Estradiol increases platelet aggregation in PlA1/A1 individuals

Estrogen concentration similar to that expected in HRT resulted in an increase in platelet aggregation in PlA1/A1 individuals, but not in PlA1/A2 individuals. The data may provide further insight for the increase in coronary events seen in HRT clinical trials and suggest that further evaluation is needed to better define the role of pharmacogenetics in HRT.