Background: Adequate platelet inhibition before percutaneous coronary intervention (PCI) reduces periprocedural and long-term ischemic complications. Reduced response to clopidogrel has been associated with subsequent major adverse cardiovascular events. Strategies to optimize platelet inhibition pre-PCI are under investigation. This study evaluated the effect on platelet aggregation of four different dosing regimens of clopidogrel given before elective PCI in a randomized, prospective, double-blind, and placebo-controlled design.
Methods: One hundred twenty participants were randomized to one of four groups of clopidogrel: (a) 300 mg on the day prior to angiography; (b) 600 mg on the day prior to angiography; (c) 300 mg followed by 75 mg daily started 1 week prior to angiography; and (d) 300 mg followed by 150 mg daily started 1 week prior to angiography. Platelet aggregation was assessed by light transmission aggregometry (LTA) after stimulation with adenosine diphosphate 20 microM at baseline and at the time of diagnostic coronary angiography. The absolute change in platelet aggregation between these two time points was considered the main outcome measure.
Results: At the time of diagnostic coronary angiography, the 300-mg/150-mg daily regimen achieved the greatest decrease in platelet aggregation (37 +/- 19%), while the 300 mg regimen provided the smallest (20 +/- 22%), an absolute difference between the two groups of 17.2 +/- 5.1% (P = 0.005).
Conclusions: A 300-mg loading dose of clopidogrel followed by 150 mg daily for 1 week prior to coronary angiography provides more effective platelet inhibition, as defined by LTA, compared to the standard 300-mg loading dose regimen at the time of coronary intervention.