03.04 Mechanical and Structural Characteristics of Carotid Plaques: Analysis by Multi-Array Echotracking System and MRI

Abstract

Background

Combining functional and structural approaches may improve the predictive value for plaque rupture and ischemic events. Two distinct patterns were previously determined along the common carotid artery (CCA) (Paini et al. Stroke 2007): Pattern A (larger radial strain at the plaque level than at adjacent CCA) and its opposite, Pattern B.

Aim

To correlate arterial mechanics and composition of an atherosclerotic plaque at the site of the CCA.

Method

27 patients with carotid stenosis and an atherosclerotic plaque on the ipsilateral CCA were included: 18 asymptomatics (AS) and 9 symptomatics (S, i.e. with previous ischemic stroke). Mechanical parameters were measured at 127 sites on a 4 cm long CCA segment by a novel non-invasive echotracking system (ArtLab®) and plaque composition was determined by non invasive magnetic resonance imaging (MRI).

Results

There was a trend for pattern A (21 patients) being more often associated with “simple” plaque (i.e. AHA stage I-III) than complex plaque (AHA stage IV-VII), by contrast to pattern B (25 patients) (chi square P = 0.054). Pattern B was more frequently observed in S than AS patients (75% vs 43%, P < 0.04). In S patients, plaques were characterized by an outward remodeling (increased external diameter and no change in internal diameter) whereas AS plaques grew according to an inward remodeling.

Conclusion

Patients with previous ischemic stroke had a stiffer carotid at the level of the plaque and present a more “complex” plaque composition than asymptomatic patients. Pattern B and complex plaque composition may lead to a higher risk of rupture.