Multi-modal magnetic resonance imaging quantifies atherosclerosis and vascular dysfunction in patients with type 2 diabetes mellitus

Renal Function, Albumin-Creatinine Ratio and Pulse Wave Velocity Predict Silent Coronary Artery Disease and Renal Outcome in Type 2 Diabetic and Prediabetic Subjects

INTRODUCTION

Silent coronary heart disease is frequently undetected in type 2 diabetes mellitus (DM2) and pre-diabetes determined by glucose intolerance (GI). Pulse wave velocity (PWV) and albumin-creatinine ratio (ACR) have been considered markers of cardiovascular mortality, coronary heart disease and chronic renal failure.

AIM

To evaluate the incidence of coronary artery disease (CAD) and the relationship between urinary albumin-creatinine ratio, glomerular filtration rate (GFR) and PWV in type 2 DM with silent CAD.

METHODS

We analyzed 92 individuals (44 male), 49 (60±7y) type 2 DM non-insulin dependents and 43 prediabetics (43±4y), with Grade I-II hypertension and no symptoms of CAD. All type 2 DM patients were under antidiabetic treatment with A1C hemoglobin between 5.5 and 6.5%. Every patient underwent a myocardial perfusion SPECT scan. In those subjects with ischemic patterns, coronary angiography was performed. In addition, PWV, glomerular filtration rate, and ACR were evaluated.

STATISTICS

mean±SEM, and ANOVA among groups.

RESULTS

48.59% of DM2 and 25.58% of GI patients had silent coronary artery had silent coronary artery disease and higher ACR, PWV and reduced GFR. Higher ACR and PWV and reduced GFR. DM2 and GI showed a negative relationship between GFR and ACR. Moreover, this relation was also observed in different levels of GFR (>60 ml/min and <60ml.min (p<0.05) in patients with CAD, suggesting a cardio-renal interaction in DM2.

CONCLUSION

Higher PWV, lower GFR and ACR predict the incidence of CAD in DM2. Dysglycemic individuals also represent a group of higher risk for coronary artery disease with similar predictors as in DM2. Diabetic and prediabetics still develop renal microalbuminuria. Thus, PWV seems to represent a reliable marker of renal impairment and coronary artery disease.

Degradation of Glycocalyx and Multiple Manifestations of Endothelial Dysfunction Coincide in the Early Phase of Endothelial Dysfunction Before Atherosclerotic Plaque Development in Apolipoprotein E/Low-Density Lipoprotein Receptor-Deficient Mice

Background

The impairment of endothelium‐dependent vasodilation, increased endothelial permeability, and glycocalyx degradation are all important pathophysiological components of endothelial dysfunction. However, it is still not clear whether in atherosclerosis, glycocalyx injury precedes other features of endothelial dysfunction or these events coincide.

Methods and Results

Herein, we demonstrate that in 4‐ to 8‐week‐old apolipoprotein E/low‐density lipoprotein receptor‐deficient mice, at the stage before development of atherosclerotic plaques, impaired acetylcholine‐induced vasodilation, reduced NO production in aorta, and increased endothelial permeability were all observed; however, flow‐mediated dilation in the femoral artery was fully preserved. In 4‐week‐old mice, glycocalyx coverage was reduced and endothelial stiffness was increased, whereas glycocalyx length was significantly decreased at 8 weeks of age. Early changes in endothelial function were also featured by increased plasma concentration of biomarkers of glycocalyx disruption (endocan), biomarkers of endothelial inflammation (soluble vascular cell adhesion molecule 1), increased vascular permeability (angiopoietin 2), and alterations in hemostasis (tissue plasminogen activator and plasminogen activator inhibitor 1). In 28‐week‐old mice, at the stage of advanced atherosclerotic plaque development, impaired NO production and nearly all other features of endothelial dysfunction were changed to a similar extent, compared with the preatherosclerotic plaque phase. The exceptions were the occurrence of acetylcholine‐induced vasoconstriction in the aorta and brachiocephalic artery, impaired flow‐mediated vasodilation in the femoral artery, and further reduction of glycocalyx length and coverage with a concomitant further increase in endothelial permeability.

Conclusions

In conclusion, even at the early stage before the development of atherosclerotic plaques, endothelial dysfunction is a complex multifactorial response that has not been previously appreciated.

Cardiovascular MRI evidence of reduced systolic function and reduced LV mass in rheumatoid arthritis: impact of disease phenotype

