Growth Factors in the Collateral Circulation of Chronic Total Coronary Occlusions

High-Resolution Iodine-Enhanced Micro-Computed Tomography of Intact Human Hearts for Detailed Coronary Microvasculature Analyses

Identifying the detailed anatomies of the coronary microvasculature remains an area of research; one needs to develop methods for non-destructive, high-resolution, three-dimensional imaging of these vessels for computational modeling. Currently employed Micro-Computed Tomography (Micro-CT) protocols for vasa vasorum analyses require organ dissection and, in most cases, non-clearable contrast agents. Here, we describe a method developed for a non-destructive, economical means to achieve high-resolution images of the human coronary microvasculature without organ dissection. Formalin-fixed human hearts were cannulated using venogram balloon catheters, which were then fixed into the specimen's aortic root. The canulated hearts, protected by a polyethylene bag, were placed in radiolucent containers filled with insulating polyurethane foam to reduce movement. For vasculature staining, iodine potassium iodide (IKI, Lugol's solution; 6.3% Potassium Iodide, 4.1% Iodide) was injected. Contrast distributions were monitored using a North Star Imaging X3000 micro-CT scanner with low-radiation settings, followed by high-radiation scanning (3600 rad, 60 kV, 900 mA) for the final high-resolution imaging. We successfully imaged four intact human hearts presenting with chronic total coronary occlusions of the right coronary artery. This imaging enabled detailed analyses of the vasa vasorum surrounding stenosed and occluded segments. After imaging, the hearts were cleared of iodine and excess polyurethane foam and returned to their initial formalin-fixed state for indefinite storage. Conclusions: the described methodologies allow for the non-destructive, high-resolution micro-CT imaging of coronary microvasculature in intact human hearts, paving the way for detailed computational 3D microvascular reconstructions with a macrovascular context.

Transcoronary Gradients of Mechanosensitive MicroRNAs as Predictors of Collateral Development in Chronic Total Occlusion

Background and Objectives: In this present study, we investigated the impact of mechanosensitive microRNAs (mechano-miRs) on the collateral development in 126 chronic total occlusion (CTO) patients, selected from 810 undergoing angiography. Materials and Methods: We quantified the collateral blood supply using the collateral flow index (CFI) and assessed the transcoronary mechano-miR gradients. Results: The patients with favorable collaterals had higher CFI values (0.45 ± 0.02) than those with poor collaterals (0.38 ± 0.03, p < 0.001). Significant differences in transcoronary gradients were found for miR-10a, miR-19a, miR-21, miR-23b, miR-26a, miR-92a, miR-126, miR-130a, miR-663, and let7d (p < 0.05). miR-26a and miR-21 showed strong positive correlations with the CFI (r = 0.715 and r = 0.663, respectively), while let7d and miR-663 were negatively correlated (r = -0.684 and r = -0.604, respectively). The correlations between cytokine gradients and mechano-miR gradients were also significant, including Transforming Growth Factor Beta with miR-126 (r = 0.673, p < 0.001) and Vascular Endothelial Growth Factor with miR-10a (r = 0.602, p = 0.002). A regression analysis highlighted the hemoglobin level, smoking, beta-blocker use, miR-26a, and miR-663 as significant CFI determinants, indicating their roles in modulating the collateral vessel development. Conclusions: These findings suggest mechanosensitive microRNAs as predictive biomarkers for collateral circulation, offering new therapeutic perspectives for CTO patients.

Therapeutic angiogenesis in coronary artery disease: a review of mechanisms and current approaches

INTRODUCTION

Despite tremendous advances, the shortcomings of current therapies for coronary disease are evidenced by the fact that it remains the leading cause of death in many parts of the world. There is hence a drive to develop novel therapies to tackle this disease. Therapeutic approaches to coronary angiogenesis have long been an area of interest in lieu of its incredible, albeit unrealized potential.

AREAS COVERED

This paper offers an overview of mechanisms of native angiogenesis and a description of angiogenic growth factors. It progresses to outline the advances in gene and stem cell therapy and provides a brief description of other investigational approaches to promote angiogenesis. Finally, the hurdles and limitations unique to this particular area of study are discussed.

EXPERT OPINION

An effective, sustained, and safe therapeutic option for angiogenesis truly could be the paradigm shift for cardiovascular medicine. Unfortunately, clinically meaningful therapeutic options remain elusive because promising animal studies have not been replicated in human trials. The sheer complexity of this process means that numerous major hurdles remain before therapeutic angiogenesis truly makes its way from the bench to the bedside.

Influence of Obstructive Sleep Apnoea Severity on Coronary Collateral Recruitment During Coronary Occlusion

PURPOSE

Obstructive sleep apnoea (OSA) which results in hypoxia may affect the ability to recruit coronary collaterals. The aim of this study was to determine whether the severity of OSA affects collateral recruitment in patients with total coronary occlusions.

METHODS

Patients with total coronary artery occlusion were reviewed. Records from the sleep investigation laboratory were reviewed to identify those patients who had undergone diagnostic polysomnography. Robust coronary collaterals were those with Rentrop grade 2 or 3 collaterals.

RESULTS

Sixty-four patients with a total coronary occlusion had polysomnography performed, of whom 60 patients had OSA. Thirty-two patients (53.3%) had poor collaterals, whilst 28 (46.7%) had robust collaterals. Twenty-four (40%) patients had mild OSA, 10 (16.7%) had moderate OSA and 26 (43.3%) had severe OSA. Patients with robust collaterals were more likely to be males (96.4% vs 74.3%, p < 0.05) and have a history of hypercholesterolaemia (88.9% vs 51.6%, p < 0.01). Patients with robust collaterals had a lower apnoea-hypopnoea index (13.6 vs 45.5, p < 0.05), a higher MinS_aO₂ (85.4% vs 79.8%, p < 0.05), less time S_aO₂ < 90% (0 min vs 30.4 min, p < 0.05) and lower oxygen desaturation index (6.9 vs 26.8, p < 0.05). Those with moderate OSA had a higher mean Rentrop grade (1.6 ± 0.3) than those with mild OSA (1.5 ± 1.1) and severe OSA (0.6 ± 0.2).

CONCLUSION

The presence of more severe OSA is associated with poorer coronary collateral recruitment in patients with total coronary artery occlusion. The effect of treatment of OSA on subsequent ability to recruit collaterals and other cardioprotective mechanisms requires further research.

