Multicenter analysis of the incidence of in-stent stenosis following the deployment of flow-redirection endoluminal device in the treatment of intracranial aneurysms

Introduction: The Flow Re-direction Endoluminal Device (FRED) is a novel flow diverter with a unique double stent design, with an inner stent composed of 48 nitinol wires, and an outer stent with 16 nitinol wires. It is designed for endovascular cerebral aneurysm treatment, although, limited data exist regarding in-stent stenosis (ISS) rates associated with FRED devices.

Methods: A registry encompassing two North American comprehensive stroke centers was the base of this study. We longitudinally assessed patients implanted with FRED devices, emphasizing baseline demographics, aneurysmal characteristics, procedural data, aneurysmal occlusion, and the incidence of ISS.

Results: In our cohort of 87 patients receiving 88 FRED devices, ISS occurred in 10.4% (9) of cases. Mild ISS (<50%) was noted in 8.0% (7) of patients, moderate ISS (50-75%) in 1.1% (1), and severe ISS (>75%) in 1.1% (1). Analysis indicated ISS in 17.0% (8) of patients with the FRED device and 5.7% (2) with the FRED-X device; all ISS cases in the FRED-X group were mild. Differences in ISS rates between device types were not significant (p = 0.122). Delayed thrombotic events were documented in 6.9% (6) of patients. Aneurysm occlusion rates, measured via the Raymond-Roy Scale (RRS), showed adequate occlusion (RRS 1 or 2) in 68.8% at 3 months, 74.6% at 6 months, and 89.3% at 12 months.

Conclusions: The study elucidates the efficacy and safety profile of FRED devices, presenting favorable aneurysm occlusion rates and low retreatment needs while underscoring the manageability of ISS.