Angiotensin-converting enzyme inhibition with quinapril improves endothelial vasomotor dysfunction in patients with coronary artery disease. The TREND (Trial on Reversing ENdothelial Dysfunction) Study

Hereditary hemochromatosis with homozygous C282Y HFE mutation: possible clinical model to assess effects of elevated reactive oxygen species on the development of cardiovascular disease

Hereditary hemochromatosis with the homozygous C282Y HFE mutation (HH-282H) is a genetic condition which causes iron overload (IO) and elevated reactive oxygen species (ROS) secondary to the IO. Interestingly, even after successful iron removal therapy, HH-282H subjects demonstrate chronically elevated ROS. Raised ROS are also associated with the development of multiple cardiovascular diseases and HH-282H subjects may be at risk to develop these complications. In this narrative review, we consider HH-282H subjects as a clinical model for assessing the contribution of elevated ROS to the development of cardiovascular diseases in subjects with fewer confounding clinical risk factors as compared to other disease conditions with high ROS. We identify HH-282H subjects as a potentially unique clinical model to assess the impact of chronically elevated ROS on the development of cardiovascular disease and to serve as a clinical model to detect effective interventions for anti-ROS therapy.

Preventive Therapies in Peripheral Arterial Disease

Atherosclerosis, while initially deemed a bland proliferative process, is now recognized as a multifactorial-lipoprotein-mediated inflammation-driven pathway. With the rising incidence of atherosclerotic disease of the lower extremity arteries, the healthcare burden and clinical morbidity and mortality due to peripheral artery disease (PAD) are currently escalating. With a healthcare cost burden of over 21 billion USD and 200 million patients afflicted worldwide, accurate knowledge regarding the pathophysiology, presentation, and diagnosis of the disease is crucial. The role of lipoproteins and their remnants in atherosclerotic vessel occlusion and plaque formation and progression has been long established. This review paper discusses the epidemiology, pathophysiology, and presentation of PAD. PAD has been repeatedly noted to portend to poor cardiovascular and limb outcomes. We discuss major therapeutic avenues for the prevention of major cardiovascular adverse events and major limb adverse events in patients with PAD.

Leukocyte-endothelial interaction in CKD

Chronic kidney disease (CKD) represents an independent risk factor for cardiovascular diseases (CVD). Accordingly, CKD patients show a substantial increased risk of cardiovascular mortality. Inflammation represents an important link between CKD and CVD. The interaction between endothelial cells and effector cells of the innate immune system plays a central role in the development and progression of inflammation. Vascular injury causes endothelial dysfunction, leading to augmented oxidative stress, increased expression of leukocyte adhesion molecules and chronic inflammation. CKD induces numerous metabolic changes, creating a uremic milieu resulting in the accumulation of various uremic toxins. These toxins lead to vascular injury, endothelial dysfunction and activation of the innate immune system. Recent studies describe CKD-dependent changes in monocytes that promote endothelial dysfunction and thus CKD progression and CKD-associated CVD. The NLR family pyrin domain containing 3-interleukin-1β-interleukin-6 (NLRP3-IL-1β-IL-6) signaling pathway plays a pivotal role in the development and progression of CVD and CKD alike. Several clinical trials are investigating targeted inhibition of this pathway indicating that anti-inflammatory therapeutic strategies may emerge as novel approaches in patients at high cardiovascular risk and nonresolving inflammation. CKD patients in particular would benefit from targeted anti-inflammatory therapy, since conventional therapeutic regimens have limited efficacy in this population.

Snake Venom Components as Therapeutic Drugs in Ischemic Heart Disease

Ischemic heart disease (IHD), especially myocardial infarction (MI), is a leading cause of death worldwide. Although coronary reperfusion is the most straightforward treatment for limiting the MI size, it has nevertheless been shown to exacerbate ischemic myocardial injury. Therefore, identifying and developing therapeutic strategies to treat IHD is a major medical challenge. Snake venoms contain biologically active proteins and peptides that are of major interest for pharmacological applications in the cardiovascular system (CVS). This has led to their use for the development and design of new drugs, such as the first-in-class angiotensin-converting enzyme inhibitor captopril, developed from a peptide present in Bothrops jararaca snake venom. This review discusses the potential usefulness of snake venom toxins for developing effective treatments against IHD and related diseases such as hypertension and atherosclerosis. It describes their biological effects at the molecular scale, their mechanisms of action according to their different pharmacological properties, as well as their subsequent molecular pathways and therapeutic targets. The molecules reported here have either been approved for human medical use and are currently available on the drug market or are still in the clinical or preclinical developmental stages. The information summarized here may be useful in providing insights into the development of future snake venom-derived drugs.

Allicin, an Emerging Treatment for Pulmonary Arterial Hypertension: An Experimental Study

We assessed whether allicin, through its antihypertensive and antioxidant effects, relieves vascular remodeling, endothelial function, and oxidative stress (OS), thereby improving experimental pulmonary arterial hypertension (PAH). Allicin (16 mg/kg) was administered to rats with PAH (monocrotaline 60 mg/kg). Allicin encouraged body weight gain and survival rate, and medial wall thickness and the right ventricle (RV) hypertrophy were prevented. Also, angiotensin II concentrations in the lung (0.37 ± 0.01 vs. 0.47 ± 0.06 pmoles/mL, allicin and control, respectively) and plasma (0.57 ± 0.05 vs. 0.75 ± 0.064, allicin and control respectively) and the expressions of angiotensin-converting enzyme II and angiotensin II type 1 receptor in lung tissue were maintained at normal control levels with allicin. In PAH rats treated with allicin, nitric oxide (NO) (31.72 ± 1.22 and 51.4 ± 3.45 pmoles/mL), tetrahydrobiopterin (8.43 ± 0.33 and 10.14 ± 0.70 pmoles/mL), cyclic guanosine monophosphate (5.54 ± 0.42 and 5.64 ± 0.73 pmoles/mL), and Ang-(1-7) (0.88 ± 0.23 and 0.83 ± 0.056 pmoles/mL) concentrations increased in lung tissue and plasma, respectively. In contrast, dihydrobiopterin increase was prevented in both lung tissue and plasma (5.75 ± 0.3 and 5.64 ± 0.73 pmoles/mL); meanwhile, phosphodiesterase-5 was maintained at normal levels in lung tissue. OS in PAH was prevented with allicin through the increased expression of Nrf2 in the lung. Allicin prevented the lung response to hypoxia, preventing the overexpression of HIF-1α and VEGF. Allicin attenuated the vascular remodeling and RV hypertrophy in PAH through its effects on NO-dependent vasodilation, modulation of RAS, and amelioration of OS. Also, these effects could be associated with the modulation of HIF-1α and improved lung oxygenation. The global effects of allicin contribute to preventing endothelial dysfunction, remodeling of the pulmonary arteries, and RV hypertrophy, preventing heart failure, thus favoring survival. Although human studies are needed, the data suggest that, alone or in combination therapy, allicin may be an alternative in treating PAH if we consider that, similarly to current treatments, it improves lung vasodilation and increase survival. Allicin may be considered an option when there is a lack of efficacy, and where drug intolerance is observed, to enhance the efficacy of drugs, or when more than one pathogenic mechanism must be addressed.

