Abstract 1717: Impact of a 600-mg Loading Dose of Clopidogrel on 30-Day Outcome in Unselected Patients Undergoing Percutaneous Coronary Intervention

Abstract

Background: Based on biological studies of platelet reactivity (PR), the recent ACC/AHA guidelines recommend a 600-mg loading dose (LD) of clopidogrel in patients undergoing percutaneous coronary intervention (PCI). However, there is lack of studies addressing the clinical impact of such a LD of clopidogrel. Objective: We aimed to compare the clinical efficacy and safety of a 600-mg LD of clopidogrel compared to a 300-mg LD in an unselected cohort of patients undergoing PCI. Methods: A cohort of 4105 unselected patients undergoing PCI in our institution was included in the study and divided according to the LD used: the high LD group (600mg) included 3146 patients and the low LD (300mg) group included 959. The primary endpoint was the rate of major adverse cardiovascular events (MACE) at 1 month. Results: Patients in lthe ow LD group more often had diabetes mellitus and a history of myocardial infarction (36.8 vs 31.9%; p = 0.01). Left ventricular ejection fraction was similar (0.49 ± 0.14 vs 0.48 ± 0.14; p = 0.25). Angiographic and procedural characteristics were identical between the 2 groups. Patients in the high LD group had fewer MACE after 1 month (2.9 vs 5.2%; p < 0.001). In multivariate analysis, a 600-mg LD of clopidogrel was significantly associated with MACE at 1-month follow-up, with an odds ratio of 0.62 (95% CI 0.41– 0.95; p = 0.03). Conclusions: A 600-mg LD was associated with a significant decrease in the rate of post PCI-MACE at 1 month without any increase in bleeding complications. The results of our study therefore support the current guideline of a 600-mg LD of clopidogrel in patients undergoing PCI.