Monitoring Plavix using the PFA-100
Here is a question about the bleeding time from Sue Hillyard:
I was recently asked to perform a bleeding time on a patient who was on Plavix. The reason for this was that the "PFA is insensitive to Plavix, the bleeding time is more sensitive." Is this technically correct? If so, why?
Hi, Sue. You can monitor for Plavix (clopidogrel) efficacy using the bleeding time, Accumetrics VerifyNow, and the reference method, platelet aggregometry. The bleeding time is not reproducible and has been largely discontinued. The PFA-100, according to Mueller T, Haltmayer M, Poelz W, Haidinger D. Monitoring aspirin 100 mg and clopidogrel 75 mg therapy with the PFA-100 device in patients with peripheral arterial disease. Vasc Endovascular Surg 2003;37:117-23, is sensitive to aspirin but not Plavix, and Siemens, which manufactures and distributes the PFA-100, makes no claim for Plavix monitoring. Accumetrics has an FDA-approved system for monitoring Plavix. My personal preference, if available, is whole blood platelet aggregometry, which is easy to perform and reproducible. I hope this is helpful. Geo.
