Peripheral augmentation index as a biomarker of vascular aging: an invasive hemodynamics approach

The impact of prediabetes and diabetes on endothelial function in a large population-based cohort

BACKGROUND

Diabetes and prediabetes are well-recognized risk factors for cardiovascular disease (CVD) and are marked by vascular endothelial dysfunction (ED). However, there is a scarcity of thorough population-based studies examining ED in individuals with diabetes/prediabetes free from manifest CVD. Here, we examined the association between ED assessed by reactive hyperaemia index (RHI) in the finger and diabetes/prediabetes in a large middle-aged population cohort.

METHODS

Within the Malmö Offspring Study, following the exclusion of participants <30 years and participants with prevalent CVD, 1384 participants had complete data on all covariates. The RHI was calculated using pulse amplitude tonometry. ED was defined as RHI < 1.67. Multivariable logistic and linear regression models were conducted to investigate associations between ED and RHI with diabetes and prediabetes.

RESULTS

The study population had a mean age of 53.6 ± 7.6 years (53% women). In study participants with manifest diabetes (n = 121) and prediabetes (n = 514), ED was present in 42% and 25% respectively, compared to 23% in those with normal glucometabolic status. In multivariable logistic regression analyses, prevalent diabetes was significantly associated with ED (OR 1.95; 95%CI 1.57-3.39; p = 0.002), as well as with lower RHI (β-coeff. -0.087; p = 0.002). However, prediabetes showed no association with neither ED nor RHI.

CONCLUSION

In a population free from CVD, vascular endothelial dysfunction was primarily associated with manifest diabetes, but not with prediabetes, implying that finger ED may develop when diabetes is established, rather than being an early sign of glucose intolerance. Further research is needed to explore whether addressing glucose intolerance could potentially delay or prevent vascular ED onset.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

Community-Based Evaluation of the Associations Between Well-Being and Cardiovascular Disease Risk

Background Although the effects of psychological health and optimism have been extensively investigated, data from community-based cohorts assessing the association between psychological health and cardiovascular disease risk factors are sparse, and the concurrent relationship between subjective well-being and cardiovascular health has not been studied. Methods and Results The current cross-sectional study examined the association between well-being and cardiovascular risk factors among 719 individuals living in a middle- to low-income neighborhood. After adjusting for age, sex, race, body mass index, education, smoking status, and exercise status, we found that higher levels of well-being were significantly associated with lower odds of dyslipidemia (odds ratio [OR], 0.7 [95% CI, 0.55-0.85]) and hypertension (OR, 0.8 [95% CI, 0.63-0.92]). Greater well-being was also significantly associated with lower triglyceride levels (mean difference [M_diff], 7.6 [-14.31 to -0.78]), very low-density lipoprotein (M_diff, 0.9 [-1.71 to -0.16]), total cholesterol to high-density lipoprotein ratio (M_diff, 3.9 [-6.07 to -1.73]), higher high-density lipoprotein levels (M_diff, 1.6 [0.46-2.75]), and lower Framingham Risk Scores (M_diff, -7.1% [-10.84% to -3.16%]). Well-being also moderated the association between age and arterial stiffness. The strongest association between arterial stiffness and age was found for those with the lowest well-being scores; there was no association between age and arterial stiffness at high levels of well-being. Conclusions In a community-based cohort, individuals reporting higher levels of well-being have lower odds of hypertension and dyslipidemia as well as lower rates of age-dependent increase in vascular stiffness. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03670524.

Association of coronary calcium score with endothelial dysfunction and arterial stiffness

BACKGROUND AND AIMS

The aim of the study was to determine potential associations between endothelial dysfunction and arterial stiffness, measured by peripheral arterial tonometry, and coronary artery calcium score (CACS) assessed by computed tomography (CT).

