Sténoses Carotidiennes Asymptomatiques - Asymptomatic Carotid Stenoses

1. Ballotta E et al. (2005). "Prospective randomized study on asymptomatic severe carotid stenosis and perioperative stroke risk in patients undergoing major vascular surgery: prophylactic or deferred carotid endarterectomy?" Ann Vasc Surg 19(6): 876-81.
2. Halliday, A., A. Mansfield, et al. (2004). "Prevention of disabling and fatal strokes by successful carotid endarterectomy in patients without recent neurological symptoms: randomised controlled trial." Lancet 363(9420): 1491-502
3. Inzitari, D., M. Eliasziw, et al. (2000). "The causes and risk of stroke in patients with asymptomatic internal-carotid-artery stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators." N Engl J Med 342(23): 1693-70
4. Baker, W. H., V. J. Howard, et al. (2000). "Effect of contralateral occlusion on long-term efficacy of endarterectomy in the asymptomatic carotid atherosclerosis study (ACAS). ACAS Investigators." Stroke 31(10): 2330-4
5. Moore, W. S., R. F. Kempczinski, et al. (1998). "Recurrent carotid stenosis: results of the asymptomatic carotid atherosclerosis study." Stroke 29(10): 2018-25.
6. (1995). "Risk of stroke in the distribution of an asymptomatic carotid artery. The European Carotid Surgery Trialists Collaborative Group." Lancet 345(8944): 209-12
7. (1995). "Endarterectomy for asymptomatic carotid artery stenosis. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study." Jama 273(18): 1421-8
8. Hobson, R. W., 2nd, D. G. Weiss, et al. (1993). "Efficacy of carotid endarterectomy for asymptomatic carotid stenosis. The Veterans Affairs Cooperative Study Group." N Engl J Med 328(4): 221-7.

1. Ballotta, E., L. Renon, et al. (2005). "Prospective randomized study on asymptomatic severe carotid stenosis and perioperative stroke risk in patients undergoing major vascular surgery: prophylactic or deferred carotid endarterectomy?" Ann Vasc Surg 19(6): 876-81.
We compared the perioperative (30-day) stroke risk in asymptomatic patients with severe carotid stenosis who underwent carotid endarterectomy (CEA) before or after major vascular surgery. Seventy-nine patients with asymptomatic severe carotid lesion were randomly assigned to group I (n = 40) or group II (n = 39) to receive prophylactic CEA (within 1 week before major surgery) or deferred CEA (between 30 days and 6 months after major surgery), respectively. All procedures were eversion CEAs performed under deep general anesthesia and cerebral protection involving continuous electroencephalographic monitoring for selective shunting. There were no perioperative deaths or strokes relating to the major surgical procedure in either group. All group II patients underwent deferred CEA as planned (median 47 days, range 38-94) with no subsequent perioperative deaths or strokes. Two of these patients (5.1%) suffered a minor stroke, however, 65 and 78 days after their major surgical procedure, while awaiting carotid revascularization. Although data emerging from this analysis indicate that severe asymptomatic carotid disease may be safely postponed in patients undergoing major noncarotid vascular surgery, only a multicenter prospective study could determine the most appropriate management of this subset of patients.

2. Halliday, A., A. Mansfield, et al. (2004). "Prevention of disabling and fatal strokes by successful carotid endarterectomy in patients without recent neurological symptoms: randomised controlled trial." Lancet 363(9420): 1491-502.
BACKGROUND: Among patients with substantial carotid artery narrowing but no recent neurological symptom (stroke or transient ischaemia), the balance of surgical risks and long-term benefits from carotid endarterectomy (CEA) was unclear. METHODS: During 1993-2003, 3120 asymptomatic patients with substantial carotid narrowing were randomised equally between immediate CEA (half got CEA by 1 month, 88% by 1 year) and indefinite deferral of any CEA (only 4% per year got CEA) and were followed for up to 5 years (mean 3.4 years). Kaplan-Meier analyses of 5-year risks are by allocated treatment. FINDINGS: The risk of stroke or death within 30 days of CEA was 3.1% (95% CI 2.3-4.1). Comparing all patients allocated immediate CEA versus all allocated deferral, but excluding such perioperative events, the 5-year stroke risks were 3.8% versus 11% (gain 7.2% [95% CI 5.0-9.4], p<0.0001). This gain chiefly involved carotid territory ischaemic strokes (2.7% vs 9.5%; gain 6.8% [4.8-8.8], p<0.0001), of which half were disabling or fatal (1.6% vs 5.3%; gain 3.7% [2.1-5.2], p<0.0001), as were half the perioperative strokes. Combining the perioperative events and the non-perioperative strokes, net 5-year risks were 6.4% versus 11.8% for all strokes (net gain 5.4% [3.0-7.8], p<0.0001), 3.5% versus 6.1% for fatal or disabling strokes (net gain 2.5% [0.8-4.3], p=0.004), and 2.1% versus 4.2% just for fatal strokes (net gain 2.1% [0.6-3.6], p=0.006). Subgroup-specific analyses found no significant heterogeneity in the perioperative hazards or (apart from the importance of cholesterol) in the long-term postoperative benefits. These benefits were separately significant for males and females; for those with about 70%, 80%, and 90% carotid artery narrowing on ultrasound; and for those younger than 65 and 65-74 years of age (though not for older patients, half of whom die within 5 years from unrelated causes). Full compliance with allocation to immediate CEA or deferral would, in expectation, have produced slightly bigger differences in the numbers operated on, and hence in the net 5-year benefits. The 10-year benefits are not yet known. INTERPRETATION: In asymptomatic patients younger than 75 years of age with carotid diameter reduction about 70% or more on ultrasound (many of whom were on aspirin, antihypertensive, and, in recent years, statin therapy), immediate CEA halved the net 5-year stroke risk from about 12% to about 6% (including the 3% perioperative hazard). Half this 5-year benefit involved disabling or fatal strokes. But, outside trials, inappropriate selection of patients or poor surgery could obviate such benefits.

