Abstract 262: Endovascular coiling of very small unruptured aneurysms: Subgroup analysis from the ECOSA registry

Introduction and aim Endovascular treatment of ruptured and unruptured Intracranial aneurysm (IA) treatment has evolved over the recent years since the publication of the ISAT and BRAT trials. However, very small (≤3 mm) unruptured aneurysm treatment remains unclear. The aim of this study was to describe outcomes in patients with (≤3 mm aneurysms who were treated with endovascular coiling. Methods The Endovascular Coil Embolization of Small Unruptured Cerebral Aneurysm (ECOSA) registry was utilized and patients with aneurysms ≤3 mm were identified. Baseline characteristics, treatment modalities, periprocedural outcomes and long‐term clinical and angiographic outcomes were reported. Results Out of 903 aneurysms within the ECOSA study, 116(12.4%) were very small aneurysms. Mean (standard deviation [SD]) age of patients was 52.3(12.1). Most patients were females (76.3%) and white (61.7%). More than half of patients were hypertensive (61.2%) while 6.9% were diabetic. Active smoking was prevalent in 31.9% of the cohort. Most common aneurysms were incidental in (78.4%). Mean(SD) max diameter of aneurysms was 2.66 (0.87) mm. Most common location of aneurysm was the ICA (36.2%) followed by ACA/acomm (21.7%). Stent‐assisted coiling was utilized in 23.3% of patients and balloon‐assisted coiling in 15.2%. In terms of outcomes, thromboembolic events occurred in 1.7% of patients, and all were asymptomatic. No periprocedural mortality occurrence was reported. Clinical follow‐up was available for 84.5% of patients with mean 7.15 months and angiographic in 52.7% of patients with median of 7.75 months. Good functional outcome (mRS0‐2)was achieved in 93.9% of patients. Most patients (73.8%) had complete occlusion(RROCI) and adequate occlusion(RROC I‐II) was achieved in 86.3%. Modality of follow‐up imaging was DSA in 28.4%, MRA in 26.7% and CTA in 5.2%. Conclusion Endovascular coiling can be performed safely and effectively in patients with unruptured ≤3 mm aneurysms.