ihtObtura: A novel liquid embolic agent with post-embolization radiopacity loss, in endovascular treatment of brain arteriovenous malformations, dural arteriovenous fistulas, and tumors: CLARIDAD trial

Abstract

Background: Endovascular embolization is frequently used for vascular lesions of the head and neck. Newer agents may help to enhance visualization and improve treatment outcomes.

Methods: The CLARIDAD clinical trial was a prospective, single center, first-in-man investigation of neurovascular embolization using the novel embolic agent _ihtObtura for a broad indication, covering the need for a liquid embolic agent in head and neck procedures. The primary outcomes assessed were therapeutic efficacy to deliver _ihtObtura to embolize the catheterized pedicle and associated angiographic vascularity, and subsequent loss of radiopacity. Safety endpoints included procedural adverse events, modified Rankin Scale (mRS) score, morbidity, and mortality. Radiologic and clinical follow-up evaluations were conducted at 30, 90, 180 days, and 1 year post-treatment.

Results: 65 consecutive patients (mean age 37.8 years, 50.8% women) were treated over 129 sessions. A total of 42 brain arteriovenous malformations (AVMs; 90% grades III and IV), 8 dural arteriovenous fistulas (DAVFs), and 15 hypervascular tumors were treated with _ihtObtura using an average of 3.9 mL per session and 7.7 mL per patient. We achieved therapeutic effectiveness in 99% of catheterizations. Radiopacity loss was complete after 74.3% of the sessions at 30 days, 95.6% at 90 days, and 100% at the 1 year follow-up. Serious adverse events (mRS score >2) occurred in two patients (3.1%) with previously ruptured high grade AVMs leading to one death and one permanent disabling morbidity.

Conclusions: The study showed that _ihtObtura was a novel, safe, and effective liquid embolic agent for the treatment of AVMs, DAVFs, and hypervascular tumors. Its key property of significant radiopacity loss contributes to improve anatomical understanding, particularly in staged procedures, as well as reduction in post-procedural imaging artifact. There may be additional benefits of eliminating tantalum from the embolic mixture in terms of lesion penetration.

Keywords: Arteriovenous Malformation; Embolic; Fistula; Liquid Embolic Material; Tumor.

Figure 1. Radiopacity loss associated with cerebellar treatment using _ihtObtura. (A) Vertebral artery angiogram showing the arteriovenous malformation (AVM). (B, C) Embolic agent cast visible after the first session and follow-up. (D) Angiogram at 6 month follow-up. (E) Brain CT after embolization showing lack of embolic agent related artifacts after the first session. (F) Brain CT at follow-up

Figure 2. Treatment process of a high grade parieto-occipital arteriovenous malformation using _ihtObtura. (A, B) Internal carotid and vertebral angiograms showing two compartments of the arteriovenous malformation. (C, D) Embolic agent cast visible after the first session and after 1 month after the third last session. Arrows indicate the pressure cooker remaining after radiopacity loss. (E, F) Internal carotid and vertebral angiograms at 6 months showing stability of total occlusion.