Recruitment and maturation of the coronary collateral circulation: Current understanding and perspectives in arteriogenesis

The coronary collateral circulation is a rich anastomotic network of primitive vessels which have the ability to augment in size and function through the process of arteriogenesis. In this review, we evaluate the current understandings of the molecular and cellular mechanisms by which this process occurs, specifically focussing on elevated fluid shear stress (FSS), inflammation, the redox state and gene expression along with the integrative, parallel and simultaneous process by which this occurs. The initiating step of arteriogenesis occurs following occlusion of an epicardial coronary artery, with an increase in FSS detected by mechanoreceptors within the endothelium. This must occur within a 'redox window' where an equilibrium of oxidative and reductive factors are present. These factors initially result in an inflammatory milieu, mediated by neutrophils as well as lymphocytes, with resultant activation of a number of downstream molecular pathways resulting in increased expression of proteins involved in monocyte attraction and adherence; namely vascular cell adhesion molecule 1 (VCAM-1), monocyte chemoattractant protein 1 (MCP-1) and transforming growth factor beta (TGF-β). Once monocytes and other inflammatory cells adhere to the endothelium they enter the extracellular matrix and differentiate into macrophages in an effort to create a favourable environment for vessel growth and development. Activated macrophages secrete inflammatory cytokines such as tumour necrosis factor-α (TNF-α), growth factors such as fibroblast growth factor-2 (FGF-2) and matrix metalloproteinases. Finally, vascular smooth muscle cells proliferate and switch to a contractile phenotype, resulting in an increased diameter and functionality of the collateral vessel, thereby allowing improved perfusion of the distal myocardium subtended by the occluded vessel. This simultaneously reduces FSS within the collateral vessel, inhibiting further vessel growth.

Effect of Recruitment of Acute Coronary Collaterals on In-Hospital Mortality and on Left Ventricular Function in Patients Presenting With ST Elevation Myocardial Infarction

Recruitment of the coronary collateral circulation is frequently observed during ST elevation myocardial infarction (STEMI) and is of uncertain significance. The aim of this study was to identify and determine the predictors and prognostic implications of the presence of robust collaterals during STEMI. All patients presenting to a large tertiary centre with a STEMI undergoing percutaneous coronary intervention from 2010 to 2018 were reviewed. Patients with poor collateral recruitment were defined as those with Rentrop grade 0 or 1 collaterals, whilst patients with robust collateral recruitment were defined as Rentrop grade 2 or 3. A total of 1,625 patients were included in the study, with 1,280 (78.8%) patients having poor collateral recruitment and 345 patients (21.2%) having robust collateral recruitment. Patients with robust collaterals were younger (63.1 vs 65.1 years, p < 0.05), had a longer ischemic time (628.5 minutes vs 433.1 minutes, p < 0.0001), and more likely to have a chronic total occlusion of a noninfarct related artery (10.4% vs 5.3%, p < 0.001). The presence of robust collaterals was associated with higher rates of normal or mildly impaired left ventricular function (83.5% vs 63.2%, p < 0.0001) and lower in-hospital mortality (2.1% vs 7.6%, p < 0.0001). After correcting for left ventricular function, collateral recruitment was not an independent predictor of mortality. In conclusion, in patients presenting with STEMI, the presence of robust coronary collaterals appears to be associated with improved left ventricular function. Further research is required to identify mechanisms of collateral maturation and recruitment.

Angiogenic Abnormalities in Diabetes Mellitus: Mechanistic and Clinical Aspects

CONTEXT

Diabetes causes severe pathological changes to the microvasculature in many organs and tissues and is at the same time associated with an increased risk of coronary and peripheral macrovascular events. We herein review alterations in angiogenesis observed in human and experimental diabetes and how they contribute to diabetes onset and development of vascular complications.

EVIDENCE ACQUISITION

The English language medical literature was searched for articles reporting on angiogenesis/vasculogenesis abnormalities in diabetes and their clinical manifestations, mechanistic aspects, and possible therapeutic implications.

EVIDENCE SYNTHESIS

Angiogenesis is a complex process, driven by a multiplicity of molecular mechanisms and involved in several physiological and pathological conditions. Incompetent angiogenesis is pervasive in diabetic vascular complications, with both excessive and defective angiogenesis observed in various tissues. A striking different angiogenic response typically occurs in the retina vs the myocardium and peripheral circulation, but some commonalities in abnormal angiogenesis can explain the well-known association between microangiopathy and macroangiopathy. Impaired angiogenesis can also affect endocrine islet and adipose tissue function, providing a link to diabetes onset. Exposure to high glucose itself directly affects angiogenic/vasculogenic processes, and the mechanisms include defective responses to hypoxia and proangiogenic factors, impaired nitric oxide bioavailability, shortage of proangiogenic cells, and loss of pericytes.

CONCLUSIONS

Dissecting the molecular drivers of tissue-specific alterations of angiogenesis/vasculogenesis is an important challenge to devise new therapeutic approaches. Angiogenesis-modulating therapies should be carefully evaluated in view of their potential off-target effects. At present, glycemic control remains the most reasonable therapeutic strategy to normalize angiogenesis in diabetes.

Endocan: a novel biomarker associated with well-developed coronary collateral circulation in patients with stable angina and chronic total occlusion

Angiogenesis and arteriogenesis have a crucial role in the formation of coronary collateral vessels. It has been shown that endocan and vascular cell adhesion molecule-1 (VCAM-1) are potential angiogenetic factors. We investigated the relationship between serum endocan levels and grade of coronary collaterals, and also the correlation of endocan levels with serum VCAM-1 levels. Patients with stable angina and at least one total coronary occlusion at invasive coronary angiography were included in our study. Collateral degree was graded according to Rentrop and Cohen's classification. Patients who had grade 0 or 1 collateral vessels were included in the poorly-developed collateral group, and those with grade 2 or 3 coronary collateral vessels were included in the well-developed collateral group. Serum endocan and VCAM-1 levels were significantly higher in the well-developed collateral group (436.6 ± 213.3 ng/mL vs. 216.1 ± 78.5 ng/mL, p < .001; 11.02 ± 6.58 ng/mL vs. 6.78 ± 1.14 ng/mL, p < .001, respectively). In a logistic regression analysis, only serum endocan level remained as an independent predictor for good collateral development. In the ROC curve analysis, 282 ng/mL endocan level had an a 82 % sensitivity and 86 % specificity for prediction of the well-developed collateral group. Higher endocan level was related to better coronary collateral development. In the event that these results are confirmed in further studies, endocan may be considered as an anti-ischemic treatment strategy in order to improve collateral development.

