What are the long-term occlusion rates for brain aneurysms treated with the WEB (Woven EndoBridge) device?

Long-Term Occlusion Rates for Brain Aneurysms Treated with WEB Device

The Woven EndoBridge (WEB) device demonstrates complete occlusion rates of 51.7% at 1 year, with adequate occlusion (complete occlusion plus neck remnant) reaching approximately 79-88% in long-term follow-up studies, though this is inferior to the durability of surgical clipping. 1, 2, 3

Occlusion Rates by Follow-up Period

Short-term Occlusion (6 months)

• Complete occlusion achieved in approximately 68% of cases 4
• Adequate occlusion (complete occlusion plus neck remnant) in up to 88% of cases 1

Medium-term Occlusion (12-18 months)

• Complete occlusion rates improve to 87-88% at 12-18 months 4, 3
• French Observatory study showed 51.7% complete occlusion at 1 year 2
• Neck remnant observed in 27.6% of cases at 1 year 2
• Aneurysm remnant in 20.7% of cases at 1 year 2

Long-term Stability

• Of aneurysms completely occluded at 6 months, 90.3% maintained complete occlusion at final follow-up 1
• 11.5% of initially occluded aneurysms showed some recurrence 1
• Positive predictive value of complete occlusion at first follow-up was 88.4% 1

Factors Affecting Occlusion Rates

Anatomical Factors

• Neck size and dome-to-neck ratio significantly associated with aneurysm occlusion (p < 0.05) 4
• Less favorable results in aneurysms with very large necks 4
• Aneurysm neck diameter affects occlusion status at follow-up 3
• Angle between parent artery and aneurysm dome impacts occlusion 3

Technical Factors

• Undersized WEB device 3
• WEB shape change 3
• Ruptured presentation associated with lower occlusion rates 3
• Immediate contrast agent stagnation may predict better occlusion 4

Comparison to Other Treatment Modalities

Compared to Coil Embolization

• Traditional coil embolization achieves complete occlusion in only 54% of aneurysms initially 5
• Recanalization rates for coiled aneurysms range from 20-35% for large aneurysms and up to 59.1% for giant aneurysms 5
• Small aneurysms with small necks have better outcomes with coiling (5.1% recanalization) 5

Compared to Surgical Clipping

• Microsurgical clipping provides more definitive long-term treatment 5
• Only 1.5% of initially obliterated lesions exhibit recurrence after clipping 5
• Annual regrowth rate for completely clipped aneurysms is 0.1-0.52% 5

Clinical Implications and Follow-up Recommendations

• Repeat imaging is important even when complete occlusion is achieved in the short term 1
• Follow-up can be performed using DSA, MRA, or CTA with similar predictive value 1
• WEB device treatment shows very good safety profile with low morbidity (0.9-3.2%) 3, 2

Caveats and Pitfalls

• Technical difficulties occur in approximately 12.5% of procedures 4
• Additional interventions may be needed in 7.6% of cases (stenting, antiplatelet infusion, or additional coiling) 3
• Aneurysm location may influence success rates, with MCA bifurcation, anterior communicating artery, and basilar tip being common treatment locations 3
• Incomplete occlusion increases risk of aneurysm growth (up to 49% in incompletely occluded aneurysms) 5
• Degree of occlusion is an important predictor of hemorrhage risk 5

The WEB device represents an important advancement for treating wide-neck bifurcation aneurysms, but patients should be followed long-term as recurrence can occur even after initial complete occlusion.