Despite the development of dedicated carotid artery stenting systems and years of experience, interventional treatment has not fared better than endarterectomy or best medical therapy in preventing stroke or death.
Only one study to date has shown that carotid artery stenting was superior to surgery in treating symptomatic patients. Others have reported no difference or poor outcomes following the procedure. As for treating asymptomatic patients, data do not support revascularization of any kind, said speakers at the 2007 meeting of the Cardiovascular and Interventional Radiology Society of Europe.
"Carotid artery stenting should not be offered as a routine standard of care to asymptomatic patients. The treatment of asymptomatic lesions should be reserved for randomized clinical trials," said Dr. Barry Katzen, founder and director of the Baptist Cardiac and Vascular Institute in Miami.
Admittedly, clinical trials of carotid artery stenting are plagued by small numbers of patients, and they tend to lump asymptomatic and symptomatic patients together.
"We are looking at fewer than 1000 patients in the trials in order to try and get some decision making on what we should do," said Dr. Trevor Cleveland of the Sheffield Vascular Institute in the U.K. "It is very difficult to tease out the symptomatic and the asymptomatic patients. Therefore, in terms of concluding what we can say from clinical trials, it's difficult."
Nevertheless, the risk of cardiovascular accident has been consistently higher after stenting than after endarterectomy in symptomatic patients. In the early Wallstent trial, the risk of death within 30 days was 12.1% for stenting and 3.6% for endarterectomy. Stenting was equivalent to endarterectomy in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS). Although only 25% of patients had stents and the stents were crude early devices, outcomes were similar between the endovascular and surgical patients, Cleveland said.
In the 2006 Endarterectomy vs. Stenting in patients with Symptomatic Severe Carotid Stenosis (EVA-3S) French trial, the risk of stroke or death and the risk of disabling stroke or death at 30 days had not improved even with more advanced stenting systems, Cleveland said. Carotid endarterectomy had a 3.9% risk of stroke or death and a 1.5% risk of disabling stroke or death within a month of surgery. Stenting had a 9.6% risk of stroke or death and a 3.45% risk of disability.
The European Stent Protection Angioplasty vs. Carotid Endarterectomy (SPACE) trial showed equality between stenting and endarterectomy, with a 30-day risk of a severe adverse event (stroke or death) of 6.34% for surgery and 6.84% for intervention. The trial has been stopped, however, because of lack of funding.
Stenting and Angioplasty with Protection in Patients at High-Risk for Endarterectomy (SAPPHIRE) appeared to offer cause for celebration among interventionalists, Cleveland said, because the risk of 30-day events was much lower (4.2%) for stenting than for endarterectomy (15.4%). But fewer than 100 symptomatic patients were included in the trial before it was stopped. In the end, meta-analyses show no difference in outcome between surgery and stenting.
The overall risk of stroke is declining, just as is the risk of acute myocardial infarction, because of the use of aggressive medical therapies. Best medical therapy alone, therefore, is clearly benefiting asymptomatic patients.
"The question with carotid angioplasty and stenting is, do they come close to best medical care in asymptomatic patients. And I would offer to you that at this point, I don't think we are close to it," Katzen said.
