Vitamin D and Vulnerable Carotid Plaque

Symptomatic non-stenotic carotid disease: current challenges and opportunities for diagnosis and treatment

Symptomatic non-stenotic carotid plaques (SyNC) are an under-researched and under-recognized source of stroke. Various imaging markers of non-stenotic carotid plaques that are associated with stroke risk have been identified, but these causal relationships need to be confirmed in additional prospective studies. Currently, there exists neither a standardized SyNC definition nor a dedicated set of imaging protocols, although researchers have started to address these shortcomings. Moreover, many neuroradiologists are still unaware of the condition, and hence do not comment on high-risk plaque features other than stenosis in their reports. Regarding SyNC treatment, scant data exist as to whether and to what extent medical, interventional and surgical treatments could influence the course of the disease; the relative lack of data on the 'natural' history of untreated SyNC makes treatment comparisons difficult. In our opinion, endovascular SyNC treatment represents the most promising treatment option for SyNC, since it allows for targeted elimination of the embolic source, with few systemic side effects and without the need for general anesthesia. However, currently available carotid devices are designed to treat stenotic lesions, and thus are not optimally designed for SyNC. Developing a device specifically tailored to SyNC could be an important step towards establishing endovascular SyNC treatment in clinical practice. In this review, we provide an overview of the current state of evidence with regard to epidemiological, clinical and imaging features of SyNC, propose a SyNC definition based on imaging and clinical features, and outline a possible pathway towards evidence-based SyNC therapies, with a special focus on endovascular SyNC treatment.

Killing the Culprit: Pharmacological Solutions to Get Rid of Cholesterol Crystals

Cholesterol crystals (CCs) play a key role in the pathophysiology of cardiovascular diseases (CVD) via triggering inflammation, plaque formation and subsequently plaque rupture. Although statins can stabilize plaques via calcification and alteration of the lipid composition within plaques, there is still a high residual risk of CVD events among statins users. Several studies have tried to blunt the detrimental effects of cholesterol crystals by pharmacological interventions. Cyclodexterins (CDs) and other nanoformulations, including polymers of CDs and liposomes, have the ability to dissolve CCs in vitro and in vivo. CDs were the first in their class that entered clinical trials and showed promising results, though their ototoxicity outweighed their benefits. Moreover, small molecules with structural similarity to cholesterol may also perturb cholesterol-cholesterol interactions and prevent from expansion of 2D crystalline domains to large 3D CCs. The results from ethyl eicosapentaenoic acid and ursodeoxycholic acid were encouraging and worth further consideration. In this review, the significance of CCs in pathogenesis of CVD is discussed and pharmacological agents with the ability to dissolve CCs or prevent from CCs formation are introduced.

Vitamin D Deficiency and Gender Alter Vasoconstrictor and Vasodilator Reactivity in Rat Carotid Artery

The vitamin-D-sensitivity of the cardiovascular system may show gender differences. The prevalence of vitamin D (VD) deficiency (VDD) is high, and it alters cardiovascular function and increases the risk of stroke. Our aim was to investigate the vascular reactivity and histological changes of isolated carotid artery of female and male rats in response to different VD supplies. A total of 48 male and female Wistar rats were divided into four groups: female VD supplemented, female VDD, male VD supplemented, male VDD. The vascular function of isolated carotid artery segments was examined by wire myography. Both vitamin D deficiency and male gender resulted in increased phenylephrine-induced contraction. Acetylcholine-induced relaxation decreased in male rats independently from VD status. Inhibition of prostanoid signaling by indomethacin reduced contraction in females, but increased relaxation ability in male rats. Functional changes were accompanied by VDD and gender-specific histological alterations. Elastic fiber density was significantly decreased by VDD in female rats, but not in males. Smooth muscle actin and endothelial nitric oxide synthase levels were significantly lowered, but the thromboxane receptor was elevated in VDD males. Decreased nitrative stress was detected in both male groups independently from VD supply. The observed interactions between vitamin D deficiency and sex may play a role in the gender difference of cardiovascular risk.

