The VerifyNow P2Y12 Test is a whole blood test to measure the level of platelet reactivity in response to P2Y12 drugs (theinopyridines), such as Plavix® (clopidogrel) and Effient® (prasugrel).

What is Reported?

The lab report will look similar to the following:

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Result NameResultUnitsReference
P2Y12 Reactivity Unit164PRU194-418
Platelet Reactivity BASE328Base PRU194-418
P2Y12% Inhibition50%See Below (1)
 
(1) Test results are reported in percent inhibition.
    Therapeutic - Higher % inhibition associated with expected antiplatelet effect
    Presurgical - <20% inhibition
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P2Y12 Reaction Units (PRU) - indicate the amount of ADP-mediated aggregation specific to the platelet P2Y12 receptor. PRU is determined based on the rate and extent of platelet reactivity (by way of aggregation) in the ADP channel.

P2Y12 Reaction Units (PRU) Expected Results4

P2Y12 Reaction Units (PRU);n=147

Platelet Function BASE (base PRU) - indicates the amount of thrombin receptor activating peptide (iso-TRAP) mediated aggregation specific to the platelet PAR-1 and PAR-4 receptors. The BASE result serves as an estimate of baseline platelet reactivity independent of P2Y12 receptor inhibition. The BASE result is normalized to report units that are equivalent to baseline PRU.

P2Y12 Percent Inhibition (%) - is the percent change from baseline aggregation, and is calculated from the PRU result and the BASE result. Expected values are in the range of 0-100%. Higher percent inhibition values are reported if the thienopyridine has produced a greater antiplatelet effect.

Lower Response Increases Risk of Ischemic Events

Patients who are not responding adequately to their antiplatelet medications may be at approximately 5 times greater risk of MI, stent
thrombosis and death.2,3


Up to 1/3 of patients on antiplatelet medications may not receive the expected platelet inhibiting effect.4

Numerous factors may contribute to inadequate response7, including:
  • Drug Interactions (e.g. Proton Pump Inhibitors)
  • Genetic polymorphisms
  • Pre-existing health conditions (e.g. diabetes)
  • Non-compliance

Pre-Surgical Screen

Patients administered thienopyridines are at risk of perioperative bleeding because the active metabolite produces an irreversible alteration of the platelet ADP binding site. Clopidogrel generally has been recommended to be discontinued for 5 days prior to surgery.5 However, medical research suggests that there is patient variability in response to clopidogrel4, and some patients may not need to wait 5 days.6

After discontinuation, high P2Y12 percent inhibition values indicate residual responsiveness.

Low P2Y12 percent inhibition values are reported if clopidogrel is no longer producing the expected antiplatelet effect.


Conditions that May Affect Test Results:

  • Will not report a result if patient has been exposed to GP llb/llla inhibitors within :
    - 48 hours of eptifibitide (Integrilin®)
    - 10 days of abciximab (ReoPro®)
  • Improper sample collection (platelet activation)
  • Hematologic related issues : Hct, Platelet Count
Download Interpreting Results

References
  • Malinin, A. et. al. Monitoring platelet inhibition after clopidogrel with the VerifyNow-P2Y12 analyzer: the VERIfy Thrombosis risk ASsessment (VERITAS Study) Thromb Res. (2007):119:277—284.
  • Buonamici, P. et al. Impact of platelet reactivity after clopidogrel administration on drug-eluting stent thrombosis. J Am Coll Cardiol. 2007 Jun 19;49(24):2312-7.
  • Price, MJ. et al. Prognostic significance of post-clopidogrel platelet reactivity assessed by a point-of-care assay on thrombotic events after drug-eluting stent implantation. Eur Heart J. 2008 Apr;29(8):992-1000.
  • Dupont, AG. et al. Antiplatelet therapies and the role of antiplatelet resistance in acute coronary syndrome. Thromb Res. 2009 May;124(1):6-13.
  • Eagle, KA. et. al. ACC/AHA 2004. Guideline update for coronary artery bypass graft surgery.
  • Price, MJ. et. al. Onset and Offset of Platelet Inhibition after high-dose clopidogrel loading and standard daily therapy measured by a point-of-care assay in healthy volunteers. Am J Cardiol 2006;98: 681– 6847.
  • Maree, AO. et al. Variable platelet response to aspirin and clopidogrel in atherothrombotic disease. Circulation 2007;115;2196-2207.

VerifyNow P2Y12 Test results should be interpreted in conjunction with other clinical and laboratory data available to the clinician.
VerifyNow is a registered trademark of Accumetrics, Inc. Integrilin is a registered trademark of Milennium Phamaceuticals. ReoPro is a registered trademark of Centocor, Inc. Plavix a registered trademark of Sanofi-Synthelabo, Inc. Effient is a registered trademark of Lilly-Daiichi Sankyo.