The accelerated risk of cardiovascular disease (CVD) in Rheumatoid Arthritis (RA) requires further study of the underlying pathophysiology and determination of the at-risk RA phenotype. Our objectives were to describe the cardiac structure and function and arterial stiffness, and association with disease phenotype in patients with established) RA, in comparison to healthy controls, as measured by cardiovascular magnetic resonance imaging (CMR). 76 patients with established RA and no history of CVD/diabetes mellitus were assessed for RA and cardiovascular profile and underwent a non-contrast 3T-CMR, and compared to 26 healthy controls. A univariable analysis and multivariable linear regression model determined associations between baseline variables and CMR-measures. Ten-year cardiovascular risk scores were increased in RA compared with controls. Adjusting for age, sex and traditional cardiovascular risk factors, patients with RA had reduced left ventricular ejection fraction (mean difference - 2.86% (- 5.17, - 0.55) p = 0.016), reduced absolute values of mid systolic strain rate (p < 0.001) and lower late/active diastolic strain rate (p < 0.001) compared to controls. There was evidence of reduced LV mass index (LVMI) (- 4.56 g/m2 (- 8.92, - 0.20), p = 0.041). CMR-measures predominantly associated with traditional cardiovascular risk factors; male sex and systolic blood pressure independently with increasing LVMI. Patients with established RA and no history of CVD have evidence of reduced LV systolic function and LVMI after adjustment for traditional cardiovascular risk factors; the latter suggesting cardiac pathology other than atherosclerosis in RA. Traditional cardiovascular risk factors, rather than RA disease phenotype, appear to be key determinants of subclinical CVD in RA potentially warranting more effective cardiovascular risk reduction programs.

Cardiovascular magnetic resonance measures of aortic stiffness in asymptomatic patients with type 2 diabetes: association with glycaemic control and clinical outcomes

BACKGROUND

We aimed to investigate in patients with type 2 diabetes whether aortic stiffness is: (i) associated with glycaemic control, (ii) associated with adverse outcomes and (iii) can be reversed on treatment with RAAS inhibition.

METHODS

Patients with type 2 diabetes (N = 94) and low vascular risk underwent assessment of cardiovascular risk and CMR assessment of ascending aortic distensibility (AAD), descending aortic distensibility (DAD) and aortic pulse wave velocity (PWV). Of these patients a subgroup with recent onset microalbuminuria (N = 25) were treated with renin-angiotensin-aldosterone system (RAAS) inhibition and imaging repeated after 1 year. All 94 patients were followed up for 2.4 years for major adverse cardiovascular disease (CVD) events including myocardial infarction detected on late gadolinium enhancement CMR.

RESULTS

Ascending aortic distensibility, DAD and PWV all had a significant association with age and 24 h systolic blood pressure but only AAD had a significant association with glycaemic control, measured as HbA1c (Beta - 0.016, P = 0.04). The association between HbA1c and AAD persisted even after correction for age and hypertension. CVD events occurred in 19/94 patients. AAD, but not DAD or PWV, was associated with CVD events (hazard ratio 0.49, 95% confidence interval 0.25-0.95, P = 0.01). On treatment with RAAS inhibition, AAD, but not DAD or PWV, showed significant improvement from 1.51 ± 1.15 to 1.97 ± 1.07 10-3 mmHg-1, P = 0.007.

CONCLUSIONS

Ascending aortic distensibility measured by CMR is independently associated with poor glycaemic control and adverse cardiovascular events. Furthermore it may be reversible on treatment with RAAS inhibition. AAD is a promising marker of cardiovascular risk in asymptomatic patients with type 2 diabetes and has potential use as a surrogate cardiovascular endpoint in studies of novel hypoglycaemic agents. Clinical trials registration https://clinicaltrials.gov/ct2/show/NCT01970319.

Arterial Effects of Canakinumab in Patients With Atherosclerosis and Type 2 Diabetes or Glucose Intolerance

Background

Evidence suggests that interleukin (IL)-1β is important in the pathogenesis of atherosclerosis and its complications and that inhibiting IL-1β may favorably affect vascular disease progression.

Objectives

The goal of this study was to evaluate the effects of IL-1β inhibition with canakinumab versus placebo on arterial structure and function, determined by magnetic resonance imaging.

Methods

Patients (N = 189) with atherosclerotic disease and either type 2 diabetes mellitus or impaired glucose tolerance were randomized to receive placebo (n = 94) or canakinumab 150 mg monthly (n = 95) for 12 months. They underwent magnetic resonance imaging of the carotid arteries and aorta.

Results

There were no statistically significant differences between canakinumab compared with placebo in the primary efficacy and safety endpoints. There was no statistically significant change in mean carotid wall area and no effect on aortic distensibility, measured at 3 separate anatomic sites. The change in mean carotid artery wall area was –3.37 mm² after 12 months with canakinumab versus placebo. High-sensitivity C-reactive protein was significantly reduced by canakinumab compared with placebo at 3 months (geometric mean ratio [GMR]: 0.568; 95% confidence interval [CI]: 0.436 to 0.740; p < 0.0001) and 12 months (GMR: 0.56; 95% CI: 0.414 to 0.758; p = 0.0002). Lipoprotein(a) levels were reduced by canakinumab compared with placebo (–4.30 mg/dl [range: –8.5 to –0.55 mg/dl]; p = 0.025] at 12 months), but triglyceride levels increased (GMR: 1.20; 95% CI: 1.046 to 1.380; p = 0.01). In these patients with type 2 diabetes mellitus or impaired glucose tolerance, canakinumab had no effect compared with placebo on any of the measures assessed by using a standard oral glucose tolerance test.

