A question from my colleague and our former graduate student, Rebecca Jones:
Hey, George. When patients are sent to general surgery or to have a stent put in, how much inhibition of platelets is acceptable for procedures to be performed? We have been doing a calculation giving surgeons percent inhibition, but are being asked to switch to the PRU system instead. Thanks so much!
Hi, Rebecca, it is good to hear from you. I presume from your message that you plan to be using the VerifyNow P2Y12 cartridge for monitoring Plavix before and after surgery and reporting the result in PRUs. This may be an acceptable substitute for platelet aggregometry provided your surgeons understand the result is qualitative, indicating only that the assay is positive or negative for Plavix’s antiplatelet effect. They should not interpret either aggregometry results or the PRU results as indicating a degree of antiplatelet effect, they should just think “all or nothing.” I don’t recommend a % inhibition calculation.
The guidelines for management of aspirin or plavix at the time of surgery are available from Douketis JD, Alex C. Spyropoulos AC, Spencer FA , et al. Perioperative Management of Antithrombotic Therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines CHEST 2012; 141:e326S–e350S.
Their recommendation is “In patients who are receiving ASA and require CABG surgery, we suggest continuing ASA around the time of surgery instead of stopping ASA 7 to 10 days before surgery (Grade 2C). In patients who are receiving dual antiplatelet drug therapy and require CABG surgery, we suggest continuing ASA around the time of surgery and stopping clopidogrel/prasugrel 5 days before surgery instead of continuing dual antiplatelet therapy around the time of surgery (Grade 2C).”
This is a little different from the 2008 Chest guidelines, which recommended discontinuing aspirin and plavix 7-10 days before surgery, and the current grade 2C level of recommendation is weak, so your surgeons are justified in making their own interpretation. However, whether you use the 2008 and 2012 guidelines, Plavix should be discontinued at least five days before surgery. I hope this helps. Geo.