Microvascular involvement in cardiac pathology

The Eye as the Window to the Heart: Optical Coherence Tomography Angiography Biomarkers as Indicators of Cardiovascular Disease

Alterations in microvasculature represent some of the earliest pathological processes across a wide variety of human diseases. In many organs, however, inaccessibility and difficulty in directly imaging tissues prevent the assessment of microvascular changes, thereby significantly limiting their translation into improved patient care. The eye provides a unique solution by allowing for the non-invasive and direct visualization and quantification of many aspects of the human microvasculature, including biomarkers for structure, function, hemodynamics, and metabolism. Optical coherence tomography angiography (OCTA) studies have specifically identified reduced capillary densities at the level of the retina in several eye diseases including glaucoma. This narrative review examines the published data related to OCTA-assessed microvasculature biomarkers and major systemic cardiovascular disease. While loss of capillaries is being established in various ocular disease, pilot data suggest that changes in the retinal microvasculature, especially within the macula, may also reflect small vessel damage occurring in other organs resulting from cardiovascular disease. Current evidence suggests retinal microvascular biomarkers as potential indicators of major systemic cardiovascular diseases, including systemic arterial hypertension, atherosclerotic disease, and congestive heart failure.

Endogenous humoral determinants of vascular endothelial dysfunction as triggers of acute poisoning complications

The vascular endothelium is not only the semipermeable membrane that separates tissue from blood but also an organ that regulates inflammation, vascular tone, blood clotting, angiogenesis and synthesis of connective tissue proteins. It is susceptible to the direct cytotoxic action of numerous xenobiotics and to the acute hypoxia that accompanies acute poisoning. This damage is superimposed on the preformed state of the vascular endothelium, which, in turn, depends on many humoral factors. The probability that an exogenous toxicant will cause life-threatening dysfunction of the vascular endothelium, thereby complicating the course of acute poisoning, increases with an increase in the content of endogenous substances in the blood that disrupt endothelial function. These include ammonia, bacterial endotoxin, indoxyl sulfate, para-cresyl sulfate, trimethylamine N-oxide, asymmetric dimethylarginine, glucose, homocysteine, low-density and very-low-density lipoproteins, free fatty acids and products of intravascular haemolysis. Some other endogenous substances (albumin, haptoglobin, haemopexin, biliverdin, bilirubin, tetrahydrobiopterin) or food-derived compounds (ascorbic acid, rutin, omega-3 polyunsaturated fatty acids, etc.) reduce the risk of lethal vascular endothelial dysfunction. The individual variability of the content of these substances in the blood contributes to the stochasticity of the complications of acute poisoning and is a promising target for the risk reduction measures. Another feasible option may be the repositioning of drugs that affect the function of the vascular endothelium while being currently used for other indications.

Upregulated Angiogenesis Is Incompetent to Rescue Dilated Cardiomyopathy Phenotype in Mice

Dilated cardiomyopathy (DCM) is characterized by pathologic cardiac remodeling resulting in chambers enlargement and impaired heart contractility. Previous reports and our in-silico analysis support the association of DCM phenotype and impaired tissue angiogenesis. Here, we explored whether the modulation in cardiac angiogenesis partly intervenes or rescues the DCM phenotype in mice. Here, a DCM mouse model [α-tropomyosin 54 (α-TM54) mutant] was crossbred with microRNA-210 transgenic mice (210-TG) to develop microRNA-210 (miR-210) overexpressing α-TM54 mutant mice (TMx210). Contrary to wild-type (WT) and 210-TG mice, a significant increase in heart weight to body weight ratio in aged mixed-gender TMx210 and DCM mice was recorded. Histopathological analysis revealed signs of pathological cardiac remodeling such as myocardial disarray, myofibrillar loss, and interstitial fibrosis in DCM and TMx210 mice. Contrary to WT and DCM, a significant increase in angiogenic potential was observed in TMx210 and 210-TG mice hearts which is reflected by higher blood vessel density and upregulated proangiogenic vascular endothelial growth factor-A. The echocardiographic assessment showed comparable cardiac dysfunction in DCM and TMx210 mice as compared to WT and 210-TG. Overall, the present study concludes that miR-210 mediated upregulated angiogenesis is not sufficient to rescue the DCM phenotype in mice.

Heart Dysfunction Following Long-Term Murine Cytomegalovirus Infection: Fibrosis, Hypertrophy, and Tachycardia

Human cytomegalovirus (HCMV) is associated with increased risk of chronic diseases of the heart and vasculature, including myocarditis, atherosclerosis, and transplant vasculopathy. To investigate CMV infection of the heart, murine cytomegalovirus (MCMV) was used to evaluate both acute and latent infection and the subsequent phenotypic and functional consequences of infection. Female BALB/c mice were intraperitoneally (i.p.) inoculated with 1 × 106 pfu of MCMV and evaluated at 14 and 50 days postinfection (dpi). At each time point, echocardiography was used to evaluate cardiac function and histology was conducted for phenotypic evaluation. MCMV replication in the heart was detected as early as 3 dpi and was no longer detectable at 14 dpi. Infected animals had significant cardiac pathology at 14 and 50 dpi when compared to uninfected controls. Histology revealed fibrosis of the heart as early as 14 dpi and the presence of white fibrous deposits on the surface of the heart. Functional evaluation showed significantly increased heart rate and muscle thickening in the latently infected animals when compared to the control animals. At 50 dpi, latent virus was measured by explant reactivation assay, demonstrating that MCMV establishes latency and is capable of reactivation from the heart, similar to other tissues such as spleen and salivary glands. Collectively, these studies illustrate that MCMV infection results in phenotypic alterations within the heart as early as 14 dpi, which progress to functional abnormalities during latency. These findings are similar to sinus tachycardia and hypertrophy of the heart muscle observed in cases of HCMV-induced acute myocarditis.

Unraveling Cardiovascular Risk in Renal Patients: A New Take on Old Tale

Chronic kidney disease (CKD), defined by an estimated glomerular filtration rate <60 ml/min/1.73 m² and/or an increase in urine protein excretion (i.e., albuminuria), is an important public health problem. Prevalence and incidence of CKD have risen by 87 and 89%, worldwide, over the last three decades. The onset of either albuminuria and eGFR reduction has found to predict higher cardiovascular (CV) risk, being this association strong, independent from traditional CV risk factors and reproducible across different setting of patients. Indeed, this relationship is present not only in high risk cohorts of CKD patients under regular nephrology care and in those with hypertension or type 2 diabetes, but also in general, otherwise healthy population. As underlying mechanisms of damage, it has hypothesized and partially proved that eGFR reduction and albuminuria can directly promote endothelial dysfunction, accelerate atherosclerosis and the deleterious effects of hypertension. Moreover, the predictive accuracy of risk prediction models was consistently improved when eGFR and albuminuria have been added to the traditional CV risk factors (i.e., Framingham risk score). These important findings led to consider CKD as an equivalent CV risk. Although it is hard to accept this definition in absence of additional reports from scientific Literature, a great effort has been done to reduce the CV risk in CKD patients. A large number of clinical trials have tested the effect of drugs on CV risk reduction. The targets used in these trials were different, including blood pressure, lipids, albuminuria, inflammation, and glucose. All these trials have determined an overall better control of CV risk, performed by clinicians. However, a non-negligible residual risk is still present and has been attributed to: (1) missed response to study treatment in a consistent portion of patients, (2) role of many CV risk factors in CKD patients not yet completely investigated. These combined observations provide a strong argument that kidney measures should be regularly included in individual prediction models for improving CV risk stratification. Further studies are needed to identify high risk patients and novel therapeutic targets to improve CV protection in CKD patients.

