Larry Brace, PhD, Edward Hospital, Naperville, IL. writes that a pathologist is building a protocol to employ platelet concentrate transfusions for reversal of platelet inhibition for patients who are on Plavix or aspirin and are having bleeding or need surgery. He is looking for an objective way to quickly evaluate the status of the platelet population after transfusion. Dr. Brace is looking for any information about suitable lab testing. The aggregation-based P2Y12 inhibition assay for Plavix is a measurement designed to see if the Plavix is working to inhibit function, not to learn if the platelets are properly working, Same for VerifyNow for aspirin, to determine if aspirin is inhibiting function, not to see if platelets are overall working properly. The Siemens PFA100 might be the answer, but would require some literature confirmation. How would you respond? Thanks,
George suggested using thromboelastometry or thromboelastography, but would like to leanr our participants’ suggestions.
Whole blood platelet
Whole blood platelet aggregation would be the test for platelet function when looking at the P2Y12 inhibitors. The PFA-200 has a cartridge specific for the P2Y12 inhibitors. However it is not available in the USA. The ADP cartridge for the PFA-100 is not suitable for this issue.
From Geo: thanks to Dave for this comment, and it is true, there is no US FDA-approved P2Y12 cartridge for the PFA-100. Further, assays for Plavix or aspirin EFFICACY will probably not be able to indicate platelet function recovery.
More from Vadim Kostousov,
More from Vadim Kostousov, PhD, arrived via e-mail:
TEG platelet mapping assay might be compromised in the presence of heparin:
Nelles NJ, Chandler WL. Platelet mapping assay interference due to platelet activation in heparinized samples. Am J Clin Pathol 2014;142:331–8.
While PFA-100 has been shown
While the PFA-100 has been shown to be useful to monitor PLT transfusion in bleeding patients due to other causes, this test is not sensitive to Plavix. That’s why it could not be used to monitor Plavix reversal by PLT concentrate:
It looks like only light transmittance or whole blood aggregometry is appropriate, more details in recent free access papers:
Effects of ex vivo platelet supplementation on platelet aggregability in blood samples from patients treated with acetylsalicylic acid, clopidogrel, or ticagrelor http://bja.oxfordjournals.org/content/112/3/570.full.pdf+html
Looking into the future of platelet transfusion in the presence of P2Y12 inhibitors (editorial):
Inefficacy of platelet transfusion to reverse ticagrelor http://www.nejm.org/doi/full/10.1056/NEJMc1409373#t=article