CHICAGO, IL -- Sept. 22, 1998 -- A small subgroup of people with completely blocked carotid arteries are at especially high risk for subsequent stroke, according to an article in the Sept. 23/30 issue of The Journal of the American Medical Association.

Robert Grubb, Jr., M.D., of Washington University in St. Louis, and colleagues studied 81 patients over four years who had suffered a stroke or a transient ischemic attack (stroke-like symptoms that resolve within a few hours) to determine whether a subgroup of people with carotid artery occlusion (complete blockage of one of several large blood vessels that feeds blood to the brain) have an independent risk factor for suffering a subsequent stroke.

Using a very specialised test called positron emission tomography (PET), the researchers were able to measure which of the participants were in stage II hemodynamic failure, which is an indication that the brain is not receiving enough oxygenated blood to function normally.

The ability to pinpoint those in hemodynamic failure allows researchers to determine who may most likely have carotid artery occlusion, which increases a person's chances of having a stroke. A majority of people with occlusion may not know they have it because they do not experience any symptoms.

The researchers found that of the 81 patients, 39 had stage II hemodynamic failure (subgroup) on one side of the brain and 42 did not. The researcher determined that this subgroup was six times more likely to suffer an overall stroke and more than seven times more likely to suffer a stroke on one side of the brain than those who did not have stage II hemodynamic failure.

The researchers found that stroke occurred in 12 out of 39 patients (31 percent) in the subgroup but only three out of 42 patients (seven percent) who were not. Eleven of 39 patients (28 percent) in the subgroup suffered stroke on one side of the brain while only two out of 42 not in the subgroup suffered a stroke on one side.

"Although this study establishes that stage II hemodynamic failure is a strong predictor of subsequent stroke in patients with symptomatic carotid occlusion, it cannot establish the mechanism [exact cause] for these subsequent strokes,” they write. “The demonstration of hemodynamic failure at baseline does not necessarily prove that all subsequent strokes are hemodynamically mediated."

The researchers urge further research into the best treatment options, including surgery alternatives, for this high-risk group of stroke patients.

Thanks to The Doctor's Guide to the Internet™ for the article