Antiplatelet response to the 150-mg maintenance dose of clopidogrel in patients with insufficient platelet inhibition after clopidogrel loading for elective coronary stent placement.

Aims: Our prospective study sought to investigate whether inadequate platelet responses to clopidogrel can be corrected by increasing the daily maintenance dose from 75 mg to 150 mg.

Methods And Results: In 117 patients with elective PCI after loading with 600 mg clopidogrel, we determined residual platelet aggregation in response to 5 micromol/l ADP (RPA) by optical aggregometry after the first 75 mg maintenance dose (baseline), and at days 14 and 28. In patients with RPA >14% at baseline, we increased the daily dose to 150 mg.

Cytochrome P450 2C19 681G>A polymorphism and high on-clopidogrel platelet reactivity associated with adverse 1-year clinical outcome of elective percutaneous coronary intervention with drug-eluting or bare-metal stents.

Objectives: We investigated whether the loss of function CYP2C19 681G>A *2 polymorphism is associated with high (>14%) residual platelet aggregation (RPA) on clopidogrel and whether high on-clopidogrel RPA impacts clinical outcome after elective coronary stent placement.

Background: The cytochrome P450 (CYP)-dependent conversion of clopidogrel to its active metabolite may contribute to the variability in antiplatelet effect of clopidogrel.

Methods: The study included 797 consecutive patients undergoing percutaneous coronary intervention, who were followed-up for 1 year.