Progression from Early Minor Recanalization to Major Recanalization in Ruptured Intracranial Aneurysms After Successful Coil Embolization: Risk Factors and Proposal of a Novel Predicting Variable

Background: The risk factors for the progression from early minor recanalization to major recanalization are not well established. Herein, we evaluated ruptured intracranial aneurysms (IAs) with minor recanalization within 1 year of coiling and their progression to major recurrence. Methods: We retrospectively reviewed our database of coiled IAs and searched for ruptured saccular IAs that were successfully embolized without residual sacs. We selected IAs with minor recanalization confirmed on radiological studies within 1 year of coil embolization. All the IA cases had a follow-up period longer than 36 months based on the radiological results. Results: Minor recanalization occurred in 45 IAs within 1 year of coil embolization. Among them, 14 IAs (31.1%) progressed to major recanalization, and 31 remained stable. Progression to major recanalization was detected 12 months after minor recanalization in 2 patients, 24 months in 7 patients, and 36 months in 5 patients. Moreover, the progression to major recanalization occurred more frequently in IAs at the posterior location (P = 0.024, odds ratio 11.20) and IAs with a proportional forced area > 9 mm² (P = 0.002, odds ratio 17.13), which was a newly proposed variable in the present study. Conclusions: Our results showed that approximately one third of the ruptured IAs with early minor recanalization after coiling progressed to major recanalization within 3 years. Physicians should focus on the progression of ruptured IAs from minor to major recanalization, especially those with a posterior circulation location and a proportional forced area >9 mm².