Comparison of Triple Antiplatelet (Aspirin, Clopidogrel, and Cilostazol) and Modified Dual Antiplatelet (Aspirin and Low-Dose Prasugrel) Therapy in Patients With High On-Treatment Platelet Reactivity Undergoing Stent-Assisted Coil Embolization for an Unruptured Intracranial Aneurysm: A Prospective Randomized Clinical Trial.

Background and objectives: Modified antiplatelet therapies in patients with high on-treatment platelet reactivity (HTPR) remains unknown in neurointerventional treatment. We aimed to compare the safety and effectiveness of two different modified antiplatelet therapies in patients with HTPR undergoing stent-assisted coil embolization for an unruptured intracranial aneurysm.

Methods: We conducted a prospective, randomized clinical trial. Participants with HTPR were randomly assigned (1:1) to the triple antiplatelet therapy (TAT, addition of cilostazol) or modified dual antiplatelet therapy (MDAT, switched from clopidogrel to low-dose prasugrel) group. The primary outcome was all-bleeding-events during the 90-day follow-up period. The secondary outcomes were thromboembolic events and changes in the P2Y12 reaction unit (PRU) value throughout the follow-up period. Intention-to-treat (ITT) and per-protocol (PP) analyses were performed.

Results: In total, 172 of the 198 participants maintained initial antiplatelet therapy for 90 days. There was no significant difference in the all-bleeding-event rate between the two groups, both in the ITT population (hazard ratio [HR], 0.77 [95% CI, 0.49-1.20]; P = .26) and the PP population (HR, 0.79 [95% CI, 0.50-1.30]; P = .34). The thromboembolic event rate did not differ between the 2 groups in either the ITT population (HR, 0.33 [95% CI, 0.03-3.20]; P = .34) or the PP population (HR, 0.42 [95% CI, 0.04-4.70]; P = .48). Compared with those in the TAT group, the PRU values in the MDAT group greatly decreased over time, particularly for PRU after loading.

Conclusion: Among patients with HTPR who underwent stent-assisted coil embolization for an unruptured intracranial aneurysm, there was no significant difference between the TAT and MDAT groups regarding the risk of all bleeding events and thromboembolic events during the 90 days of follow-up.