Korean Society of Heart Failure Guidelines for the Management of Heart Failure: Management of the Underlying Etiologies and Comorbidities of Heart Failure

Most patients with heart failure (HF) have multiple comorbidities, which impact their quality of life, aggravate HF, and increase mortality. Cardiovascular comorbidities include systemic and pulmonary hypertension, ischemic and valvular heart diseases, and atrial fibrillation. Non-cardiovascular comorbidities include diabetes mellitus (DM), chronic kidney and pulmonary diseases, iron deficiency and anemia, and sleep apnea. In patients with HF with hypertension and left ventricular hypertrophy, renin-angiotensin system inhibitors combined with calcium channel blockers and/or diuretics is an effective treatment regimen. Measurement of pulmonary vascular resistance via right heart catheterization is recommended for patients with HF considered suitable for implantation of mechanical circulatory support devices or as heart transplantation candidates. Coronary angiography remains the gold standard for the diagnosis and reperfusion in patients with HF and angina pectoris refractory to antianginal medications. In patients with HF and atrial fibrillation, long-term anticoagulants are recommended according to the CHA2DS2-VASc scores. Valvular heart diseases should be treated medically and/or surgically. In patients with HF and DM, metformin is relatively safer; thiazolidinediones cause fluid retention and should be avoided in patients with HF and dyspnea. In renal insufficiency, both volume status and cardiac performance are important for therapy guidance. In patients with HF and pulmonary disease, beta-blockers are underused, which may be related to increased mortality. In patients with HF and anemia, iron supplementation can help improve symptoms. In obstructive sleep apnea, continuous positive airway pressure therapy helps avoid severe nocturnal hypoxia. Appropriate management of comorbidities is important for improving clinical outcomes in patients with HF.

Korean Society of Heart Failure Guidelines for the Management of Heart Failure: Management of the Underlying Etiologies and Comorbidities of Heart Failure

Most patients with heart failure (HF) have multiple comorbidities, which impact their quality of life, aggravate HF, and increase mortality. Cardiovascular comorbidities include systemic and pulmonary hypertension, ischemic and valvular heart diseases, and atrial fibrillation. Non-cardiovascular comorbidities include diabetes mellitus (DM), chronic kidney and pulmonary diseases, iron deficiency and anemia, and sleep apnea. In patients with HF with hypertension and left ventricular hypertrophy, renin-angiotensin system inhibitors combined with calcium channel blockers and/or diuretics is an effective treatment regimen. Measurement of pulmonary vascular resistance via right heart catheterization is recommended for patients with HF considered suitable for implantation of mechanical circulatory support devices or as heart transplantation candidates. Coronary angiography remains the gold standard for the diagnosis and reperfusion in patients with HF and angina pectoris refractory to antianginal medications. In patients with HF and atrial fibrillation, long-term anticoagulants are recommended according to the CHA2DS2-VASc scores. Valvular heart diseases should be treated medically and/or surgically. In patients with HF and DM, metformin is relatively safer; thiazolidinediones cause fluid retention and should be avoided in patients with HF and dyspnea. In renal insufficiency, both volume status and cardiac performance are important for therapy guidance. In patients with HF and pulmonary disease, beta-blockers are underused, which may be related to increased mortality. In patients with HF and anemia, iron supplementation can help improve symptoms. In obstructive sleep apnea, continuous positive airway pressure therapy helps avoid severe nocturnal hypoxia. Appropriate management of comorbidities is important for improving clinical outcomes in patients with HF.

Benefit and risk evaluation of quinapril hydrochloride

INTRODUCTION

Angiotensin-converting enzyme (ACE) inhibitors are a mainstay of antihypertensive therapy. Quinapril hydrochloride, a less commonly used, and less-studied ACE inhibitor has been approved for its primary use in hypertension. Studies also indicate its off-label use for congestive heart failure and diabetic nephropathy. The ANDI and TREND trials have been pivotal in demonstrating the effectiveness of quinapril.

AREAS COVERED

The authors conducted a review of the literature analyzing the clinical efficacy and safety profile of quinapril. This review discusses the development of quinapril, provides an updated summary of the indications and contraindications, and presents a comparison with other ACE inhibitors.

EXPERT OPINION

Quinapril is a safe and well-tolerated antihypertensive medication with a favorable safety profile compared to other ACE inhibitors. However, a lack of ample recent clinical trials and post-marketing data investigating the efficacy of quinapril in large cohorts has resulted in limited use in clinical practice. Quinapril may be an effective antihypertensive option for elderly populations as well as those who cannot tolerate the side effects profiles of other ACE inhibitors and as an additional treatment option for patients with heart failure with preserved ejection fraction.

Coronary microvascular dysfunction: A review of recent progress and clinical implications

The coronary microcirculation plays a cardinal role in regulating coronary blood flow to meet the changing metabolic demands of the myocardium. Coronary microvascular dysfunction (CMD) refers to structural and functional remodeling of the coronary microcirculation. CMD plays a role in the pathogenesis of obstructive and non-obstructive coronary syndromes as well as myocardial diseases, including heart failure with preserved ejection fraction (HFpEF). Despite recent diagnostic advancements, CMD is often under-appreciated in clinical practice, and may allow for the development of novel therapeutic targets. This review explores the diagnosis and pathogenic role of CMD across a range of cardiovascular diseases, its prognostic significance, and the current therapeutic landscape.

Sustained Activation of CLR/RAMP Receptors by Gel-Forming Agonists

Background: Adrenomedullin (ADM), adrenomedullin 2 (ADM2), and CGRP family peptides are important regulators of vascular vasotone and integrity, neurotransmission, and fetoplacental development. These peptides signal through CLR/RAMP1, 2, and 3 receptors, and protect against endothelial dysfunction in disease models. As such, CLR/RAMP receptor agonists are considered important therapeutic candidates for various diseases. Methods and Results: Based on the screening of a series of palmitoylated chimeric ADM/ADM2 analogs, we demonstrated a combination of lipidation and accommodating motifs at the hinge region of select peptides is important for gaining an enhanced receptor-activation activity and improved stimulatory effects on the proliferation and survival of human lymphatic endothelial cells when compared to wild-type peptides. In addition, by serendipity, we found that select palmitoylated analogs self-assemble to form liquid gels, and subcutaneous administration of an analog gel led to the sustained presence of the peptide in the circulation for >2 days. Consistently, subcutaneous injection of the analog gel significantly reduced the blood pressure in SHR rats and increased vasodilation in the hindlimbs of adult rats for days. Conclusions: Together, these data suggest gel-forming adrenomedullin analogs may represent promising candidates for the treatment of various life-threatening endothelial dysfunction-associated diseases such as treatment-resistant hypertension and preeclampsia, which are in urgent need of an effective drug.

Presence of Coronary Endothelial Dysfunction, Coronary Vasospasm, and Adenosine-Mediated Vasodilatory Disorders in Patients With Ischemia and Nonobstructive Coronary Arteries

BACKGROUND

Coronary function testing in patients with ischemia and nonobstructive coronary arteries (INOCA) commonly includes assessment of adenosine-mediated vasodilation and acetylcholine spasm provocation. The purpose of this study was to evaluate the diagnostic value of additional endothelial function testing for the diagnosis of vasomotor dysfunction in patients with INOCA.

METHODS

In this retrospective cohort study, we included patients with INOCA who underwent clinically indicated comprehensive coronary function testing. Endothelial dysfunction was defined as a <50% increase in coronary blood flow, determined by Doppler flow, and/or epicardial vasoconstriction compared to baseline, in response to low-dose acetylcholine. Coronary artery spasm (CAS) was defined as vasospastic angina or microvascular angina in response to coronary high-dose acetylcholine. An impaired adenosine-mediated vasodilation was defined as a coronary flow reserve <2.5 and/or hyperemic microvascular resistance ≥2.5.

