Arterial stiffness: methods of measurement, physiologic determinants and prediction of cardiovascular outcomes

Effects of exercise modalities on arterial stiffness and wave reflection: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVES

Physical activity is associated with lower cardiovascular and all-cause mortality. However, the effects of different exercise modalities on arterial stiffness are currently unclear. Our objectives were to investigate the effects of exercise modalities (aerobic, resistance or combined) on pulse wave velocity (PWV) and augmentation index (AIx), and to determine whether the effects on these indices differed according to the participants' or exercise characteristics.

METHODS

We searched the Medline, Embase and Cochrane Library databases from inception until April 2014 for randomized controlled trials lasting ≥ 4 weeks investigating the effects of exercise modalities on PWV and AIx in adults aged ≥ 18 years.

RESULTS

Forty-two studies (1627 participants) were included in this analysis. Aerobic exercise improved both PWV (WMD: -0.63 m/s, 95% CI: -0.90, -0.35) and AIx (WMD:-2.63%, 95% CI: -5.25 to -0.02) significantly. Aerobic exercise training showed significantly greater reduction in brachial-ankle (WMD: -1.01 m/s, 95% CI: -1.57, -0.44) than in carotid-femoral (WMD: -0.39 m/s, 95% CI: -0.52, -0.27) PWV. Higher aerobic exercise intensity was associated with larger reductions in AIx (β: -1.55%, CI -3.09, 0.0001). In addition, aerobic exercise had a significantly larger effect in reducing PWV (WMD:-1.0 m/s, 95% CI: -1.43, -0.57) in participants with stiffer arteries (PWV ≥ 8 m/s). Resistance exercise had no effect on PWV and AIx. There was no significant effect of combined exercise on PWV and AIx.

CONCLUSIONS

We conclude that aerobic exercise improved arterial stiffness significantly and that the effect was enhanced with higher aerobic exercise intensity and in participants with greater arterial stiffness at baseline.

TRIAL REGISTRATION PROSPERO

Database registration: CRD42014009744.

Antioxidant vitamin supplementation reduces arterial stiffness in adults: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Several studies tested the effects of supplementation with antioxidant vitamins on arterial stiffness, but the results were contradictory.

OBJECTIVES

The aim of our study was to conduct a systematic review and meta-analysis investigating the effect of antioxidant vitamins on arterial stiffness and to determine whether the effects on arterial stiffness vary according to dose, duration of intervention, and health or nutritional status of the included participants.

METHODS

We searched 3 databases (Medline, Embase, and Scopus) for articles that potentially met the following eligibility criteria: 1) randomized controlled trials comparing antioxidant vitamins (vitamins C, E, and A and β-carotene) to either placebo or no active control in 2) adult participants aged ≥18 y; 3) antioxidant vitamins administered alone or in combination, irrespective of dose, duration, and route of administration; and 4) changes in arterial stiffness or arterial compliance. Data were pooled as standardized mean differences (SMDs) and analyzed using fixed- and random-effects models.

RESULTS

Data synthesis showed that antioxidant vitamins reduced arterial stiffness significantly (SMD: -0.17; 95% CI: -0.26, -0.08; P < 0.001). This effect was significant in experimental (SMD: -1.02; 95% CI: -1.54, -0.49; P < 0.001) and primary prevention (SMD: -0.14; 95% CI: -0.24, -0.04; P < 0.01) studies, whereas a trend for reduced arterial stiffness was observed in studies including participants with diseases (SMD: -0.19; 95% CI: -0.40, 0.02; P = 0.08). Vitamin supplementation improved arterial stiffness irrespective of age group and duration of intervention. Antioxidant vitamins were more effective in participants with low baseline plasma concentrations of vitamins C (SMD: -0.35; 95% CI: -0.62, -0.07; P < 0.016) and E (SMD: -0.79; 95% CI: -1.23, -0.33; P < 0.01).

CONCLUSIONS

Supplementation with antioxidant vitamins has a small, protective effect on arterial stiffness. The effect may be augmented in those with lower baseline plasma vitamin E and C concentrations. This trial was registered at PROSPERO as CRD42014007260.

