Previous stent thrombosis was associated with a higher prevalence of ASA resistance (48%) compared to matched controls (32%, p=NS) and healthy volunteers (0%, p=0.01).
Case-Control (n=82)
Is previous stent thrombosis associated with an impaired platelet aggregation response to aspirin and clopidogrel therapy compared to matched controls?
Patients with previous stent thrombosis have an impaired response to aspirin that is not overcome by adding clopidogrel, suggesting aspirin resistance may contribute to stent thrombosis.
Absolute Event Rate: 48% vs 32%
p-value: p=ns
OBJECTIVES: We sought to evaluate the response to antiplatelet therapy in patients with stent thrombosis (ST). BACKGROUND: Stent thrombosis is associated with considerable morbidity and mortality. An impaired response to antiplatelet therapy might be related to an increased risk for ST. METHODS: Eighty-two patients were included in the present study: 23 patients with previous ST, 50 matched controls (coronary stenting without ST), and 9 healthy volunteers. Platelet aggregation (PA) was studied (optical aggregometry) under monotherapy with acetylsalicylic acid (ASA) 100 mg daily for one month, followed by dual therapy with ASA 100 mg and clopidogrel 75 mg daily (loading dose 300 mg) for another month. RESULTS: Maximal (5 and 20 micromol) adenosine diphosphate-induced PA was significantly higher in patients with ST compared with controls (5 micromol, p 20% aggregation with 0.5 mg/ml arachidonic acid) was more prevalent in patients with ST (48%) compared with control patients (32%, p = ns) and volunteers (0%, p = 0.01). Clopidogrel significantly reduced PA in all three groups, but intergroup differences persisted. Clopidogrel resistance (<10% relative change) was similar in patients with ST, control patients, and volunteers (4%, 6%, and 11%, respectively, all p = NS). However, combined ASA and clopidogrel resistance was more prevalent in patients with ST (52%) compared with controls (38%, p = NS) and volunteers (11%, p < 0.05). CONCLUSIONS: Patients with previous ST show an impaired response to antiplatelet therapy with ASA compared with controls and volunteers. Additional treatment with clopidogrel is not able to overcome these differences in PA. Acetylsalicylic acid but not clopidogrel resistance appears to be associated with ST.
Wenaweser et al. (2005) conducted a case-control in Stent thrombosis (n=82). Previous stent thrombosis vs. Coronary stenting without stent thrombosis (matched controls) and healthy volunteers was evaluated on Resistance to ASA (>20% aggregation with 0.5 mg/ml arachidonic acid) (p=ns). Previous stent thrombosis was associated with a higher prevalence of ASA resistance (48%) compared to matched controls (32%, p=NS) and healthy volunteers (0%, p=0.01).