Relationship between thrombospondin-1, endostatin, angiopoietin-2, and coronary collateral development in patients with chronic total occlusion

This study is aimed to investigate whether serum angiostatic factors (thrombospondin-1 [TSP-1] and endostatin) or angiogenic factors (angiopoietin-2 [Ang-2]) are related to coronary collateral vessel development in patients with chronic total occlusion (CTO).A total of 149 patients were enrolled in the study, and 39 patients with coronary artery disease but without significant stenosis were included in control group. In 110 patients with CTO lesion, 79 with Rentrop grades 2 to 3 collaterals were grouped as good collateral, while 31 with Rentrop grades 0 to 1 collaterals were grouped as poor collateral. Serum TSP-1, endostatin, and Ang-2 levels were studied.Serum endostatin level was significantly higher in poor collateral group compared with control group and good collateral group, respectively (96.2 ± 30.4 vs 77.8 ± 16.5 ng/mL, P = 0.007; 96.2 ± 30.4 vs 81.2 ± 30.4 ng/mL, P = 0.018). In multivariate analysis, decreased serum endostatin level was independently related to good coronary collateral development. Serum TSP-1 level was lower in patients with CTO compared with control group. However, no difference in TSP-1 level was detected between poor and good collateral group. The serum Ang-2 level did not show a significant difference among 3 groups.Circulatory endostatin may be a useful biomarker for coronary collateral development and potential target for therapeutic angiogenesis in patients with CTO.

Biomarkers of coronary endothelial health: correlation with invasive measures of collateral function, flow and resistance in chronically occluded coronary arteries and the effect of recanalization

OBJECTIVES

In the presence of a chronically occluded coronary artery, the collateral circulation matures by a process of arteriogenesis; however, there is considerable variation between individuals in the functional capacity of that collateral network. This could be explained by differences in endothelial health and function. We aimed to examine the relationship between the functional extent of collateralization and levels of biomarkers that have been shown to relate to endothelial health.

METHODS

We measured four potential biomarkers of endothelial health in 34 patients with mature collateral networks who underwent a successful percutaneous coronary intervention (PCI) for a chronic total coronary occlusion (CTO) before PCI and 6-8 weeks after PCI, and examined the relationship of biomarker levels with physiological measures of collateralization.

RESULTS

We did not find a significant change in the systemic levels of sICAM-1, sE-selectin, microparticles or tissue factor 6-8 weeks after PCI. We did find an association between estimated retrograde collateral flow before CTO recanalization and lower levels of sICAM-1 (r=0.39, P=0.026), sE-selectin (r=0.48, P=0.005) and microparticles (r=0.38, P=0.03).

CONCLUSION

Recanalization of a CTO and resultant regression of a mature collateral circulation do not alter systemic levels of sICAM-1, sE-selectin, microparticles or tissue factor. The identified relationship of retrograde collateral flow with sICAM-1, sE-selectin and microparticles is likely to represent an association with an ability to develop collaterals rather than their presence and extent.

Mitochondrial Aldehyde Dehydrogenase 2 Regulates Revascularization in Chronic Ischemia: Potential Impact on the Development of Coronary Collateral Circulation

OBJECTIVE

Revascularization is an essential process to compensate for cardiac underperfusion and, therefore, preserves cardiac function in the face of chronic ischemic injury. Recent evidence suggested a vital role of aldehyde dehydrogenase 2 (ALDH2) in cardiac protection after ischemia. This study was designed to determine whether ALDH2 regulates chronic ischemia-induced angiogenesis and to explore the underlying mechanism involved. Moreover, the clinical impact of the ALDH2 mutant allele on the development of coronary collateral circulation (CCC) was evaluated.

APPROACH AND RESULTS

Mice limb ischemia was performed. Compared with wild-type, ALDH2 deletion significantly reduced perfusion recovery, small artery and capillary density, and increased muscle atrophy in this ischemic model. In vitro, ALDH2-knockdown reduced proliferation, migration and hypoxia triggered endothelial tube formation of endothelial cells, the effects of which were restored by ALDH2 transfection. Further examination revealed that ALDH2 regulated angiogenesis possibly through hypoxia-inducible factor-1α/vascular endothelial growth factor pathways. To further discern the role of ALDH2 deficiency in the function of bone marrow stem/progenitor cells, cross bone marrow transplantation was performed between wild-type and ALDH2-knockout mice. However, there was no significant improvement for wild-type bone marrow transplantation into knockout mice. ALDH2 genotyping was screened in 139 patients with chronic total occlusion recruited to Zhongshan Hospital (2011.10-2014.4). Patients with poor CCC (Rentrop 0-1; n=51) exhibited a higher frequency of the AA genotype than those with enriched CCC (Rentrop 2-3; n=88; 11.76% versus 1.14%; P=0 0.01). However, the AA group displayed less enriched CCC frequency in Logistic regression model when compared with the GG group (odds ratio=0.08; 95% confidence interval, 0.009-0.701; P=0 0.026). Furthermore, serum vascular endothelial growth factor level tended to be lower in patients with ALDH2 mutation.

CONCLUSIONS

This study demonstrated that ALDH2 possesses an intrinsic capacity to regulate angiogenesis via hypoxia-inducible factor-1α and vascular endothelial growth factor. Patients with ALDH2-deficient genotype displayed a higher risk of developing poor CCC. Therapeutic individualization based on ALDH2 allele distribution may thus improve the therapeutic benefit, especially in the East Asian decedents.

Maternal and fetoplacental hypoxia do not alter circulating angiogenic growth effectors during human pregnancy

One causal model of preeclampsia (PE) postulates that placental hypoxia alters the production of angiogenic growth effectors (AGEs), causing an imbalance leading to maternal endothelial cell dysfunction. We tested this model using the natural experiment of high-altitude (HA) residence. We hypothesized that in HA pregnancies 1) circulating soluble fms-like tyrosine kinase 1 (sFlt-1) is increased and placental growth factor (PlGF) decreased, and 2) AGE concentrations correlate with measures of hypoxia. A cross-sectional study of healthy pregnancies at low altitude (LA) (400 m) versus HA (3600 m) compared normal (n = 80 at HA, n = 90 at LA) and PE pregnancies (n = 20 PE at HA, n = 19 PE at LA). Blood was collected using standard serum separation and, in parallel, by a method designed to inhibit platelet activation. AGEs were measured by enzyme-linked immunosorbent assays. AGEs did not differ between altitudes in normal or PE pregnancies. AGE concentrations were unrelated to measures of maternal or fetal hypoxia. PlGF was lower and sFlt-1 higher in PE, but overlapped considerably with the range observed in normal samples. PlGF correlated with placental mass in both normal and PE pregnancies. The contribution of peripheral cells to the values measured for AGEs was similar at LA and HA, but was greater in PE than in normotensive women. Hypoxia, across a wide physiological range in pregnancy, does not alter levels of circulating AGEs in otherwise normal pregnancies. Peripheral cell release of AGEs with the hemostasis characteristic of standard blood collection is highly variable and contributes to a doubling of the amount of sFlt-1 measured in PE as compared to normal pregnancies.