RESULTS

Among all 110 patients, 79% had endothelial dysfunction, 62% had CAS, and 29% had an impaired adenosine-mediated vasodilation. Endothelial dysfunction was present in 80% of patients who tested positively for CAS and/or an impaired adenosine-mediated vasodilation. Endothelial function testing increases the diagnostic yield of coronary function testing that only incorporates adenosine testing and spasm provocation by 17% to 92%. Of patients with normal adenosine-mediated vasodilation and no inducible CAS, 68% had endothelial dysfunction.

CONCLUSIONS

Concomitant endothelial dysfunction was prevalent in the vast majority of patients with INOCA with inducible CAS and/or an impaired adenosine-mediated vasodilation. In patients with INOCA without inducible CAS and normal adenosine-mediated vasodilation, two-thirds had endothelial dysfunction. These results indicate the relevance to perform endothelial function testing in patients with INOCA in view of its therapeutic implication.

The Endothelium and COVID-19: An Increasingly Clear Link Brief Title: Endotheliopathy in COVID-19

The endothelium has a fundamental role in the cardiovascular complications of coronavirus disease 2019 (COVID-19). Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) particularly affects endothelial cells. The virus binds to the angiotensin-converting enzyme 2 (ACE-2) receptor (present on type 2 alveolar cells, bronchial epithelial cells, and endothelial cells), and induces a cytokine storm. The cytokines tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6 have particular effects on endothelial cells-leading to endothelial dysfunction, endothelial cell death, changes in tight junctions, and vascular hyperpermeability. Under normal conditions, apoptotic endothelial cells are removed into the bloodstream. During COVID-19, however, endothelial cells are detached more rapidly, and do not regenerate as effectively as usual. The loss of the endothelium on the luminal surface abolishes all of the vascular responses mediated by the endothelium and nitric oxide production in particular, which results in greater contractility. Moreover, circulating endothelial cells infected with SARS-CoV-2 act as vectors for viral dissemination by forming clusters that migrate into the circulation and reach distant organs. The cell clusters and the endothelial dysfunction might contribute to the various thromboembolic pathologies observed in COVID-19 by inducing the formation of intravascular microthrombi, as well as by triggering disseminated intravascular coagulation. Here, we review the contributions of endotheliopathy and endothelial-cell-derived extracellular vesicles to the pathogenesis of COVID-19, and discuss therapeutic strategies that target the endothelium in patients with COVID-19.

Mechanisms and clinical implications of endothelium-dependent vasomotor dysfunction in coronary microvasculature

Coronary microvascular disease (CMD), which affects the arterioles and capillary endothelium that regulate myocardial perfusion, is an increasingly recognized source of morbidity and mortality, particularly in the setting of metabolic syndrome. The coronary endothelium plays a pivotal role in maintaining homeostasis, though factors such as diabetes, hypertension, hyperlipidemia, and obesity can contribute to endothelial injury and consequently arteriolar vasomotor dysfunction. These disturbances in the coronary microvasculature clinically manifest as diminished coronary flow reserve, which is a known independent risk factor for cardiac death, even in the absence of macrovascular atherosclerotic disease. Therefore, a growing body of literature has examined the molecular mechanisms by which coronary microvascular injury occurs at the level of the endothelium and the consequences on arteriolar vasomotor responses. This review will begin with an overview of normal coronary microvascular physiology, modalities of measuring coronary microvascular function, and clinical implications of CMD. These introductory topics will be followed by a discussion of recent advances in the understanding of the mechanisms by which inflammation, oxidative stress, insulin resistance, hyperlipidemia, hypertension, shear stress, endothelial cell senescence, and tissue ischemia dysregulate coronary endothelial homeostasis and arteriolar vasomotor function.

Mechanisms and Clinical Implications of Endothelial Dysfunction in Arterial Hypertension

The endothelium is composed of a monolayer of endothelial cells, lining the interior surface of blood and lymphatic vessels. Endothelial cells display important homeostatic functions, since they are able to respond to humoral and hemodynamic stimuli. Thus, endothelial dysfunction has been proposed as a key and early pathogenic mechanism in many clinical conditions. Given the relevant repercussions on cardiovascular risk, the complex interplay between endothelial dysfunction and systemic arterial hypertension has been a matter of study in recent years. Numerous articles have been published on this issue, all of which contribute to providing an interesting insight into the molecular mechanisms of endothelial dysfunction in arterial hypertension and its role as a biomarker of inflammation, oxidative stress, and vascular disease. The prognostic and therapeutic implications of endothelial dysfunction have also been analyzed in this clinical setting, with interesting new findings and potential applications in clinical practice and future research. The aim of this review is to summarize the pathophysiology of the relationship between endothelial dysfunction and systemic arterial hypertension, with a focus on the personalized pharmacological and rehabilitation strategies targeting endothelial dysfunction while treating hypertension and cardiovascular comorbidities.

CU06-1004 enhances vascular integrity and improves cardiac remodeling by suppressing edema and inflammation in myocardial ischemia-reperfusion injury

Ischemia-reperfusion (I/R) injury accelerates the cardiomyocytes (CMs) death by oxidative stress, and thereby deteriorates cardiac function. There has been a paradigm shift in the therapeutic perspective more towards the prevention or amelioration of damage caused by reperfusion. Cardiac microvascular endothelial cells (CMECs) are more vulnerable to reperfusion injury and play the crucial roles more than CMs in the pathological process of early I/R injury. In this study, we investigate that CU06-1004, as a vascular leakage blocker, can improve cardiac function by inhibiting CMEC's hyperpermeability and subsequently reducing the neutrophil's plugging and infiltration in infarcted hearts. CU06-1004 was delivered intravenously 5 min before reperfusion and the rats were randomly divided into three groups: (1) vehicle, (2) low-CU06-1004 (1 mg/kg, twice at 24 h intervals), and (3) high-CU06-1004 (5 mg/kg, once before reperfusion). CU06-1004 treatment reduced necrotic size and cardiac edema by enhancing vascular integrity, as demonstrated by the presence of intact junction proteins on CMECs and surrounding pericytes in early I/R injury. It also decreased the expression of vascular cell adhesion molecule 1 (VCAM-1) on CMECs, resulting in reduced infiltration of neutrophils and macrophages. Echocardiography showed that the CU06-1004 treatment significantly improved cardiac function compared with the vehicle group. Interestingly, single high-dose treatment with CU06-1004 provided a greater functional improvement than repetitive low-dose treatment until 8 weeks post I/R. These findings demonstrate that CU06-1004 enhances vascular integrity and improves cardiac function by preventing lethal myocardial I/R injury. It can provide a promising therapeutic option, as potential adjunctive therapy to current reperfusion strategies.

Coronary Microvascular Dysfunction Across the Spectrum of Cardiovascular Diseases: JACC State-of-the-Art Review

Coronary microvascular dysfunction (CMD) encompasses several pathogenetic mechanisms involving coronary microcirculation and plays a major role in determining myocardial ischemia in patients with angina without obstructive coronary artery disease, as well as in several other conditions, including obstructive coronary artery disease, nonischemic cardiomyopathies, takotsubo syndrome, and heart failure, especially the phenotype associated with preserved ejection fraction. Unfortunately, despite the identified pathophysiological and prognostic role of CMD in several conditions, to date, there is no specific treatment for CMD. Due to the emerging role of CMD as common denominator in different clinical phenotypes, additional research in this area is warranted to provide personalized treatments in this "garden variety" of patients. The purpose of this review is to describe the pathophysiological mechanisms of CMD and its mechanistic and prognostic role across different cardiovascular diseases. We will also discuss diagnostic modalities and the potential therapeutic strategies resulting from recent clinical studies.

