2, March 2010
By Roni Caryn Rabin
US and British researchers get disparate results using stents to treat blocks in carotid artery
Thefindings,releasedonFridayatamedical meeting in San Antonio, have the potential to make the less invasive procedure -inserting a small tube called a stent in the carotid artery – a more appealing option for many patients.
Yet just a day earlier, European investigators reported dismal results from another international trial involving carotid stents, published online by the British medical journal The Lancet. In that study, patients treated with stents suffered almost double the rate of complications as those treated surgically, leading the British researchers to conclude that surgical treatment of carotid blockages, called endarterectomy, remains the treatment of choice.
The disparate findings left the scientists trying to explain why two fairly similar clinical trials came to such starkly different conclusions.
"We had out standing results, and our study, we think, is representative of these treatments in the US and Canada," said Thomas G Brott, director for research at the MayoClinic campus in Jackson ville, Florida, and lead author of the North American study, called Crest (for Carotid Revascularisation Endarterectomy versus Stenting Trial).
"Prior to the Crest trial, we really did not have the best evidence, but these results indicate that we have two very safe and effective methods to prevent stroke."
Though there are differences in risk between the two procedures and individual variations, he said: "the results from stenting are very comparable to those for carotid surgery."
But Martin M Brown, chief investigator for the European trial, the International Carotid Stenting Study,saidal though differences in the groups studied might explain the disparate results, "nobody has really shown stenting is better than surgery, so why choose a stent?" Brown added: "Even if Crest shows little difference between the two, there are three other trials that suggest surgery is safer."
The Crest trial, sponsored by the National Institute of Neurological Disorders and Stroke with additional financing from the stent maker Abbott Vascular, is one of the largest randomised clinical trials to study the two major procedures used to open blocked neck arteries and restore blood flow to the brain.
It included 2,502 patients at more than 100 hospitals in the US and Canada, who were randomly assigned to receive either surgery or stenting over a period of nine years.
Most patients had an artery blockage greater than 70 per cent. The trial included patients who had suffered a stroke or a ministroke and those who were asymptomatic.
The death rate in the trial was very low, but risks varied depending on the procedure.
Within the first month after the procedure, 4.1 per cent of stent patients had suffered a stroke, compared with 2.3 per cent of the surgery patients. But surgery patients were at higher risk for heart attack, with 2.3 per cent suffering a heart attack in the first 30 days compared with 1.1 per cent of stent patients.
Strokeshadahigherimpactonthepatient's quality of life, the study reported.
Patients under 70 had better results with stenting, while older patients had better results with surgery, the study found.
Long-termfollow-upofpatients,whichwas over two years on average but is continuing, found both groups at equal risk of suffering a stroke that should have been prevented by the procedure: 2 per cent of those in the stent group compared with 2.4 per cent of the surgical patients.
The European trial, which included 1,713 patients randomly assigned to either stent or endarterectomy, found that stent patients were at much higher risk of stroke, death or heart attack in the first 30 days after surgery, with 7.4 per cent suffering one of these adverse events, compared with 4 per cent of the surgery group.
Among the possible explanations offered for the disparities are that the European study included only symptomatic patients, who may have had more advanced disease, and that the North American trial carefully screened the doctors doing the stenting procedure, including only highly skilled physicians with a lot of experience.
Walter J Koroshetz, deputy director of the institute that sponsored the North American trial, said the Crest trial was the first in which the results of stenting and surgery had been found to be equivalent -suggesting that the stent procedure had improved with time.
The most important message is that the overall death rate was extremely low, 0.6 per cent, said one of the study's principal investigators, Gary S Roubin, the chairman of cardiovascular medicine at Lenox Hill Hospital in New York.
"What this trial has done overwhelmingly," he said, "is shown that in North America, with the very skilled surgeons and physicians performingstenting,theoutcomeswereextremely safe."