Effect and mechanism of thrombospondin-1 on the angiogenesis potential in human endothelial progenitor cells: an in vitro study

Objective

Coronary collateral circulation plays a protective role in patients with coronary artery disease (CAD). We investigated whether thrombospondin-1(TSP-1) has an inhibitory effect on angiogenesis potential in endothelial progenitor cells(EPCs) and tested whether TSP-1 are altered in plasma of patients who had chronic total occlusion (CTO) in at least one coronary artery and with different collateral stages(according to Rentrop grading system).

Methods and Results

We isolated early and late EPCs from human cord blood and investigated a dose-dependent effect of TSP-1 on their angiogenesis potential by Matrigel angiogenesis assay. We found that TSP-1 (5 µg/ml) inhibited early EPCs incorporation into tubules after pretreatment for 1, 6 and 12 hours, respectively (83.3±11.9 versus 50.0±10.1 per field for 1 hour,161.7±12.6 versus 124.0±14.4 for 6 hours, 118.3±12.6 versus 68.0±20.1 for 12 hours, p<0.05). TSP-1 also inhibited late EPCs tubule formation at 1 µg/ml (6653.4±422.0 µm/HPFversus 5552.8±136.0 µm/HPF, p<0.05), and the inhibition was further enhanced at 5 µg/ml (6653.4±422.0 µm/HPF versus 2118.6±915.0 µm/HPF p<0.01). To explore the mechanism involved, a small interfering RNA was used. In vitro, CD47 siRNA significantly attenuated TSP-1's inhibition of angiogenesis on late EPCs and similar results were obtained after functional blocking by anti-CD47 antibody. Then we investigated pathways downstream of CD47 and found TSP-1 regulated VEGF-induced VEGFR2 phosphorylation via CD47. Furthermore, we examined plasma TSP-1 levels in patients with CTO who developed different stages of collaterals and found a paradoxical higher level of TSP-1 in patients with good collaterals compared with bad ones (612.9±554.0 ng/ml versus 224.4±132.4 ng/ml, p<0.05).

Conclusion

TSP-1 inhibited angiogenesis potential of early and late EPCs in vitro. This inhibition may be regulated by TSP-1's interaction with CD47, resulting in down regulation of VEGFR2 phosphorylation. In patients with CTO, there may be a self-adjustment mechanism in bad collaterals which is shown as low level of angiogenesis inhibitor TSP-1, and thus favoring collateral formation.

The collateral circulation of the heart in coronary total arterial occlusions in man: systematic review of assessment and pathophysiology

BACKGROUND

Anatomical and functional assessment of the collateral circulation of the heart in total arterial occlusions is challenging, and this is particularly true of the microcirculation. The pathophysiology of the collateral circulation has historically been and remains of considerable research focus but with diverging and sometimes conflicting results. Our purpose was to conduct a systematic review on the assessment and pathophysiology of the collateral circulation of the heart in total coronary arterial occlusions.

METHODS

We extracted data from Pubmed, Ovid, EMBASE, and Cochrane database from 1966 to December 2012. Two investigators independently reviewed the identified articles for eligibility and extracted the data.

RESULTS

Seventy-seven studies met inclusion criterion. An invasive assessment of the collateral circulation with pressure and/or Doppler wires is the gold standard in the assessment of collateral physiology and anatomy, although this can only be undertaken after successful passage of the sensor in the true lumen of the occluded vessel. A collateral circulation can provide resting metabolic requirements for the heart but invariably cannot meet demands on stress irrespective of the degree of collateralization as assessed by coronary angiography. In the case of myocardium subtending a totally occluded epicardial artery coronary collateral grading systems or physiological assessment of collateral flow is only moderately sensitive and poorly specific at predicting viability. Regression of collaterals seems more profound in totally occluded arteries versus nonoccluded lesions postrevascularization.

CONCLUSIONS

Key controversies in the assessment and pathophysiology of the collateral circulation of the heart in total coronary arterial occlusions are systematically evaluated.

Mechanistic, technical, and clinical perspectives in therapeutic stimulation of coronary collateral development by angiogenic growth factors

Stimulation of collateral vessel development in the heart by angiogenic growth factor therapy has been tested in animals and humans for almost two decades. Discordance between the outcome of preclinical studies and clinical trials pointed to the difficulties of translation from animal models to patients. Lessons learned in this process identified specific mechanistic, technical, and clinical hurdles, which need to be overcome. This review summarizes current understanding of the mechanisms leading to the establishment of a functional coronary collateral network and the biological processes growth factor therapies should stimulate even under conditions of impaired natural adaptive vascular response. Vector delivery methods are recommended to maximize angiogenic gene therapy efficiency and reduce side effects. Optimization of clinical trial design should include the choice of clinical end points which provide mechanistic proof-of-concept and also reflect clinical benefits (e.g., surrogates to assess increased collateral flow reserve, such as myocardial perfusion imaging). Guidelines are proposed to select patients who may respond to the therapy with high(er) probability. Both short and longer term strategies are outlined which may help to make therapeutic angiogenesis (TA) work in the future.

Severity of coronary atherosclerosis in patients with a first acute coronary event: a diabetes paradox

AIMS

We aimed to compare coronary artery disease (CAD) at the time of a first acute coronary syndrome (ACS) in type II diabetic and non-diabetic patients by coronary angiography and by optical coherence tomography (OCT).

METHODS AND RESULTS

Two different patient populations with a first ACS were enrolled for the angiographic (167 patients) and the OCT (72 patients) substudy. Angiographic CAD severity was assessed by Bogaty, Gensini, and Sullivan scores, whereas collateral development towards the culprit vessel was assessed by the Rentrop score. Optical coherence tomography plaque features were evaluated at the site of the minimum lumen area (MLA) and of culprit segment. In the angiographic substudy, at multivariate analysis, diabetes was associated with both the stenosis score and the extent index (P = 0.001). Furthermore, well-developed collateral circulation (Rentrop 2-3) towards the culprit vessel was more frequent in diabetic than in non-diabetic patients (73% vs. 16%, P = 0.001). In the OCT substudy, at MLA site lipid quadrants were less and the lipid arc was smaller in diabetic than in non-diabetic patients (2.3 ± 1.3 vs. 3.0 ± 1.2; P = 0.03 and 198° ± 121° vs. 260° ± 118°; P = 0.03). Furthermore, the most calcified cross-section along the culprit segment had a greater number of calcified quadrants and a wider calcified arc in diabetic than in non-diabetic patients (1.7 ± 1.0 vs. 1.2 ± 0.9; P = 0.03 and 126° ± 95° vs. 81° ± 80°; P = 0.03). Superficial calcified nodules were more frequently found in diabetic than in non-diabetic patients (79 vs. 54%, P = 0.04).

