Background: Recurrent ischemic events occurred even during routine use of 75 mg clopidogrel in addition to aspirin, that indicated a potentially insufficient maintenance dosage of clopidogrel. The aim of the present study was to evaluate the short-term efficacy and safety of a 150 mg maintenance dose of clopidogrel following a 600 mg loading dose in patients with an acute coronary syndrome (ACS) undergoing drug eluting stent (DES) implantation.
Methods: Between November 2005 and November 2006, a total of 813 consecutive ACS patients undergoing DES implantation were enrolled. A 600 mg loading dose was administered before percutaneous coronary intervention (PCI) and patients were randomized to receive clopidogrel 75 mg or 150 mg for 30 days in addition to 300 mg aspirin daily. Primary end points were the composite of cardiac death, non-fatal myocardial infarction (MI) and urgent target vessel revascularization (UTVR). Secondary end points included stent thrombosis (ST), major and minor bleeding events at 30 days.
Results: At a follow-up period of 30 days, 4 (1.0%) patients in the 150 mg group and 9 (2.2%) patients in the 75 mg group (P > 0.05) reached the primary end points. There was no significant difference in the incidences of MI (0.5% vs 1.2%, P > 0.05), UTVR (0.7% vs 2.0%, P > 0.05), and cardiac death (0.2% vs 0.2%, P > 0.05) between the two groups. The incidence of ST (0 vs 1.5%, P < 0.05) was significantly lower in the 150 mg group than that in the 75 mg group. There were no significant differences between both groups regarding the risk of major (0.2% vs 0, P > 0.05) or minor (0.5% vs 0.2%, P > 0.05) bleedings.
Conclusion: A high clopidogrel maintenance dose of 150 mg daily following a 600 mg loading dose for the first month after PCI procedure reduces the risk of ST and appears to be safe in patients with ACS undergoing DES implantation.