High-normal blood pressure, impaired glucose regulation and metabolic syndrome have variable impact on central artery stiffness

Type 2 diabetes exacerbates changes in blood pressure-independent arterial stiffness: cross-sectional and longitudinal evidence from the SUMMIT study

Greater central artery stiffness is observed in people with type 2 diabetes (T2DM). Elevated blood pressure (BP) and altered arterial wall structure/composition in T2DM are generally considered as main drivers for this alteration. However, because conventional arterial stiffness measures are BP-dependent and as such an influence of BP remains in a measure, it is unclear if greater central artery stiffness is a function of greater BP, or due to changes in the structure and composition of the arterial wall. We aimed to measure BP-independent arterial stiffness (β0) cross-sectionally and longitudinally in T2DM. We studied 753 adults with T2DM (DM+) and 436 adults without (DM-) at baseline (Phase 1), and 310 DM+ and 210 DM- adults at 3-yr follow-up (Phase 2). We measured carotid-femoral pulse wave velocity and used it to calculate β0. In Phase 1, β0 was significantly greater in DM+ than DM- after adjusting for age and sex [27.5 (26.6-28.3) vs. 23.6 (22.4-24.8) au, P < 0.001]. Partial correlation analyses after controlling for age and sex showed that β0 was significantly associated with hemoglobin A1c (r = 0.15 P < 0.001) and heart rate [(HR): r = 0.23 P < 0.001)] in DM+. In Phase 2, percentage-change in β0 was significantly greater in DM+ than DM- [19.5 (14.9-24.0) vs. 5.0 (-0.6 to 10.6) %, P < 0.001] after adjusting for age, sex, and baseline β0. β0 was greater in DM+ than DM- and increased much more in DM+ than in DM- over 3 yr. This suggests that T2DM exacerbates BP-independent arterial stiffness and may have a complemental utility to existing arterial stiffness indices.NEW & NOTEWORTHY We demonstrate in this study a greater BP-independent arterial stiffness β0 in people with type 2 diabetes (T2DM) compared to those without, and also a greater change in β0 over 3 yr in people with T2DM than those without. These findings suggest that the intrinsic properties of the arterial wall may change in a different and more detrimental way in people with T2DM and likely represents accumulation of cardiovascular risk.

Is Stiffness Parameter β Useful for the Evaluation of Atherosclerosis?~ Its Clinical Implications, Limitations, and Future Perspectives ~

Atherosclerosis comprises two components, atherosis and sclerosis, characterized by morphological wall thickening and functional stiffening, respectively, of the arterial wall. In recent years, much interest has been directed to the role of functional changes in large arteries, i.e., increased stiffness or decreased elasticity, on the development of cardiovascular diseases. In fact, the clinical evaluation of arterial stiffness is increasingly performed in patients with cardiovascular risk factors. Local arterial stiffness is measured using an ultrasound technique implemented with an echo-tracking system at the common carotid and femoral arteries. Several indices of local arterial stiffness are obtained by ultrasound, among which stiffness parameter β is unique because it is the least affected by blood pressure at the time of measurement. Evidence from cross-sectional studies indicates that increased stiffness parameter β is associated with a number of cardiovascular risk factors, such as older age, smoking, insufficient physical activity, hypertension, obesity, metabolic syndrome, insulin resistance, type 2 diabetes, chronic kidney disease, and comorbid cardiovascular disease. Results from several prospective observational studies also suggest that carotid stiffness parameter β is a useful surrogate marker of cardiovascular events and/or mortality, although the results differ depending on the characteristics of the study subjects. Furthermore, several interventional studies have shown that carotid stiffness parameter β improved after lifestyle modification or drug treatment. In this review, we summarize the current evidence of stiffness parameter β of the carotid artery and discuss its clinical implications as a marker of vascular health or as a predictor of cardiovascular outcomes.

Associations between arterial structure and function and serum levels of liver enzymes in obese adolescents

AIM

To determine the structural and functional alterations of systemic arteries in obese adolescents and their relationships with adiposity, metabolic and lipid profile, and serum liver enzyme levels.

METHODS

Carotid intima-media thickness (IMT), carotid stiffness index, and brachial-ankle pulse wave velocity (baPWV) were measured in 56 obese adolescents and 58 lean controls. Obese adolescents had additional liver ultrasound and determination of fasting blood indices of glucose metabolism and lipid profile, and serum levels of liver enzymes.

RESULTS

Carotid IMT (P < 0.0001), carotid stiffness index (P < 0.0001) and baPWV (P = 0.001) were significantly greater in obese than control subjects. Thirty-seven (66%) obese subjects had fatty liver changes and their aspartate aminotransferase, alanine aminotransferase (ALT), alkaline phosphatase, and gamma-glutamyl transferase levels were significantly higher than those without (all P < 0.05). Univariate analyses showed positive correlations between serum ALT (r = 0.29, P = 0.03) and alkaline phosphatase (r = 0.28, P = 0.04) levels and carotid IMT, aspartate aminotransferase level and carotid stiffness (r = 0.41, P = 0.002), and gamma-glutamyl transferase level and baPWV (r = 0.34, P = 0.02) in obese subjects. Multivariate linear regression revealed serum ALT level (β = 0.02, P = 0.006) as an independent correlate of carotid stiffness.