LncEGFL7OS regulates human angiogenesis by interacting with MAX at the EGFL7/miR-126 locus

In an effort to identify human endothelial cell (EC)-enriched lncRNAs,~500 lncRNAs were shown to be highly restricted in primary human ECs. Among them, lncEGFL7OS, located in the opposite strand of the EGFL7/miR-126 gene, is regulated by ETS factors through a bidirectional promoter in ECs. It is enriched in highly vascularized human tissues, and upregulated in the hearts of dilated cardiomyopathy patients. LncEGFL7OS silencing impairs angiogenesis as shown by EC/fibroblast co-culture, in vitro/in vivo and ex vivo human choroid sprouting angiogenesis assays, while lncEGFL7OS overexpression has the opposite function. Mechanistically, lncEGFL7OS is required for MAPK and AKT pathway activation by regulating EGFL7/miR-126 expression. MAX protein was identified as a lncEGFL7OS-interacting protein that functions to regulate histone acetylation in the EGFL7/miR-126 promoter/enhancer. CRISPR-mediated targeting of EGLF7/miR-126/lncEGFL7OS locus inhibits angiogenesis, inciting therapeutic potential of targeting this locus. Our study establishes lncEGFL7OS as a human/primate-specific EC-restricted lncRNA critical for human angiogenesis.

Shared Features of Endothelial Dysfunction between Sepsis and Its Preceding Risk Factors (Aging and Chronic Disease)

Acute vascular endothelial dysfunction is a central event in the pathogenesis of sepsis, increasing vascular permeability, promoting activation of the coagulation cascade, tissue edema and compromising perfusion of vital organs. Aging and chronic diseases (hypertension, dyslipidaemia, diabetes mellitus, chronic kidney disease, cardiovascular disease, cerebrovascular disease, chronic pulmonary disease, liver disease, or cancer) are recognized risk factors for sepsis. In this article we review the features of endothelial dysfunction shared by sepsis, aging and the chronic conditions preceding this disease. Clinical studies and review articles on endothelial dysfunction in sepsis, aging and chronic diseases available in PubMed were considered. The main features of endothelial dysfunction shared by sepsis, aging and chronic diseases were: (1) increased oxidative stress and systemic inflammation, (2) glycocalyx degradation and shedding, (3) disassembly of intercellular junctions, endothelial cell death, blood-tissue barrier disruption, (4) enhanced leukocyte adhesion and extravasation, (5) induction of a pro-coagulant and anti-fibrinolytic state. In addition, chronic diseases impair the mechanisms of endothelial reparation. In conclusion, sepsis, aging and chronic diseases induce similar features of endothelial dysfunction. The potential contribution of pre-existent endothelial dysfunction to sepsis pathogenesis deserves to be further investigated.

IL-1β reduces cardiac lymphatic muscle contraction via COX-2 and PGE2 induction: Potential role in myocarditis

The role of lymphatic vessels in myocarditis is largely unknown, while it has been shown to play a key role in other inflammatory diseases. We aimed to investigate the role of lymphatic vessels in myocarditis using in vivo model induced with Theiler's murine encephalomyelitis virus (TMEV) and in vitro model with rat cardiac lymphatic muscle cells (RCLMC). In the TMEV model, we found that upregulation of a set of inflammatory mediator genes, including interleukin (IL)-1β, tumor necrosis factor (TNF)-αand COX-2 were associated with disease activity. Thus, using in vitro collagen gel contraction assays, we decided to clarify the role(s) of these mediators by testing contractility of RCLMC in response to IL-1β and TNF-α individually and in combination, in the presence or absence of: IL-1 receptor antagonist (Anakinra); cyclooxygenase (COX) inhibitors inhibitors (TFAP, diclofenac and DuP-697). IL-1β impaired RCLMC contractility dose-dependently, while co-incubation with both IL-1β and TNF-α exhibited synergistic effects in decreasing RCLMC contractility with increased COX-2 expression. Anakinra maintained RCLMC contractility; Anakinra blocked the mobilization of COX-2 induced by IL-1β with or without TNF-α. COX-2 inhibition blocked the IL-1β-mediated decrease in RCLMC contractility. Mechanistically, we found that IL-1β increased prostaglandin (PG) E₂ release dose-dependently, while Anakinra blocked IL-1β mediated PGE₂ release. Using prostaglandin E receptor 4 (EP4) receptor antagonist, we demonstrated that EP4 receptor blockade maintained RCLMC contractility following IL-1β exposure. Our results indicate that IL-1β reduces RCLMC contractility via COX-2/PGE₂ signaling with synergistic cooperation by TNF-α. These pathways may help provoke inflammatory mediator accumulation within the heart, driving progression from acute myocarditis into dilated cardiomyopathy.

A review of strategies for infarct size reduction during acute myocardial infarction

Advances in medical and interventional therapy over the last few decades have revolutionized the treatment of acute myocardial infarction. Despite the ability to restore epicardial coronary artery patency promptly through percutaneous coronary intervention, tissue level damage may continue. The reported 30-day mortality after all acute coronary syndromes is 2 to 3%, and around 5% following myocardial infarction. Post-infarct complications such as heart failure continue to be a major contributor to cardiovascular morbidity and mortality. Inadequate microvascular reperfusion leads to worse clinical outcomes and potentially strategies to reduce infarct size during periods of ischemia-reperfusion can improve outcomes. Many strategies have been tested, but no single strategy alone has shown a consistent result or benefit in large scale randomised clinical trials. Herein, we review the historical efforts, current strategies, and potential novel concepts that may improve myocardial protection and reduce infarct size.

Strategies to attenuate micro-vascular obstruction during P-PCI: the randomized reperfusion facilitated by local adjunctive therapy in ST-elevation myocardial infarction trial

Background

Microvascular obstruction (MVO) following primary percutaneous coronary intervention (PPCI) treatment of ST-segment elevation myocardial infarction (STEMI) contributes to infarct expansion, left ventricular (LV) remodelling, and worse clinical outcomes. The REFLO-STEMI trial tested whether intra-coronary (IC) high-dose adenosine or sodium nitroprusside (SNP) reduce infarct size and/or MVO determined by cardiac magnetic resonance (CMR).

Methods and results

REFLO-STEMI, a prospective, open-label, multi-centre trial with blinded endpoints, randomized (1:1:1) 247 STEMI patients with single vessel disease presenting within 6 h of symptom onset to IC adenosine (2–3 mg total) or SNP (500 μg total) immediately following thrombectomy and again following stenting, or to standard PPCI. The primary endpoint was infarct size % LV mass (%LVM) on CMR undertaken 24–96 h after PPCI (n = 197). Clinical follow-up was to 6 months. There was no significant difference in infarct size (%LVM, median, interquartile range, IQR) between adenosine (10.1, 4.7–16.2), SNP (10.0, 4.2–15.8), and control (8.3, 1.9–14.0), P = 0.062 and P = 0.160, respectively, vs. control. MVO (% LVM, median, IQR) was similar across groups (1.0, 0.0–3.7, P = 0.205 and 0.6, 0.0–2.4, P = 0.244 for adenosine and SNP, respectively, vs. control 0.3, 0.0–2.8). On per-protocol analysis, infarct size (%LV mass, 12.0 vs. 8.3, P = 0.031), major adverse cardiac events (hazard ratio, HR, 5.39 [1.18–24.60], P = 0.04) at 30 days and 6 months (HR 6.53 [1.46–29.2], P = 0.01) were increased and ejection fraction reduced (42.5 ± 7.2% vs. 45.7 ± 8.0%, P = 0.027) in adenosine-treated patients compared with control.

Conclusions

High-dose IC adenosine and SNP during PPCI did not reduce infarct size or MVO measured by CMR. Furthermore, adenosine may adversely affect mid-term clinical outcome.

