THE PREVALENCE OF CEREBRAL INFARCTS IN THE ASYMPTOMATIC CAROTID SURGERY TRIAL (ACST) IN RELATION TO PRIOR CONTRALATERAL SYMPTOMS

Background. The ACST has randomised over 1670 patients to determine if carotid endarterectomy (CEA) prolongs stroke free survival versus bes t medical treatment alone. Some patients have had contralateral sympto ms to the side under investigation, for which CEA may have been perfor med. This study aims to determine the prevalence of hemispheric cerebr al infarcts in relation to prior contralateral symptoms. Methods. Pati ents with preoperative CT or MR scans were divided into those with pri or contralateral stroke, cortical TIA, amaurosis fugax or no symptoms. Results. There were 1144 patients with preoperative CT and 170 patien ts with MR scans. Incidence of contralateral hemispheric CT and MR inf arcts were 19% (222/1144) and 20% (34/170) respectively. Those with pr ior contralateral stroke (141) had the highest incidence of hemispheri c CT infarcts (62%). Those with TIA (129) had a 30% incidence of CT in farct. Incidence of hemispheric CT infarcts were 17% with amaurosis fu gax (46) and 10% with no prior symptoms (803). Mantel-Haenszel test fo r linear association was significant (p<0.001) for increasing severity of symptoms. Considering MR scans, those with prior contralateral str oke (17) had the highest incidence of hemispheric MR infarcts (53%). P atients with TIA (23) or amaurosis fugax (6) had a 27% incidence of MR infarction. Those with no prior symptoms (121) had a 14% incidence of MR infarcts. Mantel-Haenszel test was significant (p<0.001). Conclusi ons. In the ACST, currently asymptomatic patients have an incidence of contralateral hemispheric CT and MR infarcts proportional to the seve rity of prior contralateral symptoms.