@article {Breet983, author = {Nicoline J Breet and Jochem W van Werkum and Heleen J Bouman and Johannes C Kelder and Ankie M Harmsze and Christian M Hackeng and Jurri{\"e}n M ten Berg}, title = {High on-treatment platelet reactivity to both aspirin and clopidogrel is associated with the highest risk of adverse events following percutaneous coronary intervention}, volume = {97}, number = {12}, pages = {983--990}, year = {2011}, doi = {10.1136/hrt.2010.220491}, publisher = {BMJ Publishing Group Ltd}, abstract = {Aim High on-clopidogrel platelet reactivity (HCPR) and high on-aspirin platelet reactivity (HAPR) are associated with atherothrombotic events following coronary stenting. There are, however, few data concerning high on-treatment platelet reactivity to both aspirin and clopidogrel simultaneously. The aim of the present study was to determine the incidence of dual high on-treatment platelet reactivity (DAPR) and its impact on clinical outcome.Methods On-treatment platelet reactivity was measured in parallel by ADP- and arachidonic acid-induced light transmittance aggregometry (LTA) (n=921) and the point-of-care VerifyNow system (P2Y12 and aspirin) (n=422) in patients on dual antiplatelet therapy undergoing elective stent implantation. HCPR and HAPR were established by receiver-operator characteristic curve analysis. The primary endpoint was a composite of all-cause death, non-fatal acute myocardial infarction, stent thrombosis and ischaemic stroke at 1-year follow-up.Results The incidence of DAPR varied between 14.7\% and 26.9\% depending on the platelet function test used. DAPR, assessed by LTA and the VerifyNow system, was highly associated with an adverse clinical outcome. At 1-year follow-up the primary endpoint occurred more frequently in patients with isolated HCPR (11.7\%), isolated HAPR (9.6\%) or DAPR (10.7\%) compared with patients without high on-treatment platelet reactivity (4.2\%, all p\<0.01) when platelet function was evaluated with LTA. Using the VerifyNow system, patients exhibiting DAPR had the highest risk for the primary endpoint (17.7\% vs 4.1\% in patients without high on-treatment platelet reactivity, p=0.001).Conclusions In patients undergoing elective percutaneous coronary intervention, DAPR to aspirin and clopidogrel is present in one in five patients and is associated with a high risk for atherothrombotic events. DAPR measured by the point-of-care VerifyNow system has a higher predictability for atherothrombotic events than LTA.Clinical Trial Registration Information www.clinicaltrials.gov: NCT00352014.}, issn = {1355-6037}, URL = {https://heart.bmj.com/content/97/12/983}, eprint = {https://heart.bmj.com/content/97/12/983.full.pdf}, journal = {Heart} }