CONCLUSION

Obese adolescents have increased carotid IMT and stiffness, which are associated positively with serum liver enzyme levels.

Carotid artery stiffness is related to hyperinsulinemia and insulin-resistance in middle-aged, non-diabetic hypertensive patients

BACKGROUND AND AIMS

Glycometabolic abnormalities are frequently found in hypertension and could affect the mechanical properties of carotid arteries. The aim of the study was to investigate the relationship of glucose tolerance, plasma insulin, and insulin sensitivity with carotid distensibility in middle-aged, non-diabetic hypertensive patients free of cardiac and vascular complications.

METHOD AND RESULTS

In 93 patients with grade 1-2, uncomplicated, primary hypertension and 68 matched normotensive controls we measured plasma glucose and insulin at fast and after an oral glucose load (OGTT), calculated the HOMA-index as a marker of insulin sensitivity, and assessed distensibility of common carotid arteries by B-mode ultrasonography. Hypertensive patients were hyperinsulinemic and insulin-resistant as compared to normotensive controls. Hypertensive patients with impaired fasting glucose and/or impaired glucose tolerance had comparable distensibility of carotid arteries. Patients with decreased carotid distensibility were older and had higher body mass, fasting and post-OGTT plasma insulin, HOMA-index, and carotid IMT than the remaining patients, but no differences in glycated hemoglobin, and fasting or post-OGTT plasma glucose. Carotid coefficient of distensibility was inversely related and β-stiffness directly related with fasting and post-OGTT plasma insulin, and HOMA-index. Multivariate logistic regression showed that age and post-OGTT plasma insulin levels predicted carotid artery stiffening independent of body mass index, sex, blood pressure, and plasma glucose levels.

CONCLUSIONS

The study demonstrates that decreased insulin sensitivity and the related hyperinsulinemia but not hyperglycemia could contribute to carotid artery stiffening in middle-aged, non-diabetic hypertensive patients free of cardiovascular complications.

Evolution and predictors of morphological and functional arterial changes in the course of type 1 diabetes mellitus

BACKGROUND

Diabetes mellitus results in accelerated atherosclerosis. We evaluated preclinical, morphological and functional vascular changes in type 1 diabetes mellitus.

METHODS

Diameter, intima-media thickness, intima-media cross-section area, and elasticity features (compliance, distensibility coefficient, circumferential strain, stiffness index, incremental elastic modulus) of the common carotid arteries and carotid-femoral pulse wave velocity were studied in 42 patients with type 1 diabetes mellitus without macroangiopathy, and 41 control subjects matched for sex, age and body mass index using an ultrasonographic vessel wall-movement tracking system and applanation tonometry.

RESULTS

Significantly larger intima-media thickness (523 ± 55 versus 567 ± 89 µm, p < 0.01), intima-media cross-section area (11.60 ± 1.81 versus 13.08 ± 3.02 mm(2) , p < 0.01), SI (5.58 ± 1.24 versus 7.08 ± 2.69, p < 0.01) and pulse wave velocity (6.00 ± 0.82 versus 6.61 ± 1.56 m/s, p < 0.05) were found in type 1 diabetes mellitus patients compared to controls. When type 1 diabetes mellitus patients with short and long disease duration (≤ or > 10 years) were compared, diameter (6450 ± 433 versus 6847 ± 750 µm, p < 0.05), intima-media cross-section area (11.97 ± 1.98 versus 14.01 ± 3.43 mm, p < 0.05) and pulse wave velocity (5.90 ± 0.92 versus 7.20 ± 1.74 m/s, p < 0.01) differed significantly. When multivariate analyses were restricted to type 1 diabetes mellitus patients, age was an independent predictor of stiffness index and pulse wave velocity, the duration of diabetes mellitus of intima-media cross-section area and pulse wave velocity, systolic blood pressure of diameter and pulse wave velocity, and low-density lipoprotein-cholesterol of intima-media thickness, intima-media cross-section area and stiffness index.

CONCLUSIONS

There are differences in the time course of evolution and in predictors of morphological and functional changes in arteries in type 1 diabetes mellitus.

Metabolic syndrome increases carotid artery stiffness: the Northern Manhattan Study

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.

