Carotid plaque hemorrhage on magnetic resonance imaging strongly predicts recurrent ischemia and stroke

ObjectiveThere is a recognized need to improve selection of patients with carotid artery stenosis for carotid endarterectomy (CEA). We assessed the value of magnetic resonance imaging (MRI)-defined carotid plaque hemorrhage (MRIPH) to predict recurrent ipsilateral cerebral ischemic events, and stroke in symptomatic carotid stenosis. MethodsOne hundred seventy-nine symptomatic patients with 50% stenosis were prospectively recruited, underwent carotid MRI, and were clinically followed up until CEA, death, or ischemic event. MRIPH was diagnosed if the plaque signal intensity was >150% that of the adjacent muscle. Event-free survival analysis was done using Kaplan-Meier plots and Cox regression models controlling for known vascular risk factors. We also undertook a meta-analysis of reported data on MRIPH and recurrent events. ResultsOne hundred fourteen patients (63.7%) showed MRIPH, suffering 92% (57 of 62) of all recurrent ipsilateral events and all but 1 (25 of 26) future strokes. Patients without MRIPH had an estimated annual absolute stroke risk of only 0.6%. Cox multivariate regression analysis proved MRIPH as a strong predictor of recurrent ischemic events (hazard ratio [HR]=12.0, 95% confidence interval [CI]=4.8-30.1, p<0.001) and stroke alone (HR=35.0, 95% CI=4.7-261.6, p=0.001). Meta-analysis of published data confirmed this association between MRIPH and recurrent cerebral ischemic events in symptomatic carotid artery stenosis (odds ratio=12.2, 95% CI=5.5-27.1, p<0.00001). InterpretationMRIPH independently and strongly predicts recurrent ipsilateral ischemic events, and stroke alone, in symptomatic 50% carotid artery stenosis. The very low stroke risk in patients without MRIPH puts into question current risk-benefit assessment for CEA in this subgroup.