Clopidogrel Platelet Function Tests

Platelet Function Tests for the Detection of Clopidogrel Resistance

December 2011

The Platelet Function Analyzer or PFA-100 measures the blockage of a membrane coated with collagen and ADP by platelets, mimicking damaged endothelium. Plateletworks is a unique method that utilizes a special ADP tube which is run through the laboratory’s regular CBC impedance analyzer; the platelet count result from this tube is then compared to the patient’s platelet count from a routine EDTA tube which is run immediately prior to the special ADP tube. The Impact cone and plate(let) analyzer has only recently become available for commercial use and measures the amount of stained surface area and average size of platelet aggregates coating a special thrombogenic plate. Thromboelastography has been available for years, but its use for platelet mapping is much more recent. The RoTEM is a newer rotational form of thromboelastography which has been recently introduced to the U.S.  The last test uses detection of the downstream effect of ADP receptor stimulation by measuring the amount of phosphorylated vasodilator-stimulated phosphoprotein using flow cytometry.

< Previous Slide

Platelet Function Tests

Next Slide >

 

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