Risk Factors for In-Stent Stenosis After Flow Diverter Treatment of Intracranial Aneurysms: A Systematic Review and Meta-Analysis of 2350 Patients

BACKGROUND AND OBJECTIVES: Recent advances in flow diverter (FD) therapy for intracranial aneurysms have highlighted the need to evaluate risk factors for in-stent stenosis (ISS), a potentially serious complication. This meta-analysis aims to identify risk factors associated with an increased risk of ISS after FD treatment. METHODS: PubMed, Web of Science, Embase, and SCOPUS databases were systematically searched for studies reporting ISS rates and risk factors after FD therapy for intracranial aneurysms. Odds ratios were calculated using random-effects models to assess potential risk factors associated with ISS. RESULTS: Ten studies involving 2350 patients with 2441 aneurysms were included. Younger age ( P = .006) and male sex ( P = .003) were associated with higher ISS risk. Smoking also increased the risk ( P = .02). Aneurysm location in the posterior circulation ( P < .00001) and fusiform morphology ( P < .00001) were significant risk factors for ISS, as were ruptured aneurysms ( P = .05). Hypertension, hyperlipidemia, diabetes, allergies, and alcohol abuse, as well as aneurysm size, neck width, and parent artery diameter, did not affect ISS risk. Procedural factors like balloon angioplasty, multiple FDs, or FD/coil combinations were not significantly associated with ISS. CONCLUSION: This meta-analysis identified both nonmodifiable (younger age, male sex) and modifiable (smoking) patient factors, as well as high-risk aneurysm characteristics (posterior circulation, fusiform, ruptured), associated with an increased risk of ISS after FD treatment. These findings highlight the importance of tailored monitoring and management approaches for optimizing outcomes in FD therapy.