[Stent thrombosis and clopidogrel response variability: is the genetic test useful in clinical practice?].

The antiplatelet agent clopidogrel is an effective drug for the prevention of thrombotic events in patients with acute coronary syndrome and in those undergoing percutaneous coronary intervention with the deployment of a coronary stent. However, it has been reported that, despite adequate treatment, about 30% of patients continue to show the high degree of platelet reactivity that is central to the development of atherothrombotic complications and poorer clinical outcomes. Up to 13% of those taking clopidogrel experience a recurrent ischemic event during the first year after acute coronary syndrome, 1-3% experience subacute stent thrombosis after percutaneous coronary intervention probably due to a poor drug response, and about 1.5% experience major bleeding mainly due to an enhanced response. Recent research findings have highlighted the role of genetic variations in determining antiplatelet response variability, and this has aroused interest in genotyping all thienopyridine-eligible patients in order to identify those who would be at increased risk of harm if treated with clopidogrel. However, it remains to be determined whether this information is necessary or sufficient for risk stratification. Only when there are clinical data to support the hypothesis that genotype-guided therapy reduces the rate of ischemic and bleeding events will it be possible to justify the use of genetic testing in all potential patients. When that happens, genotype-guided antiplatelet therapy will also be available in the field of cardiovascular medicine.