04.02 The Metabolic Syndrome is Associated with Central and Peripheral Arterial Stiffness in Young Women but not in Men: The Mediating Role of Insulin Resistance and Low-Grade Inflammation. The Northern Ireland Young Hearts Project (NIYHP)

Abstract

Increased arterial stiffness may explain, at least in part, the increased cardiovascular and diabetes risk associated with the metabolic syndrome (MetS). However, the mechanisms linking the MetS to an increased (central and/or peripheral) arterial stiffness are incompletely understood and gender differences may exist. We therefore examined whether: (1) the (clustering of the) risk factors (RFs) of the MetS is associated with stiffness of central and peripheral arterial segments; (2) these associations were similar in men and women; and (3) insulin resistance and low-grade inflammation mediated any such associations.

Subjects were 313 young men and women (mean age of 23), participating in an ongoing longitudinal study (NIYHP). Subjects were categorized according to the number of RFs of the MetS; in addition, a continuous MetS score was calculated. Arterial stiffness was assessed by measuring pulse wave velocity (PWV) in three arterial segments (non-invasive optical method).

The prevalence of the MetS was similar for men (10.6%) and women (10.5%). After adjustment for potential confounders and other RFs, PWV of the three arterial segments investigated increased with increasing traits of the MetS in women only. Women with the MetS, as compared to those without RFs of the syndrome, had greater PWV of the aorto-iliac (+14.0%, p = 0.016), the aortic-radial (+13.2%, p = 0.010) and aorto-dorsalis pedis (+11.8%, p = 0.011) segments. A great deal of the association (up to 75%) between the MetS and aortic-iliac PWV was mediated by heart rate, inflammation markers (CRP and fibrinogen) and insulin resistance (HOMA-IR), whereas these variables did not explain much of the association between the MetS and PWV of the peripheral segments.

Young women with the MetS show increased stiffness of peripheral and central arteries, a mechanism that may explain their increased cardiovascular risk. Low grade inflammation, insulin resistance and sympathetic activation explain much of the adverse impact of the MetS on central, but not peripheral, arterial stiffness.