What Is the Role of Assessing Ischemia to Optimize Therapy and Outcomes for Patients with Stable Angina and Non-obstructed Coronary Arteries?

Ischemic heart disease (IHD) is a leading global cause of ill-health and premature death. Clinical research into IHD is providing new insights into the pathophysiology, epidemiology and treatment of this condition. The major endotypes of IHD include coronary heart disease (CHD) and vasomotor disorders, including microvascular angina and vasospastic angina. Considering unselected patients presenting with stable chest pain, the pre-test probability of CHD is higher in men whereas the pre-test probability of a vasomotor disorder is higher in women. The diagnostic accuracy of diagnostic tests designed to assess coronary anatomy and disease and/or coronary vascular function (functional tests) differ for coronary endotypes. Clinical management should therefore be personalized and take account of sex-related factors. In this review, we consider the definitions of angina and myocardial ischemia. We then appraise the mechanistic links between myocardial ischemia and anginal symptoms and the relative merits of non-invasive and invasive diagnostic tests and related clinical management. Finally, we describe the rationale and importance of stratified medicine of IHD.

Gallic Acid Attenuates Angiotensin II-Induced Hypertension and Vascular Dysfunction by Inhibiting the Degradation of Endothelial Nitric Oxide Synthase

Hypertension is a major cause of heart attack and stroke. Our recent study revealed that gallic acid (GA) exerts protective effects on pressure overload-induced cardiac hypertrophy and dysfunction. However, the role of GA in angiotensin II (Ang II)-induced hypertension and vascular remodeling remains unknown. C57BL/6J mice were subjected to saline and Ang II infusion. Systolic blood pressure was measured using a tail-cuff system. Vascular remodeling and oxidative stress were examined by histopathological staining. Vasodilatory function was evaluated in the aortic ring. Our findings revealed that GA administration significantly ameliorated Ang II-induced hypertension, vascular inflammation, and fibrosis. GA also abolished vascular endothelial dysfunction and oxidative stress in Ang II-infused aortas. Mechanistically, GA treatment attenuated Ang II-induced upregulation of the immunoproteasome catalytic subunits β2i and β5i leading to reduction of the trypsin-like and chymotrypsin-like activity of the proteasome, which suppressed degradation of endothelial nitric oxide synthase (eNOS) and reduction of nitric oxide (NO) levels. Furthermore, blocking eNOS activity by using a specific inhibitor (_L-N^G-nitroarginine methyl ester) markedly abolished the GA-mediated beneficial effect. This study identifies GA as a novel immunoproteasome inhibitor that may be a potential therapeutic agent for hypertension and vascular dysfunction.

Role of endothelial dysfunction in determining angina after percutaneous coronary intervention: Learning from pathophysiology to optimize treatment

Endothelial dysfunction (EnD) is a hallmark feature of coronary artery disease (CAD), representing the key early step of atherosclerotic plaque development and progression. Percutaneous coronary intervention (PCI) is performed daily worldwide to treat symptomatic CAD, however a consistent proportion of patients remain symptomatic for angina despite otherwise successful revascularization. EnD plays a central role in the mechanisms of post-PCI angina, as it is strictly associated with both structural and functional abnormalities in the coronary arteries that may persist, or even accentuate, following PCI. The assessment of endothelial function in patients undergoing PCI might help to identify those patients at higher risk of future cardiovascular events and recurrent/persistent angina who might therefore benefit more from an intensive treatment. In this review, we address the role of EnD in determining angina after PCI, discussing its pathophysiological mechanisms, diagnostic approaches and therapeutic perspectives.

Endothelial function in patients with atrial fibrillation

Atrial fibrillation (AF) is the most common heart arrhythmia and is associated with poor outcomes. The adverse effects of AF are mediated through multiple pathways, including endothelial dysfunction, as measured by flow-mediated dilatation. Flow-mediated dilatation has demonstrated endothelial dysfunction in several conditions and is associated with poor outcomes including mortality, yet can be improved with medical therapy. It is thus a useful tool in assessing endothelial function in patients. Endothelial dysfunction is present in patients with AF and is associated with poor outcomes. These patients are generally older and have other co-morbidities such as hypertension, hypercholesterolaemia and diabetes. The precise process by which AF is affiliated with endothelial damage/dysfunction remains elusive. This review explores the endothelial structure, its physiology and how it is affected in patients with AF. It also assesses the utility of flow mediated dilatation as a technique to assess endothelial function in patients with AF. Key MessagesEndothelial function is affected in patients with atrial fibrillation as with other cardiovascular conditions.Endothelial dysfunction is associated with poor outcomes such as stroke, myocardial infarction and death, yet is a reversible condition.Flow-mediated dilatation is a reliable tool to assess endothelial function in patients with atrial fibrillation.Patients with atrial fibrillation should be considered for endothelial function assessment and attempts made to reverse this condition.

Coronary Artery Disease and Endothelial Dysfunction: Novel Diagnostic and Therapeutic Approaches

Coronary artery disease is the leading cause of morbidity and mortality worldwide. The most common pathophysiologic substrate is atherosclerosis which is an inflammatory procedure that starts at childhood and develops throughout life. Endothelial dysfunction is associated with the initiation and progression of atherosclerosis and is characterized by the impaired production of nitric oxide. In general, endothelial dysfunction is linked to poor cardiovascular prognosis and different methods, both invasive and non-invasive, have been developed for its evaluation. Ultrasound evaluation of flow mediated dilatation of the branchial artery is the most commonly used method to assessed endothelial function while intracoronary administration of vasoactive agents may be also be used to test directly endothelial properties of the coronary vasculature. Endothelial dysfunction has also been the subject of therapeutic interventions. This review article summarizes the knowledge about evaluation of endothelial function in acute coronary syndromes and stable coronary artery disease and demonstrates the current therapeutic approaches against endothelial dysfunction.

Effect of Different Classes of Antihypertensive Drugs on Endothelial Function and Inflammation

Hypertension is characterized by structural and functional changes in blood vessels that travel with increased arterial stiffness, vascular inflammation, and endothelial dysfunction. Some antihypertensive drugs have been shown to improve endothelial function and reduce levels of inflammatory markers regardless of the effect of blood pressure lowering. Third-generation β-blockers, such as nebivolol and carvedilol, because they have additional properties, have been shown to improve endothelial function in patients with hypertension. Calcium channel antagonists, because they have antioxidant effects, may improve endothelial function and vascular inflammation.The Angiotensin Receptor Blocker (ARBs) are able to improve endothelial dysfunction and vascular inflammation in patients with hypertension and other cardiovascular diseases. Angiotensin converting enzyme (ACE) inhibitors have shown beneficial effects on endothelial function in patients with hypertension and other cardiovascular diseases, however there are few studies evaluating the effect of treatment with this class on the reduction of C-reactive protein (CRP) levels. Further studies are needed to assess whether treatment of endothelial dysfunction and vascular inflammation may improve the prognosis of patients with essential hypertension.