Effect of whole-body vibration for 3 months on arterial stiffness in the middle-aged and elderly

Background

Cardiovascular disease (CVD) is a common problem of middle-aged and older adults. Increased arterial stiffness is a CVD risk factor. Whole-body vibration (WBV) is a simple and convenient exercise for middle-aged and older adults; however, there have been few studies investigating the effect of WBV on arterial stiffness. This study mainly investigated the effect of WBV on arterial stiffness in middle-aged and older adults.

Methods

A total of 38 (21 women and 17 men) middle-aged and elderly subjects (average age, 61.9 years) were randomly divided into the WBV group and the control group for a 3-month trial. The WBV group received an intervention of 30 Hz and 3.2 g WBV in a natural full standing posture at a sports center. The brachial–ankle pulse wave velocity (baPWV), a marker of systemic arterial stiffness, and blood pressure and heart rate were measured before and after the intervention.

Results

After 3 months, there were no significant changes in blood pressure or heart rate in both groups. However, the bilateral baPWV was significantly reduced in the WBV group (decreased by 0.65 m/second [P=0.014]; 0.63 m/second [P=0.041] in either side), but not in the control group. The comparison between the two groups was not statistically significant.

Conclusion

This study found that 3 months of WBV had a positive effect on arterial stiffness in middle-aged and older adults and could therefore be regarded as a supplementary exercise. Larger-scale studies are needed to confirm the effects of WBV in the future.

Acute exacerbation of chronic obstructive pulmonary disease: cardiovascular links

Chronic obstructive pulmonary disease (COPD) is a chronic, progressive lung disease resulting from exposure to cigarette smoke, noxious gases, particulate matter, and air pollutants. COPD is exacerbated by acute inflammatory insults such as lung infections (viral and bacterial) and air pollutants which further accelerate the steady decline in lung function. The chronic inflammatory process in the lung contributes to the extrapulmonary manifestations of COPD which are predominantly cardiovascular in nature. Here we review the significant burden of cardiovascular disease in COPD and discuss the clinical and pathological links between acute exacerbations of COPD and cardiovascular disease.

Aortic stiffness in lone atrial fibrillation: a novel risk factor for arrhythmia recurrence

Background

Recent community-based research has linked aortic stiffness to the development of atrial fibrillation. We posit that aortic stiffness contributes to adverse atrial remodeling leading to the persistence of atrial fibrillation following catheter ablation in lone atrial fibrillation patients, despite the absence of apparent structural heart disease. Here, we aim to evaluate aortic stiffness in lone atrial fibrillation patients and determine its association with arrhythmia recurrence following radio-frequency catheter ablation.

Methods

We studied 68 consecutive lone atrial fibrillation patients who underwent catheter ablation procedure for atrial fibrillation and 50 healthy age- and sex-matched community controls. We performed radial artery applanation tonometry to obtain central measures of aortic stiffness: pulse pressure, augmentation pressure and augmentation index. Following ablation, arrhythmia recurrence was monitored at months 3, 6, 9, 12 and 6 monthly thereafter.

Results

Compared to healthy controls, lone atrial fibrillation patients had significantly elevated peripheral pulse pressure, central pulse pressure, augmentation pressure and larger left atrial dimensions (all P<0.05). During a mean follow-up of 2.9±1.4 years, 38 of the 68 lone atrial fibrillation patients had atrial fibrillation recurrence after initial catheter ablation procedure. Neither blood pressure nor aortic stiffness indices differed between patients with and without atrial fibrillation recurrence. However, patients with highest levels (≥75^th percentile) of peripheral pulse pressure, central pulse pressure and augmentation pressure had higher atrial fibrillation recurrence rates (all P<0.05). Only central aortic stiffness indices were associated with lower survival free from atrial fibrillation using Kaplan-Meier analysis.

Conclusion

Aortic stiffness is an important risk factor in patients with lone atrial fibrillation and contributes to higher atrial fibrillation recurrence following catheter ablation procedure.

Assessment of volume status and arterial stiffness in chronic kidney disease

AIM

There is limited information about arterial stiffness in chronic kidney disease (CKD) which is an independent risk factor for cardiovascular events. Pulse wave velocity (PWV), augmentation index (AIx) are using to determine arterial stiffness. We aimed to study PWV, AIx, volume status in patients with stage 3B-5 CKD and continuous ambulatory peritoneal dialysis (CAPD).

