Moving Beyond Packing Density: A Modern Reappraisal of Recurrence and Retreatment in Coiled Aneurysms

Despite advances in treatment for intracranial aneurysms, recurrence remains a clinical challenge. Studies have suggested associations between treatment modality, aneurysm morphology, and recanalization risk, but comprehensive evaluation of these factors and their relationships is limited. The goal of this study was to evaluate the role of aneurysm location and packing density (PD) as predictors for recurrence.

This is a retrospective cohort study where records of patients who underwent coiling for intracranial aneurysms from 2013 to 2023 from a single institution were reviewed. Recurrence was defined as worsening of angiographic aneurysm occlusion status. Demographics, aneurysm characteristics, clinical outcomes, and follow-up data were recorded. Analysis was performed in RStudio.

A total of 505 were included; 195 aneurysms were ruptured (38.6%). The most frequent locations were anterior communicating artery (163), internal carotid artery (85), basilar (76), posterior communicating artery (63), and middle cerebral artery (43). Mean PD was 23.3%, with 109 recurrences (21.6%) and 76 retreatments (15.1%); 31 patients (6.1%) experienced thromboembolic complications. In multivariable analysis, incomplete occlusion (Raymond-Roy [RR] Grades II-III), presence of an incorporated branch vessel, and higher size ratio independently predicted recurrence, whereas male sex and age older than 75 years were protective. Size ratio also predicted retreatment, while stent-assisted coiling reduced the likelihood of retreatment. Although higher PD was associated with better immediate RR Grade, PD (including extremes <15% vs >30%), aneurysm volume, and anatomical location were not independently associated with recurrence or retreatment after adjustment.

In this modern series, the immediate RR Grade, not PD or anatomical site, drove long-term durability; PD improved the index occlusion but had no independent association with recurrence after adjustment. Incorporated perforators independently increased recurrence risk, and stent assistance reduced retreatment. These data reframe technical priorities toward achieving complete occlusion safely, especially in perforator-bearing lesions, rather than chasing PD thresholds alone in the contemporary era.