Aneurysm

Key Points:

• Appropriate use of intracranial stenting highlighted at Society of NeuroInterventional Surgery meeting
• Early registry data promising for Wingspan; safety of adjunctive aneurysm stenting in acute subarachnoid hemorrhage explored   
  
  

Two studies presented at the recent Society of NeuroInterventional Surgery meeting, held July 27-30, 2015, in San Francisco, CA, provide new data that help define the role of intracranial stenting in certain challenging patient subsets. 

In one presentation, encouraging early results from the Wingspan registry suggest that in symptomatic patients, the device is relatively safe if implanted beyond the acute setting and by experienced operators. In another study, stents used to help repair an aneurysm in patients with subarachnoid hemorrhage did not increase mortality, although they tended to increase bleeding when used as an adjunct to coil embolization. 

WEAVE: a Wingspan Comeback?

Interim analysis of the first 50 patients enrolled in the prospective Wingspan Stent System Post Market Surveillance Study (WEAVE) trial was presented by Michael J. Alexander, MD, of Cedars-Sinai Neurovascular Center (Los Angeles, CA), at a session on July 28.

All patients were treated with a Gateway PTA balloon catheter and the self-expanding nitinol Wingspan stent system (both Stryker Neurovascular). Most met the revised FDA indication for Wingspan: symptomatic intracranial atherosclerotic disease with at least 70% stenosis and evidence of 2 prior strokes in the target artery territory, at least 1 having occurred while on preventive medical therapy that included drugs to control risk factors and at least 1 antithrombotic agent. In addition, stenting must have been performed more than 1 week after the most recent qualifying stroke. Outcomes were assessed by an independent stroke neurologist. 

The primary analysis included 45 patients treated on label. Mean stenosis in this group was 83.3%, with lesions located in the middle cerebral (41.7%), internal carotid (18.8%), and basilar (16.7%) arteries, and the vertebral artery or vertebrobasilar junction (18.8%). 

Two patients (4.4%) had a stroke or died within 72 hours (primary endpoint). In contrast, 3 of 5 patients (60%) in the off-label group experienced that outcome. 

The authors note that the rate of periprocedural complications with on-label usage in this interim analysis is better than the incidence in the off-label group and considerably lower than the 14.7% rate observed in the randomized SAMMPRIS trial.

“These early data provide impetus to continue to collect data in [WEAVE] and lend support to the concept that refined patient selection criteria and establishment of best practice techniques and management for these patients can substantially decrease the periprocedural risk of intracranial stenting,” Dr. Alexander and colleagues say. The goal is to enroll about 390 patients, with the study scheduled to be completed by 2019.   

Overcoming SAMMPRIS

In a telephone interview with WLNCMD, Philip M. Meyers, MD, of Columbia University Medical Center (New York, NY), explained that the current limited indications for Wingspan stem from the device’s poor showing in the SAMMPRIS trial. But, he observed, “most people believe that there is still a group of patients who benefit from intracranial stent-angioplasty, and the procedure can be lifesaving when properly applied.” 

Dr. Meyers explained that SAMMPRIS investigators, motivated by the earlier WASID trial’s finding that symptomatic patients with severe intracranial stenosis were at high risk of additional events, tended to revascularize early. But at that point the patients may have been too unstable to intervene safely.

“In WEAVE, by enrolling patients at least 7 days after their last event and using meticulous technique, we hope to show that revascularization with Wingspan is beneficial,” said Dr. Meyers, who is a principal investigator for the trial at Columbia.

A Minimalist Strategy

L. Nelson Hopkins, MD, of University at Buffalo Neurosurgery (Buffalo, NY), agreed that the SAMMPRIS investigators’ approach was misguided, calling the results a “wake-up call.”

“We were throwing stents into everybody, and we weren’t doing very well,” he told WLNCMD in a telephone interview. “It taught us that acutely symptomatic plaque is pretty high risk. If you let the plaque stabilize, the risk is lower.”

In fact, Dr. Hopkins advocated a cautious, stepped approach for this high-risk group: Start with minimal-inflation balloon angioplasty. When patients return a few months later for follow-up, the stenosis will be gone in some, suggesting that it was an embolism and not plaque. In another portion, the stenosis will remain sufficiently diminished to allow these patients to simply be monitored.. While some patients will have severe stenosis, because they have already undergone angioplasty, their plaque is more fibrous and less rupture-prone, making stenting much safer than if it had been performed at the outset, he said. 