METHODS

Sixty-six stage 3B-5 CKD patients, 21 CAPD patients, 34 healthy controls were included. Pulse wave velocity, AIx, volume status was evaluated by Mobil-O-Graph®, and bioimpedance spectroscopy, respectively.

RESULTS

The Median PWV was 7.5 m/s in CKD, 6.2 m/s in CAPD, 5.9 m/s in healthy controls, and while PWV was found to have increased significantly in CKD patients (p = 0.002), the Alx values were similar in all groups. The median extracellular fluid excess was higher in both the CKD and, CAPD patients when compared with healthy controls (1.26 and 1.21 L, respectively). Overhydration was more prevalent in CKD and CAPD patients (p < 0.001). Age, central systolic blood pressure, body mass index, fat mass, overhydration, CKD, eGFR were the major determinants of PWV.

CONCLUSION

Increased PWV was found in stage 3B-5 CKD patients. Overhydration may contribute this increment.

The relationship between inhibitors of the Wnt signalling pathway (Dickkopf-1(DKK1) and sclerostin), bone mineral density, vascular calcification and arterial stiffness in post-menopausal women

Epidemiological studies have shown an association between bone loss/osteoporosis and vascular calcification (VC). Recent studies have implicated the Wnt signalling pathway in the pathogenesis of VC. We investigated the association between circulating concentrations of Wnt inhibitors; DKK1 and sclerostin with bone mineral density (BMD), abdominal aortic calcification (AAC) and arterial stiffness in post-menopausal women. One hundred and forty six post-menopausal women aged (mean [SD]) 61.5[6.5] years were studied. Sclerostin and DKK1 were measured in serum. BMD was measured at the lumbar spine (LS), femoral neck (FN), total hip (TH). AAC was detected by Vertebral Fracture Assessment (VFA) imaging and quantified using an 8- and 24- point scoring methods. Arterial stiffness was determined by aortic pulse wave velocity (PWV). A significant positive correlation was observed between sclerostin and BMD at the FN (r = 0.166, p = 0.043) and TH (r = 0.165, p = 0.044). The association remained significant at the FN (p = 0.045) and TH (p = 0.026) following adjustment for confounders. No significant correlation was observed between DKK1 and BMD. In contrast, there was a significant negative correlation between log DKK1 and AAC (24-point score: r = -0.25, p = 0.008 and 8-point score: r = -0.21, p = 0.024). Subjects with AAC score of 1 or less had significantly higher DKK1 (p = 0.01). The association between DKK1 and AAC remained significant following correction for age, blood pressure, cholesterol (24-point score: p = 0.017, 8-point score: p = 0.044). In adjusted linear regression analysis, sclerostin was positively associated with AAC (24-point score: p = 0.048, 8-point score: p = 0.031). Subjects with a PWV>9 m/s had significantly higher sclerostin than those with PWV <9 m/s: 23.8[12.3], vs 29.7 [14] pmol/l, p = 0.03). No association was observed between DKK1 and PWV. The opposite association between AAC and the 2 Wnt signaling inhibitors is of interest and merits further investigations. Future longitudinal studies are needed to establish the precise role of sclerostin and DKK1 in the pathogenesis of VC.

Postprandial effect of dietary fat quantity and quality on arterial stiffness and wave reflection: a randomised controlled trial

Background

Arterial stiffness is a component of vascular function and an established risk factor for cardiovascular disease. There is a lack of conclusive evidence on the effect of a meal rich in monounsaturated fat (MUFA) compared with an isoenergetic meal rich in saturated fat (SFA) on postprandial vascular function and specifically on arterial stiffness.

Methods

Twenty healthy, non-smoking males (BMI 24 ± 2 kg/m²; age 37.7 ± 14.4 y) participated in this single-blind, randomised, cross-over dietary intervention study. Each subject was randomised to receive a high-fat test-meal (3 MJ; 56 ± 2 g fat) at breakfast on 2 separate occasions, one rich in oleic acid (MUFA-meal) and one rich in palmitic acid (SFA-meal), and the meals were isoenergetic. Blood pressure (BP), arterial stiffness (PWV) and arterial wave reflection (augmentation index, AIx) were measured using applanation tonometry at baseline and every 30 minutes up to 4 hours after the ingestion of the test-meals.

