Introduction/Purpose The presence or lack of an extensive cerebral collateral net is becoming more widely considered as an independent prognostic factor in stroke patients. We aimed to assess whether the extent of collaterals had modifying effects on first pass recanalization (FPR) and distal emboli measures in mechanical thrombectomy (MT).

Methods Two in-vitro neurovascular models were created: good collaterals model (GCM) and poor-collaterals model (PCM). The 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 (Solitaire 4×40 mm + React 71). The primary outcome measure was FPR. The secondary outcomes assessed distal embolization parameters.

Results A total of 60 MTs were performed (30 experiments per study arm). Overall rate of FPR was 30%. FPR was higher in GCM (52%) than in PCM (8%; p<0.01). Maximum distal embolus size (1.51±1.31 mm vs. 0.58±0.46 mm; p<0.05), mean size of the embolus (0.95±1.1 vs. 0.35±0.28; p<0.05), total area of emboli (2.49±3.45 vs. 0.42±0.64; p<0.05) and total count of particles >1 mm (0.97±1.03 vs. 0.27±0.69; p<0.01) were also lower in GCM than in PCM.

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

Disclosures M. Jablonska: None. J. Li: None. R. Tiberi: None. A. Tomasello: None. M. Ribo: None.