High residual platelet reactivity after switching from clopidogrel to low-dose prasugrel in Japanese patients with end-stage renal disease on hemodialysis

Background: High on-treatment platelet reactivity (HPR) under clopidogrel treatment is frequently observed in hemodialysis (HD) patients. In such patients, 10 mg of prasugrel has reportedly inhibited platelet reactivity more adequately compared with 75 mg of clopidogrel. However, the efficacy of 3.75 mg prasugrel in Japanese HD patients is largely unknown. Methods: A total of 41 Japanese coronary artery disease patients under HD who received aspirin and clopidogrel were enrolled. Clopidogrel was switched to 3.75 mg prasugrel. At day 14, prasugrel was switched to clopidogrel. Platelet reactivity was measured using VerifyNow assay (Accumetrics, San Diego, CA, USA) at baseline, day 14, and day 28. VerifyNow P2Y12 reaction units (PRU) >208 was defined as HPR. Results: The PRU level on prasugrel therapy was significantly lower than that on clopidogrel therapy before switching (219.1 ± 62.3 PRU vs. 238.2 ± 68.0 PRU, p = 0.02). Although the prevalence of HPR was numerically lower on prasugrel therapy compared with clopidogrel therapy before and after switching, the differences did not reach a statistical significance (57.6% vs. 75.7% vs. 74.2%, p = 0.13). Even under prasugrel treatment, more than half of patients showed HPR. Conclusions: Although low-dose prasugrel had somewhat better antiplatelet effect than clopidogrel, it could not significantly improve the prevalence of HPR in Japanese HD patients. Higher doses of prasugrel might be needed to achieve adequate platelet inhibition in this high thrombotic risk population.