Blood pressure normalization via pharmacotherapy improves cutaneous microvascular function through NO-dependent and NO-independent mechanisms

Hypertension is associated with endothelial dysfunction and vascular remodeling.

OBJECTIVE

To assess effects of antihypertensive pharmacotherapy on eNOS- and iNOS-dependent mechanisms and maximal vasodilator capacity in the cutaneous microvasculature.

METHODS

Intradermal microdialysis fibers were placed in 15 normotensive (SBP 111±2 mm Hg), 12 unmedicated hypertensive (SBP 142±2 mm Hg), and 12 medicated hypertensive (SBP 120±2 mm Hg) subjects. Treatments were control, iNOS-inhibited (1400w), and NOS-inhibited (l-NAME). Red cell flux, measured during local heating (42°C) and ACh dose-response protocols, was normalized to CVC (flux MAP^-1 ) and a percentage of maximal vasodilation (%CVC_max ).

RESULTS

Compared to normotensives, ACh-mediated vasodilation was attenuated in the hypertensive (P<.001), but not in medicated subjects (P=.83). NOS inhibition attenuated ACh-mediated vasodilation in normotensives compared to hypertensive (P<.001) and medicated (P<.001) subjects. With iNOS inhibition, there was no difference in ACh-mediated vasodilation between groups. Compared to the normotensives, local heat-induced vasodilation was attenuated in the hypertensives (P<.001), but iNOS inhibition augmented vasodilation in the hypertensives so this attenuation was abolished (P=.31). Compared to normotensives, maximal vasodilator capacity was reduced in the hypertensive (P=.014) and medicated subjects (P=.004).

CONCLUSIONS

In the cutaneous microvasculature, antihypertensive pharmacotherapy improved endothelial function through NO-dependent and NO-independent mechanisms, but did not improve maximal vasodilator capacity.

The binding of captopril to angiotensin I-converting enzyme triggers activation of signaling pathways

Hypertension is a global health problem, and angiotensin I (ANG I)-converting enzyme (ACE) inhibitors are largely used to control this pathology. Recently, it has been shown that ACE can also act as a transducer signal molecule when its inhibitors or substrates bind to it. This new role of ACE could contribute to understanding some of the effects not explained by its catalytic activity only. In this study, we investigated signaling pathway activation in Chinese hamster ovary (CHO) cells stably expressing ACE (CHO-ACE) under different conditions. We also investigated gene modulation after 4 h and 24 h of captopril treatment. Our results demonstrated that CHO-ACE cells when stimulated with ANG I, ramipril, or captopril led to JNK and ERK1/2 phosphorylation. To verify any physiological role at the endogenous level, we made use of primary cultures of mesangial cells from spontaneously hypertensive rats (SHR) and Wistar rats. Our results showed that ERK1/2 activation occurred mainly in primary cultures of mesangial cells from SHR rats upon captopril stimulation, suggesting that this signaling pathway could be differentially regulated during hypertension. Our results also showed that captopril treatment leads to a decrease of cyclooxygenase 2, interleukin-1β, and β-arrestin2 and a significant increase of AP2 gene expression levels. Our findings strengthen the fact that, in addition to the blockage of enzymatic activity, ACE inhibitors also trigger signaling pathway activation, and this may contribute to their beneficial effects in the treatment of hypertension and other pathologies.

The Role of Vasodilator Receptors of Renin-angiotensin System on Nitric Oxide Formation and Kidney Circulation after Angiotensin II Infusion in Renal Ischemia/Reperfusion Rats

Background:

Nitric oxide (NO) as a vasodilator factor has renoprotective effect against renal ischemia. The balance between angiotensin II (Ang II) and NO can affect kidney homeostasis. The aim of this study was to determine NO alteration in response to renin–Ang system vasodilator receptors antagonists (PD123319; Ang II type 2 receptor antagonist and A779; Mas receptor antagonist) in renal ischemia/reperfusion injury (IRI) in rats.

Materials and Methods:

Sixty-three Wistar male and female rats were used. Animals from each gender were divided into four groups received saline, Ang II, PD123319 + Ang II, and A779 + Ang II after renal IRI. Renal IRI induced with an adjustable hook. Blood pressure and renal blood flow (RBF) measured continuously. The nitrite levels were measured in serum, kidney, and urine samples.

Results:

In female rats, the serum and kidney nitrite levels increased significantly by Ang II (P < 0.05) and decreased significantly (P < 0.05) when PD123319 was accompanied with Ang II. Such observation was not seen in male. Ang II decreased RBF significantly in all groups (P < 0.05), while PD + Ang II group showed significant decrease in RBF in comparison with the other groups in female rats (P < 0.05).

Conclusion:

Males show more sensibility to Ang II infusion; in fact, it is suggested that there is gender dimorphism in the Ang II and NO production associated with vasodilator receptors.

Angiotensin-Converting Inhibitors and Angiotensin II Receptor Blockers and Longitudinal Change in Percent Emphysema on Computed Tomography. The Multi-Ethnic Study of Atherosclerosis Lung Study

RATIONALE

Although emphysema on computed tomography (CT) is associated with increased morbidity and mortality in patients with and without spirometrically defined chronic obstructive pulmonary disease, no available medications target emphysema outside of alpha-1 antitrypsin deficiency. Transforming growth factor-β and endothelial dysfunction are implicated in emphysema pathogenesis, and angiotensin II receptor blockers (ARBs) inhibit transforming growth factor-β, improve endothelial function, and restore airspace architecture in murine models. Evidence in humans is, however, lacking.

OBJECTIVES

To determine whether angiotensin-converting enzyme (ACE) inhibitor and ARB dose is associated with slowed progression of percent emphysema by CT.

METHODS

The Multi-Ethnic Study of Atherosclerosis researchers recruited participants ages 45-84 years from the general population from 2000 to 2002. Medication use was assessed by medication inventory. Percent emphysema was defined as the percentage of lung regions less than -950 Hounsfield units on CTs. Mixed-effects regression models were used to adjust for confounders.

RESULTS

Among 4,472 participants, 12% used an ACE inhibitor and 6% used an ARB at baseline. The median percent emphysema was 3.0% at baseline, and the rate of progression was 0.64 percentage points over a median of 9.3 years. Higher doses of ACE or ARB were independently associated with a slower change in percent emphysema (P = 0.03). Over 10 years, in contrast to a predicted mean increase in percent emphysema of 0.66 percentage points in those who did not take ARBs or ACE inhibitors, the predicted mean increase in participants who used maximum doses of ARBs or ACE inhibitors was 0.06 percentage points (P = 0.01). The findings were of greatest magnitude among former smokers (P < 0.001). Indications for ACE inhibitor or ARB drugs (hypertension and diabetes) and other medications for hypertension and diabetes were not associated independently with change in percent emphysema. There was no evidence that ACE inhibitor or ARB dose was associated with decline in lung function.

CONCLUSIONS

In a large population-based study, ACE inhibitors and ARBs were associated with slowed progression of percent emphysema by chest CT, particularly among former smokers. Randomized clinical trials of ACE and ARB agents are warranted for the prevention and treatment of emphysema.

Evaluation of microvascular endothelial function and capillary density in patients with infective endocarditis using laser speckle contrast imaging and video-capillaroscopy

OBJECTIVE

To evaluate the systemic microcirculation of patients with infective endocarditis (IE).