CONCLUSIONS

In spite of potent pro-inflammatory, pro-oxidant and pro-thrombotic stimuli operating in type II diabetes, diabetic patients exhibit substantially more severe coronary atherosclerosis than non-diabetic patients at the time of a first acute coronary event. Better collateral development towards the culprit vessel, a predominantly calcific plaque phenotype and, probably, yet unknown protective factors operating in diabetic patients may explain these intriguing paradoxical findings.

Plasma chemokine levels are associated with the presence and extent of angiographic coronary collaterals in chronic ischemic heart disease

BACKGROUND

In patients with chronic ischemic heart disease (IHD), the presence and extent of spontaneously visible coronary collaterals are powerful determinants of clinical outcome. There is marked heterogeneity in the recruitment of coronary collaterals amongst patients with similar degrees of coronary artery stenoses, but the biological basis of this heterogeneity is not known. Chemokines are potent mediators of vascular remodeling in diverse biological settings. Their role in coronary collateralization has not been investigated. We sought to determine whether plasma levels of angiogenic and angiostatic chemokines are associated with of the presence and extent of coronary collaterals in patients with chronic IHD.

METHODOLOGY/PRINCIPAL FINDINGS

We measured plasma concentrations of angiogenic and angiostatic chemokine ligands in 156 consecutive subjects undergoing coronary angiography with at least one ≥90% coronary stenosis and determined the presence and extent of spontaneously visible coronary collaterals using the Rentrop scoring system. Eighty-eight subjects (56%) had evidence of coronary collaterals. In a multivariable regression model, the concentration of the angiogenic ligands CXCL5, CXCL8 and CXCL12, hyperlipidemia, and an occluded artery were associated with the presence of collaterals; conversely, the concentration of the angiostatic ligand CXCL11, interferon-γ, hypertension and diabetes were associated with the absence of collaterals (ROC area 0.91). When analyzed according to extent of collateralization, higher Rentrop scores were significantly associated with increased concentration of the angiogenic ligand CXCL1 (p<0.0001), and decreased concentrations of angiostatic ligands CXCL9 (p<0.0001), CXCL10 (p = 0.002), and CXCL11 (p = 0.0002), and interferon-γ (p = 0.0004).

CONCLUSIONS/SIGNIFICANCE

Plasma chemokine concentrations are associated with the presence and extent of spontaneously visible coronary artery collaterals and may be mechanistically involved in their recruitment.

Elevated resistin opposed to adiponectin or angiogenin plasma levels as a strong, independent predictive factor for the occurrence of major adverse cardiac and cerebrovascular events in patients with stable multivessel coronary artery disease over 1-year follow-up

Background

Adipokines such as adiponectin and resistin, as well as angiogenin, may be associated with inflammation and atherosclerosis. The relationship between their levels and prognosis in high risk patients is, however, still unclear. The aim of this study was to evaluate the prognostic value of these adipokines in patients with stable multivessel coronary artery disease (MCAD).

Material/Methods

The study group comprised 107 MCAD patients (74% males, mean age 63±8 years). Adiponectin, resistin and angiogenin plasma levels were measured at admission and after 1-year follow-up. Primary end point (major adverse cardiac and cerebrovascular events – MACCE) was defined as cardiac death, nonfatal myocardial infarction, stroke, and hospitalization for angina or heart failure over a 1-year period.

Results

After 1-year follow-up, 9 (8%) patients died, all from cardiovascular causes. Primary end point was experienced by 32% of patients. Surgical treatment (CABG) was received by 51% of patients, while 49% were treated medically alone. Total cholesterol concentration levels ≥173 mg/dl were associated with a 7-fold increase (OR 7.3; 95% CI, 1.6–33.0); LDL ≥93.5 mg/dl with a 16-fold increase (OR 16.3; 95% CI, 2.8–93.8), and resistin ≥17.265 ng/ml with a 13-fold increase in MACCE risk (OR 13.5; 95% CI, 2.3–80.3). In multivariate analysis, a medical treatment strategy (p=0.001), a higher CCS class (p=0.004), resistin levels (p=0.003) and a higher Gensini score (p=0.03) were independent predictors of MACCE.

Conclusions

In stable patients with MCAD, elevated plasma resistin (as opposed to adiponectin or angiogenin) is a strong, independent predictive factor for the occurrence of MACCE over 1-year follow-up.

Relation between serum monocyte chemoattractant protein-1 and coronary collateral development

BACKGROUND

The degree of coronary collateral development is not same in every patient with similar degree of coronary stenosis. In animal studies monocyte chemoattractant protein-1 (MCP-1) has been found to be related to collateral vessel development. In this study we investigated whether a higher serum MCP-1 level is related to better coronary collateral vessel development in patients with stable coronary artery disease.

METHOD

Eighty-three patients with stable angina pectoris, who have at least one coronary stenosis equal to or greater than 70% at coronary angiography, were prospectively enrolled. Serum MCP-1 and vascular endothelial growth factor (VEGF) levels were studied. Coronary collateral development was graded according to the Rentrop method. Patients with grade 2-3 collateral developments were included in good collateral group and formed group I. The patients with grade 0-1 collateral developments were included in poor collateral group and formed group II.

RESULTS

The serum MCP-1 level was significantly higher in good collateral group (288 ± 277 pg/ml vs. 132 ± 64 pg/ml; P<0.001). There was also a positive correlation between serum MCP-1 level and Rentrop score (r=0.39, P<0.001). The patients in the good collateral group also had a significantly higher number of coronary arteries with significant stenosis (1.7 ± 0.7 vs. 1.4 ± 0.6, P=0.049), and higher VEGF levels (322 ± 147 pg/ml vs. 225 ± 161 pg/ml, P=0.007). In multivariate analysis, only serum MCP-1 level (P=0.014, odds ratio: 1.01, 95% confidence interval: 1.002-1.019) was independently related to good coronary collateral development.

CONCLUSION

Higher serum MCP-1 level is related to better coronary collateral development.

Poor coronary collateral vessel development in patients with mild to moderate renal insufficiency

BACKGROUND

The development of coronary collaterals is crucial to survival through acute ischemia. Mild to moderate loss of renal function has been suggested to play a role in this event, but evidential data are scarce. The aim of this study was to investigate the relationship between mild to moderate renal insufficiency and coronary collateral development in patients with chronic total coronary artery occlusion.

