Peripheral arterial disease--what do we need to know?

Contrast-free ultrasound imaging for blood flow assessment of the lower limb in patients with peripheral arterial disease: a feasibility study

While being a relatively prevalent condition particularly among aging patients, peripheral arterial disease (PAD) of lower extremities commonly goes undetected or misdiagnosed due to its symptoms being nonspecific. Additionally, progression of PAD in the absence of timely intervention can lead to dire consequences. Therefore, development of non-invasive and affordable diagnostic approaches can be highly beneficial in detection and treatment planning for PAD patients. In this study, we present a contrast-free ultrasound-based quantitative blood flow imaging technique for PAD diagnosis. The method involves monitoring the variations of blood flow in the calf muscle in response to thigh-pressure-cuff-induced occlusion. Four quantitative metrics are introduced for analysis of these variations. These metrics include post-occlusion to baseline flow intensity variation (PBFIV), total response region (TRR), Lag0 response region (L0RR), and Lag4 (and more) response region (L4 + RR). We examine the feasibility of this method through an in vivo study consisting of 14 PAD patients with abnormal ankle-brachial index (ABI) and 8 healthy volunteers. Ultrasound data acquired from 13 legs in the patient group and 13 legs in the healthy group are analyzed. Out of the four utilized metrics, three exhibited significantly different distributions between the two groups (p-value < 0.05). More specifically, p-values of 0.0015 for PBFIV, 0.0183 for TRR, and 0.0048 for L0RR were obtained. The results of this feasibility study indicate the diagnostic potential of the proposed method for the detection of PAD.

Economic Implications of Preventing Major Cardiovascular and Limb Events with Rivaroxaban plus Aspirin in Patients with Coronary or Peripheral Artery Disease in the United States

BACKGROUND

Patients with chronic coronary artery disease (CAD) and/or peripheral artery disease (PAD) have increased risks for cardiovascular (CV)-related morbidity and mortality. In the Cardiovascular Outcomes for People Using Anticoagulation Strategies (COMPASS) clinical trial of such patients, rivaroxaban plus aspirin demonstrated a significant reduction in major adverse CV events (MACE), a composite of stroke, myocardial infarction, and CV death, and major adverse limb events (MALE), a composite of chronic and acute limb ischemia, and major amputation resulting from vascular events, versus aspirin alone.

OBJECTIVE

To estimate the 1-year economic implications of preventing MACE and MALE with the use of rivaroxaban plus aspirin versus aspirin alone among patients with chronic CAD and/or PAD in a US commercial health plan.

METHOD

A cost-consequence model was developed to evaluate the economic impact of rivaroxaban plus aspirin in a hypothetical 1-million-member health plan. The model inputs were taken from the COMPASS study (ie, the efficacy and safety of rivaroxaban plus aspirin vs aspirin), Optum Integrated Database (ie, the prevalence of chronic CAD and/or PAD, incidence rates, and healthcare costs of MACE, MALE, and major bleeding), and the RED BOOK (ie, wholesale drug acquisition costs). The cost inputs were in 2019 US dollars. One-way sensitivity analyses and subgroup analyses were conducted.

RESULTS

A 1-year treatment with rivaroxaban plus aspirin resulted in reductions of MACE and MALE, which balance the increased risk for bleeding versus aspirin alone and indicate a net health benefit for this drug regimen. These reductions were achieved at an incremental per-member per-month (PMPM) cost of $0.16, mainly because of rivaroxaban's acquisition cost. In patients with ≥2 MACE or MALE risk factors, the incremental PMPM cost was $0.09, given the increased offset in rivaroxaban's acquisition cost by reduced rates of MACE or MALE.

CONCLUSIONS

In an era of emerging thrombocardiology, treatment with rivaroxaban plus aspirin offers an effective thrombotic risk management strategy for healthcare stakeholders in the management of chronic CAD and/or PAD. The contribution of rivaroxaban would be greater in patients with ≥2 risk factors for MACE or MALE.

