Surgery May Not Help Most People With Narrowed Brain Artery
Intensive medical treatment can prevent stroke, study says
THURSDAY, Sept. 25, 2008 (HealthDay News) -- The vast majority of people at risk of stroke because the main artery to the brain is partially blocked but have no symptoms are better off if they don't have surgery to restore blood flow, a new study contends.
"Above 95 percent of patients with asymptomatic carotid stenosis can benefit if they receive intensive medical therapy rather than endarterectomy [the surgical removal of plaque from a blocked artery] or stenting," said study leader Dr. David Spence. He is director of the Stroke Prevention & Atherosclerosis Research Centre at the Robarts Research Institute at the University of Western Ontario in Canada.
A simple test can identify the small percentage of people with symptomless partial blockage of the carotid, the main artery to the brain, who are at high risk of stroke and should have the surgical procedure endarterectomy or implantation of a stent, a metal tube to maintain blood flow, Spence said.
He was expected to present the study findings Sept. 25 at the Sixth World Stroke Congress, in Vienna, Austria.
Endarterectomy for symptom-free carotid stenosis is greatly overused in the United States, Spence said. "In the United States, between half and two-thirds of these procedures are done for asymptomatic carotid stenosis," he said. "In Australia, it is between 10 and 20 percent."
Intensive medical therapy, including "exercise, the Mediterranean diet, statin doses up to the maximum regardless of LDL (bad) cholesterol level, ACE inhibitors, niacin, whatever we can do to reduce plaque," can make the risk of stroke negligible in such cases, Spence said.
"Since 2003, only 0.8 percent of patients with asymptomatic stroke have had a stroke in the first year, and zero percent have heart attacks in the first year," he added.
The year 2003 can be used as a dividing line, because medical therapy has become much more effective since then, Spence said. A study of a diagnostic procedure called transcranial Doppler embolism detection helped prove the point, he said.
In the procedure, a helmet holding ultrasound probes is placed on the head for one hour to detect microemboli, tiny blood clots or chunks of plaque that have broken off from artery-narrowing deposits. The 96 percent of people without microemboli have only a 1 percent risk of stroke in the following year, while the presence of microemboli indicates a 14 percent one-year risk of stroke, Spence said.
The Doppler examination found microemboli in 12 percent of 199 people with asymptomatic carotid stenosis tested before 2003, but only 3.7 percent of 272 people tested after 2003, showing the increased effectiveness of medical therapy in recent years, he said.
"Since the risk of surgery is 4 to 5 percent, patients without microemboli are better off with medical therapy, including medications and lifestyle modifications," Spence said.
Dr. Colin Derdeyn, associate professor of radiology, neurology and neurological surgery at Washington University in St. Louis, said he agreed with the study findings "to a point," but he added, "I'm not sure that I completely buy it."
Data about surgery for asymptomatic carotid stenosis is based primarily on two large trials done in the 1990s, Derdeyn said. "If you combine the results, it's pretty clear that women don't benefit from that operation. The only people who benefit are asymptomatic, relatively healthy men. For that population, it is still a reasonable operation."
The recommendations he makes to men and women with the condition still are based on the results of those controlled trials, Derdeyn said. "I don't recommend surgery for women and elderly men and men who have a lot of medical problems," he said. "If they are in reasonably good health, and males, then I recommend it."
For more on carotid artery stenosis and its treatment, visit the American Heart Association.