Long-term risk of stroke and other vascular events in patients with asymptomatic carotid artery stenosis.
BACKGROUND
The annual risk of ischemic stroke in patients with asymptomatic carotid artery stenosis is about 2% during the short-term (2-3 years), but the long-term risks of stroke and other vascular events are unknown, although they may affect surgical decision making.


OBJECTIVE
To evaluate the long-term risk of stroke and other vascular events in patients with asymptomatic carotid artery stenosis.


METHODS
Cohort study with a median follow-up of 10 years (range, 5-18 years).


METHODS
The teaching hospital of the University of Toronto, Toronto, Ontario.


METHODS
From the initial cohort of 500 patients, 106 patients with asymptomatic carotid artery stenosis were selected because they had completed at least 5 years of follow-up.


METHODS
Ipsilateral stroke, myocardial infarction, and nonstroke vascular death.


RESULTS
The 10- and 15-year actuarial risks of ipsilateral stroke were 5.7% (95% confidence interval [CI], 0%-12%) and 8.7% (95% CI, 1%-17%), respectively, in patients with 0% to 49% internal carotid artery stenosis, and 9.3% (95% CI, 1%-18%) and 16.6% (95% CI, 1%-32%) in patients with 50% to 99% internal carotid artery stenosis. The 10- and 15-year risks of myocardial infarction and nonstroke vascular death were 10.1% (95% CI, 4%-16%) and 24.0% (95% CI, 14%-34%). Age (P =.02), diabetes mellitus (P =.02), and internal carotid artery stenosis of 50% or more (P =.04) were predictive of increased risks of myocardial infarction and nonstroke vascular death. Internal carotid artery stenosis of 50% or more did predict the risk of ipsilateral stroke (P =.003) when all 181 asymptomatic carotid arteries were included.


CONCLUSIONS
The annual stroke risk in patients with asymptomatic carotid artery stenosis was low and remained stable during long-term follow-up. Any benefit from carotid surgery is therefore unlikely to increase significantly with long-term follow-up. The high long-term risks of myocardial infarction and nonstroke vascular death suggest that prevention strategies should concentrate on coronary risk more than stroke risk.
Stroke Research Unit, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, Ontario, Canada. nadareishviliz@ninds.nih.gov
Zurab G
ZG
Nadareishvili
Peter M
PM
Rothwell
Vadim
V
Beletsky
Angela
A
Pagniello
John W
JW
Norris
D000368:Aged; D016893:Carotid Stenosis / Q000150:complications* / Q000175:diagnosis; D005260:Female; D005500:Follow-Up Studies; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology*; D009864:Ontario; D012306:Risk; D020521:Stroke / Q000209:etiology*; D013997:Time Factors; D014652:Vascular Diseases / Q000209:etiology