NEW YORK, Mar 14 (Reuters Health) -- Fatty deposits in the carotid arteries
-- large neck arteries supplying the brain -- can lead to stroke. But almost
half of strokes in patients with carotid artery disease can be traced to other
causes, according to results of a study.
The finding suggests that patients who are considering surgery on their
carotid arteries to reduce their stroke risk should have their overall risk of
stroke assessed, the researchers report.
"The results of this study demonstrate that even in the presence of
large-artery (disease), strokes arise from a variety of causes," according to
Dr. Henry Barnett from The John P. Roberts Research Institute in London,
Ontario, Canada and colleagues.
The authors used information collected during the North American Symptomatic
Carotid Endarterectomy Trial (NASCET) -- a study of the effectiveness of surgery
on narrowed carotid arteries to prevent strokes -- to determine the source of
subsequent strokes in 2,885 such patients. Their results are published in the
March 15th issue of The Journal of the American Medical Association.
Overall, about two thirds of strokes in these patients resulted from
blockage of the carotid arteries, the report indicates. Second most common were
lacunar strokes (20%) caused by clots in smaller arteries penetrating brain
tissue, followed by blood clots from the heart that blocked various blood
vessels in the brain (11%).
Strokes caused by blood clots from the heart resulted in disability in 51%
to 68% of the patients, the researchers note, compared with about 33% for
strokes from blocked carotid arteries, and 4% to 17% for lacunar strokes.
In light of the findings of this study, patients with risk factors for
atherosclerosis -- "hardening of the arteries" -- should undergo a thorough
examination before proceeding to carotid surgery, writes Dr. Louis Caplan from
Beth Israel Deaconess Medical Center in Boston, Massachusetts, in a related
editorial.
"Physicians need to consider the entire patient after thorough evaluation
before deciding on the optimum treatment strategies to prevent initial or
recurrent stroke," concludes Caplan.
"For patients with symptomatic, severely (narrowed) carotid arteries and no
flagrant cardiac source of (blood clots), it's reasonable to operate," Barnett
told Reuters Health. But he added that patients who do have cardiac sources of
blood clots require further evaluation and often treatment with drugs to prevent
new clots from forming.
What to do with symptomless patients with less severe narrowing of the
carotid arteries remains an open question, Barnett added. "Ongoing trials in the
US and France with these patients will, we hope, determine the best approach."
