The vulnerability to rupture of carotid plaque depends on the various types of mechanical stress including higher circumferential wall stress (CWS) in hypertensives and histological characteristics of plaque.

Objective: determine the multiaxial mechanical deformations of the common carotid artery (CCA) with an echotracking system allowing measurement of thickness, diameter, strain, distensibility, elastic modulus (Einc) and CWS on 4 cm long CCA segments including plaque. This allowed us to determine a longitudinal bending stress (BS) equal to the ratio of strain at the level of plaque to strain of adjacent CCA.

Patients: we included 25 patients with a recent cerebrovascular ischemic event and a plaque on CCA homolateral to stroke territory. We divided patients into two groups according to BS behaviour: pattern A (outward BS, larger strain at plaque site than on CCA), pattern B (inward BS).

Results: 16 patients belonged to pattern A and 8 patients to pattern B. Prevalence of dysplipidemia and diabetic were higher in pattern B (100% vs 56%, p = 0.03 and 63% vs 12%, p = 0.04). In pattern B distensibility was significantly lower at the level of plaque than in CCA it was the converse in A patients (13.1±6.5 vs 18.2±3.9, p < 0.003 and 22.3±11.2 vs 16.6±12.4 kPa⁻¹10⁻³, p < 0.001). Pattern A patients had lower Einc at the level of the plaque than of CCA (374±173 vs 802±669 kPa, p < 0.01) the opposite was observed in B patients (739±497 vs 543±146 kPa, p < 0.01). CWS in CCA was higher in B than in A patients (83±16 vs 65±15 kPa, p < 0.01), plaque CWS was similar in the two groups (60±7 vs 53±13 kPa, NS).

Conclusion: type 2 diabetes and dyslipidemia were associated with a stiffer plaque than adjacent CCA. These results suggest that the higher risk of plaque complication, reported in patients with diabetes and hypercholesterolemia, may be due to a specific pattern of strain gradient between plaque and adjacent CCA.