Conclusions

There were no statistically significant effects of canakinumab on measures of vascular structure or function. Canakinumab reduced markers of inflammation (high-sensitivity C-reactive protein and interleukin-6), and there were modest increases in levels of total cholesterol and triglycerides. (Safety & Effectiveness on Vascular Structure and Function of ACZ885 in Atherosclerosis and Either T2DM or IGT Patients; NCT00995930)

Functional and Biochemical Endothelial Profiling In Vivo in a Murine Model of Endothelial Dysfunction; Comparison of Effects of 1-Methylnicotinamide and Angiotensin-converting Enzyme Inhibitor

Although it is known that 1-methylnicotinamide (MNA) displays vasoprotective activity in mice, as yet the effect of MNA on endothelial function has not been demonstrated in vivo. Here, using magnetic resonance imaging (MRI) we profile the effects of MNA on endothelial phenotype in mice with atherosclerosis (ApoE/LDLR^-/-) in vivo, in comparison to angiotensin (Ang) -converting enzyme (ACE) inhibitor (perindopril), with known vasoprotective activity. On a biochemical level, we analyzed whether MNA- or perindopril-induced improvement in endothelial function results in changes in ACE/Ang II-ACE2/Ang-(1–7) balance, and L-arginine/asymmetric dimethylarginine (ADMA) ratio. Endothelial function and permeability were evaluated in the brachiocephalic artery (BCA) in 4-month-old ApoE/LDLR^-/- mice that were non-treated or treated for 1 month or 2 months with either MNA (100 mg/kg/day) or perindopril (10 mg/kg/day). The 3D IntraGate^®FLASH sequence was used for evaluation of BCA volume changes following acetylcholine (Ach) administration, and for relaxation time (T₁) mapping around BCA to assess endothelial permeability using an intravascular contrast agent. Activity of ACE/Ang II and ACE2/Ang-(1–7) pathways as well as metabolites of L-arginine/ADMA pathway were measured using liquid chromatography/mass spectrometry-based methods. In non-treated 6-month-old ApoE/LDLR^-/- mice, Ach induced a vasoconstriction in BCA that amounted to –7.2%. 2-month treatment with either MNA or perindopril resulted in the reversal of impaired Ach-induced response to vasodilatation (4.5 and 5.5%, respectively) and a decrease in endothelial permeability (by about 60% for MNA-, as well as perindopril-treated mice). Improvement of endothelial function by MNA and perindopril was in both cases associated with the activation of ACE2/Ang-(1–7) and the inhibition of ACE/Ang II axes as evidenced by an approximately twofold increase in Ang-(1–9) and Ang-(1–7) and a proportional decrease in Ang II and its active metabolites. Finally, MNA and perindopril treatment resulted in an increase in L-arginine/ADMA ratio by 107% (MNA) and 140% (perindopril), as compared to non-treated mice. Functional and biochemical endothelial profiling in ApoE/LDLR^-/- mice in vivo revealed that 2-month treatment with MNA (100 mg/kg/day) displayed a similar profile of vasoprotective effect as 2-month treatment with perindopril (10 mg/kg/day): i.e., the improvement in endothelial function that was associated with the beneficial changes in ACE/Ang II-ACE2/Ang (1–7) balance and in L-arginine/ADMA ratio in plasma.

Retrospectively gated MRI for in vivo assessment of endothelium-dependent vasodilatation and endothelial permeability in murine models of endothelial dysfunction

Endothelial dysfunction is linked to impaired endothelial-dependent vasodilatation and permeability changes. Here, we quantify both of these phenomena associated with endothelial dysfunction by MRI in vivo in mice. Endothelial function was evaluated in the brachiocephalic artery (BCA) and left carotid artery (LCA) in ApoE/LDLR(-/-) and high-fat diet (HFD)-fed mice as compared with control mice (C57BL/6J). The 3D IntraGate® FLASH sequence was used for evaluation of changes in vessels' cross-sectional area (CSA) and volume following acetylcholine (Ach) administration. Evaluation of endothelial permeability after administration of contrast agent (Galbumin, BioPAL) was based on the variable flip angle method for the assessment of parameters based on the relaxation time (T1 ) value. In order to confirm the involvement of nitric oxide (NO) in response to Ach, L-NAME-treated mice were also analyzed. To confirm that endothelial permeability changes accompany the impairment of Ach-dependent vasodilatation, permeability changes were analyzed in isolated, perfused carotid artery. In C57BL/6J mice, Ach-induced vasodilatation led to an approximately 25% increase in CSA in both vessels, which was temporarily dissociated from the effect of Ach on heart rate. In ApoE/LDLR(-/-) or HFD-fed mice Ach induced a paradoxical vasoconstriction that amounted to approximately 30% and 50% decreases in CSA of BCA and LCA respectively. In ApoE/LDLR(-/-) and HFD-fed mice endothelial permeability in BCA was also increased (fall in T1 by about 25%). In L-NAME-treated mice Ach-induced vasodilatation in BCA was lost. In isolated, perfused artery from ApoE/LDLR(-/-) mice endothelial permeability was increased. MRI-based assessment of endothelium-dependent vasodilatation induced by Ach and endothelial permeability using a retrospectively self-gated 3D gradient-echo sequence (IntraGate® FLASH) enables the reliable detection of systemic endothelial dysfunction in mice and provides an important tool for the experimental pharmacology of the endothelium in murine models of diseases in vivo. Copyright © 2016 John Wiley & Sons, Ltd.

