CREST-2 Registry: Tantalizing Stroke Rates With Carotid Stenting

December 23, 2019

A low rate of periprocedural stroke/death with carotid stenting for both asymptomatic and symptomatic patients has been reported in a new registry study.

The CREST-2 Registry study found that 30-day stroke/death rates were 2% overall, 1.4% in asymptomatic patients, and 2.8% in symptomatic patients.

"These figures are lower than previous published trial data," the lead author, Brajesh K. Lal, MD, told | Medscape Cardiology.

"These data suggest that over time the outcomes of carotid stenting have improved. Interventionists are becoming more comfortable with the procedure, the technology has improved, and the ability to select the right patients has gotten better," said Lal, a professor of vascular surgery at the University of Maryland, Baltimore.

"Within the US there is still considerable hesitation about atherothrombotic injury with carotid stenting, but these results suggest when performed carefully by the right interventionalists, this can minimize complications," he added.

The CREST-2 Registry results are published in the December issue of the Journal of the American College of Cardiology.

The registry study is an accompaniment to two CREST-2 randomized trials running simultaneously in patients with asymptomatic carotid stenosis. One is comparing intensive medical therapy with carotid endarterectomy surgery, and the other is comparing intensive medical therapy with carotid stenting using the traditional femoral approach.

As background, Lal explained that concerns about the risk for periprocedural stroke with carotid stenting has led to US reimbursement rules restricting funding of the procedure to patients deemed to be at high risk for surgery. This has caused the number of carotid stenting procedures performed to decline considerably.

"The CREST-2 Registry was therefore initiated as a companion to the CREST-2 trial to provide the means to maintain, enhance, and ensure requisite expertise in carotid stenting in order to conduct a rigorous randomized controlled clinical trial comparing carotid stenting to medical therapy," Lal noted.

He elaborated: "If we're going to be doing honest comparisons in the CREST-2 randomized trials, we need to ensure that we have high-quality medical therapy, stenting, and surgery. We have management committees for each of these interventions to ensure this occurs in these two studies, and we are comparing the most effective forms of all three interventions."

Interventionalists have to be invited to participate in the CREST-2 studies, and they have to have achieved minimal standards in number of cases performed and rates of periprocedural stroke and death.

"When we started these trials, we found that the pool of carotid stenting interventionists was not very large, as not many carotid stenting procedures were now being performed," Lal explained. "We therefore approached Medicare, NIH, FDA, and the academic societies for vascular surgeons and interventionalists to seek approval for a carotid stenting registry. In this way, selected interventionists with the right credentials but not enough case numbers to participate in the CREST-2 randomized trials would be able to build their experience up.

"The vast majority of interventionists have reasonably large lifetime experience of carotid stenting but less recent experience. They clearly have the wherewithal. We need to allow them to do the procedure and monitor outcomes," he added.

The registry is tracking the performance of these interventionists. In addition, interventionalists who were selected to participate in the CREST-2 randomized trials could also enroll patients into the registry who did not qualify for the randomized trials, such as those with symptomatic carotid stenosis, Lal noted.

The article by Lal and colleagues is the summary of the results so far of the largest subset of patients in that registry ― those with primary atherosclerosis.

As of December 2018, 187 interventionists from 98 sites in the United States had performed 2219 carotid stenting procedures in 2141 patients with primary atherosclerosis (78 were bilateral).

The mean age of the cohort was 68 years, 65% were men, and 92% were white; 1180 procedures (55%) were for asymptomatic disease, and 961 (45%) were for symptomatic disease. All US Food and Drug Administration (FDA)–approved stents and embolic protection devices were represented.

The 30-day rate of stroke or death was 1.4% for asymptomatic patients, 2.8% for symptomatic patients, and 2.0% for all patients.

In the group with symptomatic disease, there were four deaths, 23 strokes, two myocardial infarctions, and four major access site complications. Among those with asymptomatic disease, there were four deaths, 12 strokes, two myocardial infarctions, and nine major access site complications.