Optimal Carotid Plaque Features on Computed Tomography Angiography Associated With Ischemic Stroke

Background Stenosis has historically been the major factor used to determine carotid stroke sources. Recent evidence suggests that specific plaque features detected on imaging may be more highly associated with ischemic stroke than stenosis. We sought to determine computed tomography angiography (CTA) imaging features of carotid plaque that optimally discriminate ipsilateral stroke sources. Methods and Results In this institutional review board-approved retrospective cross-sectional study, 494 ipsilateral carotid CTA-brain magnetic resonance imaging pairs were available for analysis after excluding patients with alternative stroke sources. Carotid CTA and clinical markers were recorded, a multivariable Poisson regression model was fitted, and backward elimination was performed with a 2-sided threshold of P<0.10. Discriminatory value was determined using receiver operating characteristic analysis, area under the curve, and bootstrap validation. The final CTA carotid-source stroke prediction model included intraluminal thrombus (prevalence ratio, 2.8 [P<0.001]; 95% CI, 1.6-4.9), maximum soft plaque thickness (prevalence ratio, 1.2 [P<0.001]; 95% CI, 1.1-1.4), and the rim sign (prevalence ratio, 2.0 [P=0.007]; 95% CI, 1.2-3.3). The final discriminatory value (area under the curve=78.3%) was higher than intraluminal thrombus (56.4%, P<0.001), maximum soft plaque thickness (76.4%, P=0.007), or rim sign alone (69.9%, P=0.001). Furthermore, NASCET (North American Symptomatic Carotid Endarterectomy Trial) stenosis categories (cutoffs of 50% and 70%) had lower stroke discrimination (area under the curve=67.4%, P<0.001). Conclusions Optimal discrimination of ipsilateral carotid sources of stroke requires information on intraluminal thrombus, maximum soft plaque thickness, and the rim sign. These results argue against the sole use of carotid stenosis to determine stroke sources on CTA, and instead suggest these alternative markers may better diagnose vulnerable carotid plaque and guide treatment decisions.

What is the Current Role for Vitamin D and the Risk of Stroke?

INTRODUCTION

Increasing evidence supports the relationship between vitamin D and stroke. Vitamin D has now been proposed as a prognostic biomarker also for functional outcome in stroke patients.

METHODS

A revision of the data suggests that low vitamin D is associated more with ischemic than with haemorrhagic stroke, even if the role of optimal vitamin D levels for vascular wall is still unclear. Vitamin D deficiency induces with different mechanisms an alteration of vascular wall.

RESULTS

However, to date, the research supporting the effectiveness of vitamin D supplementation in stroke and in post-stroke recovery is still inadequate and conclusive evidences have not been published.

CONCLUSION

In this review, we provide a better understanding of the role of vitamin D in stroke.

Magnetic Resonance Imaging Detection of Intraplaque Hemorrhage

Carotid artery atherosclerosis is a major cause of ischemic stroke. For more than 30 years, future stroke risk and carotid stroke etiology have been determined using percent diameter stenosis based on clinical trials in the 1990s. In the past 10 years, magnetic resonance imaging (MRI) sequences have been developed to detect carotid intraplaque hemorrhage. By detecting carotid intraplaque hemorrhage, MRI identifies potential stroke sources that are often overlooked by lumen imaging. In addition, MRI can dramatically improve assessment of future stroke risk beyond lumen stenosis alone. In this review, we discuss the use of heavily T1-weighted MRI sequences used to detect carotid intraplaque hemorrhage. In addition, advances in ciné imaging, motion robust techniques, and specialized neck coils will be reviewed. Finally, the clinical use and future impact of MRI plaque hemorrhage imaging will be discussed.

Calcium Phosphate Product Is Associated with Subclinical Carotid Atherosclerosis in Type 2 Diabetes

AIMS

To assess whether circulating 25-hydroxyvitamin D₃ (25OHD) and mineral metabolism-related factors (serum phosphate, calcium, and parathormone) are associated with subclinical carotid atherosclerosis (SCA), defined as the presence of carotid atherosclerotic plaques (main study outcome), in patients with type 2 diabetes mellitus (T2DM) without kidney disease or previous cardiovascular disease.

METHODS

We undertook a post hoc analysis of a cross-sectional study in adults with T2DM in whom we evaluated SCA. A total of 303 subjects with T2DM were included. Clinical variables and carotid ultrasound imaging were obtained.

RESULTS

We found no association of 25OHD with the presence of SCA. However, calcium phosphate (CaP; mg²/dL²) product was positively associated with the presence of carotid plaques (OR_adj = 1.078; 95% CI: 1.017-1.142). An inverse association was observed between higher levels of 25OHD (≥30 ng/mL versus <20 ng/mL concentrations) and common carotid intima-media thickness (cIMT; mm) (β_adj ± SE = -0.055 ± 0.024). We conclude that the CaP product is independently associated with the presence of established subclinical carotid atherosclerosis in patients with T2DM.