Association of Aortic Compliance and Brachial Endothelial Function with Cerebral Small Vessel Disease in Type 2 Diabetes Mellitus Patients: Assessment with High-Resolution MRI

Objective. To assess the possible association of aortic compliance and brachial endothelial function with cerebral small vessel disease in type 2 diabetes mellitus (DM2) patients by using 3.0 T high-resolution magnetic resonance imaging. Methods. Sixty-two clinically confirmed DM2 patients (25 women and 37 men; mean age: 56.8 ± 7.5 years) were prospectively enrolled for noninvasive MR examinations of the aorta, brachial artery, and brain. Aortic arch pulse wave velocity (PWV), flow-mediated dilation (FMD) of brachial artery, lacunar brain infarcts, and periventricular and deep white matter hyperintensities (WMHs) were assessed. Pearson and Spearman correlation analysis were performed to analyze the association between PWV and FMD with clinical data and biochemical test results. Univariable logistic regression analyses were used to analyze the association between PWV and FMD with cerebral small vessel disease. Multiple logistic regression analyses were used to find out the independent predictive factors of cerebral small vessel disease. Results. Mean PWV was 6.73 ± 2.00 m/s and FMD was 16.67 ± 9.11%. After adjustment for compounding factors, PWV was found significantly associated with lacunar brain infarcts (OR = 2.00; 95% CI: 1.14–3.2; P < 0.05) and FMD was significantly associated with periventricular WMHs (OR = 0.82; 95% CI: 0.71–0.95; P < 0.05). Conclusions. Quantitative evaluation of aortic compliance and endothelial function by using high-resolution MRI may be potentially useful to stratify DM2 patients with risk of cerebral small vessel disease.

Dipeptidyl peptidase-4 inhibitors improve arterial stiffness, blood pressure, lipid profile and inflammation parameters in patients with type 2 diabetes mellitus

BACKGROUND

This uncontrolled open label study evaluated the effect of dipeptidyl peptidase-4 inhibitors (DPP-4i): sitagliptin and vildagliptin on augmentation index standardized for 75 beats per minute (cAiX@75), blood pressure (BP), lipid profile and high-sensitivity C-reactive protein (hsCRP) in patients with type 2 diabetes mellitus (T2DM).

METHODS

Fifty-one well-regulated T2DM patients were randomly assigned to either sitagliptin or vildagliptin (100 mg/day) for 3 months continuing their previous treatment. Lipid profile, cAiX@75, hsCRP, glycated hemoglobin (HbA1c) were measured at baseline at 4, 8 and 12th week were accessed. cAiX@75 and pulse wave velocity (PWV) were determined by SphygmoCor device.

RESULTS

Following DPP-4 treatment there was a significant reduction in total serum cholesterol (5.18 vs 4.62 mmol/L), low-density lipoprotein (2.89 vs 2.54 mmol/L), hsCRP (3.21 vs 1.95 mg/L), cAiX@75 (24.5 vs 22.3) and central systolic BP (131.8 vs 119.5 mmHg). The sitagliptin treated group reached cAiX@75 reduction earlier in the study period while neither sitagliptin or vildagliptin use resulted in the significant HbA1c reduction.

CONCLUSION

The treatment with DPP-4i: sitagliptin and vildagliptin provides favorable metabolic and vascular effects beyond glucose-control. Further studies are required to elucidate their implication in metabolic pathways.

Comprehensive multi-modality assessment of regional and global arterial structure and function in adults born preterm

Preterm birth is associated with higher blood pressure, which could be because preterm birth alters early aortic elastin and collagen development to cause increased arterial stiffness. We measured central and conduit artery size and multiple indices of arterial stiffness to define the extent and severity of macrovascular changes in individuals born preterm. A total of 102 young adults born preterm and 102 controls who were born after an uncomplicated pregnancy underwent cardiovascular magnetic resonance on a Siemens 1.5 T scanner to measure the aortic cross-sectional area in multiple locations. Ultrasound imaging with a Philips CX50 and linear array probe was used to measure carotid and brachial artery diameters. Carotid-femoral pulse wave velocity and the augmentation index were measured by SphygmoCor, brachial-femoral pulse wave velocity by Vicorder and aortic pulse wave velocity by cardiovascular magnetic resonance. The cardio-ankle vascular index (CAVI) was used as a measurement of global stiffness, and ultrasound was used to assess peripheral vessel distensibility. Adults born preterm had 20% smaller thoracic and abdominal aortic lumens (2.19 ± 0.44 vs. 2.69 ± 0.60 cm(2), P<0.001; 1.25 ± 0.36 vs. 1.94 ± 0.45 cm(2), P<0.001, respectively) but similar carotid and brachial diameters to adults born at term. Pulse wave velocity was increased (5.82 ± 0.80 vs. 5.47 ± 0.59 m s(-1), P<0.01, 9.06 ± 1.25 vs. 8.33 ± 1.28 m s(-1), P=0.01, 5.23 ± 1.19 vs. 4.75 ± 0.91 m s(-1), P<0.01) and carotid distensibility was decreased (4.75 ± 1.31 vs. 5.60 ± 1.48 mm Hg(-1)10(3), P<0.001) in this group compared with the group born at term. However, the global and peripheral arterial stiffness measured by CAVI and brachial ultrasound did not differ (5.95 ± 0.72 vs. 5.98 ± 0.60, P=0.80 and 1.07 ± 0.48 vs. 1.19 ± 0.54 mm Hg(-1)10(3), P=0.12, respectively). Adults who are born preterm have significant differences in their aortic structure from adults born at term, but they have relatively small differences in central arterial stiffness that may be partially explained by blood pressure variations.