METHODS AND RESULTS

The BIG3 study is a prospective longitudinal, non-interventional, pulmonary-cardiovascular cohort study exploring the three major smoking-induced diseases: cardiovascular disease, chronic obstructive pulmonary disease, and lung cancer, in a 45-75 aged cohort (mean 62 years), enriched in smokers. Computed tomography of the chest with assessment of CACS was performed in a selected subset of the participants (n = 2080). Peripheral arterial tonometry (EndoPAT) was used to assess endothelial function and arterial stiffness measured as reactive hyperaemia index (RHI) and augmentation index (AI), respectively. We observed significant associations of CACS, endothelial dysfunction, and arterial stiffness with several risk factors for coronary heart disease including age, sex, BMI, diabetes mellitus, and blood pressure. There was significant association of CACS, classified into three levels of severity, with RHI and AI (p = 0.0005 and p = 0.0009, respectively). For groups of increasing CACS (0, 1-400 and > 400 Agatston score), RHI decreased from median 1.89 (1.58-2.39), and 1.93 (1.62-2.41) to 1.77 (1.51-2.10). AI increased from median 14.3 (5.7-25.2), and 16.4 (8.1-27.6) to 18.0 (9.1-29.2). RHI, but not AI, remained significantly associated with CACS after risk factors adjustment.

CONCLUSIONS

In this large study of coronary artery calcium and vascular function, we found an association between CACS and both endothelial dysfunction and arterial stiffness, indicating that they may reflect similar mechanisms for development of cardiovascular disease.

Noninvasive validation of central and peripheral augmentation index estimated by a novel wrist-worn tonometer

BACKGROUND

The validation of new blood pressure devices with easier use and more rapid data collection may facilitate the incorporation of these measures into clinical practice. We analyze the reliability and validity of Pulse Wave Analysis as reported by a novel wrist-worn device, easy and quick to use, comparing central and peripheral augmentation index (AIx) with the same measures from the SphygmoCor. Additionally, we analyzed clinical relevance through the association of the Pulse Wave Analysis, as reported by a novel wrist-worn device, with other cardiovascular parameters.

METHODS

Cross-sectional study including 254 participants. Mean age was 51.9 ± 13.4 years and 53% were women.

MEASUREMENTS

peripheral AIx (PAIx) and central AIx (CAIx) by the wrist-worn device and SphygmoCor (MM3); carotid-femoral (cf) pulse wave velocity (PWV) by SphygmoCor (MM3); cardioankle-vascular index (CAVI), ankle-brachial index (ABI) and brachial-ankle (ba) PWV by the Vasera device and carotid-intima media thickness (IMT) by ultrasonography.

RESULTS

Intra-observer intra-class correlation coefficient (ICC) for PAIx was 0.886 (95% CI 0.803-0.934) and for CAIx 0.943 (95% CI 0.901-0.968) with Bland Altman limits of agreement -0.75 (-23.8 to 21.8) and 0.08 (-15.7 to 15.9), respectively. Inter-observer ICC for PAIx was 0.952 (95% CI 0.915-0.972) and CAIx 0.893 (95% CI 0.811-0.939) with limits of agreement -0.45 (-13.7 to 12.8) and 0.43 (-17.7 to 18.5), respectively. Comparing the wrist-worn device with SphygmoCor, the ICC was 0.849 (95% CI 0.798-0.887) for PAIx, and 0.783 (95% CI 0.711-0.838) for CAIx. In Bland-Altman, limits of agreement for PAIx 1.03 (-20.67 to 22.73), and for CAIx -2.14 (-24.79 to 20.50). PAIx and CAIx, from the wrist-worn device, correlated with age, CAVI, ABI, baPWV, cfPWV, IMT, glomerular filtration and cardiovascular risk.

CONCLUSION

AIx measurements by wrist-worn device shows a good intra-observer and inter-observer reliability, inter-device noninvasive reliability and validity when compared with SphygmoCor, and clinical relevance by association with measures of vascular structure and function, end-organ damage and cardiovascular risk.

TRIAL REGISTRATION

Clinicaltrials.gov NCT02623894; https://clinicaltrials.gov/ct2/show/NCT02623894.

Nonalcoholic Fatty Liver Disease in Hispanic Youth With Dysglycemia: Risk for Subclinical Atherosclerosis?

Context:

Obese Hispanic adolescents (OHAs) with dysglycemia have increased cardiovascular disease risk burden.

