ARTICLE IN BRIEF
A next-generation embolic protection device was reported to be safe and effective for preventing stroke.
SEATTLE—The Xact self-expanding carotid artery stent system continues to be associated with good outcomes at one year, according to results of an FDA-mandated postmarketing surveillance study.
Results from the Protected Carotid Artery Stenting in Subjects at High Risk for Carotid Endarterectomy (PROTECT) study also suggest that a next?generation embolic protection device is safe and effective for preventing stroke, Seemant Chaturvedi, MD, reported here at the AAN annual meeting.
“The bottom line is that the overall rate of primary outcome events was low in the PROTECT study,” said Dr. Chaturvedi, professor of neurology at Wayne State University and director of the Wayne State University-Detroit Medical Center Stroke Program. “The 30-day composite rate of death, stroke, or myocardial infarction of 3.1 percent was lower than in previous registries.”
“Additionally, the durability of carotid artery stenting out to 12 months continues to be shown, in both the low target lesion revascularization rate and zero stroke events after day 30,” Dr. Chaturvedi concluded in his presentation.
Several carotid stent systems have been approved by the FDA for use in patients at high risk for carotid endarterectomy, but only if postmarketing surveillance studies are done to monitor for unexpected adverse events and to track the use of these technologies in real-world settings.
The PROTECT study involved 322 high-risk surgical patients enrolled from 34 sites who received carotid stenting using the Generation 5 Emboshield Pro Rapid Exchange distal-protection system and the Xact self-expanding stent.
The self-expanding stent is designed specifically to treat diseased carotid arteries, according to Abbott Vascular, which makes the system and funded the work. The device has a closed-cell design that creates a tightly knit yet highly flexible mesh structure intended to help restore the inner diameter of the artery, promote a smooth inner vessel surface, and potentially reduce the release of emboli from a diseased vessel when it is treated. The Xact stent is intended for use in combination with the fully retractable Emboshield filter, which is designed to capture emboli that can break off during a carotid stenting procedure, according to the company.
The next-generation embolic device has “slight design changes in how it tapers and how it fits distally. It's designed to be a little easier for deployment,” Dr. Chaturvedi said.
Of the 322 patients, 10.8 percent were symptomatic and 30.1 percent were age 80 or older. Symptomatic patients had to have at least 50 percent stenosis; asymptomatic patients had to have at least 80 percent stenosis.
The study was powered to demonstrate a less than 12 percent 30-day rate of major events — death, stroke, or myocardial infarction. “So the 3.1 percent rate we saw was very favorable,” Dr. Chaturvedi said.
Considering 30-day endpoints individually, the rate of death was 0.3 percent, the rate of major stroke was 0.3 percent, the rate of minor stroke was 1.9 percent, and the rate of myocardial infarction was 0.9 percent. The composite rate of stroke or death was 2.2 percent.
Six of seven major events occurred in patients ages 80 and older, he said. The 30-day rate of death, stroke, or myocardial infarction was 7.7 percent in patients ages 80 or above versus 1.3 percent in patients under 80 years.
“We still have challenges in treating older patients. A higher complication rate in the elderly has been seen in other carotid stenting studies and this requires further scrutiny,” Dr. Chaturvedi said. For the secondary endpoint, the 30-day rate of transient ischemic attack or amaurosis fugax was 2.8 percent. “They all resolved spontaneously, without treatment,” he said.
In the subset of 176 patients followed for at least one year, there were no deaths, strokes, myocardial infarctions, or ipsilateral strokes after 30 days. There was one target lesion (revascularization) out to 390 days.
“These results may reflect improvements in outcome seen with greater practitioner experience and improved patient selection,” Dr. Chaturvedi said.
The data will be submitted to the FDA to gain approval for this new distal protection device and to help fulfill the postmarketing requirements. Per conditions of the approval, at least 305 patients will continue to be followed out to three years
Limitations of the study include moderate sample size and relatively few symptomatic patients, Dr. Chaturvedi said.
QUESTIONS ABOUT LONG-TERM EFFECTS
Asked to comment on the study for Neurology Today, Adnan I. Qureshi, MD, executive director of the Minnesota Stroke Initiative, associate chair of the department of neurology, and professor of neurology, neurosurgery, and radiology at the University of Minnesota in Minneapolis, said: “This is one of several studies showing an acceptable 30-day rate of stroke or death in patients undergoing carotid stenting.
“The short-term results are comparable to those of carotid endarterectomy. The big question is whether this is going to be better than carotid endarterectomy in the long-term,” he said.
At least in selected patients, the results seem to be comparable at one year, even three years, he said. “But there have been incremental concerns about patients going on to have higher rates of complications. If that rate goes high enough, it can take away from the benefits of the procedure, particularly in patients who are asymptomatic,” Dr. Qureshi continued.
Dr. Qureshi said that in his practice symptomatic patients who have had a minor stroke or transient ischemic attack related to carotid stenosis and who are high-risk surgical candidates, typically due to comorbidities, particularly cardiac comorbidities, are often offered stent placement. Also, asymptomatic patients with high-grade stenosis are offered stenting, he said.
He added that given a choice, patients prefer stent placement, even when told about the relative lack of long-term data.
As for older patients, “we are very cautious in patients over age 80. The question is not so much which procedure is better, but whether they should undergo a treatment at all,” Dr. Qureshi said.
“For the most part, we only perform stenting in symptomatic patients [over 80] with stenosis, as the risks without treatment are much higher. However, patients over 80 do quite well with carotid endarterectomy; that's been demonstrated in numerous studies.
“In asymptomatic [older] patients who are healthier and don't appears to have anatomic or clinical risk factors, outcomes may be worse with stent placement,” Dr. Qureshi said.