Impact of high loading and maintenance dose of clopidogrel within the first 15 days after percutaneous coronary intervention on patient outcome.

Background: An increase in clopidogrel dose results in an improved inhibition of platelet aggregation. However, whether an increase in clopidogrel dose may improve patient outcome is still debated. The aim of this study was to analyze the impact on patient outcome of an increase in clopidogrel loading and maintenance doses within the first 15 days after percutaneous coronary intervention (PCI).

Methods: Between 2003 and 2007, we included 2,954 consecutive patients who underwent PCI and stent implantation. We compared 2 historical groups. In the "low-dose" group (2003-2005, n = 1,984), patients were pretreated with a 300-mg clopidogrel loading dose followed by 75 mg/d after PCI. In the "high-dose" group (2006-2007, n = 970), patients were pretreated with a 600-mg clopidogrel loading dose followed by 150 mg/d within the first 15 days and 75 mg/d thereafter. The composite primary end point (death, myocardial infarction, stent thrombosis) and bleeding were systematically indexed during the 2-month follow-up period.

Results: Clinical and most of angiographic characteristics were similar between the 2 groups. By multivariate analysis, high dose of clopidogrel was associated with a decrease in the composite primary end point (hazard ratio 0.694, 95% CI 0.485-0.993, P = .046). The other predictors were age, left ventricular ejection fraction, diabetes, renal failure, and acute coronary syndrome. Major bleeding was similar in the low- and high-dose groups (2.8% vs 3.4%, respectively, P = .379). After propensity score matching, the high-dose group was still associated with a significant clinical benefit.

Conclusion: Our results show that a 600-mg loading dose followed by a 150-mg maintenance dose of clopidogrel within the first 15 days after PCI is independently associated with a decrease in the composite death-myocardial infarction-stent thrombosis at 2 months without increase in hemorrhagic complications.