Results

All subjects completed both arms of the dietary intervention. There was no significant difference in BP parameters, PWV or AIx at baseline between the two treatments (P > 0.05). There was a significant increase in brachial and aortic BP, mean arterial pressure (MAP), heart rate and PVW (time, P < 0.05) over the four hours after consumption of the fat-rich test-meal although the increase in PWV was no longer significant when adjusted for the increase in MAP. There was no difference in PWV between the two treatments (treatment*time, P > 0.05). There was a significant reduction in AIx (time, P < 0.05) over the four hour postprandial period although this was no longer significant when adjusted for the increase in heart rate and MAP (time, P > 0.05). There was no difference in AIx between the two treatments (treatment*time, P > 0.05). However, the reduction in heart rate corrected augmentation index (AIx₇₅) was significant when corrected for the increase in MAP (time, P < 0.01) with no differential effect of the treatments (treatment*time, P > 0.05).

Conclusions

This study has demonstrated a BP dependent increase in PWV and a decrease in arterial wave reflection in the four hour period in response to a high-fat meal. There was no evidence however that replacement of some of the SFA with MUFA had a differential effect on these parameters. The study highlights the need for further research to understand the effects of the substitution of SFA with MUFA on non-serum, new and emerging risk factors for CVD such as arterial stiffness.

Oscillometric measurement of brachial artery cross-sectional area and its relationship with cardiovascular risk factors and arterial stiffness in a middle-aged male population

An enlarged arterial diameter is associated with an increased risk for cardiovascular disease. This study examined the relationship of noninvasively measured brachial artery cross-sectional area with cardiovascular risk factors and arterial stiffness in a middle-aged male population. Absolute volumetric changes of the brachial artery were measured with a newly developed oscillometric method during a general health examination in 387 men (mean age: 38±9 years) without known cardiovascular disease. Based on the measurement, the estimated area (eA) of the brachial artery at end-diastole was obtained. Brachial artery volume elastic modulus (VE) and brachial-ankle pulse wave velocity (baPWV) were simultaneously measured as indices of arterial stiffness by the same device. The relationships of eA with cardiovascular risk factors, including age, obesity, hypertension, dyslipidemia, impaired fasting glucose/diabetes mellitus (IFG/DM), hyperuricemia, smoking and their associated continuous variables, as well as VE and baPWV, were examined. Overall, the mean eA was 12.9 ± 2.9 mm². The eA was significantly higher in subjects with obesity, hypertension or IFG/DM than in those without each of these risk factors. In a multiple linear regression analysis, body mass index (β=0.31, P<0.001), age (β=0.25, P<0.001), systolic blood pressure (β=0.16, P=0.004) and pulse rate (β=-0.13, P=0.005) were independent determinants of eA. In contrast, neither VE nor baPWV were selected as independent determinants of eA. In conclusion, enlarged brachial artery cross-sectional area was significantly associated with cardiovascular risk factors such as age, body mass index and systolic blood pressure, but it was not associated with increased arterial stiffness.

Laser beam measurement of abdominal sagittal diameter in obese children: a validation study

OBJECTIVES

Sagittal diameter (SAD) has been reported to correlate to visceral fat and cardiovascular risk factors. SAD is measured with the individual lying down, halfway between the lower rib margin and the iliac crest; it represents the mid-height of the abdomen. The aim of this study was to validate SAD measured using a recently-developed laser beam device (SAD(LDB) ) against SAD measured using MRI (SAD(MRI)).

METHODS

Of 48 obese children (25 boys, 23 girls) aged 9-11 years on the waiting list for obesity treatment, 34 agreed to a baseline measurement, which was followed by repeated measurements 6 and 12 months later in 31 and 22 children respectively. MRI was used to examine SAD(MRI) at 5 cm above (SAD(MRI,cra) ) and below (SAD(MRI,cau)) the mid plane of the L4-5 intervertebral disc.