Peripheral artery disease in outpatients with a recent history of acute coronary syndrome or at high atherothrombotic risk

OBJECTIVES

The frequency and implications of peripheral artery disease (PAD) in some risk groups are not entirely characterized in Latin America. We studied PAD prevalence, risk factors, and six-month outcomes in stable outpatients with a history of a recent acute coronary syndrome (ACS), or at high coronary risk.

METHODS

We recruited 830 outpatients in 43 Mexican sites (median age: 64.8 years; 57.8% men). Inclusion criteria were age >18 years, and ACS within 30 days, or age <55 years plus ≥2 major vascular risk factors, or age ≥55 years plus ≥1 vascular risk factors. Patients received standardized assessments at baseline and six-month follow-up for medical history, ankle-brachial index (ABI), and the Edinburgh Claudication Questionnaire (ECQ).

RESULTS

ABI <0.8 was found in 10.5%, <0.9 in 22.5%, >1.3 in 4.8%, and >1.4 in 3.6%, without differences according to sex or selection criteria. Positive ECQ was found in 7.6%. ABI <0.9 was directly associated with age, diabetes, ACS, and chronic kidney disease, but inversely associated with BMI >27. The six-month case-fatality and atherothrombotic events rates were 1.6% and 3.6%, respectively. In patients with ABI <0.9 and ABI <0.8, the six-month case-fatality rates were 2.5% (p = 0.27) and 5.4% (p = 0.03), respectively. In a Cox proportional-hazards model, baseline factors associated with death were age ≥65, ABI <0.8, and ACS.

CONCLUSIONS

Subclinical PAD is more common than symptomatic claudication in high-risk coronary outpatients. Low ABI is associated with reduced short-term survival in patients with recent ACS or at high coronary risk.

Nanoparticles for Detection and Treatment of Peripheral Arterial Disease

Peripheral arterial disease (PAD) is defined as a slow, progressive disorder of the lower extremity arterial vessels characterized by chronic narrowing that often results in occlusion and is associated with loss of functional capacity. Although the PAD occurrence rate is increasing in the elderly population, outcomes with current treatment strategies are suboptimal. Hence, there is an urgent need to develop new technologies that overcome limitations of traditional modalities for PAD detection and therapy. In this Review, the application of nanotechnology as a tool that bridges the gap in PAD diagnosis and therapy is in focus. Several materials including synthetic, natural, biodegradable, and biocompatible materials are used to develop nanoparticles for PAD diagnostic and/or therapeutic applications. Moreover, various recent research approaches are being explored to diagnose PAD through multimodality imaging with different nanoplatforms. Further efforts include targeted delivery of various therapeutic agents using nanostructures as carriers to treat PAD. Last, but not least, despite being a fairly new field, researchers are exploring the use of nanotheranostics for PAD detection and therapy.

Endovascular therapy of axillary artery disease with drug-coated balloon angioplasty

The occurrence of upper-extremity arterial disease is less common than that of the lower extremities. Nevertheless, exercise-induced symptoms, when present, can significantly affect functional capacity and limit quality of life. We report a case of exertional right upper-extremity pain and severe right axillary artery disease that was revascularized using an off-label drug-coated balloon technology with resolution of symptoms.

Geographic variation and risk factors for systemic and limb ischemic events in patients with symptomatic peripheral artery disease: Insights from the REACH Registry

Background

Patients with symptomatic peripheral artery disease (PAD) are at high risk of ischemic events. However, data about predictors of this risk are limited.

Hypothesis

We analyzed baseline characteristics and 4‐year follow‐up of patients enrolled in the international REduction of Atherothrombosis for Continued Health (REACH) Registry with symptomatic PAD and no history of stroke/transient ischemic attack to describe annual rates of recurrent ischemic events globally and geographically.

Methods

The primary outcome was systemic ischemic events (composite of cardiovascular death, myocardial infarction, or stroke) at 4 years. The secondary outcome was limb ischemic events (composite of lower limb amputation, peripheral bypass graft, and percutaneous intervention for PAD) at 2 years. Multivariate analysis identified risk factors associated with recurrent ischemic events.

