Magnetic Resonance Imaging Identified Brain Ischaemia in Symptomatic Patients Undergoing Carotid Endarterectomy Is Related to Histologically Apparent Intraplaque Haemorrhage

Abstract

Objective: Intraplaque haemorrhage (IPH) has been independently associated with a higher risk of future ipsilateral stroke in patients with carotid artery stenosis. Evaluation of plaque characteristics may contribute to risk assessment of recurrent (silent) cerebrovascular events in order to prioritise patients for timing of treatment. It is unknown if patients showing histologically apparent IPH also have increased risk of silent ischaemic brain lesions in the waiting period between index event and revascularisation.

Methods: A retrospective analysis was performed based on prospectively collected data of patients included simultaneously in the magnetic resonance imaging (MRI) substudy of the International Carotid Stenting Study and Athero-Express biobank. Patients randomised for carotid endarterectomy (CEA) underwent surgery between 2003 and 2008. Brain MRI was performed one to seven days prior to CEA. Plaques were histologically examined for presence of IPH. The primary outcome parameter was presence of silent ipsilateral brain ischaemia on magnetic resonance diffusion weighted imaging (MR-DWI) appearing hypo or isointense on apparent diffusion coefficient.

Results: Fifty-three patients with symptomatic carotid stenosis meeting the study criteria were identified, of which 13 showed one or more recent ipsilateral DWI lesion on pre-operative scan. The median time between latest ipsilateral neurological event and revascularisation was 45 days (range 6-200) in DWI negative patients vs. 34 days (range 6-74, p = .16) in DWI positive patients. IPH was present in 24/40 (60.0%) DWI negative patients vs. 12/13 (92.3%) DWI positive patients (OR 8.00; 95% CI 0.95-67.7, p = .06). Multivariable logistic regression analysis correcting for age and type of index event revealed that IPH was independently associated with DWI lesions in the waiting period till surgery (OR 10.8; 95% CI 1.17-99.9, p = .04).

Conclusion: Symptomatic patients with ipsilateral carotid stenosis and silent brain ischaemia on pre-operative MR-DWI, more often showed pathological evidence of IPH compared with those without ischaemic lesions. This identifies carotid IPH as a marker for patients at risk of silent brain ischaemia and possibly for future stroke and other arterial disease complications. Such patients may be more likely to benefit from CEA than those without evidence of ipsilateral carotid IPH.

Keywords: Carotid stenosis; Intraplaque haemorrhage; Magnetic resonance diffusion weighted imaging; Silent brain ischaemia.