Clinical Trial registration

ClinicalTrials.gov Identifier: NCT01747174; https://clinicaltrials.gov/ct2/show/NCT01747174

Soluble Flt-1 links microvascular disease with heart failure in CKD

Chronic kidney disease (CKD) is associated with an increased risk of heart failure (HF). Elevated plasma concentrations of soluble Flt-1 (sFlt-1) have been linked to cardiovascular disease in CKD patients, but whether sFlt-1 contributes to HF in CKD is still unknown. To provide evidence that concludes a pathophysiological role of sFlt-1 in CKD-associated HF, we measured plasma sFlt-1 concentrations in 586 patients with angiographically documented coronary artery disease and renal function classified according to estimated glomerular filtration rate (eGFR). sFlt-1 concentrations correlated negatively with eGFR and were associated with signs of heart failure, based on New York Heart Association functional class and reduced left ventricular ejection fraction (LVEF), and early mortality. Additionally, rats treated with recombinant sFlt-1 showed a 15 % reduction in LVEF and a 29 % reduction in cardiac output compared with control rats. High sFlt-1 concentrations were associated with a 15 % reduction in heart capillary density (number of vessels/cardiomyocyte) and a 24 % reduction in myocardial blood volume. Electron microscopy and histological analysis revealed mitochondrial damage and interstitial fibrosis in the hearts of sFlt-1-treated, but not control rats. In 5/6-nephrectomised rats, an animal model of CKD, sFlt-1 antagonism with recombinant VEGF121 preserved heart microvasculature and significantly improved heart function. Overall, these findings suggest that a component of cardiovascular risk in CKD patients could be directly attributed to sFlt-1. Assessment of patients with CKD confirmed that sFlt-1 concentrations were inversely correlated with renal function, while studies in rats suggested that sFlt-1 may link microvascular disease with HF in CKD.

The REFLO-STEMI trial comparing intracoronary adenosine, sodium nitroprusside and standard therapy for the attenuation of infarct size and microvascular obstruction during primary percutaneous coronary intervention: study protocol for a randomised controlled trial

BACKGROUND

Microvascular obstruction (MVO) secondary to ischaemic-reperfusion injury is an important but underappreciated determinant of short- and longer-term outcome following percutaneous coronary intervention (PCI) treatment of ST-elevation myocardial infarction (STEMI). Several small studies have demonstrated a reduction in the degree of MVO utilising a variety of vasoactive agents, with adenosine and sodium nitroprusside (SNP) being most evaluated. However, the evidence base remains weak as the trials have had variable endpoints, differing drug doses and delivery. As such, the results regarding benefit are conflicting.

METHODS

The REperfusion Facilitated by LOcal adjunctive therapy in STEMI (REFLO-STEMI) trial is a multicentre, prospective, randomised, controlled, open label, study with blinded endpoint analysis: Patients presenting within 6 h of onset of STEMI and undergoing planned primary PCI (P-PCI) with TIMI 0/1 flow in the infarct-related artery (IRA) and no significant bystander coronary artery disease on angiography, are randomised into one of three groups: PCI with adjunctive pharmacotherapy (intracoronary adenosine or SNP) or control (standard PCI). All receive Bivalirudin anticoagulation and thrombus aspiration. The primary outcome is infarct size (IS) (determined as a percentage of total left ventricular mass) measured by cardiac magnetic resonance imaging (CMRI) undertaken at 48 to 72 h post P-PCI. Secondary outcome measures include MVO (hypoenhancement within infarct core) on CMRI, angiographic markers of microvascular perfusion and MACE during 1-month follow-up. The study aims to recruit 240 patients (powered at 80% to detect a 5% absolute reduction in IS).

DISCUSSION

The REFLO-STEMI study has been designed to address the weaknesses of previous trials, which have collectively failed to demonstrate whether adjunctive pharmacotherapy with adenosine and/or SNP can reduce measures of myocardial injury (infarct size and MVO) and improve clinical outcome, despite good basic evidence that they have the potential to attenuate this process. The REFLO-STEMI study will be the most scientifically robust trial to date evaluating whether adjunctive therapy (intracoronary adenosine or SNP following thrombus aspiration) reduces CMRI measured IS and MVO in patients undergoing P-PCI within 6 h of onset of STEMI.

TRIAL REGISTRATION

Trial registered 20th November 2012: ClinicalTrials.gov Identifier NCT01747174.

Dynamic mitochondrial changes during differentiation of P19 embryonic carcinoma cells into cardiomyocytes

Murine P19 embryonal carcinoma cells are multipotent cells that can differentiate into cardiomyocytes when treated with dimethyl sulfoxide. This experimental model provides an invaluable tool to study different aspects of cardiac differentiation, such as the function of cardiac‑specific transcription factors and signaling pathways, and the regulation of contractile protein expression. The role of mitochondria during cardiac differentiation is unclear. In this context, we have examined the mitochondrial-related changes in undifferentiated and differentiated P19 cells. We observed that mitochondrial DNA content sharply decreased in P19 cell aggregates compared to undifferentiated cells, accompanied by decreased levels of adenosine triphosphate (ATP) and reactive oxygen species (ROS). Following the aggregation stage, the mitochondrial DNA content reached its highest level on day 7 of the differentiation process, with the intracellular ROS level showing a trend to increase, similar to cellular ATP production. In conclusion, our study on differentiating P19 embryonal carcinoma cells provides new insights into the role of mitochondria in the differentiation of P19 stem cells into beating cardiomyocytes.

Subfoveal choroidal thickness in patients with chronic heart failure analyzed by spectral-domain optical coherence tomography

PURPOSE

To evaluate the subfoveal choroidal thickness (SFCT) measured by enhanced depth imaging optical coherence tomography (EDI-OCT) in eyes of chronic heart failure (CHF) patients.

METHODS

Fifty-six patients with CHF and 56 age- and gender-matched healthy individuals were enrolled. The SFCT was measured by EDI-OCT. The ejection fraction of left ventricle (EFLV), age, intraocular pressure (IOP), axial length (AL), systolic and diastolic blood pressure, and ocular perfusion pressure (OPP) were also measured.

RESULTS

Mean SFCT was 181.2 ± 80.23 μm in the study group and 283.6 ± 52.4 μm in the control group (p = 0.000). There was a statistically significant correlation between the SFCT and each of EFLV and age. SFCT value was not statistically significantly associated with AL, IOP and OPP.

CONCLUSION

Our results suggest that SFCT is lower in eyes of CHF patients compared to age- and gender-matched healthy individuals.

Thrombospondins, potential drug targets for cardiovascular diseases

The thrombospondin (TSP) family consists of five multimeric, multidomain calcium-binding glycoproteins that act as regulators of cell-cell and cell-matrix associations as well as interact with other extracellular matrix molecules affecting their function. Increasing interest on cardiac TSP-1, TSP-2 and TSP-4 has emerged, and they have been studied in cardiac hypertrophy, myocardial infarction, heart failure, atherosclerosis and aortic valve stenosis. The aim of this MiniReview is to summarize the current knowledge on each TSP in various cardiovascular pathologies. We specifically emphasize the role of TSPs in cardiac remodelling and evaluate TSPs as potential cardiovascular drug targets. Thrombospondin-1 (TSP-1) is the most studied TSP, being antiangiogenic and able to activate transforming growth factor-β. The functions of TSP-2 and TSP-4 are linked in maintaining the composition of the matrix of the hypertrophied heart, whereas there is very little knowledge on cardiac TSP-3 and TSP-5. TSP-1, TSP-2 and TSP-4 have been shown to affect cardiac remodelling in vivo, for example, by modulating matrix metalloproteinase and transforming growth factor-β activity, collagen synthesis, myofibroblast differentiation, cell death and stretch-mediated augmentation of cardiac contractility. The detrimental role for TSPs in cardiovascular pathophysiology has been clearly demonstrated in knockout mouse models, and augmentation of TSP signalling in the heart during stress and haemodynamic overload might be beneficial. In conclusion, the role of TSP-1, TSP-2 and TSP-4 in cardiac hypertrophy, remodelling after myocardial infarction, heart failure, atherosclerosis and aortic valve stenosis encourages further investigation to validate them as potential drug targets.

High admission levels of γ-glutamyltransferase predict poor myocardial perfusion after primary percutaneous intervention

OBJECTIVE

This retrospective study aimed to investigate the relationship between admission levels of serum y-glutamyltransferase and poor myocardial perfusion after primary percutaneous coronary intervention in patients with acute myocardial infarction.

INTRODUCTION

Reperfusion injury caused by free radical release and increased oxidative stress is responsible for the pathophysiology of the no-reflow phenomenon in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention. Serum γ-glutamyltransferase is an established marker of increased oxidative stress.