Coronary Artery Disease Evaluation in Rheumatoid Arthritis (CADERA): study protocol for a randomized controlled trial

Background

The incidence of cardiovascular disease (CVD) in rheumatoid arthritis (RA) is increased compared to the general population. Immune dysregulation and systemic inflammation are thought to be associated with this increased risk. Early diagnosis with immediate treatment and tight control of RA forms a central treatment paradigm. It remains unclear, however, whether using tumor necrosis factor inhibitors (TNFi) to achieve remission confer additional beneficial effects over standard therapy, especially on the development of CVD.

Methods/Design

Coronary Artery Disease Evaluation in Rheumatoid Arthritis (CADERA) is a prospective cardiovascular imaging study that bolts onto an existing single-centre, randomized controlled trial, VEDERA (Very Early versus Delayed Etanercept in Rheumatoid Arthritis). VEDERA will recruit 120 patients with early, treatment-naïve RA, randomized to TNFi therapy etanercept (ETN) combined with methotrexate (MTX), or therapy with MTX with or without additional synthetic disease modifying anti-rheumatic drugs with escalation to ETN following a ‘treat-to-target’ regimen. VEDERA patients will be recruited into CADERA and undergo cardiac magnetic resonance (CMR) assessment with; cine imaging, rest/stress adenosine perfusion, tissue-tagging, aortic distensibility, T1 mapping and late gadolinium imaging. Primary objectives are to detect the prevalence and change of cardiovascular abnormalities by CMR between TNFi and standard therapy over a 12-month period. All patients will enter an inflammatory arthritis registry for long-term follow-up.

Discussion

CADERA is a multi-parametric study describing cardiovascular abnormalities in early, treatment-naïve RA patients, with assessment of changes at one year between early biological therapy and conventional therapy.

Trials registration

This trial was registered with Current Controlled Trials (registration number: ISRCTN50167738) on 8 November 2013.

The combined effect of hypertension and type 2 diabetes mellitus on aortic stiffness and endothelial dysfunction: an integrated study with high-resolution MRI

PURPOSE

The purpose of this study was to investigate the combined effect of hypertension and type 2 diabetes mellitus (DM2) on aortic stiffness and endothelial dysfunction by using an integrated MRI approach.

MATERIALS AND METHODS

A total of 31 non-hypertensive DM2 patients and 31 hypertensive DM2 patients underwent 3.0-T MRI. Aortic distensibility (AD), pulse wave velocity (PWV) and brachial artery flow-mediated dilation (FMD) were assessed. Student's t-test, Mann-Whitney U test, chi-squared test, Pearson correlation analysis, and univariable and multiple linear regression analyses were used for statistical analyses.

RESULTS

The hypertensive patients showed lower AD at multiple levels (ascending aorta [AA]: 2.07±0.98×10(-3)mm Hg(-1) vs. 3.21±1.70×10(-3)mm Hg(-1), p<0.01; proximal thoracic descending aorta [PDA]: 2.58±0.72×10(-3)mm Hg(-1) vs. 3.58±1.47×10(-3)mm Hg(-1), p<0.01; distal descending aorta [DDA]: 3.11±1.84×10(-3)mm Hg(-1) vs. 4.27±1.75×10(-3)mm Hg(-1), p<0.01); faster PWV (7.46±2.28m/s vs. 5.82±1.12m/s, p<0.05) and lower FMD (12.67%±6.49% vs. 20.66%±9.7%; p<0.01). Systolic blood pressure was an independent predictor of PWV, AA-AD, DDA-AD and FMD. FMD was statistically significantly associated with PWV (r=-0.37, p<0.01) and AD (p<0.01).

CONCLUSIONS

Hypertension has a contributive effect on aortic stiffness and endothelial dysfunction in DM2 patients.

Atherosclerosis and arterial stiffness in obstructive sleep apnea--a cardiovascular magnetic resonance study

OBJECTIVE

Obstructive sleep apnoea (OSA) has been linked to cardiovascular risk factors, such as hypertension, and clinical cardiovascular endpoints. Our aim was to assess whether OSA is independently associated with atherosclerosis and vascular dysfunction as assessed by cardiovascular magnetic resonance (CMR).

