneous transluminal angioplasty (PTA) with stent implantation are prone to stent thrombosis despite treatment with aspirin and clopidogrel. Impaired clopidogrel responsiveness is associated with increased risk of ischemic events in patients following coronary stent implantation. We sought to assess platelet responsiveness to clopidogrel and aspirin in patients with PAD and recurrent stent thrombosis. Platelet aggregation induced by 5 and 20 µmol/l adenosine diphosphate (ADP) and 0.5 mmol/l arachidonic acid (AA), together with platelet reactivity index (PRI) and serum thromboxane B(2) (TXB(2)), were determined in 11 patients with PAD and a history of stent thrombosis (mean, 3.1 ± 1.14) after PTA and in 15 patients with PAD with no such history, also in 11 controls with coronary artery disease (CAD) and previous stent thrombosis. Platelet aggregation to 5 µmol/l ADP was higher in subjects with PAD and stent thrombosis than in those without stent thrombosis (p = 0.0003) and CAD subjects (p = 0.002). Aggregation induced by 20 µmol/l ADP was higher in PAD group with stent thrombosis than in PAD subjects without thrombosis (p = 0.004). The PAD group with stent thrombosis had higher AA-induced platelet aggregation than CAD controls (p = 0.007) and serum TXB(2) concentrations higher than PAD group without thrombosis (p = 0.002) and CAD group (p = 0.02). Concluding, platelet responsiveness to clopidogrel and aspirin is impaired in patients with PAD and recurrent stent thrombosis following PTA, as compared with similar individuals with CAD, and PAD with no history of stent thrombosis. This indicates that atherosclerosis burden affects platelet function and might contribute to stent thrombosis following percutaneous intervention in peripheral arteries.