Effect of Prasugrel Versus Clopidogrel on Platelet Function After Bivalirudin Cessation

Study Summary

Early stent thrombosis has been noted with increased frequency in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI) who are treated with bivalirudin and clopidogrel. The brief half life of bivalirudin acting in concert with the delayed action of clopidogrel likely exposes patients to thrombosis during a vulnerable period of reduced antiplatelet effect in the immediate post stenting period. Combination therapy with bivalirudin and prasugrel is conceptually attractive as the more rapid onset of action of prasugrel could potentially significantly diminish the vulnerable period, likely reducing the potential for acute stent thrombosis. The trials which have documented the efficacy of prasugrel as compared to clopidogrel have, in general, not reported on patients in whom bivalirudin was utilized. Currently, in the United States, bivalirudin is the most commonly used adjunctive agent used during PCI. Using light transmission aggregometry, this study will examine the inhibition of platelet aggregation in patients randomized to treatment with clopidogrel vs prasugrel during the vulnerable period following the discontinuation of bivalirudin therapy. The investigators anticipate that this study will document significant enhancement of inhibition of platelet aggregation in patients randomized to prasugrel treatment.

Primary Outcome

To document the extent of inhibition of ADP mediated platelet aggregation following the discontinuation of bivalirudin therapy in patients treated with prasugrel as compared to patients treated with clopidogrel. The percent inhibition of platelet aggregation was measured by light transmission aggregometry of platelet-rich plasma in response to P2Y12 and PAR1 and PAR4 thrombin receptor agonists at baseline and at 1, 2, 4 and 16 h following the cessation of bivalirudin infusion. Platelet response

Interventions

• DRUG Clopidogrel
• DRUG Prasugrel