METHODS

This is a comparative study of patients with definite IE by the modified Duke criteria admitted to our center for treatment. A reference group of sex- and age-matched healthy volunteers was included. Microvascular flow was evaluated in the forearm using a laser speckle contrast imaging system, for noninvasive measurement of cutaneous microvascular perfusion, in combination with skin iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP) to test microvascular reactivity. Microvascular density was evaluated using skin video-capillaroscopy.

RESULTS

We studied 22 patients with IE; 15 were male and seven female. The mean age and standard deviation (SD) were 45.5 ± 17.3 years. Basal skin microvascular conductance was significantly increased in patients with IE, compared with healthy individuals (0.36 ± 0.13 versus 0.21 ± 0.08 APU/mmHg; P < 0.0001). The increase in microvascular conductance induced by ACh in patients was 0.21 ± 0.17 and in the reference group, it was 0.37 ± 0.14 APU/mmHg (P = 0.0012). The increase in microvascular conductance induced by SNP in patients was 0.18 ± 0.14 and it was 0.29 ± 0.15 APU/mmHg (P = 0.0140) in the reference group. The basal mean skin capillary density of patients (135 ± 24 capillaries/mm²) was significantly higher, compared with controls (97 ± 21 capillaries/mm²; P < 0.0001).

CONCLUSIONS

The main findings in the microcirculation of patients with IE were greater basal vasodilation and a reduction of the endothelium-dependent and -independent microvascular reactivity, as well as greater functional skin capillary density compared to healthy individuals.

Endothelial dysfunction in human essential hypertension

Although the endothelium has a number of important functions, the term endothelial dysfunction is commonly used to describe impairment in its vasodilatory capacity. It is increasingly recognized that this is related to hypertension, although whether it predates essential hypertension or is a consequence of it is still unknown. In this review, we explore the mechanisms of endothelial dysfunction in essential hypertension, its prognostic significance and methods of pharmacological reversal.

Positron Emission Tomography-Determined Hyperemic Flow, Myocardial Flow Reserve, and Flow Gradient-Quo Vadis?

Positron emission tomography/computed tomography (PET/CT) applied with positron-emitting flow tracers such as ¹³N-ammonia and ⁸²Rubidium enables the quantification of both myocardial perfusion and myocardial blood flow (MBF) in milliliters per gram per minute for coronary artery disease (CAD) detection and characterization. The detection of a regional myocardial perfusion defect during vasomotor stress commonly identifies the culprit lesion or most severe epicardial narrowing, whereas adding regional hyperemic MBFs, myocardial flow reserve (MFR), and/or longitudinal flow decrease may also signify less severe but flow-limiting stenosis in multivessel CAD. The addition of regional hyperemic flow parameters, therefore, may afford a comprehensive identification and characterization of flow-limiting effects of multivessel CAD. The non-specific origin of decreases in hyperemic MBFs and MFR, however, prompts an evaluation and interpretation of regional flow in the appropriate context with the presence of obstructive CAD. Conversely, initial results of the assessment of a longitudinal hyperemic flow gradient suggest this novel flow parameter to be specifically related to increases in CAD caused epicardial resistance. The concurrent assessment of myocardial perfusion and several hyperemic flow parameters with PET/CT may indeed open novel avenues of precision medicine to guide coronary revascularization procedures that may potentially lead to a further improvement in cardiovascular outcomes in CAD patients.

Antioxidant therapy for management of oxidative stress induced hypertension

Hypertension is considered as the most common risk factor for cardiovascular diseases, also is regarded as a leading cause of the mortality and morbidity worldwide. The mechanisms underlying the pathological process of hypertension are not completely explained. However, there is growing evidence that increased oxidative stress plays an important role in the pathophysiology of hypertension. Several preclinical studies and clinical trials have indicated that antioxidant therapy is important for management of hypertension, using antioxidants compounds such as alpha tocopherol (Vit E) and ascorbic acid (Vit C), polyphenols with others and some antihypertensive drugs that are now in clinical use (e.g. ACEIs, ARBs, novel B-blockers, dihydropyridine CCBs) which have antioxidative pleiotropic effects. The purpose of this review is to highlight the importance of antioxidant therapy for management of oxidative stress induced hypertension. Furthermore, we review the current knowledge in the oxidative stress and its significance in hypertension.

Drug Treatment of Hypertension: Focus on Vascular Health

Hypertension, the most common preventable risk factor for cardiovascular disease and death, is a growing health burden. Serious cardiovascular complications result from target organ damage including cerebrovascular disease, heart failure, ischaemic heart disease and renal failure. While many systems contribute to blood pressure (BP) elevation, the vascular system is particularly important because vascular dysfunction is a cause and consequence of hypertension. Hypertension is characterised by a vascular phenotype of endothelial dysfunction, arterial remodelling, vascular inflammation and increased stiffness. Antihypertensive drugs that influence vascular changes associated with high BP have greater efficacy for reducing cardiovascular risk than drugs that reduce BP, but have little or no effect on the adverse vascular phenotype. Angiotensin converting enzyme ACE inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) improve endothelial function and prevent vascular remodelling. Calcium channel blockers also improve endothelial function, although to a lesser extent than ACEIs and ARBs. Mineralocorticoid receptor blockers improve endothelial function and reduce arterial stiffness, and have recently become more established as antihypertensive drugs. Lifestyle factors are essential in preventing the adverse vascular changes associated with high BP and reducing associated cardiovascular risk. Clinicians and scientists should incorporate these factors into treatment decisions for patients with high BP, as well as in the development of new antihypertensive drugs that promote vascular health.

The Central Role of Endothelial Dysfunction in Cardiorenal Syndrome

BACKGROUND

Endothelial dysfunction (ED) has emerged as a critical process in cardiorenal syndrome (CRS). The concept that ED is closely linked with cardiac and renal dysfunction has become an important target for CRS-related research and clinical practice.

SUMMARY

The sequence of events leading to ED is initiated by type I endothelial activation (almost immediately) and type II endothelial activation (over hours, days, and even months), followed by endothelial apoptosis and endothelial necrosis. The fact that ED is a continual cellular event divides this process into reversible ED (endothelial activation) and irreversible ED (endothelial apoptosis and necrosis). This basic research-defined concept may have clinical implications. Although most antihypertensive drugs (ACE inhibitors, statins, etc.) are effective in patients with hypertension and diabetes, some of them have proved to be ineffective, which may partly be attributed to irreversible ED. Even though the etiology of ED consists mainly of asymmetric dimethylarginine, nitric oxide, oxidative stress, and anti-endothelial cell antibodies, many other inducers of ED have been identified. In addition, a distinct role of ED has been reported for each type of CRS in humans.

KEY MESSAGES

Further study is warranted to prove whether ED holds promise as a pharmacological target in CRS patients.