METHODS AND RESULTS

A total of 83 patients with mild to moderate loss of renal function (30 mL/min/1.73 m(2) ≤ eGFR < 90 mL/min/1.73 m(2)) with chronic total coronary artery occlusion were included in our study. The collateral circulation was graded according to Rentrop classification and the function of collateral circulation was graded according to Werner collateral connection (CC) grades. Compared to patients with good collateral circulation (Rentrop = 2,3), eGFR was found to be lower in those patients with poor coronary collateral circulation (Rentrop = 0,1) (63.30 ± 10.51 vs. 54.13 ± 10.56, P = 0.02). eGFR was also found to be lower in poorly functioning coronary collateral circulation (CC = 0,1) than in efficiently functioning coronary collateral circulation (CC = 2) (55.22 ± 9.98 vs. 66.28 ± 9.16, P = 0.03). Multiple logistic regression analysis showed that low eGFR was independently associated with poor coronary collateral circulation (Rentrop = 0,1, 95% CI, 0.09-1.09, P = 0.044) and poor function of coronary collateral circulation (CC = 0,1, 95% CI, 0.02-0.17, P = 0.02).

CONCLUSIONS

Lower eGFR is associated with poorer coronary collateral vessel development in patients experiencing mild to moderate renal insufficiency. Moreover, eGFR represents an independent factor affecting coronary collateral vessel development.

Vascular endothelial growth factor in coronary sinus: Evidence for its association with coronary collaterals

OBJECTIVES

To explore whether local growth factors concentration, including vascular endothelial growth factor (VEGF) and transforming growth factor beta one (TGF-beta(1)), influence the formation of coronary collaterals.

DESIGN

Thirty-six patients scheduled for coronary angiography received a 6F Goodale-Lubin catheterization to collect blood from the coronary sinus (CS) and right atrium (RA).

RESULTS

Patients with coronary collaterals had a higher number of diseased vessels (2.6+/-0.2 vs. 1.4+/-0.3, p = 0.005), higher percentage of severity of stenosis (93+/-2 vs. 48+/-8, P < 0.001) and higher VEGF concentrations in CS (38.9+/-3.9 pg/ml vs. 20.8+/-1.4 pg/ml, P < 0.001) and in RA (31.7+/-3.1 pg/ml vs. 22.0+/-2.3 pg/ml, p = 0.004). There was no significant relationship between coronary collateral formation and TGF-beta(1) concentration. By binary logistic regression analysis, VEGF concentrations in CS (p = 0.030) and stenosis severity (p = 0.042) are correlated positively with collateral formation.

CONCLUSIONS

The association between local, endogenous secretion of VEGF and coronary collateral formation is compatible with a paracrine role for this growth factor in pathophysiologic collateral formation.

Local cytokine concentrations and oxygen pressure are related to maturation of the collateral circulation in humans

OBJECTIVES

Our aim was to determine cytokine and oxygen gradients over the collateral circulation in humans.

BACKGROUND

The molecular background of the maturation of the collateral circulation in response to coronary narrowing is poorly understood in humans, partly because of difficulties in obtaining local samples from the human collateral circulation.

METHODS

Coronary collateral blood was sampled in 60 patients with nontotal (n = 25) or total coronary occlusions (n = 35) using a special wide-lumen catheter. Coronary collateral flow index (CFI) was assessed by intracoronary pressure measurements. Oxygenation and lactate content was measured as well as 30 cytokines potentially involved in collateral artery growth, using a custom-made multiplex assay.

RESULTS

No rise in lactate or change in pH was found in collateral blood. Oxygen gradient between coronary and collateral arterial blood correlated inversely with CFI (r = -0.61, p < 0.001). Locally increased plasma levels were found for basic fibroblast growth factor, eotaxin, macrophage migration inflammatory factor, monocyte chemoattractant protein-1, and transforming growth factor-beta, while stem cell factor and stem cell growth factor-beta were significantly decreased. The highest cytokine gradients were found in patients with the least developed collateral circulation. The majority of cytokines correlated more strongly with the pO(2) gradient across the collateral bed than with CFI.

CONCLUSIONS

Intravascular ischemia during brief balloon coronary occlusion is absent in human coronary collateral arteries. The oxygen gradient found over the collateral circulation is increased in patients with a less matured collateral circulation and relates to local levels of several known pro-arteriogenic cytokines. In case of a more developed collateral circulation, relatively low levels of cytokines are present, suggesting that growth factor therapy might be beneficial at this stage.

Vascular endothelial growth factors in cardiovascular medicine

The discovery of vascular endothelial growth factors (VEGFs) and their receptors has considerably improved the understanding of the development and function of endothelial cells. Each member of the VEGF family appears to have a specific function: VEGF-A induces angiogenesis (i.e. growth of new blood vessels from preexisting ones), placental growth factor mediates both angiogenesis and arteriogenesis (i.e. the formation of collateral arteries from preexisting arterioles), VEGF-C and VEGF-D act mainly as lymphangiogenic factors. The study of the biology of these endothelial growth factors has allowed a major progress in the comprehension of the genesis of the vascular system and its abnormalities observed in various pathologic conditions (atherosclerosis and coronary artery disease). The role of VEGF in the atherogenic process is still unclear, but actual evidence suggests both detrimental (development of a neoangiogenetic process within the atherosclerotic plaque) and beneficial (promotion of collateral vessel formation) effects. VEGF and other angiogenic growth factors (fibroblast growth factor), although initially promising in experimental studies and in initial phase I/II clinical trials in patients with ischemic heart disease or peripheral arterial occlusive disease, have subsequently failed to show significant therapeutic improvements in controlled clinical studies. Challenges still remain about the type or the combination of angiogenic factors to be administered, the form (protein vs. gene), the route, and the duration of administration.

Cellular and molecular mechanism regulating blood flow recovery in acute versus gradual femoral artery occlusion are distinct in the mouse

BACKGROUND

Most current animal models of hindlimb ischemia use acute arterial occlusion that does not accurately reflect the pathogenesis of gradual arterial occlusion in humans. We, therefore, developed the first mouse model of gradual arterial occlusion and tested the hypothesis that the mechanisms regulating blood flow recovery are critically dependent on the rate of arterial occlusion.

METHODS

Gradual arterial occlusion was induced by placing ameroid constrictors on the proximal and distal left femoral artery, and ligating the femoral arterial branches (n = 36). Acute arterial occlusion was accomplished by excising the left femoral artery (n = 36). The blood flow recovery was studied by laser Doppler imaging. Differential gene expression between these two models was assessed by quantitative real-time polymerase chain reactions (PCR). Inflammatory and progenitor cells recruitment were determined by immunohistochemistry.