METHODS

The study population consisted of 80 patients (64 men and 16 women, mean age = 67.5 + 6.6 years) with thrombolysis in myocardial infarction 0/1 flow pre-procedurally. The patients were divided into two groups according to thrombolysis in myocardial perfusion grades that were assessed immediately following primary percutaneous coronary intervention. The two groups (group 1 and group 2) each consisted of 40 patients with thrombolysis in myocardial perfusion grades 0-1 and thrombolysis in myocardial perfusion grades 2-3, respectively.

RESULTS

Admission pain to balloon time, γ-glutamyltransferase and creatine kinase-MB isoenzyme levels of group 1 patients were significantly higher than those of group 2 patients. Pain to balloon time, γ-glutamyltransferase, peak creatine kinase-MB isoenzyme, low left ventricular ejection fraction and poor pre-procedural thrombolysis in myocardial infarction grade were significantly associated with poor myocardial perfusion by univariate analysis. However, only pain to balloon time and γ-glutamyltransferase levels showed a significant independent association with poor myocardial perfusion by backward logistic regression analysis. Adjusted odds ratios were calculated as 4.92 for pain to balloon time and 1.13 for γ-glutamyltransferase.

CONCLUSION

High admission γ-glutamyltransferase levels are associated with poor myocardial perfusion in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention, particularly in patients with prolonged pain to balloon time.

Comparison of the effects of nitroprusside versus nicorandil on the slow/no-reflow phenomenon during coronary interventions for acute myocardial infarction

Although slow/no-reflow is a serious problem complicating primary percutaneous coronary interventions (PCI) for acute myocardial infarction (AMI) and is associated with a poor prognosis, its efficacious treatment remains problematic. We compared the acute, in-hospital and long-term (1 year) effects of nitroprusside (NTP) with those of nicorandil (NC) on the slow/no-reflow phenomenon. Forty-nine of 442 consecutive patients with AMI who underwent primary PCI complicated by slow/no-reflow and who received intracoronary NTP (n = 25) or NC (n = 24) administration were studied. Both NTP and NC induced significant improvements in coronary flow, with increases in TIMI flow grade from 1.64 ± 0.62 to 2.74 ± 0.36 (p < 0.001) and 1.60 ± 0.86 to 2.23 ± 0.91 (p < 0.001), and in corrected TIMI frame count from 37.8 ± 15.1 to 13.7 ± 7.1 (p < 0.001) and 30.8 ± 20.7 to 19.3 ± 17.9 (p < 0.001), respectively. The degree of improvement in TIMI flow grade (post-pre/pre) and TIMI frame count (pre-post/pre) showed that NTP was more effective than NC (NTP vs. NC: 0.88 ± 0.79, 0.37 ± 0.37, p = 0.008; 0.59 ± 0.23, 0.36 ± 0.27, p = 0.003, respectively). Congestive heart failure did not tend to last beyond 3 days after onset in the NTP group, which was more than in the NC group, during hospitalization (1/25, 4/24, p = 0.143, respectively). At the 1-year follow-up, the NTP group tended to show more improvement than the NC group in MACE (5/25, 9/24, p = 0.175, respectively). NTP is a more effective treatment for slow/no-reflow associated with PCI in patients with AMI and may improve long-term clinical outcomes compared with NC.

MicroRNA profiling in early hypertrophic growth of the left ventricle in rats

Pressure overload induces hypertrophic growth of the heart and in the long term this condition can lead to cardiomyopathy and heart failure. Several miRNAs are upregulated in heart failure. However, it is not clear, which miRNAs (if any) are induced during the early hypertrophic growth phase. To investigate whether the upregulation of miRNAs is an integrated part of hypertrophic growth or an effect of cardiac disease we investigated miRNA expression in early hypertrophic development. Hypertrophy was induced by banding of the ascending aorta of male rats. After 14 days, the heart left ventricle weight relative to body weight of animals with aortic banding had increased 65% compared to matched control rats. Furthermore, RNA was extracted from left ventricles and reverse transcription qPCR showed that expression of the hypertrophic markers atrial natriuretic peptide and brain natriuretic peptide was highly induced in animals with aortic banding. Out of 13 miRs that have previously been reported to be associated with late-stage pressure-overload-induced hypertrophy and heart failure only four (miR-23a, miR-27b, miR-125b and miR-195) were induced during early hypertrophic growth. These miRs were previously associated with angiogenesis and cell growth and their expression in early hypertrophic growth was accompanied by a twofold upregulation of the cell-cycle regulator cyclin D2 that is a marker of cardiac growth. Our results indicate that different miRNAs are involved in early hypertrophic growth than in late stage pressure-overload induced heart failure.

GATA-4 is an angiogenic survival factor of the infarcted heart

BACKGROUND

Recent data suggest that GATA-4 is an antiapoptotic factor required for adaptive responses and a key regulator of hypertrophy and hypertrophy-associated genes in the heart. As a leading cause of chronic heart failure, reversal of postinfarction left ventricular remodeling represents an important target for therapeutic interventions. Here, we studied the role of GATA-4 as a mediator of postinfarction remodeling in rats.

METHODS AND RESULTS

Myocardial infarction, caused by ligating the left anterior descending coronary artery, significantly decreased the DNA binding activity of GATA-4 at day 1, whereas at 2 weeks the GATA-4 DNA binding was significantly upregulated. To determine the functional role of GATA-4, peri-infarct intramyocardial delivery of adenoviral vector expressing GATA-4 was done before left anterior descending coronary artery ligation. Hearts treated with GATA-4 gene transfer exhibited significantly increased ejection fraction and fractional shortening. Accordingly, infarct size was significantly reduced. To determine the cardioprotective mechanisms of GATA-4, myocardial angiogenesis, rate of apoptosis, c-kit+ cardiac stemlike cells, and genes regulated by GATA-4 were studied. The number of capillaries and stemlike cells was significantly increased, and decreased apoptosis was observed.

CONCLUSION

These results indicate that the reversal of reduced GATA-4 activity prevents adverse postinfarction remodeling through myocardial angiogenesis, antiapoptosis, and stem cell recruitment. GATA-4-based gene transfer may represent a novel, efficient therapeutic approach for heart failure.

Cardiomyocyte PDGFR-beta signaling is an essential component of the mouse cardiac response to load-induced stress

PDGFR is an important target for novel anticancer therapeutics because it is overexpressed in a wide variety of malignancies. Recently, however, several anticancer drugs that inhibit PDGFR signaling have been associated with clinical heart failure. Understanding this effect of PDGFR inhibitors has been difficult because the role of PDGFR signaling in the heart remains largely unexplored. As described herein, we have found that PDGFR-beta expression and activation increase dramatically in the hearts of mice exposed to load-induced cardiac stress. In mice in which Pdgfrb was knocked out in the heart in development or in adulthood, exposure to load-induced stress resulted in cardiac dysfunction and heart failure. Mechanistically, we showed that cardiomyocyte PDGFR-beta signaling plays a vital role in stress-induced cardiac angiogenesis. Specifically, we demonstrated that cardiomyocyte PDGFR-beta was an essential upstream regulator of the stress-induced paracrine angiogenic capacity (the angiogenic potential) of cardiomyocytes. These results demonstrate that cardiomyocyte PDGFR-beta is a regulator of the compensatory cardiac response to pressure overload-induced stress. Furthermore, our findings may provide insights into the mechanism of cardiotoxicity due to anticancer PDGFR inhibitors.

Myocardial hypertrophy in the absence of external stimuli is induced by angiogenesis in mice

Although studies have suggested a role for angiogenesis in determining heart size during conditions demanding enhanced cardiac performance, the role of EC mass in determining the normal organ size is poorly understood. To explore the relationship between cardiac vasculature and normal heart size, we generated a transgenic mouse with a regulatable expression of the secreted angiogenic growth factor PR39 in cardiomyocytes. A significant change in adult mouse EC mass was apparent by 3 weeks following PR39 induction. Heart weight; cardiomyocyte size; vascular density normalization; upregulation of hypertrophy markers including atrial natriuretic factor, beta-MHC, and GATA4; and activation of the Akt and MAP kinase pathways were observed at 6 weeks post-induction. Treatment of PR39-induced mice with the eNOS inhibitor L-NAME in the last 3 weeks of a 6-week stimulation period resulted in a significant suppression of heart growth and a reduction in hypertrophic marker expression. Injection of PR39 or another angiogenic growth factor, VEGF-B, into murine hearts during myocardial infarction led to induction of myocardial hypertrophy and restoration of myocardial function. Thus stimulation of vascular growth in normal adult mouse hearts leads to an increase in cardiac mass.

