ihtObtura®, a new liquid embolic agent for improving curative embolization of brain AVMs

BACKGROUND AND PURPOSE: We report our initial experience with ihtObtura®, a novel non-adhesive liquid embolic agent with progressive post-embolization loss of radiopacity for curative embolization of brain arteriovenous malformations (bAVMs).

MATERIALS AND METHODS: A post-hoc analysis of the Claridad trial, a single center, first-in-man study was performed. Collected data on consecutive brain bAVMs patients treated with ihtObtura® (between November 2021 to September 2022) were analyzed. Patient demographics, AVM characteristics, procedure details, and clinical treatment outcomes were collected. Imaging endpoints included complete occlusion rate at 6 months and loss of radiopacity at 4 -6 weeks.

RESULTS: A total of 42 consecutive brain bAVM patients who underwent 102 embolization procedures were included in the analysis. Most patients presented with intracranial hemorrhage (83%). The mean AVM classification was Spetzler-Martin (S-M) grade III-IV (90%), with a mean nidus size of 39 ± 14 mm. Complete occlusion was achieved in 26/28 patients (93%) who were able to complete all treatments during the study period. In the entire patient cohort, complete occlusion was observed in 62% (26/42 patients). Procedure-related disabling permanent neurological deficit and procedure-related death were observed in one case each. Both events were related to postembolization intracranial hemorrhages. Progressive reduction of embolic material radiopacity was observed in all patients.

CONCLUSIONS: ihtObtura® is a new liquid embolic agent with similar properties as currently available other ethylene vinyl alcohol (EVOH) copolymer based liquid embolics with one major innovation, progressive reduction in embolic material radiopacity. This feature significantly improves anatomical understanding of residual AVM components during staged treatment of AVMs. This study provides initial evidence that combination of EVOH based diffusion properties with progressive loss of radiopacity allows for the potential improvement in rates of complete obliteration for bAVMs.

ABBREVIATIONS: bAVMs = Brain arteriovenous malformations; S-M = Spetzler-Martin Scale; EVOH = Ethylene vinyl alcohol copolymer; MRI = Magnetic resonance imaging; CT = Computed Tomography; LEA = Liquid embolic agents; mRS = Modified Rankin Scale scores; DMSO = Dimethyl sulpha-oxide solvent; DSA = Digital subtraction angiography.