Pre-treatment with P2Y₁₂ inhibitors in ACS patients: Who, when, why, and which agent?

Dual antiplatelet therapy (DAPT) with aspirin and a P2Y₁₂ receptor inhibitor is the mainstay of treatment for acute coronary syndrome (ACS) patients, whether they undergo a percutaneous coronary intervention (PCI) or are managed medically. In recent years, the most appropriate timing for initiation and duration of P2Y₁₂ receptor inhibition has been a focus of great interest. Many observational studies and a single prospective trial (CREDO) utilizing clopidogrel had focused on whether pre-treatment with clopidogrel, i.e. its administration upstream of coronary angiography and PCI, is beneficial. Although the rationale for pre-treatment is obvious, large-scale randomized trials supporting a pre-treatment strategy with clopidogrel or with the newer P2Y₁₂ inhibitors prasugrel and ticagrelor did not exist. Proponents of a pre-treatment strategy had to rely on their best guess, on non-randomized studies, or on negative studies in which a trend for a benefit had been demonstrated. Recently, however, two randomized trials directly evaluated the value of pre-treatment - one in patients with a non-STE elevation myocardial infarction (NSTEMI) - the Comparison of Prasugrel at the Time of Percutaneous Coronary Intervention or as Pretreatment at the Time of Diagnosis in Patients with Non-ST Elevation Myocardial Infarction (ACCOAST) trial, and a second trial evaluating the use of ticagrelor in ST-elevation myocardial infarction (STEMI) patients, the Administration of Ticagrelor in the Cath Lab or in the Ambulance for New ST-elevation myocardial Infarction to open the Coronary artery (ATLANTIC) trial. Neither of the two trials, however, answered all the questions clinicians have about pre-treatment. And given the recent approval of the intravenous and rapidly acting P2Y₁₂ inhibitor cangrelor, the choice of who should receive treatment with a P2Y₁₂ inhibitor, which one should be used, and when it should be administered, should be carefully re-evaluated for all patients. This clinical review aims at evaluating the available evidence regarding the value of pre-treatment with the now four available oral and intravenous P2Y₁₂ inhibitors that can be administered to patients in whom coronary angiography followed by a possible PCI is planned.