Serum response factor neutralizes Pur alpha- and Pur beta-mediated repression of the fetal vascular smooth muscle alpha-actin gene in stressed adult cardiomyocytes

Mouse hearts subjected to repeated transplant surgery and ischemia-reperfusion injury develop substantial interstitial and perivascular fibrosis that was spatially associated with dysfunctional activation of fetal smooth muscle alpha-actin (SM alpha A) gene expression in graft ventricular cardiomyocytes. Compared with cardiac fibroblasts in which nuclear levels of the Sp1 and Smad 2/3 transcriptional-activating proteins increased markedly after transplant injury, the most abundant SM alpha A gene-activating protein in cardiomyocyte nuclei was serum response factor (SRF). Additionally, cardiac intercalated discs in heart grafts contained substantial deposits of Pur alpha, an mRNA-binding protein and known negative modulator of SRF-activated SM alpha A gene transcription. Activation of fetal SM alpha A gene expression in perfusion-isolated adult cardiomyocytes was linked to elevated binding of a novel protein complex consisting of SRF and Pur alpha to a purine-rich DNA element in the SM alpha A promoter called SPUR, previously shown to be required for induction of SM alpha A gene transcription in injury-activated myofibroblasts. Increased SRF binding to SPUR DNA plus one of two nearby CArG box consensus elements was observed in SM alpha A-positive cardiomyocytes in parallel with enhanced Pur alpha:SPUR protein:protein interaction. The data suggest that de novo activation of the normally silent SM alpha A gene in reprogrammed adult cardiomyocytes is linked to elevated interaction of SRF with fetal-specific CArG and injury-activated SPUR elements in the SM alpha A promoter as well as the appearance of novel Pur alpha protein complexes in both the nuclear and cytosolic compartments of these cells.

Advances in coronary heart disease surgery in Latin America

BACKGROUND

The beginnings of coronary artery bypass graft in Latin America could be set in the year 1971. Since then, improvements in technique and greater experience have resulted in a rapid increase in the rate of interventions performed in the region.

METHODS AND RESULTS

Searches through PubMed and Literatura Latinoamericana y del Caribe en Ciencias de la Salud, as well as personal communications from specialists from Latin America, have been the source of information. Articles were selected by their content related to the theme, and the authors' nationality and information is mainly from Latin America. Demographic information of the population of Latin America denotes higher age averages, and this implies an increase in the severity of comorbidities in patients who undergo surgery. Longer life expectancy and improvements in medical therapy have implied that patients survive a first intervention beyond the expected time a bypass persists patent. Wall vessel properties of arterial conduits, plus a better anastomotic technique, seem to be the current solution to worsening in the coronary health of patients who undergo revascularization surgery in Latin America.

CONCLUSIONS

Despite scarce economic investment in medical sciences, many academic groups contribute to the exploration of therapeutic pharmacological combinations and inclusively apply genetic strategies.

Mechanisms of pathogenesis in Chagas disease

Chagas disease, caused by the obligate unicellular parasite Trypanosoma cruzi, presents itself in a diverse collection of clinical manifestations, ranging from severe, fatal heart and digestive tract pathologies to unapparent or minor alterations that do not compromise survival. Over the years, a number of mechanisms have been proposed to explain the pathogenesis of chagasic tissue lesions, all of which have faced some criticism or been received with skepticism. This article excludes the autoimmunity hypothesis for Chagas disease because it has been extensively reviewed elsewhere, and summarizes the various alternative hypotheses that have been advanced over the years. For each of these hypotheses, an outline of its main tenets and key findings that support them is presented. This is followed by the results and comments that have challenged them and the caveats that stand on their way to wider acceptance. It is hoped that this writing will draw attention to our shortcomings in understanding the pathogenesis of Chagas disease, which, unfortunately, continues to figure among the most serious health problems of the American continent.

Time to abandon microalbuminuria?

The term microalbuminuria--a urinary albumin excretion (UAE) between 20 and 200 microg/min--has been introduced to identify subjects at increased risk of renal and cardiovascular disease. However, the relationship between albuminuria and risk is not restricted to the microalbuminuric range and extends to as low as 2-5 microg/min. On the contrary, the increase of UAE above 200 microg/min (macroalbuminuria) heralds the onset of proteinuria (urinary protein excretion above 0.5 g/24 h) and progressive renal and cardiovascular disease. Albuminuria is a component of the metabolic syndrome and may represent a marker of the increased risk of renal and cardiovascular disease associated with insulin resistance and endothelial dysfunction. Proteinuria is a sign of established kidney damage and plays a direct pathogenic role in the progression of renal and cardiovascular disease. Albuminuria reflects functional and potentially reversible abnormalities initiated by glomerular hyperfiltration, proteinuria, a size-selective dysfunction of the glomerular barrier normally associated with glomerular filtration rate (GFR) decline that may result in end-stage renal disease. Thus, the limit of 200 microg/min segregates patients with albuminuria or proteinuria who are at quite different risk. Among subjects with albuminuria, however, there is a continuous relationship between albumin excretion and risk and no lower bound between normal albuminuria and microalbuminuria can be identified that segregates subjects at different risk. Thus, the terms microalbuminuria and macroalbuminuria could be replaced by the concepts of albuminuria- and proteinuria-associated diseases. Future studies are needed to identify levels of albuminuria below which therapy is no longer beneficial.

Coronary flow reserve and heart failure in experimental coxsackievirus myocarditis. A transthoracic Doppler echocardiography study

The objective of this study was to apply transthoracic Doppler echocardiography (TTDE) in mice to study coronary flow reserve (CFR), an index of coronary microvascular function, in mild and severe forms of experimental viral myocarditis. Regarding methodology, BALB/c mice were infected with cardiotropic coxsackieviruses causing either a mild (Nancy strain) or a severe (Woodruff strain) myocarditis. Left ventricular dimensions, fractional shortening, and CFR (ratio of left coronary artery flow velocity during maximal adenosine-induced vasodilatation to rest) were measured by TTDE before infection and again 1 or 2 wk after infection. As a result, the resting flow velocity did not change after infection. In contrast, CFR reduced significantly 1 wk after infection with either virus variant [from 2.5 (SD 0.3) to 1.4 (SD 0.1) in severe and from 2.4 (SD 0.4) to 2.1 (SD 0.3) in mild myocarditis], being significantly lower in the severe than mild myocarditis. CFR remained low in severe myocarditis 2 wk after infection. Fractional shortening decreased to the same levels 1 wk after infection with either virus variant [from 0.54 (SD 0.02) to 0.43 (SD 0.03) in severe and from 0.51 (SD 0.03) to 0.44 (SD 0.02) in mild myocarditis, P < 0.05]. However, 2 wk after infection, mice with severe myocarditis had enlarged left ventricles and lower fractional shortening [0.31 (SD 0.03)] than mice with mild myocarditis [0.47 (SD 0.02), P < 0.01]. In conclusion, CFR measured with TTDE is reduced in coxsackievirus myocarditis in mice. Low CFR is associated with progressive heart failure, indicating that dysfunction of coronary microcirculation is a determinant of poor outcome in viral myocarditis.

Coronary Flow Reserve by Contrast Enhanced Transesophageal Coronary Sinus Doppler Measurements Can Evaluate Diabetic Microvascular Dysfunction

BACKGROUND

This study was undertaken to investigate whether coronary flow reserve (CFR) using coronary sinus flow (CSF), which can be measured by transesophageal Doppler echocardiography (TEDE), especially when contrast enhanced, is useful in evaluating microvascular dysfunction in patients with diabetes mellitus (DM).

