Clinical management of clopidogrel inefficiency by point of care platelet function testing and individual adjustment of anti-platelet therapy - initial experiences

Insufficient inhibition of ADP dependent platelet aggregation by clopidogrel is associated with an increased risk for adverse coronary events, such as stent thrombosis, after percutaneous coronary intervention. Here, we describe an approach to the clinical management of patients with insufficient inhibition of ADP dependent platelet aggregation by clopidogrel involving dose adjustment or switching of the thienoyridine. We put special emphasize on a patient who experienced recurrent acute myocardial infarction due to stent thrombosis associated with severe clopidogrel non response following elective coronary drug eluting stent implantation. In this patient, an inadequate clopidogrel effect at maintenance doses was confirmed by repeated platelet function assessment with a multiple electrode impedance point of care platelet function test. Subsequent dose adjustments still did not result in sufficient inhibition of ADP dependent platelet aggregation. Only after switching to the then shortly available new thienopyridine prasugrel could a sufficient platelet inhibition be obtained. However, our data from further patients show that although this may overcome inadequate clopidogrel efficiency in many cases, even under prasugrel suboptimal platelet inhibition may occur.