Associations between parameters of flow-mediated vasodilatation obtained by continuous measurement approaches and the presence of coronary artery disease and the severity of coronary atherosclerosis

We investigated the associations between the parameters of flow-mediated vasodilatation (FMD) obtained by continuous measurement approaches and the presence of coronary artery disease (CAD) and the severity of coronary atherosclerosis. The subjects consisted of 282 consecutive patients who underwent coronary angiography (CAG) and in whom we could measure FMD. Using continuous measurement approaches, we measured FMD as the magnitude of the percentage change from brachial artery diameter from baseline to peak (bFMD), the maximum FMD rate calculated as the maximal slope of dilation (FMD-MDR), and the integrated FMD response calculated as the area under the dilation curve during the 60- and 120 s dilation periods (FMD-AUC60 and FMD-AUC120). We divided the patients into two groups, the CAD group and the non-CAD group, and defined the severity of coronary atherosclerosis according to the Gensini score. The CAD group showed significantly lower %FMD, FMD-MDR, FMD-AUC60, and FMD-AUC120. Gender, smoking, dyslipidemia (DL), and diabetes mellitus (DM), in addition to FMD-AUC120, were identified as significant independent variables that predicted the presence of CAD by a multivariate logistic regression. In addition, a multiple regression analysis indicated that gender, DL, and hypertension, in addition to FMD-AUC120, were predictors of the Gensini score. Finally, we defined the cutoff value of FMD-AUC120 for the prediction of CAD in all patients as 11.1 (sensitivity 0.582, specificity 0.652) by a receiver-operating characteristic (ROC) curve analysis. In conclusion, FMD-AUC120 as assessed by continuous measurement approaches may be a superior marker for evaluating the presence of CAD and the severity of coronary atherosclerosis.

Vascular Aging: Implications for Cardiovascular Disease and Therapy

The incidence and prevalence of cardiovascular disease is highest among the elderly, in part, due to deleterious effects of advancing age on the heart and blood vessels. Aging, a known cardiovascular risk factor, is progressively associated with structural and functional changes to the vasculature including hemodynamic disturbance due to increased oxidative stress, premature cellular senescence and impairments in synthesis and/or secretion of endothelium-derived vasoactive molecules. These molecular and physiological changes lead to vessel wall stiffening and thickening, as well as other vascular complications that culminate to loss of vascular tone regulation and endothelial function. Intriguingly, the vessel wall, a biochemically active structure composed of collagen, connective tissue, smooth muscle and endothelial cells, is adversely affected by processes involved in premature or normal aging. Notably, the inner most layer of the vessel wall, the endothelium, becomes senescent and dysfunctional with advancing age. As a result, its ability to release vasoactive molecules such as acetylcholine (ACh), prostacyclin (PGI2), endothelium-derived hyperpolarizing factor (EDHF), and nitric oxide (NO) is reduced and the cellular response to these molecules is also impaired. By contrast, the vascular endothelium increases its generation and release of reactive oxygen (ROS) and nitrogen (RNS) species, vasoconstrictors such as endothelin (ET) and angiotensin (AT), and endogenous inhibitors of NO synthases (NOSs) to block NO. This skews the balance of the endothelium in favor of the release of highly tissue reactive and harmful molecules that promote DNA damage, telomere erosion, senescence, as well as stiffened and hardened vessel wall that is prone to the development of hypertension, diabetes, atherosclerosis and other cardiovascular risk factors. This Review discusses the impact of advancing age on cardiovascular health, and highlights the cellular and molecular mechanisms that underlie age-associated vascular changes. In addition, the role of pharmacological interventions in preventing or delaying age-related cardiovascular disease is discussed.

Myocardial blood flow: Putting it into clinical perspective

In recent years, positron emission tomography/computed tomography (PET/CT)-determined myocardial perfusion in conjunction with myocardial blood flow (MBF) quantification in mL·g(-1)·min(-1) has emerged from mere research application to initial clinical use in the detection and characterization of the coronary artery disease (CAD) process. The concurrent evaluation of MBF during vasomotor stress and at rest with the resulting myocardial flow reserve (MFR = MBF during stress/MBF at rest) expands the scope of conventional myocardial perfusion imaging not only to the detection of the most advanced and culprit CAD, as evidenced by the stress-related regional myocardial perfusion defect, but also to the less severe or intermediate stenosis in patients with multivessel CAD. Due to the non-specific nature of the hyperemic MBF and MFR, the interpretation of hyperemic flow increases with PET/CT necessitates an appropriate placement in the context with microvascular function, wall motion analysis, and eventually underlying coronary morphology in CAD patients. This review aims to provide a comprehensive overview of various diagnostic scenarios of PET/CT-determined myocardial perfusion and flow quantification in the detection and characterization of clinically manifest CAD.

The potential role of angiotensin-converting enzyme inhibition in peripheral arterial disease

Peripheral arterial disease (PAD) is associated with significant morbidity and mortality, and yet remains under-recognized and under-treated. Atherosclerosis is the most common cause of lower extremity PAD and pharmacological interventions that alter this central pathogenic role of atherosclerosis may alter the natural history of PAD. There is growing evidence that the renin-angiotensin system (RAS) is a significant mediator of this disease process and that treatment with angiotensin-converting enzyme (ACE) inhibitors is associated with vasculoprotective effects that are independent of the antihypertensive properties of these agents. Numerous lines of evidence suggest that ACE inhibitors directly inhibit the atherosclerotic process and improve vascular endothelial function. In patients with PAD, ACE inhibitors have been shown to improve peripheral circulation as measured by peripheral arterial blood pressure and by increases in peripheral blood flow. Preliminary evidence suggests that ACE inhibitors might improve clinical symptoms in patients with PAD. Recent evidence has confirmed that ACE inhibition is associated with a decrease in morbidity and mortality in patients with arterial disease without left ventricular dysfunction; this benefit was at least as great for the subset of patients with PAD. Overall, these data support a significant role for the RAS in the pathogenesis of all atherosclerotic diseases (including PAD) and suggest that the benefit is independent of the blood pressure lowering properties of these agents. These studies suggest that ACE inhibitor therapy should be considered in the routine management of individuals with PAD, regardless of whether they have hypertension or left ventricular dysfunction.

Nitric Oxide Signaling and Clinical Alternatives to Nitric Oxide

Nitric oxide has been implicated in numerous biological processes, particularly those involved with the cardiovascular system. Nitric oxide production is closely regulated and influenced by a number of factors in both health and disease. Nitric oxide is involved in maintaining the vascular system in its healthy, nondiseased state by producing vasorelaxation which enhances blood flow and prevents both leukocyte and platelet adhesion to the vascular wall. Dysfunctional endothelial cell nitric oxide production has been implicated in a number of disease states, including hypertension and atherosclerosis, and has been associated with adverse cardiac events. Various recent therapies may exert their beneficial effects in part by enhancing endothelial nitric oxide bloavallability. Nitric oxide has been used therapeutically in a number of cardiorespiratory disease states. An improved understanding of the pathologic processes underlying these diseases has resulted in several alternative agents being investigated and used clinically.

Review: Angiotensin-converting enzyme inhibitors and coronary heart disease prevention

A number of large randomised controlled trials have shown that angiotensin-converting enzyme (ACE) inhibitors, compared with placebo or other blood pressure-lowering drugs, improve coronary heart disease outcomes (fatal and non-fatal myocardial infarction, and coronary revascularisation) in diverse patient groups, e.g. in primary and secondary prevention, those with and without left ventricular dysfunction, and among hypertensive and non-hypertensive subjects. An updated meta-regression analysis which included five major trials in patients with established coronary artery disease (CAD) (EUROPA, INVEST, ACTION, PEACE and CAMELOT) concluded that ACE inhibitor (ACE-I) therapy has clear benefits in secondary prevention, but there are important and unexplained differences between trials in clinical outcome, baseline cardiovascular risk, blood pressure changes and trial design which deserve further discussion of the underlying mechanisms and clinical interpretation. For example, in placebo-controlled trials the biggest (20—22%) reductions in primary end points (including mortality) have been observed with perindopril and ramipril, whereas trials using trandolapril and quinapril had no effect on survival or recurrent CAD events. This review summarises and compares the major findings of these recent trials, and provides further analysis of the underlying mechanisms and clinical significance of secondary CAD prevention with ACE-I therapy.

