A meta-analysis of published studies of endothelial dysfunction does not support its routine clinical use

Endothelial Dysfunction in Youth-Onset Type 2 Diabetes: A Clinical Translational Study

BACKGROUND

Youth-onset type 2 diabetes (Y-T2D) is associated with increased risk for coronary atherosclerotic disease, but the timing of the earliest pathological features and evidence of cardiac endothelial dysfunction have not been evaluated in this population. Endothelial function magnetic resonance imaging may detect early and direct endothelial dysfunction in the absence of classical risk factors (severe hyperglycemia, hypertension, and hyperlipidemia). Using endothelial function magnetic resonance imaging, we evaluated peripheral and coronary artery structure and endothelial function in young adults with Y-T2D diagnosed ≤5 years compared with age-matched healthy peers. We isolated and characterized plasma-derived small extracellular vesicles and evaluated their effects on inflammatory and signaling biomarkers in healthy human coronary artery endothelial cells to validate the imaging findings.

METHODS

Right coronary wall thickness, coronary artery flow-mediated dilation, and brachial artery flow-mediated dilation were measured at baseline and during isometric handgrip exercise using a 3.0T magnetic resonance imaging. Human coronary artery endothelial cells were treated with Y-T2D plasma-derived small extracellular vesicles. Protein expression was measured by Western blot analysis, oxidative stress was measured using the redox-sensitive probe dihydroethidium, and nitric oxide levels were measured by 4-amino-5-methylamino-2',7'-difluororescein diacetate.

RESULTS

Y-T2D (n=20) had higher hemoglobin A1c and high-sensitivity C-reactive protein, but similar total and LDL (low-density lipoprotein)-cholesterol compared with healthy peers (n=16). Y-T2D had greater coronary wall thickness (1.33±0.13 versus 1.22±0.13 mm; P=0.04) and impaired endothelial function: lower coronary artery flow-mediated dilation (-3.1±15.5 versus 15.9±17.3%; P<0.01) and brachial artery flow-mediated dilation (6.7±14.7 versus 26.4±15.2%; P=0.001). Y-T2D plasma-derived small extracellular vesicles reduced phosphorylated endothelial nitric oxide synthase expression and nitric oxide levels, increased reactive oxygen species production, and elevated ICAM (intercellular adhesion molecule)-mediated inflammatory pathways in human coronary artery endothelial cells.

CONCLUSIONS

Coronary and brachial endothelial dysfunction was evident in Y-T2D who were within 5 years of diagnosis and did not have severe hyperglycemia or dyslipidemia. Plasma-derived small extracellular vesicles induced markers of endothelial dysfunction, which corroborated accelerated subclinical coronary atherosclerosis as an early feature in Y-T2D.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02830308 and NCT01399385.

Retinal vascular function in asymptomatic individuals with a positive family history of cardiovascular disease

PURPOSE

To compare retinal microvascular function in healthy individuals with and without a positive family history (FH) of cardiovascular disease (CVD).

METHODS

Retinal vessel reactivity was assessed by means of dynamic retinal vessel analysis in 38 healthy subjects aged between 30 and 66 years with a positive FH of CVD and 37 age- and gender-matched control subjects. Other assessments included blood pressure (BP) profiles, blood glucose and lipid metabolism markers, Framingham risk scores (FRS), carotid intima-media thickness (c-IMT) and brachial flow-mediated dilation (FMD).

RESULTS

Family history-positive subjects showed decreased retinal arterial baseline diameter fluctuation, dilation amplitude, percent dilation, and overall constriction response slope (p = 0.001; p = 0.015; p = 0.001; and p < 0.001, respectively) and increased percent constriction (p = 0.008). On the venous side, baseline-corrected flicker response and dilation response slope were decreased in the FH-positive group (p = 0.009 and p = 0.010, respectively). There were no significant differences between groups in c-IMT scores or FMD parameters (all p > 0.05). The arterial MC% correlated negatively with decreased high-density lipoprotein cholesterol (r = -0.52, p = 0.002) in only FH-positive group.

CONCLUSION

Although macrovascular function is preserved in individuals with FH positive for CVD but with low FRS, there are, however, functional impairments at the retinal microvascular level that correlate with established plasma markers for cardiovascular risk.

Should Cushing's Syndrome be Considered as a Disease with High Cardiovascular Risk in Relevant Guidelines?

