Abstract 4356: Platelet Reactivity in Clopidogrel Exposed Patients Scheduled for Coronary Artery Bypass Surgery
Background: Coronary artery bypass surgery (CABG) is typically delayed until 5 days after last clopidogrel dose. We have not found any studies substantiating this waiting period.
Material and Methods: All consenting patients underwent daily platelet reactivity (units, PRU) testing with point of care VerifyNow P2Y12 assay after receiving 600 mg of clopidogrel at the time of catheterization. Twenty-four hour interval was given between integrillin administration and testing. Of 34 patients recruited, 3 patients crossed over to medical management strategy, 1 patient died while waiting for surgery. In additional 1 patient VerifyNow could not be done due to low hematocrit. Data on remaining 29 patients (41% females, 34% with diabetes) was analyzed. Most of the patients (83%) were operated on day 6 after the last clopidogrel dose; an additional 5 patients waited for more than 6 days. Surgeons were blinded to the results of the platelet reactivity testing. The study was approved by the institutional IRB.
Results: On any given day at least 75% of the tested patients demonstrated less than 30% platelet inhibition, traditionally considered “safe” for a surgical intervention. This “safe” level was achieved on day 1 in 21% patients, day 2 in 55%, day 3 in 65%, day 4 in 86%, and day 5 in 96%. Majority (83%) of patients were operated on day 6, of these only 1 had PRU>30%. There were no significant differences in RBC (p=0.949) or platelet (p=0.864) transfusion, fresh frozen plasma (p=0.295) or cryoprecipitate (p=0.654) administration in patients delayed for more than 6 days.
Conclusions: Waiting for at least 5 days after the last clopidogrel dosing is clearly sufficient, with further delayed surgery not associated with decreased requirements in blood products. This waiting period, however, might be excessive with the majority of clopidogrel-treated patients achieving “safe” platelet responsiveness in less than 5 days upon discontinuation of the drug.