Does prior antiplatelet treatment improve functional outcome after intra-arterial treatment for acute ischemic stroke?

Background and purpose In patients with acute ischemic stroke who receive antiplatelet treatment, uncertainty exists about the effect and safety of intra-arterial treatment. Our aim was to study whether intra-arterial treatment in patients with prior antiplatelet treatment is safe and whether prior antiplatelet treatment modifies treatment effect.

Methods All 500 MR CLEAN patients were included. We estimated the effect of intra-arterial treatment with ordinal logistic regression analysis, and tested for interaction of antiplatelet treatment with intra-arterial treatment on outcome. Furthermore, safety parameters and serious adverse events were analyzed.

Results The 144 patients (29%) on antiplatelet treatment were older, more often male, and had more vascular comorbidity. Intra-arterial treatment effect size after adjustments in antiplatelet treatment patients was 1.7 (95% confidence interval 0.9-3.2), and in no antiplatelet treatment patients 1.8 (95% confidence interval: 1.2-2.6). There was no statistically or clinically significant interaction between prior antiplatelet treatment and the relative effect of intra-arterial treatment (p=0.78). However, in patients on antiplatelet treatment, the effect of successful reperfusion on functional outcome in the intervention arm of the trial was doubled: the absolute risk difference for favorable outcome after successful reperfusion in patients on prior antiplatelet treatment was 39% versus 18% in patients not on prior antiplatelet treatment (P-interaction=0.025). Patients on antiplatelet treatment more frequently had a symptomatic intracranial hemorrhage (15%) compared to patients without antiplatelet treatment (4%), without differences between the control and intervention arm.

Conclusions Prior treatment with antiplatelet agents did not modify the effect of intra-arterial treatment in patients with acute ischemic stroke presenting with an intracranial large vessel occlusion. There were no safety concerns. In patients with reperfusion, antiplatelet agents may improve functional outcome.