Background Almost all kinds of proton pump inhibitors (PPI), especially Omeprazole, have been reported to inhibit the antiplatelet activation of clopidogrel in the therapy of coronary artery disease and were associated with a higher risk of major cardiovascular events ranging from a 24.3% with lansoprazole to a 29.2% with pantoprazole in the increased risk. But recently, two clinical trials give us a paradoxical result from the above in nearly 13,800 patients with ACS. So, what the true influences of PPI on clopidogrel activation are still unclear. And especially, it has not been reported before in ACS group through PCI in Chinese patients. Objectives: To assess the effects of omeprazole on clopidogrel efficacy in patients with ACS through PCI in Chinese patients.
Methods In this randomised controlled trial, all patients (n=186) with ACS and elective PCI who received aspirin (loading dose 300 mg before PCI, followed by maintaining dose 100 mg/day) and clopidogrel (loading dose 600 mg before PCI, followed by maintaining dose 75 mg/day) were randomised to receive omeprazole (20 mg/day) or placebo for 7 days. Residual platelet activity and platelet activation inhibition rate in ADP pathway were detected in the third day after PCI with modified thrombelastograpy-mapping (TEG-mapping) in ADP induced method.
Results Between the two groups with and without omeprazole, the mean platelet activation inhibition rate with ADP induced method is 63.52%±23.11% vs 67.26±24.17 (p=0.2895) detected with TEG, respectively. But when we divided the patients into 5 levels according to the clinical meaning of platelet activation inhibition rate, the frequency distribution in these 5 levels in the tow groups showed significant difference (p=0.0062), especially the decrease of frequency in higher platelet activation inhibition rate with omeprazole. But without any changes can be seen in the distribution of highest or lowest inhibiting levels group.
Conclusion Without any significant effects of omeprazole on clopidogreal in total strength of inhibition rate to platelet can be observed in patients with ACS through PCI taking clopidogrel with 600 mg loading dose and aspirin with 300 mg loading dose. But omeprazole decrease the frequency distribution of higher platelet inhibition rate induced by clopidogrel significantly without increasing clopidogrel non-responds rate.