Li J, et al. - In this prospective observational cohort study, researchers evaluated the impact of CYP2C19 genetic polymorphism (GP) carriers on residual platelet aggregation (RPA) in post-stent patients (n=206) who received prasugrel 60 mg loading and either 5 or 10 mg daily maintenance with aspirin 100 mg. GP carriers vs noncarriers were found to have higher RPA. Findings revealed that CYP2C19 carriers had higher RPA for 5 mg and reached significance for 10 mg prasugrel. Overall, they concluded that, in Korean outpatients, RPA was influenced by CYP2C19 GP during maintenance phase prasugrel, and this impact was consistently evident for both of the approved prasugrel doses, possibly influencing long-term outcomes, like bleeding risks.