Discontinuation of long term clopidogrel therapy induces platelet rebound hyperaggregability between 2 and 6 weeks post cessation.

Background: Stent thrombosis occurs frequently within the first weeks after cessation of longterm clopidogrel therapy. We investigated if rebound platelet hyperreactivity occurs to provide a mechanism for this clinical observation.

Methods: ADP- and TRAP-induced platelet aggregation was measured by impedance aggregometry in 28 patients with coronary stent implantation (observational group, OG) before and 1, 2, 6 and 17 weeks after clopidogrel cessation.

Clopidogrel affects leukocyte dependent platelet aggregation by P2Y12 expressing leukocytes.

Up to 30% of all patients who are treated with a coronary stent do not respond sufficiently to antiplatelet therapy. This condition results in an increased risk for thrombotic complications such as stent thrombosis and myocardial infarction. The aim of the study was to determine clinical parameters modulating ASA and clopidogrel responsiveness.