METHODS

58 patients with OSA and 39 matched control subjects without OSA underwent CMR of the aorta and carotid arteries. Carotid and aortic wall thickness and aortic distensibility were measured. Multi-weighted, high resolution CMR imaging was used for carotid atheroma characterization according to the American Heart Association (AHA) atheroma classification, modified for CMR.

RESULTS

Carotid [1.47±0.03 mm vs. 1.26±0.05 mm, (P<0.01)] and aortic wall thickness [2.95±0.09 mm vs. 2.05±0.07 mm, (P<0.001)] were increased in patients with OSA compared to controls. Aortic distensibility was decreased in patients with OSA [3.62±0.3 vs. 4.75±0.2 mmHg(-1)×10(-3), (P<0.05)]. Prevalence of carotid plaque, average carotid atheroma class, and prevalence of high risk features of carotid atheroma were increased in patients with OSA (P<0.005 for all). On multivariate analysis, Oxygen desaturation index (ODI) emerged as an independent predictor of carotid and aortic wall thickness, but not of aortic stiffness.

CONCLUSIONS

OSA is associated with increased carotid and aortic atheroma burden and with advanced, high risk carotid atherosclerotic plaques, but not with aortic stiffening.

Comparison of echotracking and magnetic resonance assessment of abdominal aorta distensibility and relationships with pulse wave velocity

Arterial distensibility can be measured either by echotracking or by nuclear magnetic resonance (MRI). Little information, however, is available on the comparison between the two methods and on the relationships between the results obtained with the two approaches and the arterial stiffness gold standard measurement, i.e., pulse wave velocity (PWV). In 28 normotensive subjects (age 33.0 ± 10.4 years, mean ± SD) we measured aortic diameter 1 cm above iliac bifurcation, aortic pulse pressure by tonometry and calculated arterial distensibility via the Reneman formulae for both methods. Aortic diameter and aortic distensibility were not superimposable and higher values were systematically detected with the MRI approach than with the ultrasound one. However, PWV showed a significant correlation with aortic distensibility values obtained by both methods (r = 0.50 and r = 0.49, p < 0.05). These data provide evidence that MRI-measured distensibility value is higher than that obtained via echotracking. The significant correlation with PWV, however, suggests that both methods can be regarded as valuable approaches. Considering the greater economic cost and the lower availability in daily clinical and research practice of MRI, echotracking ultrasonography can be regarded as a reliable and feasible method to assess aortic distensibility.

Multimodal cardiovascular magnetic resonance quantifies regional variation in vascular structure and function in patients with coronary artery disease: relationships with coronary disease severity

BACKGROUND

Cardiovascular magnetic resonance (CMR) of the vessel wall is highly reproducible and can evaluate both changes in plaque burden and composition. It can also measure aortic compliance and endothelial function in a single integrated examination. Previous studies have focused on patients with pre-identified carotid atheroma. We define these vascular parameters in patients presenting with coronary artery disease and test their relations to its extent and severity.

METHODS AND RESULTS

100 patients with CAD [single-vessel (16%); two-vessel (39%); and three-vessel (42%) non-obstructed coronary arteries (3%)] were studied. CAD severity and extent was expressed as modified Gensini score (mean modified score 12.38 ± 5.3). A majority of carotid plaque was located in the carotid bulb (CB). Atherosclerosis in this most diseased segment correlated modestly with the severity and extent of CAD, as expressed by the modified Gensini score (R = 0.251, P < 0.05). Using the AHA plaque classification, atheroma class also associated with CAD severity (rho = 0.26, P < 0.05). The distal descending aorta contained the greatest plaque, which correlated with the degree of CAD (R = 0.222; P < 0.05), but with no correlation with the proximal descending aorta, which was relatively spared (R = 0.106; P = n. s.). Aortic distensibility varied along its length with the ascending aorta the least distensible segment. Brachial artery FMD was inversely correlated with modified Gensini score (R = -0.278; P < 0.05). In multivariate analysis, distal descending aorta atheroma burden, distensibility of the ascending aorta, carotid atheroma class and FMD were independent predictors of modified Gensini score.

CONCLUSIONS

Multimodal vascular CMR shows regional abnormalities of vascular structure and function that correlate modestly with the degree and extent of CAD.

