ASA: Carotid Stenting May Be Effective in Preventing Stroke

But two other studies say it has worse outcomes than endarterectomy in carotid stenosis patients

08 mar 2010-- Carotid stenting and carotid endarterectomy have similar long-term outcomes for preventing stroke in patients with carotid stenosis, according to a study presented at the American Stroke Association's 2010 International Stroke Conference, held from Feb. 23 to 26 in San Antonio. However, two studies published online Feb. 26 in The Lancet and The Lancet Neurology found that carotid stenting is associated with worse outcomes than carotid endarterectomy in patients with carotid artery stenosis in the months after the procedure and is associated with ischemic brain lesions shortly after treatment.

In the study presented at the International Stroke Conference, Thomas G. Brott, M.D., from the Mayo Clinic in Jacksonville, Fla., and colleagues randomly assigned symptomatic patients and symptomatic patients with carotid stenosis to carotid stenting or carotid endarterectomy. After a mean follow-up of 2.5 years, the researchers found that outcomes were similar in both groups in terms of stroke, heart attack, and death. However, in the weeks after the procedure, the risk of stroke was higher in the stenting group, while the risk of myocardial infarction was lower.

In The Lancet study, Martin M. Brown, M.D., of University College London, and colleagues randomly assigned patients with carotid artery stenosis to carotid artery stenting or carotid endarterectomy. After 120 days, the stenting group had a higher risk of disabling stroke or death; stroke, death, or procedural myocardial infarction; any stroke; and death from any cause. In The Lancet Neurology study, Leo H. Bonati, M.D., from University Hospital Basel in Switzerland, and colleagues performed magnetic resonance imaging on a subset of patients who participated in the trial from The Lancet. Using diffusion-weighted imaging, the researchers found that patients in the stenting group were more likely to have at least one new ischemic brain lesion after treatment.

"The widespread use of carotid stenting, especially its routine use as first-choice treatment for symptomatic carotid stenosis, does not seem to be justified for the time being," writes the author of an accompanying editorial in The Lancet Neurology, adding that "an objective outcome surrogate parameter, such as the occurrence of ischemic lesions in serial diffusion-weighted imaging, seems a promising research tool."

Both Lancet studies were partially funded by Sanofi-Synthélabo, and two authors reported financial or consulting relationships with medical device companies. The conference study was partially funded by Abbott Laboratories.

Abstract - Brown
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Abstract - Bonati
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Editorial (subscription or payment may be required)
Abstract 197
International Stroke Conference 2010

Carotid Stenosis Procedures Equally Effective for Long-Term Prevention

By Crystal Phend
BOSTON, April 9, 2008-- High-risk patients with severe carotid artery stenosis may have equivalent long-term outcomes whether treated with stenting or conventional endarterectomy, researchers found.
The cumulative incidence of major adverse events through three years was 24.6% for stenting done with emboli protection compared with 26.9% for endarterectomy (P=0.71), reported Donald E. Cutlip, M.D., of Harvard, and colleagues, in the April 10 issue of the New England Journal of Medicine.
The incidence of stroke in the Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE) trial was an identical 9% at three years whether patients had stenting or gold-standard open surgery.
Short-term safety results had likewise shown no difference between procedures, even though the EVA-3S trial had suggested an advantage for endarterectomy among symptomatic patients (See: Endarterectomy Safer than Carotid Stenting in Symptomatic Patients).
The SAPPHIRE findings represent the first look at longer-term efficacy in a randomized clinical trial, said co-author Hitinder S. Gurm, M.D., of the University of Michigan in Ann Arbor, in an interview.
Physicians can now choose between procedures for these patients based on individual anatomy and medical problems, he said, "knowing that whatever procedure the patient gets, the long-term outcome would be fairly similar."
Patients in the SAPPHIRE study had symptomatic carotid stenosis of more than 50% of the luminal diameter or asymptomatic stenosis of more than 80%.
All were at high surgical risk based on clinically significant cardiac disease, severe pulmonary disease, contralateral carotid occlusion, contralateral laryngeal-nerve palsy, recurrent stenosis, previous radical surgery or radiation therapy to the neck, or an age of more than 80 years.
The trial originally included 334 patients randomized to stenting with an emboli-protection device or carotid endarterectomy. At three years, 143 stenting group patients and 117 surgery group patients had clinical follow-up data available.
The primary endpoint of major adverse events through one year showed no difference between the groups.
Likewise for long-term outcomes, the major secondary endpoint of death and ischemic events through 30 days and death and stroke through three years showed only a nonsignificant 2.3% lower incidence for stenting versus surgery (95% CI -11.8 to 7.0).
Most of the events that occurred from one to three years of follow-up were deaths, and the majority of those were from non-neurological causes. None of the event rates differed between groups.
The cumulative incidence rates through three years for stenting versus endarterectomy included:
18.6% versus 21% for all-cause mortality (P=0.68).
2.2% versus 2.9% for neurological-related deaths (P=0.99), of which two deaths in the stenting group and three in the endarterectomy group occurred beyond one year.
9% for stroke in both groups (P=0.99).
5.4% versus 8.4% for MI (P=0.39).
2.4% versus 5.4% for target vessel revascularization (P=0.71).
These findings apply only to high surgical risk patients, the researchers cautioned.
"On the basis of the similar long-term outcomes among high-risk patients in the two treatment groups, it may be tempting to infer that endarterectomy is preferable for lower-risk patients," they said.
But physicians need to await the results of the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST), which included low- and moderate-risk patients, Dr. Gurm said.
It's also important to note, he said, that some patients might not have benefited from either invasive procedure because the death rate was high over three years, he said. A medical therapy arm was not included in this study.
Although the study included only patients referred for an intervention other than medical therapy, the researchers suggested that "invasive treatment for prevention of stroke is reasonable, even in a high-risk population, if the projected five-year mortality is less than 50% and the intervention is not itself associated with an increased risk of death or other major adverse effects related to safety."
The study was sponsored by Cordis. Dr. Gurm reported being named as an inventor on patents related to carotid artery stenting. A co-author reported being the inventor of the Angioguard emboli-protection device used in the SAPPHIRE trial, being a shareholder in Angioguard at the time of its purchase by Johnson & Johnson in 1999, and receiving recurring payments from Johnson & Johnson as a former shareholder of Angioguard. Other authors reported conflicts of interest for Cordis, Boston Scientific, Abbott Vascular Devices, Johnson & Johnson, Cook, ev3, and Lumen Medical. Two authors were employees of Cordis (a Johnson & Johnson company) and reported owning equity interest and holding stock options in Johnson & Johnson.
Primary source: New England Journal of MedicineSource reference:Gurm HS, et al "Long-term results of carotid stenting versus endarterectomy in high-risk patients" N Engl J Med 2008; 358: 1572-9.