RESULTS

Each of the differences SAD(LBD) - SAD(MRI, cau) and SAD(LBD) - SAD(MRI,cra) was subjected to a repeated-measurements ANOVA; the visit did not have a statistically significant effect in either case (p = 0.19 and p = 0.72, respectively). The difference SAD(LBD) - SAD(MRI, cau) was 1.50 on average (p < 0.0001; CI 1.26-1.74) while the corresponding figure for SAD(LBD) -SAD(MRI, cra) was 1.26 (p < 0.0001; CI 1.04-1.49). Regression of the difference on the mean gave slopes of -0.09 (p = 0.25) and -0.04 (p = 0.57) respectively. Prediction of SAD(MRI) from SAD(LDB) can be performed in different ways: by means of linear regression or by means of an additive correction.

CONCLUSIONS

Thus, this laser device can be used instead of MRI to estimate SAD by using a simple correction.

Genetic variation in CYP17A1 is associated with arterial stiffness in diabetic subjects

Hypertension and arterial stiffness are associated with an increasing risk of diabetes and cardiovascular diseases. This study aimed to identify genetic variants affecting hypertension and arterial stiffness in diabetic subjects and to compare genetic associations with hypertension between prediabetic and diabetic subjects. A total of 1,069 participants (326 prediabetic and 743 diabetic subjects) were assessed to determine the genetic variants affecting hypertension by analyzing 52 SNPs previously reported to be associated with hypertension. Moreover, the SNPs were tested for association with hemodynamic parameters related to hypertension. Out of the 52 SNPs analyzed, four SNPs including rs5326 (DRD1), rs1004467 (CYP17A1), rs2960306 (GRK4), and rs11191548 (near NT5C2) in diabetic subjects and rs1530440 (C10orf107) in prediabetic subjects showed a modest association with hypertension (P = 0.0265, 0.0020, 0.0066, 0.0078, and 0.0015, resp; all were insignificant after Bonferroni correction). Of these SNPs, rs1004467 in CYP17A1 was significantly associated with augmentation index in diabetic subjects who were not taking antihypertensive medication (P = 0.0001; corrected P = 0.006) but not in diabetic subjects receiving antihypertensive medication. This finding suggests that certain genetic variations found in diabetic subjects may confer arterial stiffness and the development of hypertension and also be affected by antihypertensive medication.

On the estimation of total arterial compliance from aortic pulse wave velocity

Total arterial compliance (C(T)) is a main determinant of cardiac afterload, left ventricular function and arterio-ventricular coupling. C(T) is physiologically more relevant than regional aortic stiffness. However, direct, in vivo, non-invasive, measurement of C(T) is not feasible. Several methods for indirect C(T) estimation require simultaneous recording of aortic flow and pressure waves, limiting C(T) assessment in clinical practice. In contrast, aortic pulse wave velocity (aPWV) measurement, which is considered as the "gold standard" method to assess arterial stiffness, is noninvasive and relatively easy. Our aim was to establish the relation between aPWV and C(T). In total, 1000 different hemodynamic cases were simulated, by altering heart rate, compliance, resistance and geometry using an accurate, distributed, nonlinear, one-dimensional model of the arterial tree. Based on Bramwell-Hill theory, the formula C(T) = k • aPWV(-2) was found to accurately estimate C(T) from aPWV. Coefficient k was determined both analytically and by fitting C(T) vs. aPWV data. C(T) estimation may provide an additional tool for cardiovascular risk (CV) assessment and better management of CV diseases. C(T) could have greater impact in assessing elderly population or subjects with elevated arterial stiffness, where aPWV seem to have limited prognostic value. Further clinical studies should be performed to validate the formula in vivo.

Increased aortic stiffness can predict perioperative cardiovascular outcomes in patients undergoing noncardiac, nonvascular surgery

BACKGROUND

Aortic stiffness is an early marker of arteriosclerosis and associated with cardiovascular mortality. However, the impact of aortic stiffness on perioperative cardiovascular outcomes in patients undergoing noncardiac surgery is unknown.

