FRED™ X Flow Diverter: Next-Generation Dual-Layer Flow Diversion with X Technology Surface Treatment

The FRED™ X is the current-generation flow diverter from MicroVention Terumo, representing a significant engineering advance over the original FRED. The X designation refers to “X Technology” — a nanoscale surface treatment applied to the nitinol wire surface that modifies the device’s thrombogenic profile at a molecular level. This surface treatment reduces the activation of platelets and clotting factors on direct contact with the implant, addressing the primary mechanism of in-stent thrombosis that has been the most important periprocedural complication of flow diversion therapy.

The FRED X is available in two system configurations: System 21, delivered via Headway 21 microcatheter for parent artery diameters of 2.5–3.0 mm; and System 27, delivered via Headway 27 microcatheter for the 3.5–5.5 mm range matching the original FRED. This System 21 variant represents a clinically important extension of flow diversion to smaller vessels that the original FRED could not safely treat, bringing flow diversion therapy to distal ICA, MCA M1, and vertebral artery aneurysms previously outside the FRED’s indications.

FRED X System 21: XFRED2508 (2.5 mm × 8 mm) through XFRED3027 (3.0 mm × 27 mm); delivered via Headway 21 (0.021 in ID). FRED X System 27: XFRED3513 (3.5 mm × 13 mm) through XFRED5526 (5.5 mm × 26 mm); delivered via Headway 27 (0.027 in ID). All FRED X devices use X Technology surface treatment on both the outer scaffold and inner mesh.

The X Technology surface modification provides two measurable improvements in delivery mechanics beyond thrombogenicity reduction: lower delivery force (the force required to advance the device through the microcatheter) and lower resheathing force (the force required to recapture and reposition the device). Operators who have used both generations consistently report that FRED X feels smoother and more controllable during deployment and repositioning than the original FRED.

X Technology’s reduced thrombogenicity has two direct clinical implications: first, it may reduce the minimum DAPT duration required post-procedure compared to the original FRED, though the specific DAPT protocol should be based on local institutional guidelines and platelet function testing. Second, it reduces the risk of very early in-stent thrombosis — a rare but catastrophic complication occurring within 24 hours of deployment — which has been the most feared complication of flow diversion therapy.

X Technology does not eliminate the need for DAPT but reduces the baseline risk that makes DAPT necessary. Operators should continue to load patients with aspirin and clopidogrel per standard flow diversion protocols and perform platelet function testing (VerifyNow P2Y12) before proceeding, regardless of FRED X’s improved thrombogenicity profile.

FRED X System 27 covers the same indications as the original FRED: large and giant unruptured aneurysms of the anterior and posterior circulation in parent arteries 3.5–5.5 mm. FRED X System 21 extends these indications to smaller vessels (2.5–3.0 mm), particularly the distal ICA, MCA M1, and A1 segments where aneurysm burden remains high but the original FRED was too large.

Size FRED X to the reference vessel diameter at the proximal landing zone, with 0.25–0.5 mm oversize to ensure adequate radial force. Length should provide a minimum 5 mm of coverage beyond the neck in both proximal and distal directions. For System 21, 3D DSA measurement is mandatory due to the small vessel calibre and the importance of precise sizing.

Modern Medical Solutions is the authorised MicroVention Terumo distributor for Tajikistan and Afghanistan. FRED X is available in both System 21 and System 27 configurations for neurointerventional programmes in Tajikistan and Afghanistan. For programs transitioning from the original FRED to FRED X, Modern Medical Solutions can advise on equivalent sizing and the differences in deployment feel.

Contact Modern Medical Solutions to discuss FRED X alongside FRED Jr for small-vessel cases, Headway 21 and 27 delivery microcatheters, and the CHIKAI/Gladius MG guidewire family for a complete flow diversion system.