An integrative view on the carotid artery alterations in metabolic syndrome

The Effect of Metabolic Syndrome on the Occurrence of Restenosis After Carotid Endarterectomy

OBJECTIVES

The metabolic syndrome (MetS) is a cluster of risk factors for cardiovascular disease. The effect of MetS on clinical outcome in patients with cerebrovascular disease remains largely unknown because conflicting results have been published. This study aimed to determine the influence of MetS on the occurrence of restenosis after carotid endarterectomy (CEA).

METHODS

All patients who underwent CEA between June 2003 and December 2014 in two tertiary academic referral centres in The Netherlands were included. MetS was defined if three or more of the following criteria were present: hypertension, obesity, high fasting serum blood glucose, high serum triglycerides, or low serum high density lipoprotein cholesterol. The primary outcome measure was the occurrence of ipsilateral restenosis after index surgery. The secondary outcome measure was (all cause) mortality during follow up. For the primary analysis, missing data were multiply imputed using multivariable imputation by chained equations. A Cox proportional hazards model was used to perform an adjusted analysis on the multiply imputed data sets.

RESULTS

A total of 1668 CEA procedures (in 1577 patients) were performed. The presence or absence of MetS could not be determined in 263 patients because of missing data. There was no significant difference in freedom from restenosis in the MetS group vs. the no-MetS group (hazard ratio [HR], 1.10; 95% confidence interval [CI] 0.98-1.23; p = .10) or in all cause mortality (HR 1.20; 95% CI 0.94-1.54; p = .14).

CONCLUSION

This study shows that MetS does not predict restenosis after CEA. Also, the presence of MetS did not influence patient survival negatively.

Associations of plasma glucose levels and traits of metabolic syndrome with carotid intima media thickness in nondiabetic elderly subjects: are they mediated by insulin resistance?

BACKGROUND

The independent role of insulin resistance (IR) and high fasting blood glucose (FBG) levels within the normal range on vascular diseases is still under debate. This study was designed to explore whether IR, FBG levels, and the traits of metabolic syndrome are associated with increased carotid intima media thickness (IMT), the early marker of subclinical atherosclerosis, independently of each other in nondiabetic elderly subjects.

METHODS

Blood analytes and anthropometric measurements were obtained. Carotid IMT was measured by ultrasonography; metabolic syndrome was diagnosed according to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria. IR was assessed through homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

At total of 207 subjects aged 68.2±3.6 years were enrolled. Subjects with increased carotid IMT (50.7%) were older (P=0.001), had a higher prevalence of metabolic syndrome (P<0.0001) and all its traits, impaired fasting glucose (IFG) (P<0.0001), and values of HOMA-IR (P<0.0001) than normal subjects. Increased carotid IMT significantly correlated with metabolic syndrome, its traits, IFG, and HOMA-IR. When multivariable regression models were constructed, central obesity [B=0.392; 95% confidence interval (CI) 0.280-0.505; P<0.0001], high-density lipoprotein cholesterol (HDL-C) (B=-0.007; 95% CI -0.013-0.000; P=0.042], hypertension (B=0.475; 95% CI 0.363-0.587; P<0.0001), and IFG (B=0.230; 95% CI 0.092-0.367; P=0.001) were found to be the independent determinants of increased carotid IMT independently of HOMA-IR, but not FBG (B=0.013; 95% CI 0.000-0.026; P=0.050) and HOMA-IR itself.

CONCLUSIONS

Our results suggest that hypertension, low HDL-C, and central obesity are independently associated with increased carotid IMT in nondiabetic elderly subjects. These associations seem to be not affected by IR. The associations of FBG levels within the normal range and IR with carotid IMT should be investigated further.

Clustering of metabolic syndrome traits is associated with maladaptive carotid remodeling and stiffening: a 6-year longitudinal study

Maladaptive arterial remodeling may constitute a mechanism underlying the risk of stroke in individuals with the metabolic syndrome (MetS), but evidence supporting this contention derives from cross-sectional studies only. We, therefore, investigated, in apparently healthy adults, whether changes in MetS status between the ages of 36 and 42 years (never [n=207, reference group], incident [n=31], recovery [n=23], and persistent [n=32]) were associated with changes in carotid interadventitial diameter, lumen diameter, intima-media thickness, circumferential wall tension and stress, and Young's elastic modulus. All data analyses were adjusted for sex, height, and (changes in) age, lifestyle variables, low-density lipoprotein cholesterol, and use of antihypertensive medication. At baseline and as compared with the reference group, individuals with persistent MetS had significantly higher interadventitial diameter, circumferential wall tension, circumferential wall stress, and Young's elastic modulus but not intima-media thickness. In the course of follow-up, these individuals (versus reference group) displayed significantly steeper increases in intima-media thickness (0.011 versus 0.005 mm/y), which were accompanied by significantly steeper increases in interadventitial diameter (0.077 versus 0.032 mm/y) and lumen diameter (0.055 versus 0.023 mm/y) but not circumferential wall stress, which decreased (-0.34 versus 0.12 kPa/y). These findings suggest that increases in intima-media thickness in young adults with the MetS may primarily reflect an adaptive mechanism that attempts to restore local hemodynamic conditions to an equilibrium rather than atherosclerosis, per se. However, carotid adaptations did not restore circumferential wall stress to levels comparable with those of the reference group, and, therefore, outward remodeling was maladaptive. Importantly, individuals who recovered from the MetS restored carotid properties to levels comparable to the reference group, emphasizing the potential for reversibility.