Ying L, et al. - Researchers assessed the effect of hepatitis B virus (HBV) infection on platelet response to clopidogrel in patients undergoing coronary stent implantation. Enrollees had taken aspirin 100 mg in combination with clopidogrel 75 mg daily ≥5 days. Among the 1,805 subjects, 102 patients were hepatitis B surface antigen (HBsAg) positive and 1,703 patients were negative. Platelet in response to adenosine diphosphate appeared to be notably higher in HBsAg positive group vs the HBsAg negative group. The difference of platelet aggregations in response to arachidonic acid was not found to be statistically significant. Researchers concluded that HBV infection served as an independent risk factor of clopidogrel low response, in addition to CYP2C19 gene mutations.