METHODS AND RESULTS

CSF recordings using contrast enhanced TEDE were performed before and after adenosine triphosphate infusion (0.15 mg x kg(-1) x min(-1)) in 16 patients with type 2 DM and diabetic retinopathy and in 13 non-DM patients (control). Coronary angiography revealed normal epicardial coronary arteries. CFR was defined as the ratio of the antegrade flow velocity time integral in hyperemic conditions and basal levels. Clear envelopes of CSF were obtained in all DM patients using contrast-enhanced TEDE. CFR using CSF in the DM group was significantly decreased compared with the control group (1.4+/-0.4 vs 2.1+/-0.5, p<0.01), but there were no significant differences of age, ejection fraction, rate of hypertension and hypercholesterolemia between the 2 groups. Using 1.7 of CFR as the cut-off value, diabetic microvascular dysfunction could be detected with 82% sensitivity and 83% specificity.

CONCLUSIONS

CFR calculated by CSF using contrast-enhanced TEDE may be useful for evaluating diabetic microvascular dysfunction.

Coronary pressure measurements in post-myocardial infarction patients

The development of pressure monitoring guide-wires has facilitated the measurements of coronary pressures distal to a stenosis. The ratio of the distal coronary and aortic pressures (P(d)/P(a)) measured during maximal hyperaemia is a useful index for diagnosis and monitoring the treatment of patients with coronary artery disease and for guiding percutaneous coronary intervention. However, the role of coronary pressure measurements in post- myocardial infarction (MI) patients is not well established. Coronary pressure measurements should be used with caution during the acute phase of MI due to serious micro-vascular impairment. The hyperaemic pressure P(d)/P(a) ratio can identify ischaemic myocardial territories in patients with recent MI. Theoretically, coronary pressure measurements may be of value in predicting myocardial recovery after revascularization in post-MI patients with a moderate stenosis of the infarct-related artery and without angiographically evident collaterals.

Plasminogen activator inhibitor-1 4G/5G polymorphism and efficacy of reperfusion therapy in acute myocardial infarction

Plasminogen activator inhibitor-1 (PAI-1) plays a central role in the modulation of intravascular thrombosis and thrombolysis. The level of transcription and the plasma level of PAI-1 are in part determined by the 4G/5G polymorphism in the promoter region of the gene. In this study we investigate the effect of 4G/5G polymorphism on the efficacy of reperfusion therapy in acute myocardial infarction (AMI). Two hundred and ninety-three patients were enrolled in two randomized trials comparing stenting plus abciximab with thrombolysis (alteplase alone or alteplase plus abciximab) in AMI. Patients were genotyped for the PAI-1 4G/5G polymorphism with a TaqMan assay. Technetium-99m sestamibi was injected before and 1-2 weeks after reperfusion treatment. Scintigrams were used to calculate the initial perfusion defect, the final infarct size and the salvage index representing the proportion of the initial defect salvaged by reperfusion. An 18-month clinical follow-up was carried out after reperfusion treatment. The distribution of genotypes was as follows: 4G4G in 28.0%, 4G5G in 49.5% and 5G5G in 22.5% of the patients. No significant differences between the three genotypes were detected for the final infarct size (%) of the left ventricle [median (interquartile range); 13.5 (5.0--27.0) for 4G4G patients, 12.0 (5.2--24.6) for 4G5G patients and 16 (7.1--31.2) for 5G5G patients; P=0.36], the salvage index [0.49 (0.25--0.75) in 4G4G patients, 0.47 (0.18--0.73) in 4G5G patients and 0.46 (0.22--0.62) in 5G5G patients; P=0.58] and the mortality 18 months after treatment (8.5% for 4G4G patients, 7.6% for 4G5G patients and 6.1% for 5G5G patients; P=0.85). There was no association in any of the two treatment groups (stenting and thrombolysis) between the 4G/5G genotype and myocardial salvage. The PAI-1 4G/5G polymorphism has no impact on the amount of myocardial salvage achieved by reperfusion with stenting or thrombolysis in patients with AMI.

Cocaine cardiovascular toxicity

Cocaine abuse kills thousands every year. Preexisting coronary artery disease appears to account for many of the deaths, but often the mechanism is much more complex. There exists a widely held but utterly mistaken notion that cocaine-related deaths are due to drug overdose. Except in the case of drug couriers ("body packers") with massive drug exposure, death is not dose related, and cocaine blood levels cannot be used to predict toxicity. Most deaths occur after prolonged drug use, which initiates a series of changes at the molecular, cellular, and tissue levels. All of these changes favor sudden death. Potentially lethal myocardial alterations include hypertrophy, fibrosis, and microangiopathy. Recently it has become clear that genetic causes, such as fully or partially expressed congenital long QT syndrome, may also play a role. The relative importance of each of these factors is reviewed.

Lack of JunD Promotes Pressure Overload–Induced Apoptosis, Hypertrophic Growth, and Angiogenesis in the Heart

Background— The Jun family of activator protein 1 (AP-1) transcription factors (c-Jun, JunB, and JunD) is involved in fundamental biological processes such as proliferation, apoptosis, tumor angiogenesis, and hypertrophy. The role of individual AP-1 transcription factors in the stressed heart is not clear. In the present study we analyzed the role of JunD in survival, hypertrophy, and angiogenesis in the pressure-overloaded mouse heart after thoracic aortic constriction.

Methods and Results— Mice lacking JunD (knockout [KO]) showed increased mortality and enhanced cardiomyocyte apoptosis and fibrosis associated with increased levels of hypoxia-induced factor-1α, vascular endothelial growth factor (VEGF), p53, and Bax protein and reduced levels of Bcl-2 protein after 7 days of severe pressure overload compared with wild-type (WT) siblings. Cardiomyocyte hypertrophy in surviving KO mice was enhanced compared with that in WT mice. Chronic moderate pressure overload for 12 weeks caused enhanced left ventricular hypertrophy in KO mice, and survival and interstitial fibrosis were comparable with WT mice. Cardiac function, 12 weeks after operation, was comparable among shams and pressure-overloaded mice of both genotypes. In addition, KO mice exposed to chronic pressure overload showed higher cardiac capillary density associated with increased protein levels of VEGF.

Conclusions— Thus, JunD limits cardiomyocyte hypertrophy and protects the pressure-overloaded heart from cardiac apoptosis. These beneficial effects of JunD, however, are associated with antiangiogenic properties.

The spatial pattern of coronary capillaries in patients with dilated, ischemic, or inflammatory cardiomyopathy

INTRODUCTION

The goal of the present study was to compare the pattern of coronary capillaries in healthy participants and in patients with end-stage heart failure due to idiopathic dilated cardiomyopathy (DCM), ischemic cardiomyopathy (ICM), or inflammatory cardiomyopathy (InfCM).

METHODS

Capillary patterns were studied in histological sections from resected hearts from patients with DCM (n=5), ICM (n=5), or InfCM (n=5) and compared with donor hearts showing no signs of cardiac disease (n=3). Patterns were characterized by the distribution of Voronoi polygon areas, A, associated with the centers of capillary profiles, nearest-neighbor distances, d, intercapillary distances (ICD), as well as by means of the pair correlation function g(r). The coefficient of variation of A, CV, was used to characterize capillary patterns as regular, random, or clustered.

RESULTS

CV increased from 30.5% (control) to 33.8% (DCM), 36.6% (ICM), and to 40.3% (InfCM). d was minimal in the control group (16.5+/-4.3 microm) and increased to 18.1+/-5.2 microm in the DCM group and to 20.9+/-6.8 and 20.6+/-6.6 microm in the ICM and InfCM groups, respectively. ICD increased from 25.6+/-7.9 (control) to 28.5+/-9.2 (DCM), 34.4+/-12.2 (ICM), and 33.6+/-12.0 microm (InfCM). In all groups, g(r) was markedly different from random points; in the control and DCM group, g(r) showed a weak but distinct first maximum, characteristic for short-range order in a point pattern.

