Routine pre-treatment with clopidogrel before diagnostic coronary angiography: the question is right, but what about the answer?

Dual antiplatelet therapy is the mainstay of antiplatelet treatment in percutaneous coronary interventions (PCIs) with stent implantation, as well as in acute coronary syndromes (ACS) with and without ST segment elevation.1–3 In ACS, dual antiplatelet therapy has been shown to reduce the risk of death and myocardial infarction (MI), both at the initial phase and in the long term. In the setting of stent implantation, dual antiplatelet therapy has been shown to reduce the risk of major adverse cardiac events (MACEs) and stent thrombosis, as compared with various other antithrombotic regimens. Ticlopidine was the first thienopyridine to be used in the setting of stent implantation, but, over time, clopidogrel has proven to be better tolerated and more efficacious.4 However, clopidogrel is a prodrug, which requires a two-step metabolism in the liver to be transformed into its active metabolite. Its onset of action is quite slow, and the level of inhibition of platelet aggregation (IPA) achieved with the recommended regimen is quite low compared with other compounds.5,6 This implies that if clopidogrel is administered at the time of stent implantation, the level of IPA could be quite low during the critical 3–4 h after the procedure.