Introduction A growing body of research has suggested the benefits of mechanical thrombectomy in large vessel occlusion with the use of newer generation of thrombectomy devices. Different device designs may influence the rate of procedural-related embolic events, which is a modifiable risk. The EmboTrap thrombectomy system features an inner stent channel with an outer stent trap design that may potentially reduce the risk of distal clot fragmentation. The objective of this study is the analysis of embolic potential during EmboTrap thrombectomy as compared with existing, FDA-cleared technology for the treatment of acute ischemic stroke.

Materials and Methods A hard, inelastic clot was injected into a patient-specific circle of Willis replica to form a middle cerebral artery occlusion. A guide catheter was placed in the cervical ICA, and delivered the guidewire which was then softly advanced through the clot. A microcatheter was navigated over the wire across the occlusive clot. The guidewire was withdrawn followed by device (EmboTrap or Solitaire 2) deployment for mechanical thrombectomy. During retriever retraction, continuous aspiration was applied through an aspiration pump. Twenty experiments were carried out for each device. The maximum number of thrombectomy attempts was limited to 3. Emboli greater than 1000μm were measured with calipers. The Coulter Principle was used to characterize emboli with size between 200µm to 1000µm.

Results EmboTrap thrombectomy resulted in a significant reduction in the frequency of large clot fragment (>1000μm) dislodgement as compared to Solitaire thrombectomy (p=0.031, Fisher’s exact test). Formation of emboli greater than 1000μm in size occurred in 3 out of 20 cases in the EmboTrap group, versus 11 of 20 experiments with the Solitaire group. Approximately 80% of >1000μm emboli were found in the MCA, regardless of device type. There was no significant difference in average clot size between EmboTrap and Solitaire groups (size ranging from 1000 to 4000μm) in the >1000μm size range. In the size range between 200 to 1000μm, a broader size distribution of emboli was observed with the Solitaire device (200- 770μm) compared to the EmboTrap device (200–325μm). There was no significant difference between the EmboTrap and Solitaire in 200 to 1000μm emboli formation (p=0.89, Mann-Whitney test). When combining all emboli in the most dangerous range (>200μm), EmboTrap offered size reduction of emboli (p=0.022). A complete flow restoration after a single pass was observed in all cases except for 1 experiment in the EmboTrap group, whereas 2 out 20 cases in the Solitaire group required more than 2 passes to achieve full recanalization.

Conclusion Based on this preliminary study, it is our conclusion that stent retriever design can be optimized to alter the particle size distribution of distal emboli. When encountering friable hard clots, the use of the EmboTrap device may provide a reduction in distal emboli to both affected and unaffected territories and should be considered.

Disclosures: J. Chueh: None. M. Marosfoi: None. R. King: None. O. Brooks: None. A. Puri: None. M. Gounis: 1; C; research grant. 6; C; Travel Support.