CONCLUSIONS

Our data suggest that, for the patients studied, (1) the pattern of coronary capillaries is not purely random, (2) the regularity of the pattern diminishes from the control to DCM, ICM, and InfCM, and (3) ICD increases, whereas capillary density (CD) decreases, from control to DCM, ICM, and InfCM.

Association between cardiac troponin T elevation and angioscopic morphology of culprit lesion in patients with non-ST-segment elevation acute coronary syndrome

BACKGROUND

It is well known that cardiac troponin T (TnT) elevation on admission indicates a high-risk subgroup among patients with non-ST-segment elevation acute coronary syndrome (NSEACS). Although the mechanism of TnT elevation is speculated to be the microthromboembolism from unstable plaques, it has not been clarified. The aim of this study is to clarify the association between the serum TnT elevation and the angioscopically evaluated morphology of culprit lesion in the patients with NSEACS.

METHODS

Among 113 patients with NSEACS who had significant coronary stenosis, 62 patients with successful angioscopic examination were prospectively and consecutively enrolled from October 2001 to August 2002. Patients were divided into 2 groups according to the serum TnT level measured before percutaneous coronary intervention: TnT-positive or TnT-negative group. Thrombus and plaque color at culprit lesion were evaluated by angioscopy and were compared between the groups. Plaque color was determined as yellow or white, and thrombus as none, small, or large. Three different definitions for TnT-positive (> or =0.1, > or =0.03, and > or =0.01 ng/mL) were used and the sensitivity and specificity for detecting thrombus was compared.

RESULTS

Prevalence of thrombus, large thrombus, and yellow plaque were all higher in TnT-positive than in TnT-negative group for 3 different cutoff values of TnT. Angiographic slow-flow occurred more frequently after percutaneous coronary intervention in TnT-positive than in TnT-negative group for 3 different cutoff values of TnT. Sensitivity/specificity of detecting large thrombus were 33%/100%, 44%/91%, and 56%/83% when TnT-positive was defined as TnT > or = 0.1, > or =0.03, and > or =0.01 ng/mL, respectively.

CONCLUSIONS

Serum TnT level was significantly associated with the prevalence of thrombus and yellow plaque at the culprit lesions of NSEACS. Troponin T, when positive was defined as > or =0.01 ng/mL, still have a high specificity for detecting intracoronary thrombus.

The impact of admission C-reactive protein levels on the development of poor myocardial perfusion after primary percutaneous intervention in patients with acute myocardial infarction

BACKGROUND

Increased preprocedural C-reactive protein (CRP) levels in patients with acute myocardial infarction (MI) undergoing primary percutaneous coronary intervention (PCI) may affect myocardial perfusion. Accordingly, this study was designed to investigate the impact of admission CRP levels on the development of poor myocardial perfusion after PCI in patients with acute MI.

METHODS

The study population consisted of 75 patients (62 men, mean age, 61.6+/-6.68 years), who were admitted to our hospital with acute anterior MI and who underwent primary PCI in the left anterior descending coronary artery. All patients underwent stenting following balloon angioplasty. Myocardial perfusion was evaluated by using Thrombolysis In Myocardial Infarction (TIMI) myocardial perfusion grade (TMPG). Patients were divided into two groups according to TMPG after PCI. Group 1 consisted of 25 patients with TMPG 0-1 and group 2 comprised 50 patients with TMPG 2-3. Admission serum high sensitive CRP (hs-CRP) levels were analysed by using nephelometric method.

RESULTS

Admission hs-CRP levels, pain to balloon time and white blood cell count (WBC) of patients in group 1 were significantly higher than those of the patients in group 2 (P<0.001; P<0.001; P=0.002, respectively). Univariate analysis identified ejection fraction, pain to balloon time, WBC and hs-CRP levels as the predictors of poor myocardial perfusion. In multivariate logistic regression analysis, hs-CRP levels and pain to balloon time were found to have statistically significant independent association with poor myocardial perfusion. Adjusted odds ratios were calculated as 1.85 for hs-CRP [P=0.003; 95% confidence interval (CI), 1.23-2.80] and 5.49 for pain to balloon time (P=0.04; 95% CI, 1.08-27.84).

CONCLUSIONS

On admission, high CRP level in patients with acute MI undergoing primary PCI is likely to be in the causal pathway leading to the development of poor myocardial perfusion, especially when combined with prolonged pain to balloon time.

The effects of prior use of atorvastatin on coronary blood flow after primary percutaneous coronary intervention in patients presenting with acute myocardial infarction

BACKGROUND

Statins exert a variety of favourable effects on the vascular system not directly related to their lipid lowering function known as pleiotropic effects. There are not enough data regarding the effects of prior statin use on coronary blood flow after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI). Accordingly, in the present study, we aimed to investigate the effects of prior statin use on coronary blood flow after primary PCI in patients with AMI using the Thrombolysis In Myocardial Infarction (TIMI) frame count method.

METHODS

The study population consisted of 200 patients (161 men; mean age=62+/-7 years) referred to cardiology clinics with AMI who subsequently underwent successful primary PCI. The study population was divided into two groups according to statin use before primary PCI. Group 1 consisted of 98 patients (75 men; mean age=63+/-7 years) not taking statin and group 2 consisted of 102 patients (86 men; mean age=61+/-7 years) taking daily dose of at least 40 mg atorvastatin for at least 6 months. Coronary blood flow was determined by TIMI frame count method using the angiographic images obtained just after PCI and stenting.

RESULTS

Only mean TIMI frame count was detected to be significantly lower in patients taking at least 40 mg atorvastatin for at least 6 months compared with that of the patients taking no statin (P<0.001). After confounding variables were controlled for, the mean TIMI frame count of patients in group 2 was significantly lower than that of the patients in group 1 (P=0.001). Pain to balloon time and vessel type were detected as important confounding variables of TIMI frame count after analysis of covariances.

CONCLUSIONS

Prior statin use may improve coronary blood flow after PCI in patients with AMI, possibly by its beneficial effects on microvascular function.

Treatment of slow/no-reflow phenomenon with intracoronary nitroprusside injection in primary coronary intervention for acute myocardial infarction

Slow/no-reflow phenomenon is a serious problem complicating primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) and is associated with a poor prognosis. From January 2002 to November 2002, 11 of the 70 consecutive patients with ST elevation AMI who were subjected to primary PCI using balloon angioplasty and/or stenting developed slow/no-reflow phenomenon (TIMI 1 flow in 2, TIMI 2 in 8, and TIMI 2.5 in 1). They were 10 men and 1 woman, aged 64 +/- 11 years (range, 46-81). The culprit vessels were six in the left anterior descending coronary artery, three in the right coronary artery, one in the left circumflex coronary artery, and one in saphenous vein graft. Multiple bolus doses (100 microg) of nitroprusside were injected into the index artery through the guiding catheter using a 3 ml syringe until the TIMI flow grade improved by at least one grade or the systolic pressure decline below 80 mm Hg (one patient). The total drug dose varied from 100 to 700 microg. Following the drug treatment, angiographic TIMI flow grade improved by at least one grade in 9 (82%) of the 11 patients (P = 0.007). The TIMI frame counts significantly decreased from 36 +/- 17 frame counts to 16 +/- 11 frame counts (P = 0.012). All patients were discharged without major adverse cardiovascular events. Intracoronary bolus injection of nitroprusside using a 3 ml syringe appears to be a feasible, safe, and effective technique for the management of slow/no-reflow phenomenon complicating primary PCI.

Development of myocardial microcirculation and metabolism in acute ST-elevation myocardial infarction evaluated with positron emission tomography

BACKGROUND

Early reperfusion is an established therapeutic objective in acute myocardial infarction (MI). The relationship of regional myocardial microcirculation and metabolism toward outcome in acute human MI is not well known.

