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

Objective There 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. Methods One 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. Results One 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). Interpretation MRIPH 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

Magnetic resonance imaging plaque hemorrhage for risk stratification in carotid artery disease with moderate risk under current medical therapy

Background and Purpose—Magnetic resonance imaging (MRI)–defined carotid plaque hemorrhage (MRIPH) can predict recurrent cerebrovascular ischemic events in severe symptomatic carotid stenosis. It is less clear whether MRIPH can improve risk stratification despite optimized medical secondary prevention in those with moderate risk. Methods—One-hundred fifty-one symptomatic patients with 30% to 99% carotid artery stenosis (median age: 77, 60.5% men) clinically deemed to not benefit from endarterectomy were prospectively recruited to undergo MRI and clinical follow-up (mean, 22 months). The clinical carotid artery risk score could be evaluated in 88 patients. MRIPH+ve was defined as plaque intensity >150% that of adjacent muscle. Survival analyses were performed with recurrent infarction (stroke or diffusion-positive cerebral ischemia) as the main end point. Results—Fifty-five participants showed MRIPH+ve; 47 had low, 36 intermediate, and 5 high carotid artery risk scores. Cox regression showed MRIPH as a strong predictor of future infarction (hazard ratio, 5.2; 95% confidence interval, 1.64–16.34; P=0.005, corrected for degree of stenosis), also in the subgroup with 50% to 69% stenosis (hazard ratio, 4.1; 95% confidence interval, 1–16.8; P=0.049). The absolute risk of future infarction was 31.7% at 3 years in MRIPH+ve versus 1.8% in patients without (P<0.002). MRIPH increased cumulative risk difference of future infarction by 47.1% at 3 years in those with intermediate carotid artery risk score (P=0.004). Conclusions—The study confirms MRIPH to be a powerful risk marker in symptomatic carotid stenosis with added value over current risk scores. For patients undergoing current secondary prevention medication with clinically uncertain benefit from recanalization, that is, those with moderate degree stenosis and intermediate carotid artery risk scores, MRIPH offers additional risk stratification

The unstable carotid plaque and brain ischaemia : non-invasive detection, pathophysiological and clinical implications

The aim of this thesis was to test the hypothesis that the detection of plaque haemorrhage by Magnetic Resonance Imaging (MRI PH+) is a clinical valid biomarker of unstable carotid disease in patients with symptomatic high grade carotid disease. This hypothesis was tested by a series of studies in patients with symptomatic high grade stenosis including a comparison of MRI PH+ to histological assessment of plaque instability, and an examination of the relationships between MRI PH+ and cerebral ischaemia as assessed by microembolisation, cerebral white matter hyperintense lesions (WMHL), diffusion weighted cerebral imaging (DWI) and clinical assessment. MRI PH+ carotid plaques were associated with features of active plaque disease, including inflammation. The senstiviity and specificity of MRI PH+ to detect spontaneous and intra-operative microembolic signals (detected by transcranial Doppler) was high (85 and 83%) and moderate (51 and 54%), respectively. Cerebral WMHL were found to be more prevalent (mean number [S.D.]: 3.3[3.3] vs. 2.1[2.5]) and larger (mean volume [S.D.]: 10.3[9.3] vs. 7.0[6.6] ml) in hemispheres ipsilateral to MRI PH+ rather than MRI PH- carotid plaques. MRI PH+ increased the risk of developing cerebral DWI ischaemic lesions (odds ratio 6.2; 95% C.I. 1.7-21.8) and were associated with multiple lesions of different ages. MRI PH + symptomatic carotid plaques increased the short-term risk of ipsilateral ischaemic neurological events with a hazard ratio of 5.9 (95% C.I. 1.4- 25.6); but not in the contralateral, asymptomatic side. This work has demonstrated that MRI PH is a potential valid biomarker of plaque instability in patients with symptomatic carotid stenosis. Further studies are required to se if risk stratification can be improved using other plaque features and improved localization of plaque haemorrhage.EThOS - Electronic Theses Online ServiceGBUnited Kingdo