Pretreatment with Dual Antiplatelet Therapy in Patients with Non-ST-Segment Elevation Acute Coronary Syndromes undergoing Percutaneous Coronary Intervention

Abstract

Background - Although dual antiplatelet therapy is the standard of care in non-ST-segment elevation acute coronary syndromes (NSTEACS), it remains unclear when a second antiplatelet agent should be initiated. We sought to assess the safety and efficacy of pretreatment with clopidogrel in patients with NSTEACS undergoing percutaneous coronary intervention (PCI). Methods - We analyzed baseline clinical and procedural characteristics of 6,817 patients with NSTEACS who underwent PCI from the Melbourne Interventional Group registry from 2005-2012. Patients were included in the pretreatment group if clopidogrel was administered prior to cardiac catheterisation. We assessed 30-day mortality, myocardial infarction (MI) and major adverse cardiovascular events (MACE). The safety endpoint was in-hospital bleeding. Results - Of the 6,817 patients, only 2,951 (43%) received pretreatment with clopidogrel. Patients in the pretreatment group were more likely to present with unstable angina (70.8% vs. 68.2%, p=0.02) and have a history of myocardial infarction (35.6% vs. 23.6%, p < 0.01) but were less likely to have PCI within 24 hours of admission (17.2% vs. 25.2%, p <0.01). There was no difference between the groups in 30-day mortality (0.9% vs. 1.4%, p=0.06), MI (2.0% vs. 2.2%, p=0.52) or MACE (3.7% vs. 4.2%, p=0.25). There was no difference in bleeding complications (1.9% vs. 1.9%, p=0.94). Conclusions - Pretreatment with dual antiplatelet therapy in NSTEACS is not routine clinical practice in Australia. Pretreatment appears safe but is not associated with improved short-term clinical outcomes.