Ultrasound Criteria for Carotid Stenosis May Overestimate Severity

Patients with internal carotid artery stenosis may be undergoing needless tests and interventions, investigators warned here.
That's because current ultrasound standards for stenoses greater than 50% are based on outmoded information, according to Hisham Bassiouny, M.D., director of the non-invasive vascular lab at the University of Chicago, and colleagues.
Duplex ultrasound velocity thresholds for estimating blood flow through stenotic arteries are too aggressive and tend to overestimate the severity of stenosis, Dr. Bassiouny reported at the Society for Vascular Surgery meeting.
The problem, he said, is that ultrasound standards developed in the 1980s (Strandness criteria) and still in use in the majority of vascular labs in the United States were based on early angiography findings.
"The limitation with angiography is that you had to guess how far the outer wall of the artery was beyond the artery's channel to determine the precise degree of artery blockage," he said. "That was a guess, an estimate. Based upon that subjective estimate, formulas were developed to look at the velocity of blood flow in the artery and determine how much narrowing existed. These formulas became the standard used to this day. However, imaging technology is much better today than when these standards were developed."
The Strandness criteria define greater than 50% stenosis as a peak systolic velocity greater than 125 cm/second, greater spectral broadening throughout systole, and heavy, prominent plaque formation.
The criteria define greater than 80% stenosis as a peak systolic velocity > 125 cm/second, marked spectral broadening and turbulence, severe plaque formation, and end diastolic velocity elevated more than 140cm/second.
To see whether the criteria held up with the use of modern equipment, Dr. Bassiouny and colleagues first compared B-mode ultrasound and computed tomography angiography images performed on 74 patients with internal carotid artery stenosis, in order to validate the accuracy of the ultrasound measurements.
They then evaluated 337 patients with either mild, moderate, or severe internal carotid artery stenoses, looking at the minimal residual lumen and the corresponding outer internal carotid artery or bulb diameter on longitudinal and transverse images. Patients with contralateral occlusion were excluded from the analysis, as were calcified artery segments.
In both the validation sample and the larger study, the highest peak systolic velocity, end diastolic velocity, and ratio of the internal carotid artery to the common carotid artery (ICA/CCA ratio) were recorded.
The investigators determined the optimum threshold for each hemodynamic parameter using receiver operating characteristic curves to predict stenosis of 50% or greater (in 281 patients) and of 80% or greater (in 62 patients) bulb internal carotid artery stenosis.
They found that "there was excellent agreement between B-mode ultrasound and computed tomography angiography (r = 0.9, P= 0.002).
But when they looked at the sensitivity, specificity, and positive- and negative-predictive value of B-mode ultrasound, they found that the Strandness criteria would rope in too many patients who did not have serious stenosis.
When both a peak systolic velocity equal to or greater than 155 cm/second and an ICA/CCA ratio of 2 or greater were combined for the detection of at least 50% internal carotid artery stenosis, a positive predictive value of 97% and an accuracy of 82% were obtained. For a stenosis of 80% or greater, and end diastolic velocity of 140 cm/second, a peak systolic velocity 370 cm/second or greater, and an ICA/CCA ratio of 6 or more had acceptable probability values.
"Compared to established velocity thresholds commonly applied in practice (Strandness criteria), a substantially higher peak systolic velocity (155 vs. 125 cm/second) was more accurate for detecting ≥ 50% bulb ICA stenosis," the authors wrote.
"In combination, a PSV of ≥155 cm/second and an ICA/CCA ratio of 2 have excellent predictive value for this stenosis category," they said. For an ≥ 80% ICA stenosis, an end diastolic velocity of 140 cm/second, a peak systolic velocity of ≥ 370 cm/second, and an ICA/CCA ratio of ≥ 6 are equally reliable."
The authors said that current criteria for duplex ultrasound detection of 50% or greater internal carotid artery stenosis may overestimate carotid bifurcation disease.
"As a result, we've changed the standards in our vascular lab," Dr. Bassiouny said. "We hope these new standards will be adopted everywhere. Such a move would save money and spare at least some patients from unnecessary procedures and tests."