Metabolic syndrome increases carotid artery stiffness: the Northern Manhattan Study

Abstract

Background: Arterial stiffness, an intermediate pre-clinical marker of atherosclerosis, has been associated with an increased risk of stroke and cardiovascular disease. The metabolic syndrome and its components are established cardiovascular disease risk factors and may also increase arterial stiffness; however, data regarding this are limited.

Aim: The goal of this study was to determine the association between the metabolic syndrome and carotid artery stiffness in an elderly multi-ethnic cohort.

Methods: Carotid artery stiffness was assessed by carotid ultrasound as part of the Northern Manhattan Study, a prospective population-based cohort of stroke-free individuals. Carotid artery stiffness was calculated as [ln(systolic BP/diastolic BP)/strain], where strain was [(systolic diameter-diastolic diameter)/diastolic diameter]. Metabolic syndrome was defined by the National Cholesterol Education Program: Adult Treatment Panel III criteria. LogSTIFF was analysed as the dependent variable in linear regression models, adjusting for demographics, education, current smoking, presence of carotid plaque and intima-media thickness.

Results: Carotid artery stiffness was analysed in 1133 Northern Manhattan Study subjects (mean age 65 +/- 9 years; 61% women; 58% Hispanic, 22% Black and 20% Caucasian). The prevalence of the metabolic syndrome was 49%. The mean LogSTIFF was 2.01 +/- 0.61 among those with the metabolic syndrome and 1.90 +/- 0.59 among those without the metabolic syndrome (P=0.003). The metabolic syndrome was significantly associated with increased logSTIFF in the final adjusted model (parameter estimate beta=0.100, P=0.01). Among individual metabolic syndrome components, waist circumference and elevated blood pressure were most significantly associated with a mean increase in logSTIFF (P<0.01).

Conclusion: The metabolic syndrome is significantly associated with increased carotid artery stiffness in a multiethnic population. Increased carotid artery stiffness may, in part, explain a high risk of stroke among individuals with the metabolic syndrome.

Figure 1

A. B and M-mode image of the CCA diameter change during the cardiac cycles B. M-mode tracing of the CCA diameter during the cardiac cycle

Figure 2

Figure 2A. Metabolic syndrome components and gender The numbers express in percentage indicate the prevalence of Metabolic Syndrome components in the overall patients. Figure 2B. Metabolic syndrome components and race-ethnicity BP indicates blood pressure ≥130/85 mm Hg; FBS indicates fasting blood sugar ≥110 mg/dL; Waist indicates waist circumference >40.8” in men and >35.2” in women; Trig. Indicates triglycerides ≥150 mg/dL; HDL indicates high-density lipoprotein <40 mg/dL in men and <50 mg/dL in women.