Background: Incomplete inhibition of P2Y
12
-mediated platelet activation during clopidogrel treatment has been associated with increased cardiovascular morbidity and mortality after percutaneous coronary intervention. This study aimed to investigate the incidence of impaired individual clopidogrel-responsiveness using a P2Y
12
-specific and pre-treatment-independent assay in a real world situation.
Methods: 100 consecutive patients with coronary artery disease on clopidogrel treatment (> 5 days including a loading dose of at least 300 mg) were screened for response to ADP-induced platelet signalling. We assessed the vasodilator-stimulated phosphoprotein-based platelet reactivity index (PRI) as the only P2Y
12
-specific assay to determine clopidogrel responsiveness. Insufficient inhibition of P2Y
12
by clopidogrel was defined as a PRI >50% based on previous studies indicating increased risk of stent thrombosis under this condition. The results were compared with conventional assays to assess ADP-induced P-selectin surface-expression and conventional turbinometric platelet aggregation to several concentrations of ADP.
Results: Clopidogrel significantly lowered functional platelet reactivity in patients with coronary artery disease compared to untreated patients. However, insufficient individual response to treatment predisposing for adverse events and therefore previously described as “non-response” was diagnosed in 69% of clopidogrel-treated patients using PRI. Conventional aggregation failed to detect insufficient P2Y
12
-inhibition in 1/3of patients with a PRI>50%.
Conclusion: Using the PRI as the only P2Y
12
-specific assay to evaluate the treatment effect of clopidogrel in patients with coronary artery disease, insufficient P2Y
12
-inhibition was present in the majority of patients in a real-world scenario. Insufficient P2Y12-inhibition could not be reliably detected by conventional aggregation More prospective studies are needed to evaluate the influence of the high prevalence of incomplete clopidogrel responsiveness to major adverse cardiac events.
Adoption and patterns of use of invasive physiological assessment of coronary artery disease in a large cohort of 40 821 real-world procedures over a 12-year period
