Failure of antithrombotic therapy and risk of stroke in patients with symptomatic intracranial stenosis.

Background And Purpose: We sought to determine if patients with intracranial stenosis who have a transient ischemic attack or stroke on antithrombotic therapy are at particularly high risk for recurrent stroke.

Methods: We compared baseline features and the rates of stroke or vascular death and stroke in the territory of the symptomatic artery between patients ON (n=299) versus OFF (n=269) antithrombotics at the time of their qualifying event for the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) trial.

Results: In univariate analyses, there was no difference in the rates of stroke or vascular death (21% versus 23%; hazard ratio [ON/OFF], 0.91; 95% CI, 0.64 to 1.29; P=0.59) or stroke in territory (13% versus 14%; hazard ratio [ON/OFF], 0.90; 95% CI, 0.57 to 1.39; P=0.61) between patients ON versus OFF antithrombotics at the time of their qualifying event. A multivariable analysis adjusted for the difference in risk factors between patients ON and OFF antithrombotic therapy also showed no significant differences in the combined end point of stroke or vascular death (hazard ratio [ON/OFF], 0.86; 95% CI, 0.55 to 1.34; P=0.51) or stroke in territory (hazard ratio [ON/OFF], 1.01; 95% CI, 0.58 to 1.77; P=0.97) between patients ON versus OFF antithrombotic therapy at the time of the qualifying event.

Conclusions: Patients with intracranial stenosis who fail antithrombotic therapy are not at higher risk of stroke than those who do not fail antithrombotic therapy. Given our finding that patients ON and OFF antithrombotic therapy are both at high risk for stroke in the territory, intracranial stenting trials should not be limited to just those who fail antithrombotic therapy.