Platelet Reactivity in Patients on a Thienopyridine and Awaiting Coronary Artery Bypass Grafting (Serial CABG)

The recent emergence of platelet reactivity testing as a potential option for evaluating the degree of platelet inhibition promises to add another level of understanding to our concept of CABG-related bleeding. There is an emerging literature that links high levels of platelet reactivity with adverse clinical events, primarily in patients on clopidogrel.

For example, studies of the VerifyNow P2Y12 platelet function assay have shown that Platelet Reactivity Units (PRU) > 235-240 in patients on clopidogrel therapy appears to predict cardiovascular events.15,16 There is a paucity of literature, however, on the use of platelet reactivity testing to predict bleeding events and complications. In other words, if excessively high levels of platelet reactivity predict ischemic events, do excessively low levels of platelet reactivity predict bleeding events? This is an especially relevant question, given the emergence of prasugrel as a therapeutic option.

The investigators therefore propose an exploratory cohort study of patients receiving a thienopyridine (clopidogrel or prasugrel) and undergoing CABG, in order to describe levels of platelet reactivity in such patients by using a variety of platelet function tests.