William A. Gray
HOLLYWOOD, Fla. — Several new technologies are available or on the horizon to improve the outcomes of carotid artery stenting, according to a speaker at the International Symposium on Endovascular Therapy (ISET).
“There has been some suppression of carotid activity in the [United States] largely based on reimbursement limitations. This has been challenging but, despite that, there has been a plethora of new technologies for carotid stenting which are meant to address some pivotal opportunities,” William A. Gray, MD, system chief of the division of cardiovascular disease at Main Line Health and president of the Lankenau Heart Institute in Wynnewood, Pennsylvania, said during a presentation.
Results of two major randomized trials of carotid artery stenting (CAS) vs. carotid endarterectomy — CREST and ACT I — demonstrated equivalence in short- and long-term outcomes in patients with carotid artery stenosis. However, both trials showed a very small but bothersome excess of minor strokes, suggesting an opportunity to improve overall technology and approaches to the devices, Gray told Cardiology Today’s Intervention.
Much of the focus on new strategies has focused on addressing three separate issues: minor stroke, which is associated with a greater number of asymptomatic diffusion-weighted MRI abnormalities when compared to CEA; late stroke that occurs off the table/within 24 hours, and non-ipsilateral stroke, Gray said.
The Paladin Carotid Post-Dilation Balloon with Integrated Embolic Protection (Contego Medical) is one example of a device designed to address minor stroke and microembolization, Gray said. The device couples together an angioplasty balloon and an integrated 40-µm filter, which is a smaller pore size than other filters and permits fewer emboli to pass, he told the audience at ISET 2018. The filter is remotely actuated at the handle and the filter is deployed at the time of balloon inflation after a stent deployment.
That device is now integrated into a single carotid stent application: the Neuroguard Integrated Embolic Protection 3-in-1 System (Contego Medical), which involves a stent, post-dilation balloon and embolic protection filter all contained on one catheter (6F). “The idea is that this is a one-step procedure, without a lot of manipulation or exchanges of wires and catheters, and is hoped to reduce overall event rates,” Gray told Cardiology Today’s Intervention. The device will be investigated in a U.S. IDE trial starting in 2018, he said.
Next, there is direct carotid access with high flow reversal with transcarotid artery revascularization (TCAR) using the Enroute device (Silk Road Medical). This technology allows for a small surgical incision above the clavicle for direct carotid access and initiation of high flow reversal into a venous circuit with a filter to protect the brain from stroke while delivering and implanting the Enroute Transcarotid Stent. Data from the ROADSTER trial showed a very low rate of stroke, including in high-risk subgroups who are symptomatic and aged older than 75 years. Additionally, TCAR showed fewer diffusion-weighted imaging abnormalities after the procedure and comparable to CEA, which Gray said demonstrates mechanistic proof of improved embolic protection.
Finally, the recent development of mesh-covered stents, which may overcome the risk for distal embolization related to plaque protrusion through stent struts and may actually mean the stent is part of the embolic protection strategy.
Data thus far “suggest that mesh-covered stents do have a future. … These meshes actually reduce the overall cell size compared to existing closed-cell stents by at least five times. This is a big advance in the field. It makes the stent a protector and not a provocateur of stroke,” Gray told Cardiology Today’s Intervention.
The Roadsaver Carotid Artery Stent System (Microvention/Terumo), the Gore Carotid Stent (W.L. Gore and Associates) and the CGuard Carotid Stent System (InspireMD) feature different constructions, but all have a mesh covering with an open- or closed-cell design, and a pore size that ranges from 180 µm to 500 µm. To date, testing with the CGuard has shown reductions in diffusion-weighted imaging abnormalities, both in volume and lesion number, according to Gray. “We look forward to those trials completing,” he said.
Most recently, Gray presented the primary endpoint data from the SCAFFOLD trial of the Gore stent at the Leipzig Interventional Course in January, showing a low rate of major adverse events at 30 days and a low rate of ipsilateral stroke from 31 days to 1 year.
“Mesh-covered carotid stents, integrated embolic protection and/or filtration, and direct carotid access with high-flow proximal protection are likely to add benefit in terms of reducing not only minor stroke events but also surrogate diffusion-weighted imaging lesions,” he said during the presentation. “This should accrue benefit to the patient.”