Safety and EffecTiveness of the Silk Vista Flow DiverteR in the TrEatment of Unruptured IntracrAnial AneurysMs

Overview

Intracranial aneurysms (IA) are abnormal outpouchings of cerebral arteries' walls that occur mostly in arteries found in the Circle of Willis and the middle cerebral artery bifurcation with a risk of rupture leading to subarachnoid hemorrhage (SAH) and potentially death. If IA is treated before rupture, survival rates improve dramatically. The IA can be treated with endovascular technique (coiling or stenting). Specifically, the parent artery reconstruction with a flow-diverter stent allows the treatment of a wide range of aneuryms with high rate of aneurysm occlusion. However, during follow-up, up to 15% of FD present deformities, associated with increased morbidity secondary to implant. This phenomenon is not predictable and its mechanism remains unexplained. The objective of this STREAM study is to generate longitudinal clinical and imaging data on the Silk Vista to further evaluate its efficacy and safety in the treatment of unruptured IA, and in particular, to assess and understand the impact of morphological changes over time associated with this device

Intracranial aneurysms (IA) are abnormal outpouchings of cerebral arteries' walls. IA prevalence ranges between 1.8% and 8% in adults, with an approximately equal male/female distribution and a mean age of 50 years at first detection. They predominantly occur in arteries found in the Circle of Willis and the middle cerebral artery bifurcation (85%). The primary concern after discovery of an unruptured IA (UIA) is the risk of rupture leading to subarachnoid hemorrhage (SAH) and potentially death. The aneurysmal SAH has been associated with up to 50% mortality, whereas approximately 30% of survivors are left with severe neurological and/or neurocognitive deficits, resulting in a significant public health burden. Given the evidence that when an IA is treated before rupture, survival rates improve dramatically, identification of aneurysms, specifically those at risk of rupture, and availability of effective treatment strategies, are essential for improving the clinical outcomes of these patients. The IA treatment management includes surgery (neurosurgical clipping has been the gold standard) or endovascular methods. However, over the past decade, the endovascular options to manage IA, ruptured or not, have rapidly evolved, making the treatment of IA less invasive and increasingly more successful. In endovascular technique, a parent artery reconstruction is realized with a flow-diverter stent. Following their specific characteristics, flow diverters (FD) were initially designed to treat giant and large. When comparing FD to the other endovascular techniques (coiling or stenting), FD have been shown to have a higher rate of occlusion for large aneurysms. However, during follow-up, up to 15% of FD present a stenosis that may affect their extremities (known as " fishmouth " stenosis) or their mid-segment (" stent collapse "). The deformities are associated with increased morbidity secondary to implant. This phenomena is not predictable and its mechanism remains unexplained. The DFT (drawn-filled tubing with platinum) technology used for braiding the latest generation of FD stents, including the SILK VISTA stent, may potentially contribute to this phenomenon. Data from an independent and comprehensive evaluation are needed to confirm safety and efficacy in this context. The Silk Vista SDF (BALT, Montmorency, France) is intended for the treatment of IA. The objective of this STREAM study is to generate longitudinal clinical and imaging data on the Silk Vista to further evaluate its efficacy and safety in the treatment of UIA, and in particular to assess and understand the impact of morphological changes over time associated with this device.