Antiplatelet Medication Response Testing: Aspirin and Clopidogrel

Leah Coppolino, MPH, MLS(ASCP), CLS(NCA)
Reviewers: Dr. Phyllis Ingham, EdD, MEd, MLS(ASCP) and Joshua J. Cannon, MS, MLS(ASCP)CMSHCM
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Continuing Education Credits

P.A.C.E.® Contact Hours: 1 hour(s)

Florida Board of Clinical Laboratory Science CE Credit Hours

Florida Board of Clinical Laboratory Science CE - General (Hematology): 1 hour(s)

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The evaluation of patient response to antiplatelet medications is important because of bleeding risks posed by use of these medications and the risk for future cardiac events, if testing indicates a lack of response to the medication. The mechanism of action and the limitations for two commonly used antiplatelet medications, aspirin and clopidogrel, are discussed in this course. Some of the more widely used procedures for assessing platelet function will also be covered.

Objectives

  • Correlate aspirin and clopidogrel response to the risk for cardiac ischemic events.
  • Describe current dosing regimens of aspirin and clopidogrel as antiplatelet medications.
  • List specimen collection and handling requirements for antiplatelet medication testing.
  • Compare and contrast assays and instruments that are available for platelet function analysis.
  • Discuss alternative treatment for aspirin or clopidogrel-resistant patients.

Course Outline

  • Course Introduction
    • Introduction
  • Aspirin Therapy and Introduction to Aspirin Resistance
    • Platelets and Aspirin
    • Aspirin Uses and Dosing
    • Aspirin Resistance
    • Algorithmic Approach For a Patient With Suspected Aspirin Resistance
    • Factors that May Limit the Effectiveness of Aspirin
    • True or False: Aspirin's ability to suppress prostaglandins and thromboxane A2 creation is due to its irreversible inactivation of the cyclooxygenase (COX-1) enzyme.
  • Clopidogrel Therapy and Clopidogrel Resistance
    • Platelets and Clopidogrel
    • Clopidogrel Dosing
    • Clopidogrel Resistance
    • Which of the following is a receptor that is located on platelet cell membranes and is inhibited by clopidogrel, thereby preventing platelet aggregation?
  • Antiplatelet Medication Response Testing: Specimen Collection and Handling Requirements
    • Specimen Collection for Platelet Function Testing
    • Specimen Processing for Platelet-Rich Plasma
    • What is the recommended platelet count for a platelet-rich plasma sample, such as those prepared for light transmission aggregometry?
  • Aspirin and Clopidogrel Response Testing
    • Monitoring Response to Aspirin and Clopidogrel Therapy
  • Optical Light Transmission
    • Aspirin Response Analysis: Optical Light Transmission Aggregometry
    • Clopidogrel Response Analysis: Optical Light Transmittance Aggregometry
  • Whole Blood Impedance Aggregometry
    • Aspirin Response Analysis: Whole Blood Impedance Aggregometry
    • Clopidogrel Response Analysis: Whole Blood Impedance Aggregometry
    • True or False: Arachidonic acid is routinely used as an agonist to assess clopidogrel effectiveness in whole blood impedance aggregometry methods.
  • Helena Laboratories PlateletWorks Kit
    • Aspirin Response Analysis: Helena Laboratories PlateletWorks Kit
    • Clopidogrel Response Analysis: Helena Laboratories PlateletWorks Kit
  • Cartridge-Based Platelet Aggregation
    • Aspirin Response Analysis: Cartridge-Based Platelet Aggregation
    • Clopidogrel Response Analysis: P2Y12 Analysis
  • Other Aspirin Response Tests
    • Aspirin Response Analysis: Shear Flow Technology
    • Aspirin Response Analysis: Urinary 11-Dehydrothromboxane B2 for Aspirin Resistance
    • Aspirin Response Analysis: AspirinWorks Analysis
    • A PFA-100 method system is used to evaluate platelet function in a patient who is on aspirin therapy. Which of the following collagen/epinephrine closure time results would show a possible aspirin resistance in this patient (Reference interval <164 s)?
    • The elevation of which of the following substances in a urine sample may indicate a decreased response to aspirin therapy and an increased potential for a future ischemic cardiovascular event in a high-risk individual?
  • Other Clopidogrel Response Tests
    • Additional Clopidogrel Response Tests
    • Clopidogrel Response Analysis: Thromboelastography
    • CYP2C19 Genotyping for Clopidogrel
    • Which platelet aggregometry methodology measures thrombi creation by tension on a wire, which is measured in a curve plot by the analyzer?
  • Treatment for Antiplatelet Medication Resistant Patients
    • Treatment Alternatives When Aspirin or Clopidogrel Non-responsiveness is Detected
  • References
    • References

Additional Information

Level of instruction: Intermediate
Intended Audience: Medical laboratory scientists, medical technologists, and technicians. This course is also appropriate for medical laboratory science students and pathology residents.
Author information:  Leah Coppolino, MPH, MLS(ASCP)CM is a Program Director at MediaLab, Inc. Previously, she was the Director of the Medical Laboratory Science Program at St. Christopher’s Hospital for Children in Philadelphia, Pennsylvania. She holds a Masters in Public Health from Thomas Jefferson University.
Reviewer information:
Dr. Phyllis Ingham, EdD, MEd, MLS(ASCP) is the Director of Clinical Laboratory Technology Phlebotomy at West Georgia Technical College in Waco, Georgia. Dr. Ingham holds a bachelor's degree from Auburn University, a master's degree in education from Alabama State University, and a Doctorate in Educational Leadership from Argosy University.
Joshua J. Cannon, MS, MLS(ASCP)CMSHCM received his Bachelor of Science and Master of Science in Medical Laboratory Science from Thomas Jefferson University in Philadelphia, PA. He holds Medical Laboratory Scientist and Specialist in Hematology certifications through the ASCP Board of Certification. He was a professor at Thomas Jefferson University for seven years before transitioning into his current role as Education Developer at MediaLab. His areas of expertise and professional passions include clinical hematology and interprofessional education.