ARE WE DETECTING AND OPERATING ON HIGH-RISK PATIENTS IN THE ASYMPTOMATIC CAROTID SURGERY TRIAL

Objective: This study aims to determine whether asymptomatic carotid s urgery trial (ACST) centres have entered and can identify high risk pa tients using duplex. Design: Retrospective study. Materials and method s: Eighty-six vascular laboratories collaborating in ACST were studied . Equipment, operator experience, methodology and interpretation crite ria were assessed. The ACST randomisation data were examined to determ ine whether patients believed to be at higher risk of stroke because o f tight stenosis, contralateral occlusion or echolucent plaque were ra ndomised. 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 plas 30-60 degrees in 65%, 60 degre es in 28% and 60-80 degrees in 6% of laboratories. Sixty-two per cent reported diameter reduction, 27% area reduction, and 11% used both met hods. One-third of 1657 randomised patients were reported to have ipsi lateral echolucent plaque. Median ipsilateral stenosis was 80%, 8% had contralateral occlusion and 8.5% had bilateral >80% stenosis. Conclus ions: Centres in ACST use experienced operators, high quality equipmen t and conscientious data recording. Variations in methods of determini ng carotid stenosis exist, but can be smoothed by simple data collecti on, 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.