Previous Antiplatelet Therapy on Ticagrelor-Aspirin and Clopidogrel-Aspirin Efficacy in Intracranial Artery Stenosis

Background and Purpose This study aims to investigate the effects of previous antiplatelet therapy on the efficacy and safety of ticagrelor-aspirin versus clopidogrel-aspirin among patients with and without intracranial artery stenosis (ICAS) using data from the Ticagrelor or Clopidogrel with Aspirin in High-Risk Patients with Acute Nondisabling Cerebrovascular Events-II (CHANCE-2) trial.Methods In this post-hoc analysis of the CHANCE-2 trial, patients who underwent intracranial artery imaging were included. The primary efficacy and safety outcomes were recurrent stroke and severe or moderate bleeding within 90 days.Results Among the 5,920 patients included, the median age was 64.8 years (interquartile range, 57.0–71.4), 2,004 (33.9%) were females, 2,385 (40.3%) had ICAS, and 701 (11.8%) had previous antiplatelet therapy before enrollment. There were significant interaction effects between previous antiplatelet therapy and dual-antiplatelet therapy regimens on the risk of recurrent stroke (P=0.003) in patients without ICAS but not in those with ICAS (P=0.557). Only in patients without ICAS without previous antiplatelet therapy, ticagrelor-aspirin therapy reduced the risk of stroke recurrence compared with clopidogrel-aspirin therapy (adjusted hazard ratio 0.47, 95% confidence interval 0.34–0.66, P<0.001). Similar effects were observed for the outcomes of composite vascular events and ischemic stroke at 3 months and 1 year. No significant differences in severe or moderate bleeding were observed between the groups.Conclusion In patients with minor stroke or high-risk transient ischemic attack carrying CYP2C19 loss-of-function alleles, those without ICAS and no history of previous antiplatelet therapy may have a better response to ticagrelor-aspirin therapy for reducing new stroke and composite vascular events.