Comparison of the Antiplatelet Effects of Once and Twice Daily Low-Dose Ticagrelor and Clopidogrel After Percutaneous Coronary Intervention.

Although Asian people are believed to be more susceptible to bleeding on currently recommended dose of ticagrelor, there is limited evidence supporting low-dose ticagrelor. We prospectively randomized patients receiving dual antiplatelet therapy with aspirin and clopidogrel into 3 groups; aspirin plus clopidogrel 75 mg versus aspirin plus ticagrelor 90 mg once daily versus aspirin plus ticagrelor 45 mg twice daily. Platelet function assessments were conducted using VerifyNow P2Y12 assay at baseline and 28 days after randomization. No differences in baseline P2Y12 reaction unit (PRU) values were observed among the 3 groups. PRU values at the end of the treatment periods were significantly lower in low-dose ticagrelor (90 mg QD group, 98.6 ± 73.4 and 45 mg BID group, 65.5 ± 58.8) compared with clopidogrel (221.2 ± 50.1, both p <0.001). There was no significant difference in PRU values between 2 groups of low-dose ticagrelor (p = 0.208). The rates of high on-treatment platelet reactivity were significantly lower in low-dose ticagrelor compared with clopidogrel, whereas clopidogrel showed higher rate of optimal on-treatment platelet reactivity than ticagrelor 45 mg BID. However, similar rate of optimal on-treatment platelet reactivity was observed in clopidogrel and ticagrelor 90 mg QD. In conclusion, low-dose ticagrelor treatment, either with 90 mg QD or 45 mg BID, was associated with a more potent antiplatelet effect compared with clopidogrel treatment and once daily dose provided similar antiplatelet effect but favorable effect on optimal platelet inhibition compared with twice daily dose.