Abstract 15857: High-on Thienopyridine Platelet Reactivity in Elderly Coronary Patients
OBJECTIVES: The aim of this study was to compare on-treatment platelet reactivity of elderly patients (>75 yrs) treated by thienopyridines in comparison with younger patients (< 75yrs).
BACKGROUND: Elderly patients represent a growing and challenging population for whom the effect of dual antiplatelet therapy on platelet inhibition has not been specifically addressed.
METHODS: The Senior Platelet study included 1271 coronary patients chronically (>14 days) treated by low dose aspirin and a thienopyridine (clopidogrel 75mg n= 1027, clopidogrel 150mg n=139 or prasugrel 10mg n=105). Platelet response to clopidogrel and prasugrelwas assessed by the VerifyNowassay and light transmission aggregrometry. Response to treatment and rate of high platelet reactivity (HPR) and inhibition (HPI) were compared between the two age categories.
RESULTS: On-treatment platelet reactivity with clopidogrel 75mg, 150mg or prasugrel 10mg was always higher in elderly patients (n=197) than in younger patients (n=1074) whatever the test used. The difference in PRU in response to ADP-PGE1 agonist between the two populations was +45; p<0.0001 in patients treated with clopidogrel 75mg, +30; p=0.17 in patients treated with clopidogrel 150mg and +20; p=0.08 with prasugrel 10mg. Elderly patients displayed a higher rate of HPR on clopidogrel 75mg than younger patients (38.2% vs. 18.2%; p<0.0001) (figure) and a lower rate of HPI (2.3% vs. 8.7%; p=0.01). Of note, diabetes and the distribution of the genotype for the loss of function allele 2C19*2 were similar in both population and could not explain the higher rate of HPR of the elderly.
CONCLUSIONS: Elderly patients present an impaired response to clopidogrel with a high rate of HPR. Clopidogrel 150mg and prasugrel 10mg blunt,but do not eliminate the difference in response observed between old and young patients.
- © 2011 by American Heart Association, Inc.