Periprocedural and postoperative complications and secondary treatments in cerebral aneurysms treated with flow-diverting stents

Aim: Flow diverter (FD) stents are next-generation stents placed in the parent artery at the level of the aneurysm neck, causing intraaneurysmal thrombosis by reducing the intraaneurysmal blood flow. The aim of this study is to evaluate the complications that occurred during and after the procedure in patients treated with flow diverter stents, and the secondary treatments applied to these complications. Materials and Methods: Between March 2008 and October 2023, 660 patients with intracranial aneurysms who were treated using endovascular methods were included in the study. The pre-procedural, peri-procedural, and post-procedural data of all cases were retrospectively reviewed. Acute complications that occurred during treatment (such as aneurysm rupture, stent migration, thromboembolic and hemorrhagic complications, technical complications) and long-term complications that occurred after treatment (such as in-stent intimal hyperplasia, shortening and deformation, and the formation of carotico-cavernous fistulas) were evaluated. Results: A total of 660 patients were included in the study. The median follow-up duration for the patients was 81 months (range 1-180 months). Clinical and radiological examinations were available for 612 patients (92.72%) at 1 year, 417 patients (63.18%) at 3 years, 253 patients (38.33%) at 5 years, and 192 patients (11,15%) at 10 years. In the early post-procedure period, acute complications were observed in 36 patients (5.45%), and late complications in 43 patients (6.52%). The total rate of technical complications during the peri- and post-procedural periods was found to be 4.55%, with a clinical complication rate of 7.42%. Technical complications included stent shortening and proximal migration in 11 patients (1,67%), stent fracture in 1 patient (0.15%), stent deformation in 9 patients (1,36%), separation of stent layers in 3 patients (0.45%), distal wire dissection and perforation in 3 patients (0.45%), and technical complications during stent deployment in 3 patients (0.45%). Clinical complications included stenosis-causing intimal hyperplasia in another 11 patients (1,67%), stent occlusion in 10 patients (1,52%), iatrogenic carotid-cavernous fistula in 3 patients (0.45%), foreign body reaction in 1 patient (0.15%), thromboembolic complications in 16 patients (2.42%), hemorrhagic complications in 6 patients (0.91%), myocardial infarction in post-procedure period in 1 patient (0.15%), and diffuse alveolar hemorrhage in another 1 patient (0.15%). The procedure-related mortality rate was 0.76%, and the morbidity rate was 4.54%. Secondary treatments were administered to 38 patients (5.76%) due to complications XIII arising after the procedure. Keywords: Intracranial Aneurysms, Flow Diverters, Stents, Endovascular Treatment, Complications, Secondary Treatments