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Benavente et al (1) recently produced the first systematic review of the
evidence to date showing a relatively small benefit in favour of surgery
for asymptomatic carotid stenosis. They concluded that the modest benefit
of surgery in unselected patients was not sufficient to justify carotid
endarterectomy pending reliable identification of a high-risk subgroup.
The meta-analysis was done on 2440 patients from five trials. Subgroup
analysis to identify patients with asymptomatic carotid stenosis at higher
risk of ipsilateral stroke that may benefit from carotid endarterectomy
was not possible. The cost of operating on patients with modest benefit is
unaffordable. In a recent editorial, Warlow (2) highlights the problems of
applying the results of randomised trials and meta-analysis in clinical
practice as clinicians treat patients as individuals. The individual risk
of stroke is very low. However there remains a group where there is
considerable doubt in the clinicians mind as to whether surgery or best
medical treatment is better. These patients in the so called "grey area",
are currently randomised in the ongoing Asymptomatic carotid surgery trial
(ACST) (3).
The ACST is a large ongoing trial aimed at 3200 patients to determine
the place of surgery in patients with significant asymptomatic carotid
stenosis. Approved collaborators may enter patients if they are
substantially uncertain whether surgery may be beneficial and the patient
is fit and willing to be followed up.
So far 137 collaborators in 26 countries have entered more than 2000
patients. Two-thirds of patients are men and the mean patient age is 68
years. Systemic risk factors found at randomisation are diabetes, coronary
artery disease, elevated cholesterol and hypertension. Local risk factors
include ipsilateral echolucent plaque, silent CT infarction and history of
contralateral occlusion or operation (4). Presently mean follow-up is 20
months per patient.
The ACST Data Monitoring Committee recently urged continued
recruitment of high-risk patients. At present, mean randomised stenosis is
76% of which 9% have bilateral >80% stenosis, and 8% have contralateral
occlusion. At its conclusion ACST will have randomised a larger number of
patients than the recent meta-analysis, with information on potentially
important variables to analyse treatment effect in possibly relevant
subgroups. This information can be used as the basis of a larger meta-
analysis with greater power to identify the high-risk group who might
benefit from surgery in a cost-effective way (5). ACST welcomes further
collaborators to help determine the place of surgery in preventing
disabling stroke.
P Robless Specialist registrar in general surgery
A Halliday Principal Investigator, ACST
ACST, Academic Surgical Unit
Division of Surgery
Imperial College School of Medicine
St. Mary's Hospital
Praed St
London W2 1NY
References
1. Benavente O, Moher D, Pham B.Carotid endarterectomy for
asymptomatic carotid artery stenosis: a meta-analysis. BMJ 1998;317: 1477-
80
2. Warlow. Carotid endarterectomy for asymptomatic carotid artery
stenosis: Better data but the case is still not convincing. BMJ
1998;317:1468
3. Halliday AW for the Steering Committee and for the Collaborators.
The Asymptomatic carotid surgery trial (ACST) rationale and design. Eur J
Vasc Surg 1994;8:703-10
4. Robless P, Emson M, Thomas D, Mansfield A and Halliday A. Are we
detecting and operating on high risk patients in the Asymptomatic carotid
surgery trial. Eur J Vasc Endovasc Surg 1998; 16:59-64
5. Rothwell P M, Slattery J, Warlow CP. A systematic comparison of
the risks of stroke and death due to carotid endarterectomy for
symptomatic and asymptomatic stenosis. Stroke 1996;27:266-69
Carotid endarterectomy for asymptomatic carotid stenosis: better data, but the grey area persists
EDITOR
Benavente et al (1) recently produced the first systematic review of the
evidence to date showing a relatively small benefit in favour of surgery
for asymptomatic carotid stenosis. They concluded that the modest benefit
of surgery in unselected patients was not sufficient to justify carotid
endarterectomy pending reliable identification of a high-risk subgroup.
The meta-analysis was done on 2440 patients from five trials. Subgroup
analysis to identify patients with asymptomatic carotid stenosis at higher
risk of ipsilateral stroke that may benefit from carotid endarterectomy
was not possible. The cost of operating on patients with modest benefit is
unaffordable. In a recent editorial, Warlow (2) highlights the problems of
applying the results of randomised trials and meta-analysis in clinical
practice as clinicians treat patients as individuals. The individual risk
of stroke is very low. However there remains a group where there is
considerable doubt in the clinicians mind as to whether surgery or best
medical treatment is better. These patients in the so called "grey area",
are currently randomised in the ongoing Asymptomatic carotid surgery trial
(ACST) (3).
The ACST is a large ongoing trial aimed at 3200 patients to determine
the place of surgery in patients with significant asymptomatic carotid
stenosis. Approved collaborators may enter patients if they are
substantially uncertain whether surgery may be beneficial and the patient
is fit and willing to be followed up.
So far 137 collaborators in 26 countries have entered more than 2000
patients. Two-thirds of patients are men and the mean patient age is 68
years. Systemic risk factors found at randomisation are diabetes, coronary
artery disease, elevated cholesterol and hypertension. Local risk factors
include ipsilateral echolucent plaque, silent CT infarction and history of
contralateral occlusion or operation (4). Presently mean follow-up is 20
months per patient.
The ACST Data Monitoring Committee recently urged continued
recruitment of high-risk patients. At present, mean randomised stenosis is
76% of which 9% have bilateral >80% stenosis, and 8% have contralateral
occlusion. At its conclusion ACST will have randomised a larger number of
patients than the recent meta-analysis, with information on potentially
important variables to analyse treatment effect in possibly relevant
subgroups. This information can be used as the basis of a larger meta-
analysis with greater power to identify the high-risk group who might
benefit from surgery in a cost-effective way (5). ACST welcomes further
collaborators to help determine the place of surgery in preventing
disabling stroke.
P Robless Specialist registrar in general surgery
A Halliday Principal Investigator, ACST
ACST, Academic Surgical Unit
Division of Surgery
Imperial College School of Medicine
St. Mary's Hospital
Praed St
London W2 1NY
References
1. Benavente O, Moher D, Pham B.Carotid endarterectomy for
asymptomatic carotid artery stenosis: a meta-analysis. BMJ 1998;317: 1477-
80
2. Warlow. Carotid endarterectomy for asymptomatic carotid artery
stenosis: Better data but the case is still not convincing. BMJ
1998;317:1468
3. Halliday AW for the Steering Committee and for the Collaborators.
The Asymptomatic carotid surgery trial (ACST) rationale and design. Eur J
Vasc Surg 1994;8:703-10
4. Robless P, Emson M, Thomas D, Mansfield A and Halliday A. Are we
detecting and operating on high risk patients in the Asymptomatic carotid
surgery trial. Eur J Vasc Endovasc Surg 1998; 16:59-64
5. Rothwell P M, Slattery J, Warlow CP. A systematic comparison of
the risks of stroke and death due to carotid endarterectomy for
symptomatic and asymptomatic stenosis. Stroke 1996;27:266-69
Competing interests: No competing interests