Elastic properties of the common carotid artery in different stroke subtypes associated with arterial hypertension

Background and Purpose: Arterial hypertension is the major risk factor for intracerebral haemorrhage (ICH) and lacunar infarction (LI) and both types of cerebral lesions originate from pathology of the same deep perforating small arteries. It has also a key role in the atherodegenerative process in large blood vessels resulting in large vessel atherosclerotic disease (LVA). Decreased elasticity and increased stiffness in large and medium-sized arteries are markers of structural and functional vessel wall properties and have been associated with cardiovascular risk. Increased aortic stiffness has been shown to be a strong and independent predictor of cardiovascular and cerebrovascular mortality in patients with essential hypertension. Moreover, common carotid arterial stiffness has been associated cross-sectionally with atherosclerosis at various sites in the vascular tree, generalised narrowing of the retinal arterioles and spontaneous cervical artery dissection. In contrast to these findings, little is known regarding the relationship between the local stiffness of the CCA and manifest cerebrovascular disease. We aimed to evaluate cross-sectionally the distensibility of the common carotid artery (CCA) in the former 3 stroke subtypes that are etiologically related to hypertension and in a subgroup of control patients.

Methods: We prospectively collected data from 249 first-ever stroke patients (79 cases with LVA, 92 cases with LI and 78 cases with ICH) and in 80 control subjects who were referred to the hypertension center of our institution. All subjects underwent ultrasonographic measurements of the CCA-distensibility. Logistic regression modeling was used to determine the factors (established vascular risk factors, severity and duration of hypertension, concomitant medications, CCA-distensibility, CCA-intima-media-thickness) that were significantly associated with each stroke subgroup.

Results: The CCA distensibility (inverse of CCA stiffness) was significantly lower in LVA and LI than in control subjects even after adjusting for blood pressure values, diastolic CCA-diameter and height. CCA-IMT and CCA distensibility were similar between ICH and control patients. For each decrease of 0.1mm in the CCA distensibility, the likelihood of suffering from LVA and LI independently increased by 31.2% (95% CI:8.8%-58.5%; p=0.006) and 26.5% (95% CI: 5.8%-51.5%; p=0.009) respectively, even after adjustment for cardiovascular risk factors and CCA-IMT.

Conclusions: Increased CCA stiffness is associated with LVA and LI independent of conventional risk factors and CCA-IMT. This finding suggests that the assessment of carotid stiffness can provide useful information in predicting stroke risk independent of the extent of large artery atherosclerosis. Ultrasonographic measurements of CCA-IMT and CCA distensibility may be useful non-invasive diagnostic tools for the risk assessment of specific stroke subtypes in hypertensive patients.

Key words: Hypertension, stroke, atherosclerosis, distensibility, stiffness, elastic properties, carotid artery.