Introduction The presence or lack of an extensive cerebral collateral net is becoming more widely considered as an independent prognostic factor in stroke patients.

Aim of Study We aimed to assess whether the extent of collaterals had modifying effects on first-pass recanalization (FPR) and distal emboli measures (DEM) in mechanical thrombectomy (MT).

Methods Two in-vitro neurovascular models were created: good collaterals model (GCM) and poor-collaterals model (PCM). Two models were identical up to the M2 segment of middle cerebral artery (MCA). The GCM included anastomoses of the M2-MCA branches with anterior cerebral arteries and vertebrobasilar circulation. In the PCM these anastomoses were missing. Synthetic uniform clots (stiffness=95.77±5.80 kPa) were embolized to the M1-MCA. In all cases MT was performed using Solumbra technique. The primary outcome measure was FPR. The secondary outcomes assessed DEM.

Results Sixty MTs were performed (thirty experiments per study arm). The overall rate of FPR was 32%. FPR was higher in GCM (57%) than in PCM (7%; p<0.001). Maximum embolus size (1.51±1.31 mm vs. 0.58±0.46 mm; p=0.001), mean embolus size (MES) (0.95±1.1 vs. 0.35±0.28; p<0.01), total area of emboli (2.49±3.45 vs. 0.41±0.64; p<0.01), and total count of emboli >1 mm (0.97±1.03 vs. 0.27±0.69; p<0.01) in the new territory as well as MES (0.78±0.88 vs. 0.39±0.56; p<0.05) and area of emboli >1 mm (2.03±8.43 vs. 1.86±3.33; p<0.01) in a previously affected territory were also lower in GCM than in PCM.

Conclusion The degree of collateral circulation may modify MT outcomes. Good collaterals might facilitate the achievement of FPR and prevent distal embolization.

Disclosure of Interest Magda Jablonska has nothing to disclose.

Jiahui Li has nothing to disclose.

Riccardo Tiberi has nothing to disclose.

Alejandro Tomasello reports receiving consulting fees from Anaconda Biomed, Balt, Medtronic, MicroVention, Cerus, Merlin Medical, and Stryker.

Marc Ribo is a consultant for Medtronic, Cerenovus, Vesalio.