Successful surgery for narrowed neck arteries halves the risk of having a stroke over the next 5 years, and benefit persists for at least 10 years. But, operating on the main arteries that take blood to the brain involves about a 3% risk of causing an immediate stroke. Among older patients this immediate risk may outweigh the long-term benefit. Among men and women under 75 years of age who are in good health except for a narrowed neck artery, however, there is likely to be net benefit from operating, as long as the surgical risks remain low. These are the findings of an Article in this week's Surgery Special Edition of The Lancet , written by Professor Alison Halliday and Professor Sir Richard Peto of the University of Oxford, UK, and their international collaborators from 30 countries.
Patients in whom substantial (eg, 60%) narrowing is discovered in the left or right carotid artery that has not yet caused a stroke are at substantially increased long-term risk of having an ischaemic stroke, especially in the side of the brain supplied by that artery (the ipsilateral carotid territory of the brain). Carotid endarterectomy (CEA) can remove the fatty deposits that cause the arterial narrowing, but the procedure itself causes some immediate risk of stroke or death. In this randomised trial, the authors assessed the long-term effects of successful CEA in patients who have carotid artery narrowing that has so far remained asymptomatic (ie, has caused no recent stroke, transient cerebral ischaemia, or other neurological symptoms), and had been detected by ultrasound or some other type of scanning. Most of these asymptomatic patients are 'discovered' because they have had problems with arteries in other parts of the body (eg, the heart, or legs).
The study (ACST-1) involved 3120 patients with narrowed carotid arteries where the doctor and the patient were both substantially uncertain whether or not to have immediate surgery, and randomly allocated half of the patients to have immediate CEA and half to have indefinite deferral of any carotid procedure (until there was considered to be a more definite need for it). As some of those allocated deferral did eventually get operated on, and some patients eventually had the artery on the opposite side of the neck operated on, a total of 1979 CEAs were done during the study. Among them, the perioperative risk of stroke or death within 30 days was 3•0%; this included 26 non-disabling strokes plus 34 disabling or fatal events.
The median follow-up was 9 years. Excluding perioperative events, among those who continued to be followed up the stroke risks (immediate vs deferred CEA) were 4•1% versus 10•0% at 5 years and 10•8% versus 16•9% at 10 years. Combining perioperative events and strokes, net risks were 6•9% versus 10•9% at 5 years and 13•4% versus 17•9% at 10 years. Medical treatment with a combination of antiplatelet, antihypertensive, and lipid-lowering drugs substantially reduces stroke risk, but was equally widely used in both the immediate CEA and the deferral groups. Throughout the study, most patients were on antithrombotic and antihypertensive therapy but routine use of statin therapy rose steeply from below 10% when the study began in the mid-1990s to over 80% in recent years. There was net benefit from immediate CEA whether or not statins were being used, and net benefit for both men and women up to 75 years of age at entry (although not for older patients).
The authors say: "For otherwise healthy men and women younger than 75 years...the results from this trial suggest net benefit from CEA, as long as perioperative risks remain low."
They conclude: "Successful CEA for asymptomatic patients younger than 75 years of age reduces 10-year stroke risks. Half this reduction is in disabling or fatal strokes. Net benefit in future patients will depend on their risks from unoperated carotid lesions (which will be reduced by medication), on future surgical risks (which might differ from those in trials), and on whether life expectancy exceeds 10 years."
Carotid artery lesions generally involve the same sort of fatty deposits that coronary artery lesions do, but as the left and right carotid arteries provide the main blood supply to the brain carotid lesions can cause a fatal or permanently disabling stroke. Professor Halliday says:* "This trial took more than 15 years to complete, because we wanted to know about the long-term effects of surgery. The finding that successful carotid artery surgery can substantially reduce the stroke risk for many years is remarkable because it means that most of the risk of stroke over the next 5 years in patients with a narrowed carotid artery is caused by that single carotid lesion. The definite benefits that we have found will be of practical value to doctors and patients deciding in the future whether to take the immediate risk of having such surgery." She added: "An alternative to carotid artery surgery is inserting a stent** into a narrowed carotid artery to hold it open. If patients have not yet had a stroke, both carotid surgery and carotid stenting cause an immediate stroke risk of about 3%. Our next trial (ACST-2) is comparing their long-term protective effects, but its final results will take at least another decade to emerge."
In the linked Comment, Professor Pierre Amarenco, Bichat Hospital, Department of Neurology and Stroke Center, Paris, France, and colleagues say: "The investigators correctly noted that generalisability of these results depends heavily on a periprocedural risk of less than 3%, and they call for nationwide registries to better identify factors that increase stroke risk because of the patients, the carotid stenosis, the procedure, and the operator."
They add that more research should be carried out on patients over 75, to establish whether factors could be indentified that would mean some patients in this age group could still benefit from immediate carotid endarterectomy.
To contact Professor Halliday and Professor Peto, please call Jonathan Wood, University of Oxford Press Office T) +44 (0) 1865 280 530 E) Jonathan.Wood@admin.ox.ac.uk
Professor Pierre Amarenco, Bichat Hospital, Department of Neurology and Stroke Center, Paris, France. T) +33 1 4025 8725 E) pierre.amarenco@bch.aphp.fr
For full Article and Comment see: http://press.thelancet.com/tl10year.pdf
Notes to editors: *A quote direct from Professor Halliday that cannot be found in text of Article
**Note an Article comparing endarterectomy and carotid stenting was published Online First by The Lancet on 10 September 2010. The pdf of this article is also in the link above
The Lancet