VIENNA – Guidelines used around the world for the management of carotid stenosis, both in asymptomatic and symptomatic cases, are often outdated and do not match current evidence, according to the results of a systematic review undertaken by an international group of experts.*

Furthermore, the qualifying statements used to back up the recommendations are often confused and too simplistic, being based only on the degree of randomized data used.

Sara Freeman/Frontline Medical NewsDr. Anne Abbott

“Other problems were that the guidelines often didn’t even define asymptomatic carotid artery stenosis or symptomatic carotid artery stenosis or they left out procedural standards,” said Dr. Anne Abbott, who presented the findings at the annual European Stroke Conference.

“A number of important discoveries have been made in recent years to better inform treatment decisions for patients with carotid stenosis,” Dr. Abbott, a neurologist at Monash University in Melbourne, Australia, observed.

For instance, based on evidence available today, it is clear that medical therapy alone is best for patients with moderate or severe (50%-99%) asymptomatic disease. Surgery in these patients might actually be harmful, she noted, and it is unknown if or by how much carotid endarterectomy improves stroke prevention versus medical therapy alone.

“We just haven’t done the studies, and this is where we should be concentrating our efforts with respect to randomized, placebo-controlled trials,” Dr. Abbott proposed. “But we do know that the 6% 30-day stroke/death rate [with endarterectomy] is really now too high.”

It’s also now apparent that carotid angioplasty or stenting is more harmful than carotid endarterectomy in asymptomatic patients and “shouldn’t be recommended for routine practice.” Many of the guidelines were still supporting this as an option, she observed, based on the supposed counterbalancing argument that surgical intervention was more likely to increase the risk for heart attacks than stenting. However, the evidence shows that the greatest risk to patients in the periprocedural period is the stroke risk, which is increased by stenting.

Dr. Abbott explained how the team of 16 experts had reviewed all the latest available guidelines for asymptomatic and symptomatic carotid stenosis that they could find from published from January 2008 until January 2015. She noted that guidelines were often difficult to access were often only found because the team knew of their existence through their professional networks.

A total of 34 guidelines from 23 regions or countries in six languages were identified and included in the review. Each of these was independently assessed by two to six of the team, looking at the clinical scenarios covered, the nature of the recommendations made and what evidence was being used to support the recommendations.

Of 28 guidelines that gave recommendations for asymptomatic carotid stenosis, surgery was endorsed for patients at average surgical risk and only one (4%) endorsed medical treatment alone. Eighteen (64%) recommended that stenting be performed or considered, and 24 (86%) supported the use of endarterectomy. “This is despite current evidence that these procedures are now more likely to harm than help patients,” Dr. Abbott said.

“Of major concern I think is that a high proportion, about half, of these guidelines are recommending stenting for high surgical risk asymptomatic patients, she cautioned. “This includes patients with major medical comorbidities – heart failure, respiratory failure – who have a very short life expectancy and are least likely to benefit and are more likely to be at risk from the procedures.”

Somewhat similar findings were seen regarding the use of stenting and surgery in the 33 guidelines that gave recommendations for the management of symptomatic carotid stenosis. Endarterectomy was recommended for average-surgical-risk symptomatic patients by 31 (94%) guidelines and, worryingly, stenting was still being advocated in 19 (58%) guidelines with only nine (27%) saying that stenting should not be used. Stenting was also being endorsed in symptomatic patients at high surgical risk.

Dr. Abbott said that the guidelines were hard to compare because they used a variety of qualifying statements to try to advise on the degree to which a procedure was recommended. There was no consistency or standardization: six guidelines did not use any qualifying statements or were not defined in two guidelines, 10 guidelines used class or grade to denote the strength of the recommendation being made, and 27 guidelines used class, grade, or other means to denote the strength of the evidence the recommendations were being based on.

All this means, however, that there are many opportunities to modernize the guidelines and bring them up-to-date with current knowledge. They shouldn’t be recommending stenting over surgery, for example, and they need to standardize what the recommendations are based on.

“The guidelines should always define their target population properly and that comes straight from randomized trials usually,” Dr. Abbott noted. Procedural standards also need to be given. “Guidelines also need to be consistent throughout, self-contained, and be more accessible.”

Dr. Abbott had no relevant disclosures.

*CORRECTION: 6/21/2015 An error in identification of the stent was corrected.

Carotid artery stenosis guidelines need modernizing