Results

The primary endpoint rate reached 4.7% during the first year and increased continuously (by 4%–5% each year) to 17.6% by year 4, driven mainly by cardiovascular mortality (11.1% at year 4). Japan experienced lower adjusted ischemic rates (P < 0.01) vs North America. Renal impairment (P < 0.01), congestive heart failure (P < 0.01), history of diabetes (P < 0.01), history of myocardial infarction (P = 0.01), vascular disease (single or poly, P < 0.01), and older age (P < 0.01) were associated with increased risk of systemic ischemic events, whereas statin use was associated with lower risk (P = 0.03). The limb ischemic event rate was 5.7% at 2 years.

Conclusions

Four‐year systemic ischemic risk in patients with PAD and no history of stroke or transient ischemic attack remains high, and was mainly driven by cardiovascular mortality.

Association between Plaque Score of the Carotid Artery and the Severity of Sleep Apnea Syndrome in Patients with Chronic Kidney Disease

BACKGROUND

Recently, sleep apnea syndrome (SAS) has been associated with hypertension, cardiovascular disease and death. Patients with chronic kidney disease (CKD) have higher rates of SAS, atherosclerotic complications and death than do patients without CKD. Although the relationship between SAS and atherosclerosis is well known, few papers have described this relationship in humans, especially in CKD patients.

PATIENTS AND METHODS

This was a cross-sectional study of 110 clinically stable, non-dialysis patients with CKD who attended a CKD educational program from April 2014 to September 2015. The diagnosis of SAS and its severity were assessed using a type 3 portable monitor. Other atherosclerosis-related data were obtained from the patients' medical records in order to determine the factors associated with the severity of SAS.

RESULTS

95 men and 15 women with a mean age of 71.4 ± 9.9 years were included in the study. The patients' mean body mass index was 24.0 ± 3.9, their mean blood pressure 134.3 ± 21.2/73.6 ± 13.4 mm Hg and their mean estimated glomerular filtration rate 19.8 ± 9.5 ml/min/1.7 m(2). Adjusted plaque score was a significant predictor of severe SAS (odds ratio = 1.13, p = 0.0182). Mixed plaque was significantly associated with severe SAS (correlation ratio = 0.48, p < 0.0001).

CONCLUSIONS

Many patients with CKD also have SAS. Our findings demonstrate the relationship between plaque score and the severity of SAS.

Fucoidan Stimulates Monocyte Migration via ERK/p38 Signaling Pathways and MMP9 Secretion

Critical limb ischemia (CLI) induces the secretion of paracrine signals, leading to monocyte recruitment and thereby contributing to the initiation of angiogenesis and tissue healing. We have previously demonstrated that fucoidan, an antithrombotic polysaccharide, promotes the formation of new blood vessels in a mouse model of hindlimb ischemia. We examined the effect of fucoidan on the capacity of peripheral blood monocytes to adhere and migrate. Monocytes negatively isolated with magnetic beads from peripheral blood of healthy donors were treated with fucoidan. Fucoidan induced a 1.5-fold increase in monocyte adhesion to gelatin (p < 0.05) and a five-fold increase in chemotaxis in Boyden chambers (p < 0.05). Fucoidan also enhanced migration 2.5-fold in a transmigration assay (p < 0.05). MMP9 activity in monocyte supernatants was significantly enhanced by fucoidan (p < 0.05). Finally, Western blot analysis of fucoidan-treated monocytes showed upregulation of ERK/p38 phosphorylation. Inhibition of ERK/p38 phosphorylation abrogated fucoidan enhancement of migration (p < 0.01). Fucoidan displays striking biological effects, notably promoting monocyte adhesion and migration. These effects involve the ERK and p38 pathways, and increased MMP9 activity. Fucoidan could improve critical limb ischemia by promoting monocyte recruitment.

