Background Flow diverters (FDs) have revolutionized the endovascular treatment of intracranial aneurysms (IAs) over the past two decades. During this time, they have benefited from several technical improvements, including increased visibility, enhanced delivery, opening, and reduced thrombogenicity. However, concerns have recently arisen regarding the stability of the braid over time. The phenomenon of flow diverter braid deformation (FDBD) lacks clear predictive factors, and the clinical impact remains uncertain. In response to these concerns, we conducted a review of a large database from a single center to assess the frequency, predictive factors, and clinical impact of FDBD.

Methods A single-center French database comprising consecutive IAs treated with various generations of FDs from different manufacturers, between January 2018 and July 2023, was reviewed to identify FDBD. FDBD was defined as the deformation of a FD that was first seen normally implanted, without any external action or force applied to it. Detection of FDBD could occur intraoperatively or during angiographic follow-up and was categorized as follows: fish-mouth, braid-collapse, braid-hump, and shortening. Patients without angiographic follow-up were excluded. Patient demographics, aneurysm characteristics, procedural details, and FD specifications were retrieved and analyzed using both univariate and multivariable analyses. Additionally, occlusion rates at follow-up and morbidity (defined as a score of +1 in the modified Rankin Scale at 3 months) were assessed.

Results In total, 245 FD procedures were conducted in 228 patients; mean age was 52.8±10.9 years and 76% were female. FDBD was observed in 36/245 cases (14.7%), with the majority detected during follow-up angiography at 6 months (32/36 [88.9%]). All types of FDBD were observed; fish-mouth was the most common (16/36 [44.4%]). Morbidity was significantly associated with FDBD (4.8% versus 13.9%; p=0.04). However, angiographic occlusion rates at 6 months and at the last available follow-up (median 17 months) were similar in both groups (p=0.54 and p=0.36, respectively). Drawn filled tubing (DFT) with platinum technology (aOR=6.2, 95% CI [2.8–14.5]; p<0.01) and larger FD diameter (aOR=2.4, 95% CI [1.5–4.1]; p<0.01) were identified as independent predictors of FDBD. The type of metal composing the FD (nitinol versus cobalt-chromium) did not influence FDBD (p=0.13). FD with coating was significantly associated in univariate analysis (p=0.03) but not in multivariable analysis (p=0.25).

Conclusion In this study involving 245 FD embolizations for IAs, FDBD was observed in 14.7% of cases and was associated with increased morbidity. Only specific FD characteristics (DFT technology and larger FD diameter) were identified as independent determinants of FDBD. It is hypothesized that the incorporation of platinum in the DFT reduces individual wire strength relative to uniform nitinol or cobalt-chromium wires. This may reduce the radial strength of the FD and ultimately contribute to FDBD. Larger multicenter studies are warranted to confirm these findings.

Disclosures J. Cortese: 1; C; Balt, Microvention, Medtronic, Phenox, SFNR French Society of Neuroradiology, SFR French Society of Radiology. A. Popica: None. A. Oliver: None. F. Rodriguez-Erazú: None. V. Plaforet: None. I. Diaz: None. V. Chalumeau: None. L. Ikka: None. S. Gallas: None. C. Mihalea: None. J. Caroff: 2; C; Balt, Medtronic, Stryker. 6; C; Cerenovus. L. Spelle: 2; C; Balt, Medtronic, Stryker, Phenox, Microvention.