RESULTS

We found that hypoxia-related genes increased significantly in the calf, but not in the thigh, after gradual and acute femoral arterial occlusion (P < .05). Shear-stress dependent genes and inflammatory genes were upregulated immediately in the thigh only after acute femoral arterial occlusion (P < .05). These differences in gene expression were consistent with increased SDF-1alpha expression, recruitment of macrophages and hemangiocytes, and higher blood flow recovery after acute arterial occlusion than after gradual arterial occlusion (P < .05).

CONCLUSION

This is the first study to show the mechanisms that regulate blood flow recovery are critically dependent on the rate of arterial occlusion. This novel model of gradual arterial occlusion may more closely resemble the human diseases, and may provide more accurate mechanistic insights for creating novel molecular therapies.

Interferon-β Signaling Is Enhanced in Patients With Insufficient Coronary Collateral Artery Development and Inhibits Arteriogenesis in Mice

Stimulation of collateral artery growth in patients has been hitherto unsuccessful, despite promising experimental approaches. Circulating monocytes are involved in the growth of collateral arteries, a process also referred to as arteriogenesis. Patients show a large heterogeneity in their natural arteriogenic response on arterial obstruction. We hypothesized that circulating cell transcriptomes would provide mechanistic insights and new therapeutic strategies to stimulate arteriogenesis. Collateral flow index was measured in 45 patients with single-vessel coronary artery disease, separating collateral responders (collateral flow index, >0.21) and nonresponders (collateral flow index, ≤0.21). Isolated monocytes were stimulated with lipopolysaccharide or taken into macrophage culture for 20 hours to mimic their phenotype during arteriogenesis. Genome-wide mRNA expression analysis revealed 244 differentially expressed genes (adjusted P , <0.05) in stimulated monocytes. Interferon (IFN)-β and several IFN-related genes showed increased mRNA levels in 3 of 4 cellular phenotypes from nonresponders. Macrophage gene expression correlated with stimulated monocytes, whereas resting monocytes and progenitor cells did not display differential gene regulation. In vitro, IFN-β dose-dependently inhibited smooth muscle cell proliferation. In a murine hindlimb model, perfusion measured 7 days after femoral artery ligation showed attenuated arteriogenesis in IFN-β–treated mice compared with controls (treatment versus control: 31.5±1.2% versus 41.9±1.9% perfusion restoration, P <0.01). In conclusion, patients with differing arteriogenic response as measured with collateral flow index display differential transcriptomes of stimulated monocytes. Nonresponders show increased expression of IFN-β and its downstream targets, and IFN-β attenuates proliferation of smooth muscle cells in vitro and hampers arteriogenesis in mice. Inhibition of IFN-β signaling may serve as a novel approach for the stimulation of collateral artery growth.

Arteriogenesis: basic mechanisms and therapeutic stimulation

Pharmacological attempts to stimulate the growth of collateral arteries (arteriogenesis) are evolving towards a new treatment option for patients with vascular occlusive diseases. This enlargement of small pre-existing anastomoses towards large conductance arteries takes place independent of local oxygen tension and is driven by changes in luminal shear stress and infiltration of circulating cells. With the increasing knowledge regarding the distinct differences between capillary sprouting (angiogenesis) and arteriogenesis, several cytokines and growth factors have been demonstrated to stimulate the growth of arterial blood vessels in preclinical models of vascular disease. However, the translation towards clinical practice remains difficult and first in-man trials show limited success. Intensive research especially regarding new drug delivery platforms and the potentially serious side effects of pro-arteriogenic therapeutics is warranted before stimulation of arteriogenesis could become a significant treatment option for vascular occlusive diseases. This review focuses on the recent advances in the field of collateral artery growth. In addition, possible means to overcome the hurdles that have hampered the clinical implementation of pro-arteriogenic therapies will be discussed.

Angiopoietin-1, Angiopoietin-2 and Tie-2 in the Coronary Circulation of Patients With and Without Coronary Collateral Vessels

BACKGROUND

The role of the angiopoietin (Ang)/Tie-2 system in coronary collateral growth is not well understood, so the purpose of this study was to investigate and elucidate the relationship of this system to coronary collateral formation in patients with coronary artery disease (CAD).

METHODS AND RESULTS

Fifty-nine patients with CAD were recruited. Blood samples from the left ventricle (LV) and coronary sinus (CS) were obtained during cardiac catheterization, and serum concentrations of Ang-1, Ang-2, and Tie-2 were measured by enzyme-linked immunosorbent assay. Patients were then classified as mild CAD (n=30), defined as </=90% stenosis of the coronary arterial luminal diameter, or severe CAD (n=29), which was total (or near total) coronary occlusion requiring coronary collateral growth. Ang-1, Ang-2, and Tie-2 in the LV and CS sera were not significantly different between groups. In the severe CAD group, spillover of Tie-2 (CS-LV value) from the coronary circulation was found in comparison with the mild CAD group (3.43+/-2.22 vs -3.29+/-1.54 ng/ml, p=0.01), whereas the CS-LV values of Ang-1 and Ang-2 did not differ between groups. Tie-2 production was markedly increased in patients with well-developed collaterals. A positive and significant correlation was found between coronary Ang-2 and Tie-2 levels (r=0.44, p<0.001).

CONCLUSIONS

Tie-2 is probably produced in the coronary circulation and may induce the development or maintenance of coronary collaterals in CAD patients. Furthermore, the role of Ang-2 in the formation of coronary collaterals may be more important than that of Ang-1.

Humoral and cellular factors responsible for coronary collateral formation

Clinical observations suggest that patients with coronary artery disease (CAD) display a marked heterogenerty in collateral formation despite similar degrees of coronary obstruction. The development of coronary collaterals helps protect the myocardium from ischemic damage, yet the factors responsible for collateral formation are poorly understood. To better understand the biochemical and cellular mechanisms of collateral artery formation, monocyte function and circulating levels of pro- and antiangiogenic factors were measured in 101 patients with angiographically assessed CAD and extensively developed (score 2, n = 33) or absent (score 0, n = 68) collateral circulations. Compared with patients with score 0, those with score 2 were slightly older and had more advanced CAD. The score 2 group was also more likely to have had a previous myocardial infarction or coronary artery bypass grafting and a family history of CAD. At the same time, there were no significant differences between groups with regard to circulating levels of vascular endothelial growth factor-A(165), platelet-derived growth factor-betabeta, fibroblast growth factor-2, fibroblast growth factor-4, hepatocyte growth factor, tumor necrosis factor-alpha, interleukin-1beta, endostatin, matrix metalloproteinase-9, promatrix metalloproteinase-1, and CD40 ligand. Monocytes isolated from patients with score 2 and 0 collateral circulations demonstrated no differences in migration assays. However, adhesion to fibrinogen and collagen was significantly higher for monocytes from patients with score 0 (p = 0.05 and 0.04, respectively). In conclusion, these data suggest that the degree of coronary collateral formation is not determined by differences in systemically measurable levels of pro- or antiangiogenic factors assessed in this study. Rather, cellular properties, such as cell adhesion, or genetic differences between patients may be the driving force for collateral development.

