Propensity score analysis of flow diverters placed in scaffolding stents

Background and Purpose: Flow-diverter deployment within a stent remains controversial, but flow-diverter deployment within a scaffolding stent has been performed occasionally. To date, an analysis of this scaffolding technique has not been reported. We aimed to evaluate whether the scaffolding technique adversely affects the outcomes of flow diversion. Materials and Methods: Patients who had undergone intracranial aneurysm treatment using a Silk flow diverter with (scaffolding group) or without (bare flow-diverter group) a scaffolding stent were identified retrospectively and compared. Propensity score matching was used to match the aneurysms in both groups for variables with a significant difference between groups. Aneurysm occlusion rates and clinical outcomes were compared. Results: There were 84 patients (105 aneurysms) in the bare flow-diverter group and 21 patients (22 aneurysms) in the scaffolding group (using 20 LEO stents and 1 Enterprise stent). The aneurysms in the scaffolding group were larger (mean, 13.1 [SD, 10.7] versus 7 [SD, 4.5] mm, P=.001) and more likely to be fusiform (40.9% versus 5.7%, P<.001) than in the bare flow-diverter group. After 2:1 propensity score matching, 24 aneurysms in the bare flow-diverter group and 15 in the scaffolding group were matched. Aneurysm occlusion rates did not significantly differ between groups at 1-3 months (41.2 versus 33.3%, P>.99), 3-6 months (55.5 versus 75.0%, P=.44), 7-12 months (65.0 versus 90.0%, P=.21), or beyond 1 year (73.6 versus 91.6%, P=.36). There was no difference in complication rates between the groups (P>.99). Conclusions: Placement of a scaffolding stent before flow diversion does not adversely affect aneurysm occlusion or complication rates.