Assessment of VerifyNow P2Y12 assay accuracy in evaluating clopidogrel-induced platelet inhibition.
The emergence of point-of-care assays enabling bedside testing such as the VerifyNow P2Y12 system might prove useful in clinical settings. The aim of this study was to evaluate the ability of the VerifyNow P2Y12 assay to estimate the inhibition of platelet aggregation provided by clopidogrel in the absence of baseline off-drug aggregation data. Sixty-eight patients with coronary artery disease scheduled to initiate clopidogrel therapy underwent platelet aggregation testing by VerifyNow P2Y12 at baseline and after clopidogrel administration. The inhibition reported by the VerifyNow assay (relative to thrombin receptor activating peptide-induced platelet aggregation, serving as baseline) was compared with that calculated with the actual adenosine diphosphate-induced baseline obtained with the same methodology. The postclopidogrel thrombin receptor activating peptide-induced aggregation showed a great discordance with that induced by adenosine diphosphate before clopidogrel with a bias of 24 units (95% limits of agreement from -142 to 190 units). Moreover, the inhibition reported by the assay overestimated the standard before-and-after testing data by an average of 8% (95% limits of agreement from -49% to 65%), making its use without a true baseline comparator unsatisfactory. The VerifyNow P2Y12 assay fails to accurately quantify platelet inhibition achieved by clopidogrel compared with before-and-after testing. Further studies are required to establish the clinical usefulness of the VerifyNow P2Y12 assay to accurately predict the occurrence of major adverse cardiovascular events in patients with reduced clopidogrel efficacy before it can be implemented in clinical practice. At present, the use of this assay in clinical care cannot be recommended for monitoring clopidogrel therapy.
Faculties of Pharmacy, Université de Montréal, Montreal, Canada.
Marie
M
Lordkipanidzé
Chantal
C
Pharand
Thuy Anh
TA
Nguyen
Erick
E
Schampaert
Jean G
JG
Diodati
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D000527:Alprostadil / Q000494:pharmacology; D000077144:Clopidogrel; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D019095:Point-of-Care Systems; D011446:Prospective Studies; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000378:metabolism*; D058925:Receptors, Purinergic P2Y12; D018401:Sample Size; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000494:pharmacology
C548576:P2RY12 protein, human; D010446:Peptide Fragments; D010975:Platelet Aggregation Inhibitors; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12; C086309:thrombin receptor peptide SFLLRNP; D000244:Adenosine Diphosphate; D000077144:Clopidogrel; D000527:Alprostadil; D013988:Ticlopidine