Intrasaccular Device Effective, Safe for Difficult Aneurysms

Caroline Helwick

April 24, 2019

SAN DIEGO, California — The Woven EndoBridge Intrasaccular Therapy device (WEB) proved safe and effective for treating wide-neck bifurcation aneurysms in the prospective, single-arm WEB-IT study.

The results, which led to approval of the device by the US Food and Drug Administration on December 31, 2018, were presented at a plenary session here at the American Association of Neurological Surgeons (AANS) 2019 Annual Meeting.

"This is the safest treatment we've ever studied for aneurysms, despite being used in a population that's very difficult to treat, and the effectiveness rate was noninferior to what we have in the literature of these lesions" with other approaches, said principal investigator Adam S. Arthur, MD, MPH, a neurosurgeon at the Semmes-Murphey Neurologic and Spine Clinic and professor of neurosurgery at the University of Tennessee, in Memphis.

Arthur reported that 1 year after undergoing treatment, more than 99% of patients were free of death or disabling stroke, 55% were found to have complete aneurysm occlusion, and 85% were found to have adequate occlusion.

Commenting on the study for Medscape Medical News, Robert E. Harbaugh, MD, the University Distinguished Professor and chair of the Department of Neurosurgery at Penn State Health in Hershey, Pennsylvania, said he expects that for treating wide-neck bifurcation aneurysms, the device "is clearly a step forward and should find rapid acceptance."

Wide-Neck Bifurcation Aneurysms

"Wide-neck bifurcation aneurysms account for 30% to 40% of all aneurysms and are probably worse than we realize," Arthur noted. "They have a complex anatomy and are difficult to treat."

Current treatment is "often incomplete and risky," he added. "They're associated with relatively low rates of complete occlusion, and periprocedural complications are not uncommon."

In published studies, the complete occlusion rate for treatment with various modalities is less than 50%, and complications occur in approximately 20% to 25% of cases.

The WEB is a new intrasaccular device that is placed directly in the aneurysm. The three-dimensional device is available in two sizes and can be used on both ruptured and unruptured lesions. It is deployed into the aneurysm at the base (not in the parent artery). Once detached, it produces an organized and thorough impediment to the flow within the aneurysm, resulting in stasis that promotes healing.

In 21 US and six international sites, WEB-IT enrolled 150 patients (mean age, 59 years) with wide-neck bifurcation aneurysms, either ruptured (94%) or unruptured (6%). The aneurysms were located in the basilar apex (39%), the middle cerebral artery bifurcation (30%), the anterior communicating artery complex (27%), or the internal carotid artery terminus (4%).

In the patients in the study, aneurysm necks were ≥4 mm, or the dome-to-neck ratio was < 2. The mean neck width was 4.8 mm, and the mean sac width was 6.4 mm. One quarter of the lesions were ≤5 mm.

"The aneurysms were the widest population of aneurysms ever studied and published in an adjudicated study," he said. "And rather than treat mostly for middle cerebral artery aneurysms, we treated a mixed bag. We had mostly unruptured aneurysms (related to some issues with consent and convenience), but the ruptured and unruptured populations were the same in terms of outcomes and size."

For patients to be eligible for the trial, angiograms from the index procedure had to be available, and data had to be available from 6-month and 1-year follow-up visits. A core laboratory adjudicated all angiographic outcomes, and a clinical events adjudicator assessed for adverse events, device failures, and site deviations. The final analysis included 143 patients for efficacy and 147 for safety.

The efficacy primary endpoint was complete occlusion at 12 months with no re-treatment, no recurrent subarachnoid hemorrhage, and no significant parent artery stenosis (>50%).

The prespecified effectiveness endpoint was >35%, determined on the basis of published literature of similar approved devices. The primary safety endpoint was major stroke and all-cause death through 30 days and major ipsilateral stroke and neurologic death at 12 months.

Complete Occlusion in 55%

At 12-month angiographic follow-up, 54.8% of patients in the intent-to-treat population had achieved complete aneurysm occlusion (P < .0001 vs published reports of other devices). This was consistent with results in the per-protocol population (P < .0001). In the worst-case imputation, the endpoint was also met (P < .0001), Arthur reported.

Adequate occlusion was achieved in 121 of 143 patients (84.6%), as determined using a modified Raymond scale. Angiographic recurrence within 12 months was observed in 12.6%; 13 patients experienced residual neck recurrences, and five experienced residual aneurysms.

"We met that [the primary endpoint] with no problem, with a 55% complete occlusion rate and low P value," Arthur said. "More importantly, adequate occlusion was achieved in 85% of the cases, and angiographic recurrences were rare, with only a few re-treatments."

The WEB was successfully implanted during the index procedure in 98.7% of patients. An adjunctive device was used in 4.7%. Treatment time was short, averaging half an hour for fluoroscopy time, he added.

"Markedly Safer" Than Other Approaches

Only one primary safety event (0.67%) occurred during the study — a delayed ipsilateral parenchymal hemorrhage, which occurred on postoperative day 22. There were no primary safety events after 30 days through 1 year.

In addition, there were no deaths through day 365, and there were no major ipsilateral strokes between days 31 and 365. The primary safety composite, therefore, was easily met (P < .0001).

"The safety profile was incredible," Arthur commented. The only patient who had any kind of safety problem was a 54-year-old woman who was treated for an anterior communicating lesion, he said. "An MRI after the treatment indicated no embolic strokes, but despite that, 22 days later, she experienced a right parietal hemorrhage. We thought this may have been due to vasculitis, but it was adjudicated to likely be related to the index procedure."

Arthur concluded, "The results of this trial suggest that the WEB device provides an option for patients with wide-neck bifurcation aneurysms that is as effective as currently available therapies and markedly safer."

"I thought this was a very impressive presentation for several reasons," Harbaugh commented in an interview. "One, the type of aneurysm this is designed for is very difficult to treat with any kind of present therapy.

"And two, the investigators conducted a nice study where the complication rate was remarkably low and the occlusion rate was higher than we see with any other endovascular treatment," he said. "It's still not quite as high as with open surgery, but this is clearly less dangerous. I think this device is certainly a step forward."

Arthur has consulted for Terumo-Microvention, Meddronic, Stryker, Johnson & Johnson, Siemens Medical Systems, and Cerebrotech; he has received grants or other industry support from Medtronic, Siemens, Cerebrotech, and Bendit; and he owns stock in Penumbra. He reported that his employer, the Semmes-Murphey Clinic, was paid for his time as the principal investigator of the WEB-IT trial. Harbaugh has disclosed no relevant financial relationships.

American Association of Neurological Surgeons (AANS) 2019 Annual Scientific Meeting: Abstract 489. Presented April 17, 2019.

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