Coronary artery distensibility assessed by 3.0 Tesla coronary magnetic resonance imaging in subjects with and without coronary artery disease

Coronary vessel distensibility is reduced with atherosclerosis and normal aging, but direct measurements have historically required invasive measurements at cardiac catheterization. Therefore, we sought to assess coronary artery distensibility noninvasively using 3.0 Telsa coronary magnetic resonance imaging (MRI) and to test the hypothesis that this noninvasive technique can detect differences in coronary distensibility between healthy subjects and those with coronary artery disease (CAD). A total of 38 healthy, adult subjects (23 men, mean age 31 ± 10 years) and 21 patients with CAD, diagnosed using x-ray angiography (11 men, mean age 57 ± 6 years) were studied using a commercial whole-body MRI system. In each subject, the proximal segment of a coronary artery was imaged for the cross-sectional area measurements using cine spiral MRI. The distensibility (mm Hg(-1) × 10(3)) was determined as (end-systolic lumen area - end-diastolic lumen area)/(pulse pressure × end-diastolic lumen area). The pulse pressure was calculated as the difference between the systolic and diastolic brachial blood pressure. A total of 34 healthy subjects and 19 patients had adequate image quality for coronary area measurements. Coronary artery distensibility was significantly greater in the healthy subjects than in those with CAD (mean ± SD 2.4 ± 1.7 mm Hg(-1) × 10(3) vs 1.1 ± 1.1 mm Hg(-1) × 10(3), respectively, p = 0.007; median 2.2 vs 0.9 mm Hg(-1) × 10(3)). In a subgroup of 10 patients with CAD, we found a significant correlation between the coronary artery distensibility measurements assessed using MRI and x-ray coronary angiography (R = 0.65, p = 0.003). In a group of 10 healthy subjects, the repeated distensibility measurements demonstrated a significant correlation (R = 0.80, p = 0.006). In conclusion, 3.0-Tesla MRI, a reproducible noninvasive method to assess human coronary artery vessel wall distensibility, is able to detect significant differences in distensibility between healthy subjects and those with CAD.

Short-term exposure to exogenous lipids in premature infants and long-term changes in aortic and cardiac function

OBJECTIVE

Intravenous lipid use is associated with an acute hyperlipidemia, but long-term consequences have not been studied. We investigated whether elevated lipids in humans during the critical period of preterm neonatal life have a long-term impact on aortic and myocardial function relevant to adult disease.

METHODS AND RESULTS

We followed up 102 subjects born prematurely and now aged 23 to 28 years. Eighteen received intravenous lipids as neonates and were matched to controls with equivalent perinatal characteristics. Global and regional aortic stiffness and left ventricular function were assessed by cardiovascular magnetic resonance. Those who received intravenous lipids had greater aortic stiffness in early adulthood (P=0.0002), with greater stiffness in the abdominal aorta (P=0.012). The relationship was graded according to the elevation in neonatal cholesterol induced by intravenous lipids (P<0.0001) but not other metabolic parameters altered by the infusion. Peak systolic circumferential strain was also reduced in the lipid group (P=0.006), which, again, was proportional to neonatal cholesterol level (P<0.01).

CONCLUSIONS

Aortic and myocardial function in young adulthood is associated with intralipid exposure during neonatal life for preterm infants, in a graded manner related to the rise in cholesterol. Circulating cholesterol during critical developmental periods may have long-term impacts on the human cardiovascular system.

Aortic stiffness: current understanding and future directions

The aorta stiffens with aging, a process that is accelerated by arterial hypertension. Decreased arterial compliance is one of the earliest detectable manifestations of adverse structural and functional changes within the vessel wall. The use of different imaging techniques optimized for assessment of vascular elasticity and quantification of luminal and vessel wall parameters allows for a comprehensive and detailed view of the vascular system. In addition, several studies have also documented the prognostic importance of arterial stiffness (AS) in various populations as an independent predictor of cardiovascular morbidity and all-cause mortality. Measurement of AS by applanation tonometry with pulse-wave velocity has been the gold-standard method and is well-validated in large populations as a strong predictor of adverse cardiovascular outcomes. Because aortic stiffness depends on the prevailing blood pressure, effective antihypertensive treatment is expected to reduce it in proportion to the blood pressure reduction. Nevertheless, drugs lowering blood pressure might differ in their effects on structure and function of the arterial walls. This review paper not only will discuss the current understanding and clinical significance of AS but also will review the effects of various pharmacological and nonpharmacological interventions that can be used to preserve the favorable profile of a more compliant and less stiff aorta.

The effect of obesity and weight loss on aortic pulse wave velocity as assessed by magnetic resonance imaging

Obesity is an escalating global health problem associated with both an increased risk of death and an increased risk of cardiovascular events. Our goal was to use magnetic resonance imaging (MRI) to determine the effect of obesity and weight loss, in the absence of the traditional cardiovascular risk factors, on aortic pulse wave velocity (PWV) a reliable, reproducible, and accurate clinical measure of aortic stiffness linked to increased mortality. Fifty obese (BMI 38.3 ± 6.8 kg/m(2)) and eighteen normal-weight controls (BMI 22.0 ± 1.7 kg/m(2)) with no identifiable cardiovascular risk factors underwent vascular MRI to assess PWV between the ascending aorta at the level of the pulmonary artery and the abdominal aorta (AA). Twenty-eight subjects underwent repeat imaging after a 1-year period of weight loss. Both groups were well matched for age, systolic blood pressure, fasting glucose, and total cholesterol. Obesity was associated with a 14% increase in PWV (P = 0.021), and with elevated C-reactive protein (CRP) (P < 0.01) and leptin levels (P < 0.001) factors known to cause increase arterial stiffness. Weight loss (average 50% excess weight) was associated with a 14% improvement in PWV (P = 0.03), and with reductions in serum leptin levels (P < 0.01). Obesity, in the absence of the traditional cardiovascular risk factors, is associated with increased aortic PWV, a noninvasive clinical measure of aortic stiffness independently predictive of cardiovascular mortality. Significant weight loss results in improvements in aortic PWV. This may provide a potential link between both obesity and increased mortality, and the reduction in mortality that occurs with weight loss.

