Metabolic syndrome amplifies the LDL-cholesterol associated increases in carotid atherosclerosis

Carotid intima-media thickness (IMT) is a useful surrogate marker of cardiovascular disease. In addition to low-density lipoprotein cholesterol (LDL-C), metabolic syndrome has been linked to the pathogenesis of atherosclerosis. The present study investigated whether the clustering of multiple components of metabolic syndrome has a greater impact on vascular parameters than individual components of metabolic syndrome, and assessed the association between carotid IMT and LDL-C and metabolic syndrome.

Carotid IMT was evaluated on B-mode ultrasonography in 760 patients (340 men aged 64+/-16 years and 420 women aged 69+/-13 years) in the Medical Department of Seiyo Municipal Nomura Hospital. The subjects did not demonstrate any clinical signs of cardiovascular disease. We investigated the association between carotid IMT and confounding risk factors including LDL-C and metabolic syndrome using the 2005 Japanese criteria.

Carotid IMT increased with increasing numbers of metabolic syndrome components (p for trend<0.001). Multiple regression models, including age, sex, body mass index, smoking status, LDL-C, diabetes mellitus as well as each individual component of metabolic syndrome as continuous variables, showed that both metabolic syndrome (beta=0.100; p=0.029) and LDL-C (beta=0.210, p<0.001) were independent determinants of carotid IMT. Metabolic syndrome amplified the LDL-C associated increases in carotid atherosclerosis.

Even after taking into account each individual component of MS, the clustering of visceral obesity with at least 2 of the 3 components, and LDL-C are independently associated with increased carotid IMT. This suggests that the components of metabolic syndrome interact to synergistically impact vascular thickness.