Tonic levels of angiotensin II reduce tonic levels of vascular nitric oxide even in salt-replete man

Introduction

Losartan improves stimulated endothelial function in patients with cardiovascular disease, but there are no data to establish whether losartan has this effect in normal man. Furthermore, whether losartan improves basal nitric oxide (NO) activity is controversial. We therefore examined whether treatment with losartan improved basal NO activity in normal, salt-replete man. If so, this would imply that tonic levels of angiotensin II (Ang II) reduce tonic basal levels of NO, even in salt-replete normal man.

Methods

We performed a randomised, placebo-controlled, double-blind crossover study in 24 healthy volunteers, comparing losartan 50 mg daily for one month versus placebo. Brachial artery endothelial function was assessed by bilateral venous occlusion plethysmography, measuring the response to intra-arterial infusions of the endothelial-dependent and endothelial-independent vasodilators, acetylcholine and sodium nitroprusside respectively and the endothelial-dependent vasoconstrictor NG-monomethyl-L-arginine. Results were analysed by multiple analysis of variance and statistical significance was taken as a p value of ≤ 0.05.

Results

Losartan significantly increased the vasoconstriction in response to N G-monomethyl-L-arginine (-37 2% vs. -32+2%, losartan vs. placebo; p=0.05). Losartan improved the vasodilatation response to acetylcholine; however, this result did not reach significance (214+2 0% vs. 174+20%, losartan vs. placebo; p=0.15). Losartan did not affect the response to nitroprusside (172+15% vs. 176+16%, losartan vs. placebo; p=0.84). There was no significant difference in blood pressure between the two study days.

Conclusions

Losartan improves basal NO bioactivity in healthy salt-replete volunteers. Even in salt-replete man, basal Ang II levels exert a tonic effect, which reduces basal NO.

High Angiotensin II Responsiveness is Associated with Decreased Endothelium-Dependent Relaxation in Human Arteries

Introduction. Animal studies demonstrated an interaction between angiotensin II (Ang II) responsiveness and endothelium-dependent relaxation (EDR). However, this relation has not been well described in humans. Therefore, we investigated the relation between Ang II responsiveness and EDR in isolated human arteries.

Materials and Methods. Segments of the internal mammary artery (IMA) were harvested from 89 patients undergoing coronary bypass surgery. Rings of these segments were exposed in organ bath experiments to metacholine (ME; 10 nmol/L -0.1 mmol/L) after precontraction with phenylephrine (PE; 10 µmol/L), and secondly to increasing concentrations of Ang II (0.1 nmol/L —1 µmol/L).

Results. Patients with the highest contraction to Ang II showed the lowest ME relaxation (r=0.312; p=0.003). Angiotensin-converting enzyme (ACE)-inhibition significantly increased Ang II sensitivity (p=0.03). This increase was accompanied by a tendency toward decreased EDR (p=0.07). The inverse relation between Ang responsiveness and endotheliumdependent relaxation could not be explained by an increased tissue or serum ACE-inhibition in patients with a higher endothelium-dependent relaxation.

Conclusions. High Ang II responsiveness inversely correlates to EDR in IMA's of patients with established coronary artery disease. Short-term treatment with an ACE-inhibitor increased the response to Ang II, but had an adverse effect on EDR.

Impaired brachial artery endothelium dependent flow mediated dilation in systemic lupus erythematosus: preliminary observations

Our objective was to compare brachial artery endothelium dependent and independent vasodilation in lupus patients and healthy females, by means of high-resolution noninvasive brachial artery ultrasound. Endothelially mediated vasodilation was estimated noninvasively by examination of brachial artery responses to postischemic reactive hyperemia and endothelial independent vasodilation from response to sublingual glycerlynitrate (GTN) using high-resolution external vascular ultrasound. Five patients with known coronary artery disease (CAD), five with subclinical CAD, five with no CAD and five control subjects were assessed. Endothelium dependent vasodilation was significantly blunted in lupus patients with CAD as compared with healthy female controls (0.11 versus 11.1%, P 1/4 0.018). Corresponding values for lupus patients with subclinical CAD and no CAD were 11 and 9.6%, respectively. For each subject, endothelium dependent vasodilation (EDV) was related to endothelium independent vasodilation (EIV) to adjust for varying vascular smooth muscle responses to GTN in individual subjects. This ratio was markedly depressed in lupus patients with CAD as compared with control subjects (0.12 versus 1.15). The corresponding EDV/EIV ratios for patients with subclinical CAD and no CAD were similar at 0.69 and 0.65, respectively. The conclusion was that flow mediated vasodilation in lupus patients with coronary artery disease is markedly depressed as compared to healthy subjects.

The effects of quinapril and atorvastatin on the responsiveness to sildenafil in men with erectile dysfunction

Phosphodiesterase-5 (PDE-5) inhibitors are an effective therapy for the majority of men with erectile dysfunction (ED). However, many men with ED still report a suboptimal or partial response even after an adequate trial of oral PDE-5 therapy. Since ED is associated with impaired vascular function and both atorvastatin and quinapril have been previously shown to improve vascular function, we examined the effects of adjunctive treatment with these medications in men with vasculogenic ED who were suboptimal responders to 100 mg of sildenafil. Men with ED and suboptimal response to sildenafil were randomly assigned to 3 months of treatment with atorvastatin 40 mg ( n = 12), quinapril 10 mg ( n = 10), or placebo ( n = 13), along with continued adjunctive sildenafil use. Measured variables included: International Index of Erectile Function (IIEF) questionnaire, brachial artery flow-mediated dilation (FMD), endothelium-independent dilation (EID) via nitroglycerin, penile Doppler blood flow, blood pressure (BP), lipids, and C-reactive protein (CRP). Compared to placebo, quinapril ( p < 0.01) significantly improved symptoms of ED as measured by the IIEF-5 questionnaire. There was a trend toward a significant improvement in IIEF-5 with atorvastatin. Similarly, quinapril significantly improved the IIEF ED Domain ( p < 0.05). Other peripheral and penile vascular parameters were unchanged with drug therapy as compared to placebo. In conclusion, treatment with quinapril, in combination with sildenafil, improved ED in men with suboptimal response to sildenafil alone. Atorvastatin demonstrated a trend toward improved ED in this group.

Insulin Resistance and Endothelial Dysfunction Constitute a Common Therapeutic Target in Cardiometabolic Disorders

Insulin resistance and other risk factors for atherosclerosis, such as hypertension and hypercholesterolemia, promote endothelial dysfunction and lead to development of metabolic syndrome which constitutes an introduction to cardiovascular disease. The insulin resistance and endothelial dysfunction cross talk between each other by numerous metabolic pathways. Hence, targeting one of these pathologies with pleiotropic treatment exerts beneficial effect on another one. Combined and expletive treatment of hypertension, lipid disorders, and insulin resistance with nonpharmacological interventions and conventional pharmacotherapy may inhibit the transformation of metabolic disturbances to fully developed cardiovascular disease. This paper summarises the common therapeutic targets for insulin resistance, endothelial dysfunction, and vascular inflammatory reaction at molecular level and analyses the potential pleiotropic effects of drugs used currently in management of cardiovascular disease, metabolic syndrome, and diabetes.