METHODS AND RESULTS

In 8 patients, positron emission tomography (PET) was performed with oxygen 15-labeled water at 3 hours, 24 hours, and 3 weeks after the start of fibrinolytic treatment, with carbon 11 acetate at 3 hours and with fluorine 18 fluorodeoxyglucose at 24 hours and 3 weeks. Absolute quantification of perfusion and water-perfusable tissue fraction (PTF), metabolic activity, and substrate extraction in 4 regions of interest was performed. Coronary angiography was performed at 24 hours. Short-term outcome at 3 weeks was evaluated by contractile reserve with dobutamine stress echocardiography and lung water measurements with PET. Early regional perfusion, PTF, and extraction and utilization of oxygen and glucose decreased closer to the infarct region ( P < .001 for all). Infarct-related oxygen utilization and extraction of oxygen and glucose were closely related to outcome ( P < .01 for all). PTF improved significantly in the infarct-related regions over time in proportion to early oxygen extraction and utilization.

CONCLUSIONS

This pilot study indicates that PET might be useful in the evaluation of treatment efficacy and that restoration of oxidative metabolism is more closely related to myocardial damage recovery than perfusion in the early phase after MI.

Effect of acute myocardial infarction on the utility of fractional flow reserve for the physiologic assessment of the severity of coronary artery narrowing

Fractional flow reserve (FFR) has been shown to be a useful physiologic index of coronary lesion severity in myocardial beds of patients without prior infarction and in those with remote infarction. Acute myocardial infarction (AMI) causes myocardial necrosis and microvascular stunning, embolization, and damage. Whether FFR remains a useful index of epicardial flow in the setting of recent myocardial infarction is not established. Cardiac risk factors, serum troponin I, angiographic minimal lumen diameter (MLD), percent diameter stenosis (DS), lesion length, vessel reference diameter, hyperemic central aortic pressure, hyperemic pressure distal to stenosis, and FFR were compared in 43 vessels subtending recent AMI beds to 25 control vessels, matched by lesion length and MLD, in patients without AMI. There were no differences in DS, MLD, lesion length, or reference diameter between AMI and non-AMI groups. Patients with AMI had mean troponin I levels of 91.8 +/- 162 ng/ml. Left ventricular ejection fraction was significantly lower in patients with than without AMI (55 +/- 9% vs 62 +/- 8%, p <0.05). There were no significant differences in hyperemic central aortic pressure (92 +/- 13 vs 99 +/- 15 mm Hg, p = NS), hyperemic pressure distal to the stenosis (62 +/- 17 vs 66 +/- 19 mm Hg, p = NS), or FFR (0.67 +/- 17 vs 0.68 +/- 17, p = NS) between recent AMI and non-AMI control patients. There was a significant correlation between DS and FFR for both patients with (p <0.001) and without (p = 0.003) infarctions. Thus, FFR and the relation between FFR and DS of lesions subtending AMI was not significantly different from FFR of angiographically matched lesions in patients without AMI.

Microcirculation in insulin resistance and diabetes: more than just a complication

The microvascular bed is an anatomical entity which is governed by specific, highly regulated mechanisms which are closely adapted to the specific function of each vascular segment. Among those, small arteriolar vasomotion and capacity of small vessels to constrict in response to physical and humoral stimuli play a major role. Other processes of importance for the adequacy of nutritive perfusion are haemorheological properties of whole blood and red cells, adhesiveness of leukocytes and capillary permeability. This review provides some description of these phenomena, how they impact on organ function and how they appear in diabetes. Metformin, as a unique example among the drug arsenal, exerts various effects preferentially at the level of smallest vessels (arterioles, capillaries, venules). This review summarises our actual knowledge and includes several new data showing its high potential for reducing microvascular dysfunction. Most of these unique properties have also been demonstrated in non-diabetic animals or humans, suggesting they are intrinsic to the drug and not secondary to diabetic metabolic improvement. A particular focus is put on the relevance of metformin's capacity to stimulate slow wave arteriolar vasomotion and improve functional capillary density, whereby nutritive flow can be re-established. Finally, the implication of microcirculation in other aspects of insulin resistance and diabetes, such as macroangiopathy and metabolic control, is discussed and strengthens the concept of a broad involvement of microvascular dysfunction in these diseases as well as the potential interest of introducing adapted treatment early in the history of a patient's diabetes.

Profiling gene transcription reveals a deficiency of mitochondrial oxidative phosphorylation in Trypanosoma cruzi-infected murine hearts: implications in chagasic myocarditis development

In this study, we report the host genetic responses that characterize Trypanosoma cruzi-induced myocarditis in a murine model of infection and disease development. The mRNA species from the myocardium of infected mice were assessed using cDNA microarray technology at immediate early, acute, and chronic stages of infection. The immediate early reaction of the host to T. cruzi infection was marked by up-regulation of transcripts indicative of proinflammatory and interferon-induced immune responses. Following acute infection, overexpression of transcripts for extracellular matrix (ECM) proteins, possibly initiated in response to myocardial injuries by invading and replicating parasites, was suggestive of active reparative and remodeling reactions. Surprisingly, progression to the cardiac disease phase was associated with coordinated down-regulation of a majority (>70%) of the differentially expressed genes. Among the most repressed genes were the troponins, essential for contractile function of the myofibrils, and the genes encoding components of oxidative phosphorylation (OXPHOS) pathways. Reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and biochemical assays confirmed the microarray results and provided evidence for the deficiency of OXPHOS complex IV in the chagasic murine heart. We discuss the apparent role of OXPHOS dysfunction in the cardiac hypertrophic and remodeling processes with the development of chagasic cardiomyopathy (CCM).

Resolution of refractory no-reflow with intracoronary epinephrine

Refractory no-reflow is associated with adverse outcomes in patients undergoing percutaneous coronary intervention. Charts were reviewed to identify 29 consecutive patients in whom intracoronary epinephrine was administered for refractory no-reflow. The effects of intracoronary epinephrine on coronary flow (TIMI grade), cardiac rhythm, and systolic blood pressure in the cardiac catheterization laboratory were assessed. Administration of intracoronary epinephrine (mean dose, 139 +/- 189 microg) resulted in significant improvement in coronary flow. After administration, TIMI 3 flow was established in 69% of patients. Overall, TIMI flow significantly increased (mean TIMI flow form 1.0 +/- 1.0 to 2.66 +/- 0.55; P = 0.0001). Intracoronary epinephrine resulted in significant but tolerable increase in heart rate (72 +/- 19 to 86 +/- 26 beats/min; P = 0.009), but no cases of acute dysrhythmia. These findings indicate that intracoronary epinephrine may exert salutary effects in patients suffering refractory no-reflow following elective or acute coronary interventions.

Reoxygenating microvascular endothelium exhibits temporal dissociation of NF-kappaB and AP-1 activation

Alterations of cellular redox balance in microvascular endothelium results in changes of essential cell functions. These alterations may arise, in part, due to modifications in the pattern of gene expression produced by transcription factor activation. Endothelium subjected to hypoxia/reoxygenation becomes redox imbalanced, thereby leading to activation and perhaps production of a proinflammatory state. A human dermal microvascular endothelial cell line (HMEC-1) was exposed to 6 h of hypoxia (3% O(2)) followed by return to normoxia atmospheric conditions. Reactive oxygen species (ROS) generation (dichlorofluoroscein epifluorescence) was immediate and significant following reoxygenation. Electrophoretic mobility shift assays revealed activation of the oxidant sensitive transcription factors NFkappaB and AP-1, though importantly, peak activation of each factor was separated temporally by greater than 60 min. NFkappaB activation occurred without degradation of the inhibitory protein IkappaBalpha. Reoxygenating HMEC-1 exhibited a greater than 500-fold increase in polymorphonuclear neutrophil (PMN) adhesion when compared to normoxic controls. Exposure of reoxygenating HMEC-1 to the antioxidant pyrrolidine dithiocarbamate produced complete abrogation of NFkappaB activation and the intensive PMN adhesion observed in untreated, posthypoxic HMEC-1. Though rexoygenation stress induced significant upregulation of PMN adhesion, no upregulation of interleukin-8 production was observed. Our results suggest that ROS generation occurring in endothelium following onset of reoxygenation stress signals activation of key transcription factors and that their activation takes place in a temporal fashion. The temporal feature of transcription factor activation may be key to production of a postischemic proinflammatory state.