Partial (SAVE) versus Complete (Solumbra) Stent Retriever Retraction Technique for Mechanical Thrombectomy: A Randomized In Vitro Study.

Background and purpose: Mechanical thrombectomy has become a first-line treatment for acute ischemic stroke. Several techniques combining stent retrievers and distal aspiration catheters have been described. We aimed to characterize the efficacy of 2 commonly used techniques according to clot characteristics.

Materials and methods: Soft (mean stiffness = 95.77 [SD, 5.80] kPa) or stiff (mean stiffness = 205.63 [SD, 6.70] kPa) clots (3 × 10 mm and 2 × 10 mm, respectively) were embolized to the distal M1 segment of the MCA in an in vitro model. The technique was randomly allocated (1:1): stent retriever assisted vacuum-locked extraction (SAVE) versus complete retraction (Solumbra). The primary end point was the percentage of first-pass recanalization. Secondary end points were periprocedural distal embolization measures.

Results: A total of 130 mechanical thrombectomies were performed (50 for soft clots and 15 for stiff clots per arm). Overall, the rate of first-pass recanalizaton was 35% with Solumbra and 15% with SAVE (P < .01). For stiff clots, the first-pass recanalizaton was equal for both methods (27%; P = 1.00). With soft clots, the first-pass recanalizaton was higher with Solumbra (38%) than with SAVE (12%; P < .01). When we used soft clots, the maximum embolus size (mean, 1.19 [SD, 0.9] mm versus 2.16 [SD, 1.48] mm; P < .01) and total area of emboli (mean, 1.82 [SD, 2.73] versus 3.34 [SD, 3.2]; P = .01) were also lower with Solumbra than with SAVE.

Conclusions: Clot characteristics may influence the efficacy of the thrombectomy technique. In occlusions caused by soft clots, complete retrieval into the distal aspiration catheters achieved higher rates of first-pass recanalizaton and lower embolization.