Patients with carotid stenosis, a narrowing of the carotid artery that supplies blood to the brain, could have a better treatment outcome by removing the material causing the narrowing with a surgery called endarterectomy. The other alternative is balloon angioplasty with or without the placing of a stent (small wire mesh tube in the artery) also known as endovascular treatment (ET). Surgery reduces the risk of both short-term and long-term stroke. It also diminishes the risk of repeat stenosis, which itself reduces the risk of stroke. Those are the conclusions reported in two articles published Online First and in the October edition of The Lancet Neurology. They are the work of Professor Martin M Brown, UCL Institute of Neurology, The National Hospital for Neurology and Neurosurgery, London, UK, and colleagues from the CAVATAS investigators group.
The main causes of stroke and transient ischaemic attack (TIA) are the narrowing of the carotid artery due to deposits of fatty material (atherosclerosis). Carotid atherosclerosis causes about 20 percent of all strokes. The severity of the narrowing justifies surgery in 5 to 10 percent of stroke and TIA patients.
• The surgery, known as carotid endarterectomy: it involves removal of the fatty deposits in the artery through an incision in the neck. To prevent a stroke during the operation, the surgeon clamps the carotid artery and may put in a temporary bypass (shunt). He or she then cuts out the fatty deposits from the wall of the artery. It is then followed by the removal of the clamps and shunt. The incision is then sowed. Endarterectomy is frequently done under general anaesthetic, but can be done under local anaesthetic.
• Endovascular treatment: it involves dilation of the narrowed portion of the artery by inflation of a balloon inside the artery (angioplasty). It can be done with or without insertion of a wire mesh (stenting) to hold open the artery from inside. The balloon or the stent are threaded up to the neck through a narrow tube called a catheter which is inserted into a groin artery under local anaesthesia.
There is publication of prior studies comparing surgery and ET. However, they do not consider long-term follow-up data on the risks of these procedures for patients. The first paper examined 504 patients. Between 1992 and 1997 they presented at a participating hospital with confirmed carotid stenosis. They were equally suitable for treatment with either surgery or ET. 251 patients underwent surgery and 253 received ET.
Within 30 days of treatment, results indicated that there were more minor strokes that lasted less than 7 days in the ET group (8) than in the surgery group (1). Following the perioperative period of 30 days after treatment, the 8-year incidence of ipsilateral stroke which is a stroke on the same side as the carotid stenosis was higher in the ET group (11.3 percent). In the surgery group it was 8.6 percent. The combined endpoint was stroke or TIA. Its occurrence was of 19.3 percent in the ET group and 17.2 percent in the surgery group. Still, none of the post-operative differences in stroke outcomes were statistically important.
The authors write in conclusion: “More patients had stroke during follow-up in the endovascular group than in the surgical group, but the rate of ipsilateral non-perioperative stroke was low in both groups and none of the differences in the stroke outcome measures was significant. However, the study was underpowered and the confidence intervals were wide. More long-term data are needed from the ongoing stenting versus endarterectomy trials.”
The second paper considered patients who had been followed up for an average of five years. They had had a neck ultrasound to examine the carotid artery for recurrence of stenosis (restenosis) on yearly intervals. The researchers found that the estimated incidence of severe restenosis with a narrowing of 70 percent or more of the artery was 31 percent in the ET group and 10 percent in the surgery group. The patients who received ET had a risk three times superior. The risk to develop severe restensois for patients who received ET involving stenting doubled compared to those who did not. In addition, patients who developed severe restenosis in the year after treatment were more than twice as likely to go on to experience an ipsilateral stroke or TIA within five years (23 percent) than those with no restenosis (11 percent).
In closing, the authors write: “Restenosis is about three times more common after endovascular treatment than after endarterectomy and is associated with recurrent ipsilateral cerebrovascular symptoms; however, the risk of recurrent ipsilateral stroke is low. Further data are required from ongoing trials of stenting versus endarterectomy to ascertain if long-term ultrasound follow-up is necessary after carotid revascularisation.”
In an associated comment, Professor Peter M Rothwell, John Radcliffe Hospital, Oxford, UK, mentions: “A meta-analysis of all the available data on long-term outcome in randomised trials of endovascular treatment versus endarterectomy for symptomatic carotid stenosis now shows a significantly worse outcome after endovascular treatment*. Carotid stenting could still be used, at least in patients with inoperable stenosis or if patients strongly prefer endovascular treatment, although the recent finding of the GALA (general anaesthetic versus local anaesthetic for carotid surgery) trial – that endarterectomy can be done at least as safely under local anaesthetic as it is under general anaesthetic – should influence patients’ preferences.”
He mentions that, in anticipation of the publication of results of two other recently completed trials, ‘The routine use of stenting in patients with recent symptoms of carotid stenosis who are suitable for endarterectomy can no longer be justified’.
“Endovascular treatment with angioplasty or stenting versus endarterectomy in patients with carotid artery stenosis in the Carotid And Vertebral Artery Transluminal Angioplasty Study (CAVATAS): long-term follow-up of a randomised trial”
Jörg Ederle, Leo H Bonati, Joanna Dobson, Roland L Featherstone, Peter A Gaines, Jonathan D Beard, Graham S Venables, Hugh S Markus, Andrew Clifton, Peter Sandercock, Martin M Brown, on behalf of the CAVATAS Investigators
DOI: 10.1016/S1474-4422(09)70228-5
Written by Stephanie Brunner (B.A.)