A considerable amount of data supports a 1.8-7.4-fold increased mortality associated with Cushing's syndrome (CS). This is attributed to a high occurrence of several cardiovascular disease (CVD) risk factors in CS [e.g. adiposity, arterial hypertension (AHT), dyslipidaemia and type 2 diabetes mellitus (T2DM)]. Therefore, practically all patients with CS have the metabolic syndrome (MetS), which represents a high CVD risk. Characteristically, despite a relatively young average age, numerous patients with CS display a 'high' or 'very high' CVD risk (i.e. risk of a major CVD event >20% in the following 10 years). Although T2DM is listed as a condition with a high CVD risk, CS is not, despite the fact that a considerable proportion of the CS population will develop T2DM or impaired glucose tolerance. CS is also regarded as a risk factor for aortic dissection in current guidelines. This review considers the evidence supporting listing CS among high CVD risk conditions.

Simultaneous Noninvasive Assessment of Systemic and Coronary Endothelial Function

BACKGROUND

Normal endothelial function is a measure of vascular health and dysfunction is a predictor of coronary events. Nitric oxide-mediated coronary artery endothelial function, as assessed by vasomotor reactivity during isometric handgrip exercise (IHE), was recently quantified noninvasively with magnetic resonance imaging (MRI). Because the internal mammary artery (IMA) is often visualized during coronary MRI, we propose the strategy of simultaneously assessing systemic and coronary endothelial function noninvasively by MRI during IHE.

METHODS AND RESULTS

Changes in cross-sectional area and blood flow in the right coronary artery and the IMA in 25 patients with coronary artery disease and 26 healthy subjects during IHE were assessed using 3T MRI. In 8 healthy subjects, a nitric oxide synthase inhibitor was infused to evaluate the role of nitric oxide in the IMA-IHE response. Interobserver IMA-IHE reproducibility was good for cross-sectional area (R=0.91) and blood flow (R=0.91). In healthy subjects, cross-sectional area and blood flow of the IMA increased during IHE, and these responses were significantly attenuated by monomethyl-l-arginine (P<0.01 versus placebo). In patients with coronary artery disease, the right coronary artery did not dilate with IHE, and dilation of the IMA was less than that of the healthy subjects (P=0.01). The blood flow responses of both the right coronary artery and IMA to IHE were also significantly reduced in patients with coronary artery disease.

CONCLUSIONS

MRI-detected IMA responses to IHE primarily reflect nitric oxide-dependent endothelial function and are reproducible and reduced in patients with coronary artery disease. Endothelial function in both coronary and systemic (IMA) arteries can now be measured noninvasively with the same imaging technique and promises novel insights into systemic and local factors affecting vascular health.

Endothelial Dysfunction and Racial Disparities in Mortality and Adverse Cardiovascular Disease Outcomes

BACKGROUND

The contribution of arterial endothelial dysfunction (ED) to increased cardiovascular disease (CVD) risk among Blacks is not known.

HYPOTHESIS

We investigated whether peripheral arterial ED explains racial disparity in CVD events.

METHODS

Data from the Heart Strategies Concentrating on Risk Evaluation (Heart SCORE) study was used. Endothelial dysfunction was assessed by the Framingham reactive hyperemia index (fRHI), measured using pulse amplitude tonometry (PAT). Lower values of fRHI indicate more severe ED. The primary outcome of interest was combined CVD events and all-cause mortality.

RESULTS

1454 individuals (62% female, 40% Black, mean age 59 ± 8 years) had available data on fRHI (mean [SD]: 0.74 [0.46]). Over a mean follow-up period of 8.0 ± 2.4 years (11,186 person-years), 116 events were observed. Black race, male sex, smoking, diabetes, blood pressure, triglycerides, C-reactive protein, and interleukin-6 were inversely correlated with fRHI in univariate models. In an unadjusted Cox regression model, fRHI was associated with 20% lower risk of the primary outcome events (hazard ratio [HR] per 1-SD higher fRHI: 0.80, 95% confidence interval [CI]: 0.66-0.97). However, this association was no longer significant after adjustment for CVD risk factors (HR: 0.90, 95% CI: 0.74-1.11). In an age- and sex-adjusted model, Blacks had 1.68 (95% CI: 1.16-2.43) higher risk of primary outcome compared with Whites. This association was not significantly attenuated by addition of fRHI to the multivariable models.

CONCLUSION

Black race is associated with increased risk of CVD events and mortality independent of its associations with ED, as measured by PAT.