An interesting substudy of TRILOGY ACS was published in JAMA recently in which a group of patients with ACS underwent evaluation of platelet function after prasugrel or clopidogrel. All patients were also on aspirin. Thus, platelet function studies were performed after treatment with aspirin + prasugrel and aspirin + clopidgorel. TRILOGY ACS trial was a randomized, double-blind, active-comparator trial comparing prasugrel with clopidogrel in patients with unstable angina or non–ST-segment elevation myocardial infarction (UA/NSTEMI) who were managed medically without planned revascularization.Platelet function was assessed in a subset of enrolled patients using VerifyNow kits. VerifyNow P2Y12 is a whole-blood, turbidimetric-based assay that measures platelet agglutination to fibrinogen-coated polystyrene beads after platelet activation with adenosine diphosphate. The results are expressed in PRU (P2Y12 reaction units). There was no significant association between platelet reactivity and occurrence of ischemic outcomes during a 30 month follow-up period.
The results of this study are important; it is a large study, enrolling a high-risk population and followed for a relatively longer period of time. While trials of antiplatelet agents have established, beyond doubt, that platelet play an important (if not essential) role in the pathogenesis of ACS and perhaps also in the development and progression of atherosclerosis, studies have generally failed to find an association of platelet function with future events. Probably the most likely explanation is that we have, so far, been unable to identify a platelet function test that ACTUALLY measures platelet function in a way which is important clinically. We can predict bleeding but not aggregability. We do need to explore existing platelet function tests for association with future events that have not yet been examined and we also need to develop newer tests that are more closer in measuring what happens inside the vessel.
No comments:
Post a Comment