METHODS

The study population was composed of 660 consecutive adults aged 18 years and over (mean age = 65.3 ± 14 years) who underwent intermediate-risk (nonvascular), noncardiac surgery between January 2010 and February 2011. Nonemergency, non-day-case, open surgical procedures were enrolled. Aortic stiffness indices were calculated from the aortic diameters measured by echocardiography. Electrocardiography and cardiac biomarkers were evaluated 1 day before surgery, and on days 1, 3, and 7 after surgery.

RESULTS

Eighty patients (12.1%) experienced perioperative cardiovascular events (PCE). Preoperative aortic distensibility (AD) (2 ± 1.3 vs. 2.9 ± 1.1 cm2/dyn/10(3), P < 0.001) and aortic strain (AS) (4.4 ± 2.4 vs. 6.4 ± 1.9, P < 0.001) of the patients with PCE were significantly lower than in patients without PCE. Univariate analysis showed a significant association between age, diabetes mellitus (DM), coronary artery disease, preoperative atrial fibrillation, American Society of Anesthesiologists (ASA) status, Revised Cardiac Risk Index, left ventricle ejection fraction (LVEF), AD, aortic strain, and in-hospital PCE. However, on multivariate logistic regression analysis, only AD (OR: 1.94, 95% CI: 1.1-3.4; P = 0.02), AS (OR: 0.45, 95% CI: 0.3-0.6; P < 0.001), DM (OR: 2.28, 95% CI: 1.08-4.82; P = 0.03), and LVEF (OR: 0.96, 95% CI: 0.93-0.99; P = 0.03) remained as significant variables associated with PCE.

CONCLUSION

Impaired elastic properties of the aorta are associated with increased PCE rates in patients undergoing noncardiac, nonvascular surgery.

Thioredoxin interacting protein (TXNIP) rs7212 polymorphism is associated with arterial stiffness in the Brazilian general population

Thioredoxin interacting protein plays a pivotal role in several important processes of cardiovascular homeostasis by functioning as a biological sensor for biomechanical and oxidative stress. However, the effects of genetic variants in the modulation of arterial stiffness are unknown. In this scenario, the present study evaluated the relationship between the TXNIP rs7212 polymorphism and arterial stiffness. In the overall sample and in the diabetic group, individuals carrying CG+GG genotypes had higher PWV values compared with CC genotype group (10.0 vs 9.8 m s (-1), P=0.03; 12.3 vs 11.2 m s(-1), P=0.01; respectively). Our findings indicated that the G allele may contribute to increased arterial stiffness in the Brazilian general population and suggest a possible interaction with diabetes.

Depression, anxiety, and arterial stiffness

BACKGROUND

Arterial stiffness gains attention as a potential mechanism underlying the frequently found association between depression or anxiety and cardiovascular disease. However, observations regarding stiffness and psychopathology were often based on small samples. The current study aimed to examine whether subjects with a diagnosis of depressive or anxiety disorder showed increased stiffness and to explore associations between various psychiatric characteristics and arterial stiffness.

METHODS

The sample included 449 cases with DSM-IV based lifetime diagnoses of depressive and/or anxiety disorder and 169 control subjects. Subjects were participating in the Netherlands Study of Depression and Anxiety and were aged 20 to 66 years. Characteristics included comorbidity, subtype of disorder, symptom severity and duration, age of onset, and use of antidepressant medication. Arterial stiffness was measured by calibrated radial tonometry (heart rate normalized central augmentation index [AIx75]; in percentage) and carotid M-mode ultrasound (distensibility coefficient).

RESULTS

After adjustment for covariates, AIx75 was increased in current (1-month) depression or anxiety (15.7% vs. 13.3% in control subjects, p = .01). Disorder characteristics associated with AIx75 were depression and anxiety comorbidity (15.3%, p = .02), higher depression severity (β = .10, p < .001) and anxiety severity (β = .10, p < .001), and longer symptom duration (β = .07, p = .01). No significant associations were found between distensibility coefficient and psychopathology.

CONCLUSIONS

Current depressive or anxiety disorders were associated with a higher central augmentation index, a manifestation of early wave reflection because of arterial stiffness. Exposure to depression and anxiety may therefore enhance the development and progression of atherosclerosis and other cardiovascular conditions.