Left versus right carotid artery IMT: differential impact of age, gender, and cardiovascular risk factors

Carotid artery intima-media thickness (IMT), an important clinical marker of atherosclerosis, is used widely in screening for cardiovascular risk and prognosis. Measurements of carotid artery IMT are made on both the left and right sides of the body, however as per the Mannheim consensus, an average of these measurements is usually reported. Nevertheless, there is considerable debate whether there are side differences in the carotid artery IMT in terms of both measurements and determinants. In a large sample of Caucasian patients (n = 1888) referred for cardiovascular risk assessment, we compared the left and the right common carotid artery IMT measurements, and assessed whether age, gender and cardiovascular risk factors have differential effects. We found that the left common carotid artery IMT (0.7141 ± 0.1733 mm) is larger than the right (0.6861 ± 0.1594, p < 0.0001), but not in the young (< 30 years) or the elderly (> 69 years), and that this side difference is less in women (0.019 ± 0.116 mm) than in men (0.036 ± 0.148 mm, p < 0.001). In addition to age (p < 0.0001) and gender (p < 0.0001), the left common carotid artery IMT was determined by dyslipidaemia (protective, p = 0.016) and diabetes mellitus (p = 0.022); whereas the right common carotid artery IMT was determined by hypertension (p = 0.0002). The differential determinants of left versus right common carotid artery IMT were similar in men and women, and in young and old. In conclusion, side differences in measurements of the common carotid artery IMT depend upon age and gender. In addition, cardiovascular risk factors have differential effects on the left and right common carotid artery IMT.