Rate of Rebleed and Retreatment of Previously Treated Intracranial Aneurysms.

[BACKGROUND] Intracranial aneurysms (IAs) can be treated through endovascular treatment (EVT) or microsurgery (MS). Treated IAs can recanalize, which can lead to rupture or retreatment.

[OBJECTIVE] The aim of our study was to evaluate the natural history of previously treated IA, by evaluating the risk of rupture and the risk of retreatment.

[METHODS] All patients treated for an IA between 2007 and 2017 in 4 hospitals were included. The rate of (recurrent) hemorrhage and the rate of prophylactic retreatment were retrospectively evaluated. Kaplan-Meier survival analysis with log-rank tests was used to compare the rates of rupture or retreatment. Patients with ruptured and unruptured aneurysms were separated, and we compared the risk of retreatment between EVT and the surgical treatment.

[RESULTS] A total of 4997 IAs were included in the study, corresponding to 20,489 patient-years. Overall, 28 (0.6%) aneurysms that had been previously treated demonstrated hemorrhage. Moreover, 237 (4.7%) aneurysms were retreated for recanalization without hemorrhage. The rate of retreatment was higher in the EVT-treated IAs as compared with the MS-treated IAs (LogRank: P < 0.0001) and higher in the previously ruptured IAs versus unruptured IAs (LogRank: P < 0.0001). However, the rate of posttreatment hemorrhage/IA rupture was similar for both groups.

[CONCLUSIONS] The rate of IA retreatment is low; however, the rate of hemorrhage/rupture from treated IAs is even lower. A higher rate of retreatment was noted in EVT-treated IAs versus MS-treated IAs and in ruptured IAs versus unruptured IAs; however, the rate of hemorrhage or rerupture was comparable between the groups.