Reproducibility and accuracy of automated measurement for dynamic arterial lumen area by cardiovascular magnetic resonance

Bright blood cine images acquired using magnetic resonance imaging contain simple contrast that is tractable to automated analysis, which can be used to derive a measure of arterial compliance that is known to correlate with disease severity. The purpose of this work was to evaluate whether automated methods could be used reliably on a clinically relevant population, and to assess the precision of these measurements so that it could be compared with expert manual assessment. In this paper we apply an algorithm similar to that used by Krug et al., and the exact processing steps are described in detail to allowing easy reproduction of our methods. Phantoms of different sizes have been assessed and the MRI measurements are found to correlate well (r = 0.9998) with physical measurement. Reproducibility assessment was performed on 33 CAD subjects in three anatomical locations along the aorta. Six normal volunteers and ten patients with more severe aortic plaques were investigated to assess reproducibility and sensitivity to pathological changes, respectively. The performance was also assessed on carotid vessels in 40 patients with known arterial plaques. In the human aorta the method is found to be robust (failing in only 7% of cases, all due to clear errors with image acquisition), and to be quantifiably consistent with expert clinical measurement, but showing smaller errors than that approach [<1.21% (5.62 mm(2)) manual vs. <0.58% (2.71 mm(2)) automated, for the aortic area] and with reduced bias, and operated correctly in advanced disease. We have proved over a large number of subjects the superiority of this automated method for evaluating dynamic area changes over the Gold-standard manual approach.

In vivo comparison of atherosclerotic plaque progression with vessel wall strain and blood flow velocity in apoE(-/-) mice with MR microscopy at 17.6 T

OBJECT

At present, in vivo plaque characterization in mice by MRI is typically limited to the visualization of vascular lesions with no accompanying analysis of vessel wall function. The aim of this study was to analyze the influence of atherosclerotic plaque development on the morphological and mechanical characteristics of the aortic vessel wall in a pre-clinical murine model of atherosclerosis.

MATERIALS AND METHODS

Groups of apolipoprotein E-deficient (apoE(-/-)) and C57BL/6J control mice fed a high-fat diet were monitored over a 12-week time period by high-field MRI. Multi-Slice-Multi-Spin-Echo and Phase-Contrast MRI sequences were employed to track changes to aortic vessel wall area, blood flow velocity and distensibility.

RESULTS

After 6- and 12-weeks, significant changes in vessel wall area and circumferential strain were detected in the apoE(-/-) mice relative to the control animals. Blood flow velocity and intravascular lumen remained unchanged in both groups, findings that are in agreement with the theory of positive remodeling of the ascending aorta during plaque progression.

CONCLUSION

This study has demonstrated the application of high-field MRI for characterizing the temporal progression of morphological and mechanical changes to murine aortic vasculature associated with atherosclerotic lesion development.

Early changes in arterial structure and function following statin initiation: quantification by magnetic resonance imaging

Effective LDL-cholesterol (LDL-C) reduction improves vascular function and can bring about regression of atherosclerosis. Alterations in endothelial function can occur rapidly, but changes in atherosclerosis are generally considered to occur more slowly. Vascular magnetic resonance imaging (MRI) is a powerful technique for accurate non-invasive assessment of central and peripheral arteries at multiple anatomical sites. We report the changes in atherosclerosis burden and arterial function in response to open label statin treatment, in 24 statin-naïve newly diagnosed stable coronary artery disease patients. Patients underwent MRI before, and 3 and 12 months after commencing treatment. Mean LDL-C fell by 37% to 70.8 mg/dL (P<0.01). The plaque index (normalised vessel wall area) showed reductions in the aorta (2.3%, P<0.05) and carotid (3.1%, P<0.05) arteries at 3 months. Early reductions in atherosclerosis of aorta and carotid observed at 3 months were significantly correlated with later change at 12 months (R(2)=0.50, P<0.001; R(2)=0.22, P<0.05, respectively). Improvements in aortic distensibility and brachial endothelial function that were apparent after 3 months treatment were sustained at the 12-month time point.

Atherosclerosis and thrombosis: identification of targets for magnetic resonance imaging

Imaging techniques are needed that will allow earlier and more refined diagnosis, guide targeted treatment in individual patients and monitor response to that treatment. Magnetic resonance imaging is well-suited to these tasks as it can provide anatomical, structural, and functional data on the arterial wall. Its capabilities are further enhanced by the use of a range of increasingly sophisticated contrast agents that target specific molecules, cells, and biological processes. This article will consider the pathogenesis of atherosclerosis and systematically identify biologically relevant targets for imaging at different stages of disease process.