The last group more or less resembles the patients now being treated under the WEAVE protocol, he commented.

“After SAMMPRIS, Wingspan was basically discredited for intracranial disease in this country,” and now the WEAVE trial has the potential to help rehabilitate it, Dr. Hopkins said. “But people still need to realize just how dangerous these plaques are and treat them accordingly,” he cautioned.

Stenting to Help Repair Aneurysm in Subarachnoid Hemorrhage

In the second study, presented July 30 by Hormuzdiyar H. Dasenbrock, MD, of Brigham and Women’s Hospital (Boston, MA), researchers used data from the Nationwide Inpatient Sample (2005-2011) to identify 13,260 patients with subarachnoid hemorrhage who underwent aneurysm repair via a microsurgical or endovascular approach. Of this cohort, 104 patients (0.94%) received an intracranial stent. The frequency of stent use varied from a low of 0.5% in 2006 to a high of 1.9% in 2010. Those who required a ventriculostomy for cerebrospinal fluid diversion were less likely to receive a stent (P = .003). 

The incidence of in-hospital mortality was higher in stented than nonstented patients (16.0% vs 12.8%), but on multivariate analysis stenting was no longer associated with increased risk, nor did it result in more postoperative, neurological, or hematologic complications, or greater likelihood of nonroutine hospital discharge (table 1).

Table 1. In-Hospital Outcomes With vs Without Stent Placement

However, in subgroup analyses limited to patients treated via an endovascular approach, there was a trend toward more hematologic complications in those who had adjuvant stent placement compared with those who underwent coil embolization alone (25.6% vs 18.5%; P = .05).

Stenting a ruptured aneurysm in the context of subarachnoid hemorrhage presents a dilemma, Dr. Meyers said: Although an antithrombotic regimen is needed to protect against stroke stemming from device thrombosis, platelet inhibition could cause or exacerbate intracranial hemorrhage. Antithrombotic drugs like aspirin, clopidogrel, and glycoprotein IIb/IIIa inhibitors may also complicate other needed procedures, such as insertion of ventricular drainage catheters.

Some clinicians—including Dr. Meyers—favor a more traditional, staged strategy to try to sidestep this problem. First, a coil procedure is performed to occlude the aneurysm as well as possible during the acute period, and then, when other procedures are no longer an issue, aspirin and clopidogrel can be given during and after stent implantation.  

“These new results may encourage additional physicians to use stenting to treat aneurysmal subarachnoid hemorrhage,” Dr. Meyers commented, adding that centers less adept at surgical clipping may be more inclined to adopt the stenting paradigm.

“To this point, stenting has been largely reserved for unruptured cerebral aneurysms, Dr. Meyers observed. “How to apply stents to the treatment of patients with subarachnoid hemorrhage from bleeding aneurysms remains unknown, although these data suggest it is possible at some level of risk.”

Dr. Hopkins was also cautious. “The study supports use of a stent in extreme situations where it is really needed,” he said, citing the example of an aneurysm with a very wide neck that cannot be effectively coiled. “On the other hand, I would like to see a lot more data before I would use stenting routinely.”

Sources:

1. Alexander M, Aauner A, Chaloupka J, et al. Interim report on the WEAVE intracranial stent trial: 50 consecutive patients. Presented at: Society of NeuroInterventional Surgery Annual Meeting; July 28, 2015; San Francisco, CA.

2. Dasenbrock H, Subat Y, Frerichs K, et al. Intracranial stent placement for aneurysm repair in acute subarachnoid hemorrhage: a nationwide analysis. Presented at: Society of NeuroInterventional Surgery Annual Meeting; July 30, 2015; San Francisco, CA.

Disclosures:

• The WEAVE study is sponsored by Stryker Neurovascular.
• Dr. Dasenbrock reports no relevant conflicts of interest. 
• Dr. Alexander reports serving as a consultant to and receiving speaker fees from Stryker Neurovascular. 
• Dr. Meyers reports being a principal investigator for the WEAVE trial.

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