Residual platelet reactivity and outcomes with 5 mg prasugrel therapy in elderly patients undergoing percutaneous...

In acute coronary syndrome (ACS) patients older than 75 years old, prasugrel 10 mg maintenance therapy has shown less clinical efficacy and higher risk of bleeding. In patients older than 75 years, a prasugrel dose of 5 mg should be used if treatment is deemed necessary.

The aim of this study was to compare platelet reactivity and outcomes in elderly patients receiving prasugrel 5mg therapy with non-elderly patients receiving prasugrel 10 mg therapy.

Consecutive ACS patients undergoing percutaneous coronary intervention (PCI) treated with prasugrel were included. Of 718 patients, 228 (32%) had ≥75 years and received prasugrel 5 mg/day. Residual platelet reactivity (RPR) was 47±18% and 36±16% in the elderly and non-elderly group, respectively (p=0.001). High RPR (≥70%) was found in 9% and 2% (p=0.0001) in elderly and non-elderly patients, respectively. In the 6-month follow-up, there was no difference in mortality, stent thrombosis, and reinfarction rates between the 2 groups but a higher rate of TIMI minor bleeding (7.9% vs 2.4%; p=0.001) in elderly as compared with younger patients. Age≥75 years was independently associated with bleeding events (HR 2.162 [1.105-4.229]; p=0.024).

Elderly patients receiving prasugrel 5mg are more likely to experience high RPR than younger patients treated by prasugrel 10 mg. Despite the use of a reduced prasugrel maintenance dose and a higher level of RPR, elderly patients show increased risk of bleeding during prasugrel therapy as compared to younger patients.