Abstract 67: Importance Of Previous Brain Infarcts In Patients With Asymptomatic Carotid Stenosis And The Impact Of Surgery From The Asymptomatic Carotid Surgery Trial-1

Abstract

Background and aims: Silent brain infarcts are common in patients at increased risk of stroke and are associated with a poor prognosis. Similar adverse associations were claimed in asymptomatic carotid stenosis (ASCS) patients but the impact of previous infarction or symptoms on the beneficial effects of carotid endarterectomy (CEA) is not clear. Our aim was to evaluate the importance of prior brain infarcts (PBI) in ASCS patients enrolled in ACST-1 - a large trial with 10-year follow-up. Methods: Of 3120 patients included in ACST-1, 787 patients without baseline imaging were excluded. Trial patients (2333) with brain imaging at trial entry were identified & divided into those with PBI (i.e. radiological evidence of an asymptomatic infarct or prior ischaemic symptoms [PIS] >6 months prior to randomization) (group 1, 1331 patients) & those with normal imaging and no PIS (group 2, 1002 patients). The trial allocated immediate CEA treatment to about half of the patients in both groups. First stroke and vascular death in these groups were compared during follow-up irrespective of treatment assignment and, for both groups, the impact of CEA was analyzed. Results: Baseline characteristics of excluded & analyzed patients were similar, male gender and hypertension being commoner in group 1 with slightly tighter ipsilateral stenosis in group 2. After 10 years stroke was significantly commoner in group 1 (absolute risk increase [ARI] 5.8% [1.8-9.8], p=0.004) as was risk of stroke and vascular death (6.9% [1.9-12.0] ARI, p=0.007). Multivariate analysis confirmed that PBI was associated with greater risk of stroke (HR=1.51 95%CI:1.17-1.95) and of any stroke or other vascular death (HR=1.30 95%CI:1.11-1.52). Benefits of CEA at 5 years appeared greater for group 1 patients (gain 4.9% p=0.005%) than for group 2 (gain at 5 years, 3.9% p=0.02%) though it must be emphasized that the trial was not designed to test this comparison. Conclusions: ASCS patients with prior brain infarcts have higher stroke risk during long-term follow-up than those without PBI and may benefit more from CEA.