Among the 1180 patients with asymptomatic disease enrolled in the registry, 264 were potentially eligible for the CREST-2 trial (normal risk/asymptomatic). The rate of stroke/death among these patients was 0.8%, compared with 1.5% for the remaining 916 trial-ineligible patients enrolled in the registry.

"This study is the largest, prospective, multicenter registry evaluating contemporary carotid stenting outcomes in the United States. It is the first national registry for carotid stenting cosponsored by federal and industry partners that creates a cost-effective national quality assurance program for carotid stenting," the authors write.

The 30-day rate of stroke/death of 1.4% for asymptomatic patients in this registry compares favorably to the 2.5% rate reported by the recent SPACE-2 trial, which also required minimum standards for participating interventionalists, they note. SPACE-2, however, was halted prematurely because of slow enrollment after only 197 patients were randomly assigned to undergo carotid stenting.

The CREST-2 Registry 30-day rate of stroke/death is also lower than rates reported in prior prospective trials and registries, in which there was comparatively less focus on interventionist competency, patient selection, lesion selection, procedural technique, and adjunctive medical therapy, they add.

Lal stressed that the current results were reassuring for the ongoing CREST-2 randomized trials.

"This registry study does not answer the question about whether asymptomatic patents should be stented. That will hopefully come from the CREST-2 randomized trials," he said. "But the data from this registry study reassures us that interventionist participating in the CREST-2 studies are of high quality and patients in the trial are getting best possible quality of carotid stenting."

Noting that Medicare reimbursement for carotid stenting is currently restricted to the small subset of patients at high surgical risk, the authors point out that the CREST-2 Registry has allowed selected practitioners and medical centers to perform carotid stenting for broader indications under controlled conditions and to bill for these services.

"This sort of registry could be a blueprint for how new techniques could be rolled out in future," Lal suggested.

"First Glimpse at a Carotid Stenting Comeback?"

In an accompanying editorial entitled, "The CREST-2 Registry: First Glimpse at a Carotid Stenting Comeback?," Jay Giri, MD, University of Pennsylvania Medical Center, Philadelphia, and Jeffrey W. Olin, DO, Icahn School of Medicine at Mount Sinai, New York City, say the authors of the current article "deserve tremendous credit for both running the CREST-2 trial and arranging the infrastructure to support this concurrent well conducted carotid stenting registry that aimed to independently verify the competence of the operators."

But they suggest that the low event rates reported in the CREST-2 Registry may have other explanations in addition to those outlined by the authors.

The editorialists point out that there was no independent evaluation and adjudication of potential neurologic events and that patients were assessed only at baseline and 30 days, which they say raises the possibility that some minor strokes may have been missed.

However, they conclude: "The CREST-2 Registry provides confidence ahead of the release of the CREST-2 randomized data that the carotid stenting operators performing these procedures were of exceptional quality. This will enable us to put greater trust in the results of the study, regardless of the specific outcomes ultimately reported."

Another study of a new carotid stenting approach, transcarotid artery revascularization (TCAR), was published this week and reported encouraging results on stroke rates.

The lead author of that study, Marc L. Schermerhorn, MD, Beth Israel Deaconess Medical Center, Boston, Massachusetts, agreed that results with the femoral approach are improving as a result of technological improvements, operators becoming more skilled, and better patient selection.

But he pointed out to | Medscape Cardiology that the CREST-2 Registry selected interventionalists who could participate. "If you have to be a CREST-2 investigator to get good results, this can’t be duplicated across whole of clinical practice.

"And in our study, the femoral results were also quite good, but the TCAR results were better," Schermerhorn added.

The CREST-2 Registry is funded by NINDS–National Institutes of Health and by Abbott Vascular, Boston Scientific, Cordis-Cardinal, W. L. Gore and Associates, Medtronic, and Silk Road Medical. Lal and Olin report no relevant financial relationships. Giri reports serving on advisory boards for AstraZeneca and Phillips Medical Systems and has received research support to his institution from St. Jude Medical and Recor Medical.

J Am Coll Cardiol. 2019;74:3071-3079. Abstract, Editorial

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