Introduction: Although incomplete occlusion and recurrence of intracranial aneurysms following coil embolization is a well-known problem, the factors that influence and predict recurrence are still debated. The present study sought to identify the patient, aneurysm, and procedural factors that are associated with and can be used to predict recurrence following coil embolization.
Methods: We utilized a retrospective database of 481 aneurysms treated at a single institution. Aneurysms were included in the present study if they were saccular and had follow-up angiography, and excluded if they had been treated previously or were associated with other vascular malformations. Univariate means testing was used to select pre-treatment and treatment variables for incorporation into a multivariable logistic regression model of aneurysmal treatment outcomes.
Results: In the final multivariable model, packing density (OR = 0.9, p=0.01) and RROC III (OR 15.2, p=0.002) independently predicted recurrence of aneurysms on follow-up angiography. Additionally, increased aneurysm neck diameter (OR 1.4, p=0.079) was correlated with future recurrence and trended towards significance. Further analysis revealed a linear relationship between aneurysm volume and coil volume necessary to obtain an optimal minimum packing density, which our results suggest is 31%. We additionally noted a linear relationship between coil volume and aneurysm volume to maintain this ideal packing density, which our results suggest is more easily lost in larger volume aneurysms (volume > 200 mm3) putting them at risk for increased rates of recurrence.
Conclusions: Our results suggest that predictive factors include packing density (particularly less than 30%) and residual aneurysm following treatment. This association should be useful to interventional neurosurgeons in the effort to both prevent and predict aneurysm recurrence after coil embolization
Patient Care: Our research can be used for improving endovascular outcomes and timing follow-up angiography to decrease the risk of aneurysm recurrence and to re-treat recurrent aneurysms more rapidly.
Learning Objectives: Aneurysm outcomes after coil embolization, endovascular neurosurgery technique