3. Inzitari, D., M. Eliasziw, et al. (2000). "The causes and risk of stroke in patients with asymptomatic internal-carotid-artery stenosis. North American Symptomatic Carotid Endarterectomy Trial Collaborators." N Engl J Med 342(23): 1693-700.
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.

4. Baker, W. H., V. J. Howard, et al. (2000). "Effect of contralateral occlusion on long-term efficacy of endarterectomy in the asymptomatic carotid atherosclerosis study (ACAS). ACAS Investigators." Stroke 31(10): 2330-4.
BACKGROUND AND PURPOSE: The Asymptomatic Carotid Atherosclerosis Study (ACAS) established the effectiveness of prophylactic carotid endarterectomy, for patients in good health who had stenosis >/=60%, if conducted by surgeons with a surgical morbidity and mortality of <3%. This secondary analysis was performed to determine whether the presence of contralateral cervical carotid occlusion alters the efficacy of asymptomatic ipsilateral carotid endarterectomy. METHODS: One hundred sixty-three participants who had a baseline contralateral occlusion documented by Doppler ultrasound (77 medical, 86 surgical) were compared with 1485 participants with a patent contralateral carotid artery (748 medical, 737 surgical) for the risk of a combined end point of perioperative (30-day) death or stroke or long-term (5-year) ipsilateral stroke. RESULTS: For those without contralateral occlusion, surgery was associated with a 6.7% absolute reduction in the 5-year risk (95% CI, 2.1% to 11.4%), while for those with a contralateral occlusion, surgery was associated with a 2.0% absolute increase in risk (95% CI, -9.3% to 5.2%), which was a statistically significant difference in the effect of surgery (P:=0.047). This difference is primarily attributable to low long-term risk for medically managed patients with contralateral occlusion. CONCLUSIONS: While this post hoc analysis should be interpreted with caution, the findings suggest that endarterectomy in asymptomatic subjects with contralateral occlusion provides no long-term benefit (and may be harmful) in preventing stroke and death. These findings were a result of the benign course of medically treated subjects.

5. Moore, W. S., R. F. Kempczinski, et al. (1998). "Recurrent carotid stenosis: results of the asymptomatic carotid atherosclerosis study." Stroke 29(10): 2018-25.
BACKGROUND and PURPOSE: We sought to determine the incidence of recurrent carotid stenosis in patients in the Asymptomatic Carotid Atherosclerosis Study (ACAS) who had undergone carotid endarterectomy and were prospectively followed with Doppler ultrasound for up to 5 years. METHODS: The ACAS database was interrogated to determine the rate of recurrent carotid stenosis (>/=60%) based up angiogram-validated Doppler data, with a 90% and a 95% positive predictive value, as well as information concerning the technologists' interpretation of percent stenosis. These 3 parameters are reported for each of 3 time intervals: within 3 months of operation (residual disease), between 3 and 18 months (early restenoses), and between 18 and 60 months (late restenosis). RESULTS: Of the 825 patients randomized to the surgical arm of the study, 720 actually underwent carotid endarterectomy, and 645 had complete ultrasound data. The aggregate incidence of residual and recurrent carotid stenosis for all time intervals ranged from 12.7% to 20.4%, depending on the positive predictive value confidence level desired. Residual disease occurred in 4.1% to 6.5%; true, early restenosis was found in 7.6% to 11.4%; and late restenosis occurred in 1.9% to 4.9%. None of the traditional risk factors showed a statistically significant effect on recurrent stenosis. The use of patch angioplasty closure reduced overall risk of restenosis from 21.2% to 7.1%, from 16.7% to 4.6%, and from 27.4% to 8.2%, depending on the PPV confidence level desired (P<0.001). Of the 136 patients judged to have recurrent stenosis, only 8 (5.9%) underwent reoperation (only 1 for symptoms). There was no correlation between late stroke and recurrent stenosis. CONCLUSIONS: Carotid endarterectomy is a durable procedure with a low rate of true restenosis, particularly when patch angioplasty is used to close the arteriotomy.

