Flow diverter is valid for aneurysms with incorporated branch vessels: Adding coil embolization and incorporated branch vessel diameter are predictors of treatment efficacy

Background: This study aimed to determine the efficacy of flow diverters (FDs) for small/medium (≤10 mm) aneurysms and analyzed the factors that prevent aneurysm occlusion. Methods: This retrospective single-center study evaluated the angiographic and clinical data of consecutive patients between June 2020 and February 2023. Results: Overall, 121 small/medium aneurysms were observed in 106 patients treated with FDs. The median dome diameter was 6.1 (5.1–7.2) mm. Symptomatic thromboembolic complications were observed in four (3.7 %) patients, and none showed a major ischemic stroke. Intracranial hemorrhage was detected using postprocedural computed tomography in one (0.9 %) patient with asymptomatic subarachnoid hemorrhage. The rate of permanent neurological deficits was 1.8 %, and the mortality rate was 0 %. No delayed ischemic or hemorrhagic complications were observed during follow-up. Angiographic follow-up revealed complete and adequate occlusion (O'Kelly–Marotta grades C and D) rates of 77.5 % and 90.8 %, respectively. On multivariate analysis, incomplete occlusion was only associated with the presence of a branch vessel from the aneurysm dome (P < 0.01). In aneurysms with incorporated branch vessels, univariate analysis revealed that coil usage was a predictor of complete occlusion (P = 0.03). Moreover, even without using coils, effective occlusion was achieved when the branch vessel diameter was small (P = 0.03). Conclusions: FDs are an effective and safe treatment option for small/medium aneurysms. The presence of incorporated branch vessels can predict incomplete occlusion. Even in aneurysms with incorporated branch vessels, FD can obtain therapeutic effects by adding coil embolization or treating with only FD if the branch vessel diameter is small.