Clopidogrel response: head-to-head comparison of different platelet assays to identify clopidogrel non responder patients after coronary stenting.
OBJECTIVE
We investigated the agreement between different platelet tests to identify clopidogrel non response.


BACKGROUND
Biological definition of clopidogrel non response remains controversial. Different platelet tests have been linked with recurrent ischemic events and proposed for daily practice.


METHODS
We prospectively investigated the agreement of platelet tests to isolate clopidogrel non response in patients receiving high 150 mg clopidogrel maintenance dose after coronary stenting. Clopidogrel response was assessed with ADP-induced aggregation (ADP-Ag) (non response if >70%), Platelet reactivity index VASP (PRI VASP) (non response if >50%) and Verify Now Point-of-care assay (VN) (non response if PRU > 240 AU).


RESULTS
Seventy consecutive patients were included. The rates of non-responders were respectively: 13% (n = 9) with the ADP-Ag, 39% (n = 27) with the PRI VASP and 33% (n = 23) with the VN. We observed significant correlation between different platelet tests assessing clopidogrel response: r = 0.55 (p < 0.0001) for ADP-Ag and PRI VASP, r = 0.64 (p < 0.0001) for ADP-Ag and VN and r = 0.59 (p < 0.0001) for PRI VASP and VN. However, using the most common thresholds, the agreement between the difference tests was poor: 0.35 for ADP-Ag and PRI VASP, 0.36 for ADP-Ag and VN and 0.46 for PRI VASP and VN.


CONCLUSIONS
This study showed that assessment of platelet function inhibition by clopidogrel is highly test-specific. Indeed, our results demonstrated a poor agreement between different platelet assays and suggested that identification of clopidogrel non responders is test-dependent.
Department of Cardiology, CHU Timone, Marseille, France. thomascuisset@voila.fr
Thomas
T
Cuisset
Corinne
C
Frere
Raphael
R
Poyet
Jacques
J
Quilici
Bénédicte
B
Gaborit
Laurent
L
Bali
Olivier
O
Brissy
Marc
M
Lambert
Pierre-Emmanuel
PE
Morange
Marie-Christine
MC
Alessi
Jean-Louis
JL
Bonnet
D054058:Acute Coronary Syndrome / Q000097:blood / Q000628:therapy*; D000244:Adenosine Diphosphate; D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000295:instrumentation*; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000097:blood; D000077144:Clopidogrel; D004351:Drug Resistance; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008840:Microfilament Proteins / Q000097:blood; D008875:Middle Aged; D010750:Phosphoproteins / Q000097:blood; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use*; D010979:Platelet Function Tests / Q000379:methods; D019095:Point-of-Care Systems; D011237:Predictive Value of Tests; D011446:Prospective Studies; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000097:blood; D058925:Receptors, Purinergic P2Y12; D015607:Stents; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000098662:Vasodilator-Stimulated Phosphoprotein
D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; C548576:P2RY12 protein, human; D010750:Phosphoproteins; D010975:Platelet Aggregation Inhibitors; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12; D000098662:Vasodilator-Stimulated Phosphoprotein; D000244:Adenosine Diphosphate; D000077144:Clopidogrel; D013988:Ticlopidine