Atorvastatin Increases Plasma Soluble Fms-Like Tyrosine Kinase-1 and Decreases Vascular Endothelial Growth Factor and Placental Growth Factor in Association With Improvement of Ventricular Function in Acute Myocardial Infarction

OBJECTIVES

This study examined whether atorvastatin increases plasma levels of soluble Fms-like tyrosine kinase 1 (sFlt-1) and reciprocally decreases vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) levels in patients with acute myocardial infarction (AMI).

BACKGROUND

Statins exert cardioprotective actions partly through anti-inflammatory actions. By capturing VEGF and PlGF in plasma, sFlt-1 acts as a natural inhibitor of VEGF and PlGF, which have proinflammatory properties.

METHODS

Left ventriculography and enzyme-linked immunosorbent assay of plasma levels of sFlt-1, VEGF, and PlGF were repeated after AMI in 50 consecutive patients with a first AMI. Patients were randomized to treatment with atorvastatin (10 mg/day; n=25) or placebo (n=25) within 3 days after AMI, and therapy was continued for 6 months.

RESULTS

The sFlt-1 levels were low in the acute phase, followed by an increase at 2 weeks after AMI, whereas free VEGF and PlGF levels were high in the acute phase, followed by a decrease at 2 weeks. Atorvastatin increased sFlt-1 levels and reciprocally decreased VEGF and PlGF levels at 6 months compared with placebo. The increase in sFlt-1 levels and the decrease in VEGF and PlGF levels were correlated with improvement of left ventricular ejection fraction during the follow-up period.

CONCLUSIONS

There was a reciprocal relationship between changes in sFlt-1 levels and changes in VEGF and PlGF levels after AMI; and atorvastatin increased sFlt-1 levels while decreasing VEGF and PlGF levels. These changes were associated with late improvement of post-MI ventricular function, and may represent an additional benefit of statin therapy.

Success rates of percutaneous coronary intervention of chronic total occlusions and long-term survival in patients with diabetes mellitus

The objectives of this study were to evaluate angiographic and clinical outcomes among patients with diabetes mellitus (DM) who underwent percutaneous coronary intervention (PCI) for a chronic total occlusion (CTO). We compared them with matched patients undergoing PCI of a non-CTO lesion. All patients had documented DM. Matching was performed using a propensity score for CTO. There were 506 patients with DM and CTO who were matched with a non-CTO group. Results showed that angiographic success rates were lower with CTO (75% vs. 93%, p<0.001). In-hospital major adverse cardiac event (MACE - death, urgent bypass surgery, Q-wave myocardial infarction or target vessel revascularisation) rates were equivalent (CTO 3.2% vs. non-CTO 2.6%, p=0.57). Survival was not different five years after revascularisation of CTO (75%) vs. non-CTO (79%) (p=0.20). In addition, when DM patients with CTO were analysed according to angiographic success of PCI, there were no significant differences in either in-hospital (success 1.6% vs. failure 2.4%, p=0.7) or 1-year mortality (success 22.2% vs. failure 26.8%, p=0.3). We conclude that PCI of CTO is safe in patients with DM. Angiographic failure is not associated with an increase in MACE rates or mortality as compared to matched non-CTO patients. However, there is not a measurable improvement in survival in this DM-CTO population.

Relation of various plasma growth factor levels in patients with stable angina pectoris and total occlusion of a coronary artery to the degree of coronary collaterals

We assessed (1) angiogenic factors in patients with stable angina and longstanding (> or =24 months) total occlusion of a single coronary artery and (2) the relation between plasma levels of angiogenic factors and the development of collateral vessels as evaluated by coronary angiography. Plasma concentrations of vascular endothelial growth factor (VEGF(165)), fibroblast growth factor, placenta-derived growth factors (PlGFs), and hepatocyte growth factor were assessed in 96 patients with stable angina and longstanding (> or =24 months) total occlusion of a single coronary artery. According to coronary angiographic results, 18 patients had no visible collaterals (group 0), 21 patients had visible collaterals but no filling of the recipient epicardial vessel (group 1), and 57 patients showed filling (partial or complete) of the recipient epicardial vessel by collaterals (group 2). Plasma VEGF(165) and PlGF concentrations were higher in group 1 than in groups 0 and 2 (VEGF(165) 75 pg/ml, range 24 to 105, vs 23 pg/ml, range 15 to 29, and 19 pg/ml, range 10 to 41, respectively, F = 5.53, p = 0.006; PlGF 35 pg/ml, range 3.5 to 105, vs 1 pg/ml, range 1 to 38, and 1 pg/ml, range 1 to 5, respectively, F = 7.09, p = 0.008). Plasma VEGF(165) and PlGF levels were similar in groups 0 and 2. There was no significant difference in plasma levels of fibroblast and hepatocyte growth factor concentrations across the 3 groups. In conclusion, plasma levels of angiogenic growth factors differ among patients with stable angina pectoris and longstanding total coronary occlusion.

Effects of Total Coronary Artery Occlusion on Vascular Endothelial Growth Factor and Transforming Growth Factor β

Vascular endothelial growth factor (VEGF) and transforming growth factor beta (TGF-beta1) play an important role in angiogenesis. We wanted to determine if concentrations of growth factors in the coronary sinus (CS) and right atrium (RA) are higher in coronary artery disease patients with total occlusions than in those with partial occlusions. Fifty-one patients scheduled for coronary artery angiography were evaluated for possible recruitment. A 6F Goodale-Lubin catheter was used to collect blood from the CS and RA. Data for all but four patients were gathered successfully, leaving 47 study patients. The reviewer was blinded to growth factor data when interpreting coronary angiographic findings. Of the 47 enrolled patients, 32 had at least one diseased vessel, seven of whom had at least one major total epicardial coronary occlusion. In all 32 patients, the concentrations of VEGF in the CS were higher than those in the RA (31.5 +/- 2.7 vs 27.1 +/- 1.8 pg/mL; p = 0.005). Patients with total occlusions had higher VEGF concentrations in the CS than those with non-total occlusions (38.9 +/- 8.0 vs 29.5 +/- 2.6 pg/mL; p = 0.037). The differences in TGF-beta1 in the two groups were not statistically significant. The higher CS VEGF concentrations in patients with total occlusion indicate that VEGF may play a part in the development of angiogenesis.