Longitudinal changes in central artery stiffness with lifestyle modification, washout, and drug treatment in individuals at risk for cardiovascular disease

We assessed 17 middle-aged and older individuals (58.0 +/- 7.9 years, 7 females) at risk for cardiovascular disease regarding: (1) Whether carotid artery stiffness (cAS) would be reduced with a 1-year lifestyle modification program, (2) to what degree cAS would return following washout (mean of 26.9 +/- 4.0 months) from the active intervention, and (3) whether a 24-week telmisartan treatment would reduce cAS more than our lifestyle modification program. cAS by Doppler ultrasound, cardiovascular disease risk factors, and exercise capacity were assessed at three points: Following the 1-year lifestyle modification, following the washout period, and following a 24-week telmisartan treatment. Following telmisartan, systolic blood pressure (SBP) was significantly decreased (114.8 +/- 12.3 mmHg) compared to baseline (127.9 +/- 12.7 mmHg) and following the washout period (126.1 +/- 14.9 mmHg). Similarly, diastolic blood pressure (DBP) was significantly lower following telmisaratn than following the washout period. Exercise capacity was increased following lifestyle modification but returned to the baseline level following the washout period. Following the lifestyle modification program, cAS was significantly reduced, and this reduction was maintained following the washout period. Conversely, the subsequent telmisartan treatment did not change cAS despite a significant blood pressure reduction. These results suggest that the reduced cAS achieved with lifestyle modification may not necessarily disappear following a cessation of the active program, indicating a possible role that family physicians can play in their clinical practice, and also providing a further rationale to promote lifestyle modification as an initial therapy for this population. In contrast, no additional benefit of telmisartan beyond our lifestyle intervention was observed in this study.

Metabolic syndrome, endothelial function and lifestyle modification

We evaluated (1) endothelial function (FMD, ICAM-1 and VCAM-1) cross-sectionally in subjects with (MS+) and without (MS-) metabolic syndrome who were at increased risk for cardiovascular disease due to either HNBP and/or IGR, and (2) examined in a subgroup of subjects the effects of 24-week lifestyle modification on endothelial function. MS components, FMD by Doppler ultrasound, ICAM-1 and VCAM-1 by fasting blood samples were assessed. All of the endothelial functions were similar between MS- and MS+. Although waist circumference, blood pressure, and fasting glucose showed improvements, endothelial function remained unchanged following the intervention. The results showed that in our subject population, MS does not reduce endothelial function, and our 24-week lifestyle modification programme did not result in an improvement in endothelial function in MS+ despite the improvements in some MS components.

Cardiovascular rehabilitation increase arterial compliance in type 2 diabetic patients with coronary artery disease

AIMS

The effect of a cardiovascular rehabilitation program on arterial compliance in type 2 diabetes mellitus with coronary disease was studied.

METHODS

Hemodynamic data and arterial compliance were measured with a tonometer (HDI/Pulse wave CR-2000) in coronary artery disease patients with (n=32) and without (n=24) type 2 diabetes before and after a 6-week multidisciplinary cardiac rehabilitation program.

RESULTS

A decrease in heart rate and an increase in stroke volume without significant change in resting cardiac output were obtained in diabetic patients. Arterial compliance of both small and large arteries was significantly increased. In 10 diabetic patients, this increase could be related to an increase in the anti-hypertensive treatment and to the decreased blood pressure. In the 22 remainders, the small artery compliance was significantly increased independently of blood pressure change.

CONCLUSIONS

Exercise training as well as optimization of diabetes and dyslipidemia treatment could explain the improvement of arterial compliance. If these changes are long-lasting and if they improve prognosis remains to be evaluated.

Effects of lifestyle modification on central artery stiffness in metabolic syndrome subjects with pre-hypertension and/or pre-diabetes

AIMS

To examine the effects of a 24-week lifestyle intervention prescribed by family doctors on carotid artery stiffness in metabolic syndrome (MS) subjects with pre-hypertension and/or pre-diabetes.

METHODS

Sixty-three middle-aged and older subjects with pre-hypertension and/or pre-diabetes were divided into subjects without MS (MS-) and with MS (MS+). MS components and carotid artery stiffness by ultrasound were determined at baseline, at 8 weeks, and following the 24 weeks of lifestyle intervention. Family doctors prescribed an individually customized lifestyle prescription for aerobic exercise and Mediterranean-style diet.

RESULTS

Carotid artery distensibility significantly increased in MS+ following the 24 weeks of intervention compared with baseline (0.191+/-0.012 vs. 0.143+/-0.011, 1/mmHg x 10(-2), p<0.05). Similarly, beta stiffness index decreased in MS+ following the 24 weeks of intervention (9.8+/-1.1 vs. 12.5+/-1.1 AU, p<0.05). Following the intervention, waist circumference, BP and fasting glucose levels reduced in MS+ (all p<0.05), and 13 MS+ subjects were free from MS.

CONCLUSIONS

The results show the reduction of carotid artery stiffness and the improvement of some MS components in MS subjects, suggesting a favorable effect of our lifestyle modification strategy on central artery stiffness as well as MS components in MS subjects.