“Nevertheless, we cannot rule out that this unexpected finding was because of residual confounding by patient characteristics not measured in the trials,” the authors wrote.
Experts who were not involved with the study said the analysis was well done and intriguing. Right now, symptomatic carotid stenosis is treated with stents about 15 percent of the time, they said, mostly for high-risk patients who are older or who have had neck radiation or other issues. However, stenting is much less invasive. If researchers could determine how to lower the risks, focusing on that first day when most problems seem to happen, that could benefit more patients, they agreed.
Hugo J. Aparicio, MD, MPH, assistant professor of neurology at Boston University School of Medicine and an investigator in the Framingham Heart Study, said there are a lot of questions about why the risks are so much higher with CAS, particularly since some operators use a distal filter device to prevent embolization of pieces of plaque that may be released during the procedure.
He pointed out that the trials in the meta-analysis each had different requirements — some required the filtering device, others encouraged the use of the technology, and some had no guideline.
“The take-away, unfortunately, is that more studies are needed,” Dr. Aparicio said. “The authors now need to look at the recent advances in stenting technology, since most of these patients were enrolled in the 2000s and technology has changed since then. We still need to assess the individual's risks and determine the patient characteristics that are important for making this decision between endarterectomy and stenting.”
Pierre Fayad, MD, FAHA, FAAN, professor of neurological sciences and medical director of the Nebraska Stroke Center at the University of Nebraska Medical Center in Omaha, said he was not surprised by the study results, and thought it confirmed the suspicion that stenting problems happened quite quickly. But he also pointed out that the procedures in the study used technology from 20 years ago.
“Now that the technology and materials have improved, the training has improved and the knowledge has improved. If this study was done today, would it show that the risk on the first day was lower?” he asked. “That's the biggest question in this publication: Is it the skills of the operator or the technology or the procedure itself that are to blame for these differences?”
Dr. Fayad said there should be more focus on the interventionalist performing the procedure and more research on the patients who develop a stroke or die as a result of the procedure. While it makes sense that older patients have higher risks, because they tend to have more fat deposits in their blood vessels, he wondered what other factors may play a role in preventing strokes in stenting procedures.
“It's a no-brainer today that stenting shouldn't be done in older patients, based on the results of the study, but we knew that already,” he said. “It doesn't change anything for the patient, but it's something for the researchers and device companies and for the interventionalists to brainstorm and see what we can be done with this important finding.
“It's an incentive for stent makers to try and redesign stents that are less problematic and result in less debris. A critical unanswered question is the role of embolic protective devices deployed during stenting: Are they harmful or helpful? If they are harmful, should they be improved or removed? Should the methodology of stenting be different such as the use of flow reversal instead of embolic protection devices?”
Seemant Chaturvedi, MD, professor of clinical neurology for the University of Miami Miller School of Medicine and vice chair for Veterans Affairs programming within the department of neurology, said patients should ask their doctors about their success rates and experience when it comes to stenting procedures.
“Stenting is still a newer procedure, although it's been around for 20 years,” he said. “Experience matters, and the people doing it need to be as well trained as possible, doing it regularly — 20 to 30 procedures a year with optimal techniques.”
It's important for patients and their caretakers to ask their doctors about their track records, including the stroke and death rate following the operation, particularly compared to patients who have the same risk factors such as age.
Sam O. Zaidat, MD, MS, FAHA, FAAN, a professor at North East Ohio Medical School and medical director of the neuroscience and stroke programs would like to see the surgeon's level of experience included in future studies on stenting.
“CAS is done way less than CEA, so if you're only doing five stents a year, it's going to have an impact on results,” Dr. Zaidat said.
Particularly with updated technology, stenting could potentially have lower risks, he added, if researchers compared hospitals where the procedure is performed regularly and offered frequent training.
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