Objective:

To investigate if nonalcoholic fatty liver disease (NAFLD) confers added risk for endothelial dysfunction in these youth.

Design:

Cross-sectional study.

Setting:

Academic institution.

Participants:

Thirty-six OHAs (15.3 ± 0.4 years), 20 with prediabetes and 16 with type 2 diabetes, with and without NAFLD.

Intervention:

Evaluation of reactive hyperemia index (RHI) and augmentation index (AIx) by peripheral arterial tonometry; muscle, hepatic, and adipose tissue insulin sensitivity (IS; hyperinsulinemic-euglycemic clamp 80 mu/m²/min, with [6,6 ²H₂]glucose and [²H₅] glycerol); body composition; and abdominal and hepatic fat by magnetic resonance imaging/spectroscopy.

Outcome Measures:

RHI and AIx.

Hypothesis:

OHAs with dysglycemia and NAFLD have worse RHI and AIx vs those without NAFLD.

Results:

The NAFLD (n = 23) and non-NAFLD (n = 13) groups were of similar age, sex, glycemic status, body mass index, % body fat and abdominal fat. The NAFLD group had higher hepatic fat (P < 0.001) lower skeletal muscle IS (P = 0.01), hepatic IS (P = 0.01), and adipose tissue IS (P = 0.04). The NAFLD vs non-NAFLD group had lower RHI (1.4 ± 0.05 vs 1.7 ± 0.09, P = 0.002), greater AIx (–6.0 ± 1.6 vs –12.0 ± 2.1, P = 0.03). Hepatic fat was inversely related to RHI (r = –0.49, P = 0.002) and positively related to AIx (r = 0.45, P = 0.006). Hepatic IS (r = –0.42, P = 0.01) and adipose IS (r = –.54, P = 0.001) correlated with arterial stiffness (AIx).

Conclusion:

In OHAs with dysglycemia, NAFLD is associated with worse endothelial function. RHI and AIx were related to hepatic fat content. Vascular stiffness was related to hepatic and adipose tissue insulin resistance.

Curative effect and mechanism of radiofrequency ablation nucleoplasty in the treatment of cervical vertigo

OBJECTIVE

This study aims to investigate the curative effects and mechanism of radiofrequency ablation nucleoplasty in the treatment of cervical vertigo.

METHODS

A total of 27 patients diagnosed with cervical vertigo from January 2012 to October 2014 received treatment of radiofrequency ablation nucleoplasty. The narrow-side vertebral artery diameters were examined by using Philips 1.5-T body dual-gradient MRI system. The haemodynamic parameters were detected by using transcranial Doppler sonography. Both of the vertebral artery diameters and haemodynamic parameters were recorded and compared before and after treatment. The curative effects in early post-operative application were evaluated according to the Nagashima standards.

RESULTS

Radiofrequency ablation nucleoplasty was performed in a total of 59 cervical discs in 27 patients. The average operation time was 42.7 min, and the symptoms of 92.6% patients were alleviated after radiofrequency ablation nucleoplasty post-operation application. There was no significant difference in the narrow-side vertebral artery diameters before and after treatment in both Group A (p = 0.12) and Group B (p = 0.48); however, the blood flow velocity was significantly higher than that before treatment in both Group A (p = 0.01) and Group B (p = 0.03), respectively.

CONCLUSION

Radiofrequency ablation nucleoplasty improves the blood flow in the narrow-side vertebral artery and illustrates the therapeutic effect on cervical vertigo in patients who have no direct compression of the vertebral artery. Advances in knowledge: Radiofrequency intradiscal nucleoplasty can be used as a minimally invasive procedure for treating cervical vertigo.

Endothelial Function in Youth: A Biomarker Modulated by Adiposity-Related Insulin Resistance

OBJECTIVE

To investigate the physical and metabolic determinants of endothelial dysfunction, an early marker of subclinical atherosclerosis, in normal weight and overweight adolescents with and without type 2 diabetes mellitus.

