Are we detecting and operating on high risk patients in the asymptomatic carotid surgery trial? The Asymptomatic Carotid Surgery Trial Collaborators.
OBJECTIVE
This study aims to determine whether asymptomatic carotid surgery trial (ACST) centres have entered and can identify high risk patients using duplex.


METHODS
Retrospective study.


METHODS
Eighty-six vascular laboratories collaborating in ACST were studied, Equipment, operator experience, methodology and interpretation criteria were assessed. The ACST randomisation data were examined to determine whether patients believed to be at higher risk of stroke because of tight stenosis, contralateral occlusion or echolucent plaque were randomised.


RESULTS
Laboratories (92%) had colour duplex and 62% of all operators had > 3 years experience in carotid evaluation. The Doppler angle used to obtain peak velocity was 30-60 degrees in 65%, 60 degrees in 28% and 60-80 degrees in 6% of laboratories. Sixty-two per cent reported diameter reduction, 27% area reduction, and 11% used both methods. One-third of 1657 randomised patients were reported to have ipsilateral echolucent plaque. Median ipsilateral stenosis was 80%, 8% had contralateral occlusion and 8.5% had bilateral > 80% stenosis.


CONCLUSIONS
Centres in ACST use experienced operators, high quality equipment and conscientious data recording. Variations in methods of determining carotid stenosis exist, but can be smoothed by simple data collection. Patients at higher perceived risk of stroke are being entered and with continued recruitment it should be possible to determine whether surgery improves disabling stroke-free survival.
Academic Surgical Unit, Imperial College School of Medicine at St. Mary's, London, U.K.
P
P
Robless
M
M
Emson
D
D
Thomas
A
A
Mansfield
A
A
Halliday
D000792:Angiography; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D016893:Carotid Stenosis / Q000000981:diagnostic imaging / Q000601:surgery; D002561:Cerebrovascular Disorders / Q000517:prevention & control; D016894:Endarterectomy, Carotid; D006801:Humans; D008962:Models, Theoretical; D018579:Patient Selection; D012307:Risk Factors; D013997:Time Factors; D018615:Ultrasonography, Doppler, Color