Introduction/Purpose Despite the development of new technologies dedicated to the endovascular treatment of intracranial aneurysms (IA) like flow diversion or intrasaccular flow disruption, coiling is still the first-line endovascular treatment for the management of intracranial aneurysms. In ARETA series, which included a large population of 1289 patients with 1359 treated aneurysms (recruitment period: 2013/2015), coiling including balloon-assisted coiling (BAC) was used in 88.4% of IA. The most recent evaluation of the safety and efficacy of aneurysm coiling was conducted in ARETA and took place roughly 10 years ago. So, according to the large use of aneurysm coiling, it seems appropriate to reevaluate this technique to see if the improvement of the technology is associated with improved safety and efficacy. The European study INSTANT is evaluating endovascular treatment of intracranial aneurysms with OPTIMA coils (Balt, Montmorency, France).

Materials & Methods INSTANT study included patients with ruptured, unruptured, or recanalized aneurysms treated with OPTIMA coils. The primary endpoint was evaluation of safety (morbidity and mortality at one-month). Several secondary endpoints were further evaluating safety and efficacy. All adverse events and anatomical results were independently evaluated.

Results The study population for this analysis consisted of 294 patients (mean age: 56.3 ± 12.0 years), 186 women (63.3%) included in 18 European centers during the period 04/2019 - 04/2022. Aneurysms were sacciform in all patients, ruptured in 133/294 patients (45.2%) and unruptured or recanalized in 161/294 patients (54.8%). Aneurysm location was anterior communicating artery in 126/294 patients (42.9%), middle cerebral artery in 52/294 (17.7%), carotid siphon in 95/294 patients (32.3%) and vertebrobasilar system in 21/294 (7.1%). Mortality at 1-month was 0.0% in patients with unruptured aneurysms and 3.0% in those with ruptured aneurysms, all related to subarachnoid hemorrhage and its complications. Morbidity at 1-month was 1.2% in patients with unruptured aneurysms and 21.1% in those with ruptured aneurysms. Anatomical results at 12-month will be presented and analyzed.

Conclusion INSTANT study provides a recent evaluation of safety and efficacy of coiling in the management of intracranial aneurysms.

Disclosures L. Pierot: 2; C; Balt. O. Eker: None. J. Berge: None. J. Gentric: None. O. Lévrier: None. K. Kucps: None. C. Barbier: None. A. Vega: None. R. Beaujeux: None. J. Lopez-Martinez: None. E. Chabert: None. C. Rodriguez: None. L. Valvassori: None. C. Papagiannaki: None. C. Papagiannaki: None. G. Ianucci: None. M. Muto: None. V. Costalat: None. P. Machi: None. P. Machi: None. E. Giweski: None. P. White: None. D. Herbreteau: None. A. Januel: None.