Platelet Aggregation Testing Not Effective
Prescribers should be cautious before using platelet aggregation testing in place of CYP2C19 genotyping.
Patients undergoing percutaneous coronary intervention (PCI) are at risk for future ischemic events. Medications, such as Plavix®, can help prevent these events, but are susceptible to genetic variations affecting drug metabolism. Pharmacogenetic testing can help predict this medication’s effectiveness, however, many prescribers prefer using platelet aggregation testing instead, adjusting the patient’s dose as they go.
A recent study published in Circulation showed, however, that this may not be effective. The authors found that, among 2,440 patients over the course of a year, there was no difference in outcomes between patients who received platelet aggregation testing and those who had a conventional strategy without drug or dose changes. The patients were still just as likely to have bleeding or cardiovascular events.
Endpoints investigated included death, myocardial infarction, stent thrombosis, stroke, major bleeding events or urgent revascularization.
This adds to the current body of evidence that prescribers should not be using platelet aggregation testing to try to predict a patient’s drug response. Pharmacogenetic testing for CYP2C19 loss-of-function alleles, on the other hand, has been shown to be able to predict major adverse cardiovascular events (MACE) and stent thrombosis endpoints in clopidogrel (Plavix) therapy.