6. (1995). "Risk of stroke in the distribution of an asymptomatic carotid artery. The European Carotid Surgery Trialists Collaborative Group." Lancet 345(8944): 209-12.
Screening and carotid endarterectomy have been advocated for asymptomatic carotid stenosis. However, the risk of stroke without treatment has not been adequately defined. We investigated the risk of stroke in the distribution of the asymptomatic carotid artery in 2295 patients randomised in the European Carotid Surgery Trial. During a mean follow-up of 4.5 years, there were 69 carotid territory strokes, nine of which were fatal, giving three year Kaplan-Meier risks of stroke and fatal stroke of 2.1% (95% Cl, 1.5-2.8) and 0.3% (95% Cl, 0.06-0.56) respectively. The stroke risk in the 127 patients with severe (70-99%) carotid stenosis was 5.7% (95% Cl, 1.5-9.8). Given these low stroke risks, the potential benefit of endarterectomy for asymptomatic carotid stenosis is small. Population screening is not justified and endarterectomy for asymptomatic carotid stenosis should only be performed in the context of well organised randomised controlled trials.

7. (1995). "Endarterectomy for asymptomatic carotid artery stenosis. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study." Jama 273(18): 1421-8.
OBJECTIVE--To determine whether the addition of carotid endarterectomy to aggressive medical management can reduce the incidence of cerebral infarction in patients with asymptomatic carotid artery stenosis. DESIGN--Prospective, randomized, multicenter trial. SETTING--Thirty-nine clinical sites across the United States and Canada. PATIENTS--Between December 1987 and December 1993, a total of 1662 patients with asymptomatic carotid artery stenosis of 60% or greater reduction in diameter were randomized; follow-up data are available on 1659. At baseline, recognized risk factors for stroke were similar between the two treatment groups. INTERVENTION--Daily aspirin administration and medical risk factor management for all patients; carotid endarterectomy for patients randomized to receive surgery. MAIN OUTCOME MEASURES--Initially, transient ischemic attack or cerebral infarction occurring in the distribution of the study artery and any transient ischemic attack, stroke, or death occurring in the perioperative period. In March 1993, the primary outcome measures were changed to cerebral infarction occurring in the distribution of the study artery or any stroke or death occurring in the perioperative period. RESULTS--After a median follow-up of 2.7 years, with 4657 patient-years of observation, the aggregate risk over 5 years for ipsilateral stroke and any perioperative stroke or death was estimated to be 5.1% for surgical patients and 11.0% for patients treated medically (aggregate risk reduction of 53% [95% confidence interval, 22% to 72%]). CONCLUSION--Patients with asymptomatic carotid artery stenosis of 60% or greater reduction in diameter and whose general health makes them good candidates for elective surgery will have a reduced 5-year risk of ipsilateral stroke if carotid endarterectomy performed with less than 3% perioperative morbidity and mortality is added to aggressive management of modifiable risk factors.

8. Hobson, R. W., 2nd, D. G. Weiss, et al. (1993). "Efficacy of carotid endarterectomy for asymptomatic carotid stenosis. The Veterans Affairs Cooperative Study Group." N Engl J Med 328(4): 221-7.
BACKGROUND. The efficacy of carotid endarterectomy in patients with asymptomatic carotid stenosis has not been confirmed in randomized clinical trials, despite the widespread use of operative intervention in such patients. METHODS. We conducted a multicenter clinical trial at 11 Veterans Affairs medical centers to determine the effect of carotid endarterectomy on the combined incidence of transient ischemic attack, transient monocular blindness, and stroke. We studied 444 men with asymptomatic carotid stenosis shown arteriographically to reduce the diameter of the arterial lumen by 50 percent or more. The patients were randomly assigned to optimal medical treatment including antiplatelet medication (aspirin) plus carotid endarterectomy (the surgical group; 211 patients) or optimal medical treatment alone (the medical group; 233 patients). All the patients at each center were followed independently by a vascular surgeon and a neurologist for a mean of 47.9 months. RESULTS. The combined incidence of ipsilateral neurologic events was 8.0 percent in the surgical group and 20.6 percent in the medical group (P < 0.001), giving a relative risk (for the surgical group vs. the medical group) of 0.38 (95 percent confidence interval, 0.22 to 0.67). The incidence of ipsilateral stroke alone was 4.7 percent in the surgical group and 9.4 percent in the medical group. An analysis of stroke and death combined within the first 30 postoperative days showed no significant differences. Nor were there significant differences between groups in an analysis of all strokes and deaths (surgical, 41.2 percent; medical, 44.2 percent; relative risk, 0.92; 95 percent confidence interval, 0.69 to 1.22). Overall mortality, including postoperative deaths, was primarily due to coronary atherosclerosis. CONCLUSIONS. Carotid endarterectomy reduced the overall incidence of ipsilateral neurologic events in a selected group of male patients with asymptomatic carotid stenosis. We did not find a significant influence of carotid endarterectomy on the combined incidence of stroke and death, but because of the size of our sample, a modest effect could not be excluded.