The causes and risk of stroke in patients with asymptomatic internal-carotid-artery stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators.

BACKGROUND The causes of stroke in patients with asymptomatic carotid-artery stenosis have not been carefully studied. Information about causes might influence decisions about the use of carotid endarterectomy in such patients. METHODS We studied patients with unilateral symptomatic carotid-artery stenosis and asymptomatic contralateral stenosis from 1988 to 1997. The causes, severity, risk, and predictors of stroke in the territory of the asymptomatic artery were examined and quantified. RESULTS The risk of stroke at five years after study entry in a total of 1820 patients increased with the severity of stenosis. Among 1604 patients with stenosis of less than 60 percent of the luminal diameter, the risk of a first stroke was 8.0 percent (1.6 percent annually), as compared with 16.2 percent (3.2 percent annually) among 216 patients with 60 to 99 percent stenosis. In the group with 60 to 99 percent stenosis, the five-year risk of stroke in the territory of a large artery was 9.9 percent, that of lacunar stroke was 6.0 percent, and that of cardioembolic stroke 2.1 percent. Some patients had more than one stroke of more than one cause. In the territory of an asymptomatic occluded artery (as was identified in 86 patients), the annualized risk of stroke was 1.9 percent. Strokes with different causes had different risk factors. The risk factors for large-artery stroke were silent brain infarction, a history of diabetes, and a higher degree of stenosis; for cardioembolic stroke, a history of myocardial infarction or angina and hypertension; for lacunar stroke, age of 75 years or older, hypertension, diabetes, and a higher degree of stenosis. CONCLUSIONS The risk of stroke among patients with asymptomatic carotid-artery stenosis is relatively low. Forty-five percent of strokes in patients with asymptomatic stenosis of 60 to 99 percent are attributable to lacunes or cardioembolism. These observations have implications for the use of endarterectomy in asymptomatic patients. Without analysis of the risk of stroke according to cause, the absolute benefit associated with endarterectomy may be overestimated.

[1]  D. Sackett,et al.  Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. , 1991, The New England journal of medicine.

[2]  V. Hachinski,et al.  Long-term prognosis and effect of endarterectomy in patients with symptomatic severe carotid stenosis and contralateral carotid stenosis or occlusion: results from NASCET. North American Symptomatic Carotid Endarterectomy Trial (NASCET) Group. , 1995, Journal of neurosurgery.

[3]  A. Nicolaides,et al.  Asymptomatic carotid stenosis and risk of stroke. Identification of a high risk group (ACSRS). A natural history study. , 1995, International angiology : a journal of the International Union of Angiology.

[4]  L. Caplan.  TIAs , 1988, Neurology.

[5]  E S Fisher,et al.  Variation in carotid endarterectomy mortality in the Medicare population: trial hospitals, volume, and patient characteristics. , 1998, JAMA.

[6]  M. Abrahamowicz,et al.  Outcome of asymptomatic patients with carotid disease , 1997, Neurology.

[7]  P. Despland,et al.  Asymptomatic tight stenosis of the internal carotid artery , 1986, Neurology.

[8]  Peter M. Rothwell,et al.  RISK OF STROKE IN THE DISTRIBUTION OF AN ASYMPTOMATIC CAROTID-ARTERY , 1995 .

[9]  R. Cuming,et al.  Prevalence, progression and natural history of asymptomatic carotid stenosis: is there a place for carotid endarterectomy? , 1992, European journal of vascular surgery.

[10]  A. Halliday,et al.  The Asymptomatic Carotid Surgery Trial (ACST). Rationale and design. Steering Committee. , 1994, European journal of vascular surgery.

[11]  R Brian Haynes,et al.  Low-dose and high-dose acetylsalicylic acid for patients undergoing carotid endarterectomy: a randomised controlled trial , 1999, The Lancet.

[12]  J. Norris,et al.  Outcome in patients with asymptomatic neck bruits. , 1986, The New England journal of medicine.

[13]  A. Fox,et al.  Risk factors and outcome of patients with carotid artery stenosis presenting with lacunar stroke , 2000, Neurology.

[14]  A. Fox,et al.  How to measure carotid stenosis. , 1993, Radiology.

[15]  E. Mascha,et al.  Early outcome assessment for 2228 consecutive carotid endarterectomy procedures: the Cleveland Clinic experience from 1989 to 1995. , 1997, Journal of vascular surgery.

[16]  L. Wilkins.  Carotid Surgery Versus Medical Therapy in Asymptomatic Carotid Stenosis , 1991, Stroke.

[17]  M. Eliasziw,et al.  Do the facts and figures warrant a 10-fold increase in the performance of carotid endarterectomy on asymptomatic patients? , 1996, Neurology.

[18]  W. Flanders,et al.  Carotid endarterectomy among Medicare beneficiaries: a statewide evaluation of appropriateness and outcome. , 1998, Stroke.

[19]  D. Sackett,et al.  Benefit of carotid endarterectomy in patients with symptomatic moderate or severe stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators. , 1998, The New England journal of medicine.

[20]  N. Bornstein,et al.  Vascular Risks of Asymptomatic Carotid Stenosis , 1991, Stroke.

[21]  M. Eliasziw,et al.  Causes and severity of ischemic stroke in patients with internal carotid artery stenosis. , 2000, JAMA.

[22]  G. Ferguson,et al.  Guidelines for the use of carotid endarterectomy: current recommendations from the Canadian Neurosurgical Society. , 1997, CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne.

[23]  J. Grotta,et al.  The risks and benefits of carotid endarterectomy in patients with near occlusion of the carotid artery , 1997, Neurology.

[24]  J. Toole,et al.  Guidelines for carotid endarterectomy: a statement for healthcare professionals from a special writing group of the Stroke Council, American Heart Association. , 1998, Stroke.

[25]  Y. Wilson,et al.  Unilateral asymptomatic carotid disease does not require surgery. , 1998, European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery.

[26]  N. Hertzer.  A personal view: the Asymptomatic Carotid Atherosclerosis Study results--read the label carefully. , 1996, Journal of Vascular Surgery.

[27]  M. Limburg,et al.  The clinical meaning of Rankin 'handicap' grades after stroke. , 1995, Stroke.

[28]  J. Frey,et al.  Asymptomatic carotid stenosis: Surgery's the answer, but that's not the question , 1996, Annals of neurology.

[29]  Norris Jw,et al.  A therapeutic window for carotid endarterectomy in patients with asymptomatic carotid stenosis. , 1991 .

[30]  L. Wilkins.  North American Symptomatic Carotid Endarterectomy Trial. Methods, patient characteristics, and progress. , 1991, Stroke.

[31]  N L Greengold,et al.  Prevention of a first stroke: a review of guidelines and a multidisciplinary consensus statement from the National Stroke Association. , 1999, JAMA.

[32]  W. M. Krushat,et al.  Epidemiology of carotid endarterectomy among Medicare beneficiaries: 1985-1996 update. , 1998, Stroke.

[33]  J. Szalai,et al.  Consensus against both endarterectomy and routine screening for asymptomatic carotid artery stenosis. Canadian Stroke Consortium. , 1997, Archives of neurology.

[34]  P. Austin,et al.  Determinants of outcome after carotid endarterectomy. , 1998, Journal of vascular surgery.

[35]  M. Suarez‐Almazor,et al.  Regional performance of carotid endarterectomy. Appropriateness, outcomes, and risk factors for complications. , 1997, Stroke.

[36]  P. Karanjia,et al.  Accuracy of initial stroke subtype diagnosis in the TOAST study , 1995, Neurology.