Hypoxia-induced miR-210 modulates tissue response to acute peripheral ischemia

AIMS

Peripheral artery disease is caused by the restriction or occlusion of arteries supplying the leg. Better understanding of the molecular mechanisms underpinning tissue response to ischemia is urgently needed to improve therapeutic options. The aim of this study is to investigate hypoxia-induced miR-210 regulation and its role in a mouse model of hindlimb ischemia.

RESULTS

miR-210 expression was induced by femoral artery dissection. To study the role of miR-210, its function was inhibited by the systemic administration of a miR-210 complementary locked nucleic acid (LNA)-oligonucleotide (anti-miR-210). In the ischemic skeletal muscle, anti-miR-210 caused a marked decrease of miR-210 compared with LNA-scramble control, while miR-210 target expression increased accordingly. Histological evaluation of acute tissue damage showed that miR-210 inhibition increased both apoptosis at 1 day and necrosis at 3 days. Capillary density decrease caused by ischemia was significantly more pronounced in anti-miR-210-treated mice; residual limb perfusion decreased accordingly. To investigate the molecular mechanisms underpinning the increased damage triggered by miR-210 blockade, we tested the impact of anti-miR-210 treatment on the transcriptome. Gene expression analysis highlighted the deregulation of mitochondrial function and redox balance. Accordingly, oxidative damage was more severe in the ischemic limb of anti-miR-210-treated mice and miR-210 inhibition increased oxidative metabolism. Further, oxidative-stress resistant p66(Shc)-null mice displayed decreased tissue damage following ischemia.

INNOVATION

This study identifies miR-210 as a crucial element in the adaptive mechanisms to acute peripheral ischemia.

CONCLUSIONS

The physiopathological significance of miR-210 is context dependent. In the ischemic skeletal muscle it seems to be cytoprotective, regulating oxidative metabolism and oxidative stress.

Diabetes-associated macrovascular complications: cell-based therapy a new tool?

Diabetes mellitus and its ongoing macrovascular complications represent one of the major health problems around the world. Rise in obesity and population ages correlate with the increased incidence of diabetes. This highlights the need for novel approaches to prevent and treat this pandemic. The discovery of a reservoir of stem/progenitors in bone marrow and in mesenchymal tissue has attracted interest of both biologists and clinicians. A number of preclinical and clinical trials were developed to explore their potential clinical impact, as target or vehicle, in different clinical settings, including diabetes complications. Currently, bone marrow, peripheral blood, mesenchymal, and adipose tissues have been used as stem/progenitor cell sources. However, evidences have been provided that both bone marrow and circulating progenitor cells are dysfunctional in diabetes. These observations along with the growing advantages in genetic manipulation have spurred researchers to exploit ex vivo manipulated cells to overcome these hurdles. In this article, we provide an overview of data relevant to stem-progenitors potential clinical application in revascularization and/or vascular repair. Moreover, the hurdles at using progenitor cells in diabetic patients will be also discussed.

Lactate stimulates angiogenesis and accelerates the healing of superficial and ischemic wounds in mice

Wounds notoriously accumulate lactate as a consequence of both anaerobic and aerobic glycolysis following microcirculation disruption, immune activation, and increased cell proliferation. Several pieces of evidence suggest that lactate actively participates in the healing process through the activation of several molecular pathways that collectively promote angiogenesis. Lactate indeed stimulates endothelial cell migration and tube formation in vitro, as well as the recruitment of circulating vascular progenitor cells and vascular morphogenesis in vivo. In this study, we examined whether the pro-angiogenic potential of lactate may be exploited therapeutically to accelerate wound healing. We show that lactate delivered from a Matrigel matrix improves reperfusion and opposes muscular atrophy in ischemic hindlimb wounds in mice. Both responses involve lactate-induced reparative angiogenesis. Using microdialysis and enzymatic measurements, we found that, contrary to poly-L-lactide (PLA), a subcutaneous implant of poly-D,L-lactide-co-glycolide (PLGA) allows sustained local and systemic lactate release. PLGA promoted angiogenesis and accelerated the closure of excisional skin wounds in different mouse strains. This polymer is FDA-approved for other applications, emphasizing the possibility of exploiting PLGA therapeutically to improve wound healing.