STUDY DESIGN

A cross-sectional study of 81 adolescents: 21 normal weight, 25 overweight with normal glucose tolerance, 19 overweight with impaired glucose regulation, and 16 with type 2 diabetes mellitus underwent evaluation of reactive hyperemia index (RHI) and augmentation index (AIx) at heart rate 75 bpm by peripheral arterial tonometry; oral glucose tolerance test, lipid profile, and hyperinsulinemic-euglycemic clamp to measure insulin sensitivity; and dual energy X-ray absorptiometry scan and abdominal magnetic resonance imaging for percentage of body fat and abdominal fat partitioning.

RESULTS

Participants across tertiles of RHI (1.2 ± 0.02, 1.5 ± 0.02, and 2.0 ± 0.05, P < .001) had similar age, sex, race, lipid profile, and blood pressure. Body mass index z-score, percentage body fat, abdominal fat, and hemoglobin A1c decreased, and insulin sensitivity increased from the first to third tertile. RHI was inversely related to percentage body fat (r = -0.29, P = .008), total (r = -0.37, P = .004), subcutaneous (r = -0.39, P = .003), and visceral (r = -0.26, P = .04) abdominal fat. AIx at heart rate 75 bpm was higher (worse) in the lower RHI tertiles (P = .04), was positively related to percentage body fat (r = 0.26, P = .021), and inversely related to age, insulin sensitivity, and inflammatory markers (tumor necrosis factor-α and plasminogen activator inhibition-1).

CONCLUSIONS

Childhood obesity, particularly abdominal adiposity, is associated with endothelial dysfunction manifested by worse reactive hyperemia and higher AIx. Insulin resistance appears to mediate this relationship.

Association of lipoprotein subfractions with endothelial function and arterial stiffness in acute ischemic stroke

Hypercholesterolemia represents a risk factor for the development of atherosclerosis. Lipoprotein research has recently been focused on the phenomenon of atherogenic and non-atherogenic lipoproteins. The aim of this study was to explore the association of lipoprotein subfractions with a measure for endothelial function (represented by reactive hyperemia index [RHI]) and arterial stiffness (represented by augmentation index [AI]) in patients with acute ischemic stroke. We enrolled 51 patients with acute ischemic stroke. Blood samples were obtained within 24 h after the stroke onset in a fasting condition. Electrophoresis method on polyacrylamide gel was used for the analysis of plasma lipoproteins. RHI and AI was measured by peripheral arterial tonometry (EndoPAT2000 device). We failed to find any significant correlation between RHI and baseline characteristics of the population. Significant correlation was found between AI and age, hypertension, low density lipoprotein cholesterol (LDL) 1, LDL 3-7, score for anti-atherogenic risk and atherogenic profile. Age (beta = .362, p = .006) and LDL1 (beta = -0.283, p = .031) were the only independent variables significantly associated with AI in regression analysis. Significantly higher AI was found in an atherogenic lipoprotein profile compared to a non-atherogenic profile population (median 25% vs. median 11.5%, p = .043). In conclusion, our results suggest significant inverse correlation between levels of LDL 1 subfraction and measures of AI in patients with acute ischemic stroke. Significantly higher values of AI were observed in the population with an atherogenic lipoprotein profile.

Association of age-dependent height and bone mineral density decline with increased arterial stiffness and rate of fractures in hypertensive individuals

OBJECTIVE

Hypertension and osteoporosis are age-related health risks differentially expressed in men and women. Here we have analysed their prevalence in a randomly selected cross-sectional cohort [CARTaGENE (CaG) of Quebec, Canada and explored their existing relationships along with height, arterial stiffness and bone fractures.

METHODS

The principal cohort CaG included 20 007 individuals of age 40-70 years. Participants were subjected to an extensive phenotyping and a questionnaire of medical history and habits.

RESULTS

We determined the differences in height of participants and their relation to hypertension status and sex in this cohort and validated it in two other cohorts (The Canadian Heart Health Study and a family cohort from the Saguenay Lac Saint-Jean, a region of Quebec). In all three cohorts, we found that at younger age individuals with hypertension are taller than normotensive individuals, but they have a shorter stature at an older age compared with normotensive individuals. In CaG, we observed that hypertension, low bone mineral density (BMD) and arterial stiffness are strongly associated with height when adjusted for antihypertensive medications (P < 0.0001). Fractures are the net outcome of low BMD, and a significant association is observed (odds ratio = 2.34, confidence interval = 2.12-2.57); this relation was stronger in hypertensive individuals compared with normotensive individuals particularly in younger hypertensive individuals. In addition, we observed that increased arterial stiffness was significantly correlated with a low BMD in both men and women at all ages.

