Abstract Body:
Introduction
In patients with large vessel occlusion stroke of the anterior circulation who are treated with mechanical thrombectomy (MT) and intravenous thrombolysis (IVT), there is no clear evidence that prior antiplatelet therapy (APT) significantly influences functional outcomes, successful reperfusion rates or the risk of symptomatic intracranial hemorrhage (sICH). Even less studied is the effect of APT - especially dual APT - on the outcomes of direct MT, when IVT is not administered. We therefore aimed to evaluate the effects of prior APT on the outcomes of direct MT.

Methods
We analyzed patients from the multicentric international EVA-TRISP database (from 2015 to 2023), comparing outcomes of direct MT based on their previous APT regimen, using propensity score matching and multivariable models to address for confounders. The primary efficacy outcome was a shift in the modified Rankin Scale (mRS) at 90 days. Secondary efficacy outcomes included independence at 90 days (mRS 0-2) and the rate of successful reperfusion (expanded treatment in cerebral infarction ≥2B). The primary safety outcome was the rate of sICH according to the European Cooperative Acute Stroke Study criteria.

Results
Out of 4’444 patients, 1’308 were matched successfully: 480 without APT, 764 on single antiplatelet therapy (SAPT), and 64 on dual antiplatelet therapy (DAPT). SAPT was significantly associated with a shift towards lower mRS scores at 90 days (aOR = 1.29, CI: 1.03 - 1.60). In contrast, we couldn’t confirm the same finding for the DAPT group (aOR = 1.54, CI: 0.93 - 2.57). Nevertheless, independence at 90 days was significantly associated with both SAPT (aOR = 1.56, CI: 1.16 - 2.09) and DAPT (aOR = 3.13, CI: 1.63 - 6.00). Successful reperfusion was not influenced by either SAPT (aOR = 0.90, CI: 0.66 - 1.25) or DAPT (aOR = 0.63, CI: 0.28 - 1.39). Lastly, we did not find any significant association between APT and sICH, in either the SAPT (aOR 0.71, CI: 0.41 - 1.23) or DAPT group (aOR 0.42, CI: 0.09 - 1.92).

Conclusion
We have found that in patients with large vessel occlusion stroke of the anterior circulation treated with direct MT, SAPT was significantly associated with better functional outcomes at 90 days compared with no previous APT, and that both SAPT and DAPT were safely associated with patient's functional independence at 90 days. These results should be confirmed in a larger randomized controlled trial.