Clopidogrel Platelet Function Tests

VerifyNow P2Y₁₂ Test

December 2011

The results are given as three numbers. The first number is a measure of the patient’s platelet function in the presence of clopidogrel. The second number measures activation of the patient’s platelets independently of the P2Y₁₂ receptor using 2 reagents within a second channel. The last number calculates the percent inhibition of the patient’s platelets by clopidogrel using the first two numbers. Less than twenty to thirty percent inhibition of platelet activation is considered to be resistance to clopidogrel. Some studies and institutions use values over 235 P2Y₁₂ Reaction Units (PRU) as indicative of clopidogrel resistance.

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Jump to section:

• Introduction
• Learning Objectives
• Platelet Function Tests for the Detection of Clopidogrel Resistance¹
• Platelet Function Tests for the Detection of Clopidogrel Resistance
• Caveat: There Is No Perfect Platelet Function Test...
• Problems With Testing For Clopidogrel
• How We Choose a Testing Method
• Methodology Table
• Platelet Function Testing Available at Mayo Clinic Florida
• Light Transmission Platelet Aggregometry Studies (LTA)
• Platelet Aggregation (Cont'd)
• Normal Patient
• Accumetrics VerifyNow Test
• VerifyNow P2Y₁₂ Test
• P2Y₁₂ Test Interferences
• P2Y₁₂ Antagonists²
• Can These Platelet Function Tests Be Used for Ticagrelor (Brilinta/Brilique)?
• PFA-100
• PFA–100 (Cont'd)
• INNOVANCE PFA P2Y
• TEG — Platelet Mapping
• Results of VerifyNow Testing
• 2009–2011 Clopidogrel Response at 30%
• Genetic Testing: Clopidogrel Metabolism
• Clopidogrel Metabolism
• Number of Gene Polymorphisms
• Clopidogrel Metabolism and Genetic Polymorphisms
• Why Do Genetic Testing?
• Clopidogrel Genetics (Cont'd)
• Caveats — Other Reasons for Poor Response to Clopidogrel
• CYP2C19 Polymorphism May Require Another Factor
• Controversy for Clopidogrel
• Warning: Diminished Effectiveness In Poor Metabolizers
• What Does Warning Mean For Clinicians With Patients On Clopidogrel?
• FDA Answer
• More Questions
• Summary
• References
• Questions?
• Disclosure