The FRED flow-diverter stent for intracranial aneurysms: clinical study to assess safety and efficacy

Abstract

Background and purpose: Flow-diverter stents are emerging for the endovascular treatment of difficult-to-treat or otherwise untreatable cerebral aneurysms (wide-neck, fusiform, dissecting, blisterlike, or giant). We assessed the clinical safety and efficacy of the Flow-Redirection Endoluminal Device.

Materials and methods: This was an institutional review board-approved single-center observational clinical study in 29 patients with 34 aneurysms elected to be treated by endovascular intervention. After providing informed consent, patients were included according to the following criteria: aneurysm fundus-to-neck ratio <2 or neck diameter >4 mm, fusiform, dissecting, or giant aneurysms. The primary end point for clinical safety was the absence of death, absence of major or minor stroke, and absence of transient ischemic attack. The primary end point for treatment efficacy was complete angiographic occlusion according to the O'Kelly Marotta grading scale immediately after the procedure and at follow-up after 3 and 6 months (O'Kelly Marotta D: complete occlusion).

Results: The Flow-Redirection Intraluminal Device deployment was technically successful in all cases. In 26/29 (89%) of patients, the primary end point of safety was reached; in the 3 remaining patients, 1 disabling ischemic stroke and 2 minor strokes with complete recovery at follow-up were observed. Angiographic (DSA and MRA) and clinical follow-up were available after 3 months in 29/29 (100%) and after 6 months in 25/29 (86%) patients (after 6 months, only MRA follow-up was performed according to our study protocol and institutional standard). At 3-month follow-up, complete occlusion was reached in 19/34 aneurysms (O'Kelly Marotta D: 19/34; 56%). At 6-month follow-up, aneurysm occlusion was complete in 22/30 aneurysms (O'Kelly Marotta D: 22/30; 73%).

Conclusions: Deployment of the Flow-Redirection Intraluminal Device flow-diverter stent is safe and effective in the treatment of difficult-to-treat or otherwise untreatable intracranial aneurysms.

Fig 1.

Patient 1 with a 4.4-mm residual aneurysm of the initial posterior inferior cerebellar artery segment close to its origin from the V4 segment of the left vertebral artery (solid white arrow, A). After recoiling, we implanted a FRED 3.5 × 13 mm to cover the orifice of the posterior inferior cerebellar artery origin (B). The flow-diverting working zone (inner stent) is centrally positioned over the posterior inferior cerebellar artery origin (solid white bracket marked with 1 asterisk, C). The outer stent, which provides stable vessel anchorage symmetrically, overlaps the proximal and distal edge of the inner flow-diverting stent. Its distal flared ends are marked with solid white brackets and 2 asterisks (C). At 3-month follow-up, complete occlusion of the residual aneurysm was observed, with no residual inflow (D), which was also verified on different projections and 3D DSA. At the base of the coil basket, the overprojection of a proximal posterior inferior cerebellar artery loop (dashed white arrow, D) simulates residual aneurysm filling, but contrast washes out rapidly at this position after the arterial phase (not shown). Complete occlusion was also confirmed by unenhanced and enhanced TOF-MRA at 3 and 6 months.

Fig 2.

Patient 7 with a 6.5-mm supraclinoid ICA aneurysm (A). In this case, a FRED 4.5 × 25 mm could be placed to cover the aneurysm neck with the inner stent mesh having the flow-diverting effect (dashed white line). Complete wall apposition can be appreciated along the entire carotid siphon (B). The outer stent ensuring stable vessel wall anchorage overlaps the inner flow-diverting stent over 3.5 mm at its proximal and distal ends (double-headed white arrows, B). At its termination, 4 radiopaque tips mark the flared ends. At 3-month follow-up, complete occlusion of the aneurysm could be confirmed on DSA (C) with no residual inflow, which was also confirmed by MR imaging at that time and remained stable at 6-month follow-up.