CONCLUSION

Shorter stature in elderly, low BMD and fractures correlated with increased arterial stiffness and hypertension. We propose that hypertension and osteoporosis share components of accelerated aging.

Glycemic index, glycemic load, and pulse wave reflection in adults

BACKGROUND AND AIMS

Diets with a high glycemic index (GI), high glycemic load (GL), or both, increase the risk of cardiovascular disease. This study examined the association of GI and GL in a regular diet with the peripheral augmentation index (i.e., a marker of vascular aging) in a sample of adults.

METHODS AND RESULTS

Cross-sectional study. The findings presented in this manuscript are a subanalysis of the EVIDENT study whose purpose was to analyze the relationship between lifestyle and arterial aging. For the sample population, 1553 individuals aged 20-80 years were selected through random sampling from the patients of general practitioners at six health centers in Spain. GI and GL for each patient's diet were calculated from a previously validated, semi-quantitative, 137-item food frequency questionnaire. The peripheral augmentation index corrected for a heart rate of 75 bpm (PAIx75) was measured with pulse-wave application software (A-Pulse CASP). Based on a risk factor adjusted regression model, for every 5 unit increase in GI, the PAIx75 increased by 0.11 units (95% CI: 0.04-0.19). Similarly, for every increase in 10 units in GL, the PAIx75 increased by 1.13 (95% CI: 0.21-2.05). High PAIx75 values were observed in individuals with diets in the third GI tertile (i.e., the highest), and lower PAIx75 values in those with diets in the first tertile (i.e., the lowest), (93.1 vs. 87.5, respectively, p = 0.001).

CONCLUSIONS

GI and GL were directly associated with PAIx75 values in adults without cardiovascular diseases regardless of age, gender, physical activity, and other confounders.

Relationship between objectively measured physical activity and cardiovascular aging in the general population--the EVIDENT trial

BACKGROUND

Aging has been associated with an increase in arterial stiffness. We analyzed the relationship between regular physical activity and cardiovascular aging evaluated by the radial augmentation index (rAIx), ambulatory arterial stiffness index (AASI), pulse pressure (PP) and heart age in subjects without atherosclerotic disease.

METHODS

A cross-sectional study was performed including 1365 subjects from the EVIDENT trial (mean age 54.9±13.7 years; 60.3% women). As a measure of total volume of physical activity we used counts/minute recorded in an accelerometer (Actigraph GT3X) that participants wore for seven days, collecting data in 60-sec epochs, and respondents with ≥4 valid days were retained for the analysis. Arterial stiffness was evaluated using measures of rAIx, AASI, and central and peripheral PP on the B-pro device. rAIx was adjusted to 75 heart rate(rAIx75). Cardiovascular risk and heart age was estimated by the Framingham Risk Score.

RESULTS

The median (IQR) of counts/min was 236.9 (176.3-307.8), rAIx75 90 (77-100), sleep PP 40 mmHg (33-47), central PP 39 mmHg (32-47) and heart age 57 years (45-73) and the mean±SD of the ASSI was 0.44±0.07. We found an inverse correlation between counts/minute and rAIx75 (r=-0.086; p<0.01), AASI (r=-0.146; p<0.001), heart age (r=-0.163; p<0.001) and peripherals PP. These associations were remained after controlling for potential confounders, except for rAIx75. In the multiple regression analysis, after adjustment, an inverse association persisted between counts/minute and AASI, sleep PP and heart age, but not with rAIx75. Accordingly, for every 100 higher counts/minute of accelerometer measures, both AASI and sleep PP would be lower by one measurement unit (beta=-0.979 and -1.031 respectively, p<0.001) and the estimated heart age by half year (beta=-0.525, p=0.023).

CONCLUSIONS

Regular physical activity was inversely associated with parameters related to advanced cardiovascular aging after adjustment for potentially influencing variables.

TRIAL REGISTRATION

Clinical Trials.gov Identifier: NCT01083082.

Association between smoking status and the parameters of vascular structure and function in adults: results from the EVIDENT study

Background

The present study analyses the relation between smoking status and the parameters used to assess vascular structure and function.

Methods

This cross-sectional, multi-centre study involved a random sample of 1553 participants from the EVIDENT study. Measurements: The smoking status, peripheral augmentation index and ankle-brachial index were measured in all participants. In a small subset of the main population (265 participants), the carotid intima-media thickness and pulse wave velocity were also measured.

Results

After controlling for the effect of age, sex and other risk factors, present smokers have higher values of carotid intima-media thickness (p = 0.011). Along the same lines, current smokers have higher values of pulse wave velocity and lower mean values of ankle-brachial index but without statistical significance in both cases.

Conclusions

Among the parameters of vascular structure and function analysed, only the IMT shows association with the smoking status, after adjusting for confounders.

Ticagrelor improves peripheral arterial function in patients with a previous acute coronary syndrome

OBJECTIVE

The novel P2Y12 antagonist ticagrelor inhibits adenosine diphosphate (ADP)-induced platelet aggregation more potently than clopidogrel and reduces the incidence of myocardial infarction and total death in patients with an acute coronary syndrome (ACS). Furthermore, ticagrelor inhibits adenosine reuptake and increases coronary flow reserve during adenosine infusion in man. We wanted to determine whether ticagrelor improves peripheral arterial function in patients with a previous ACS compared to patients treated with aspirin, clopidogrel, or prasugrel.

METHODS

127 patients with a previous ACS (>3 months to <3 years ago) on maintenance dose of (1) no ADP blocker (n = 35); (2) clopidogrel 75 mg (n = 35); (3) prasugrel 10 mg (n = 32), or (4) ticagrelor 90 mg twice daily (n = 25) were evaluated with peripheral arterial tonometry after forearm ischemia.

RESULTS

Ticagrelor improves peripheral arterial function compared to the other groups [(1) controls 1.78 ± 0.53; (2) clopidogrel 1.78 ± 0.45; (3) prasugrel 1.64 ± 0.33, and (4) ticagrelor 2.25 ± 0.54 (means ± SD)] with a significance of p < 0.01 for ticagrelor versus no ADP blocker, p < 0.01 for ticagrelor versus clopidogrel, and p < 0.001 for ticagrelor versus prasugrel. There were fewer patients with endothelial dysfunction (<1.67 reactive hyperemia index) in the ticagrelor group (12%) compared to aspirin (51%), clopidogrel (46%), and prasugrel (53%) (p < 0.01).

CONCLUSION

Treatment with ticagrelor improves peripheral endothelial function compared to no ADP blocker, clopidogrel, or prasugrel treatment.

Systemic vascular function is associated with muscular power in older adults

Age-associated loss of muscular strength and muscular power is a critical determinant of loss of physical function and progression to disability in older adults. In this study, we examined the association of systemic vascular function and measures of muscle strength and power in older adults. Measures of vascular endothelial function included brachial artery flow-mediated dilation (FMD) and the pulse wave amplitude reactive hyperemia index (PWA-RHI). Augmentation index (AIx) was taken as a measure of systemic vascular function related to arterial stiffness and wave reflection. Measures of muscular strength included one repetition maximum (1RM) for a bilateral leg press. Peak muscular power was measured during 5 repetitions performed as fast as possible for bilateral leg press at 40% 1RM. Muscular power was associated with brachial FMD (r = 0.43, P < 0.05), PWA-RHI (r = 0.42, P < 0.05), and AIx (r = -0.54, P < 0.05). Muscular strength was not associated with any measure of vascular function. In conclusion, systemic vascular function is associated with lower-limb muscular power but not muscular strength in older adults. Whether loss of muscular power with aging contributes to systemic vascular deconditioning or vascular dysfunction contributes to decrements in muscular power remains to be determined.