Myocardial ischemia-reperfusion injury: Possible role of melatonin

Our knowledge and understanding of the pathophysiology of coronary atherosclerosis has increased enormously over the last 20 years. Reperfusion through thrombolysis or percutaneous coronary angioplasty is the standard treatment for preventing acute myocardial infarction. Early reperfusion is an absolute prerequisite for survival of the ischemic myocardium, but reperfusion itself may lead to accelerated and additional myocardial injury beyond that generated by ischemia alone. These outcomes, in a range of reperfusion-associated pathologies, are collectively termed "reperfusion injuries". Reactive oxygen species are known to be produced in large quantities in the first few minutes of the post-ischemia reperfusion process. Similarly, scientific evidence from the last 15 years has suggested that melatonin has beneficial effects on the cardiovascular system. The presence of vascular melatoninergic receptor binding sites has been demonstrated; these receptors are functionally linked to vasoconstrictor or vasodilatory effects of melatonin. It has been shown that patients with coronary heart disease have a low melatonin production rate, especially those with higher risk of cardiac infarction and/or sudden death. Melatonin attenuates molecular and cellular damage resulting from cardiac ischemia-reperfusion in which destructive free radicals are involved.

Impaired coronary microvascular endothelial function in men with metabolic syndrome

AIM

To assess coronary endothelial function of conduit and resistance vessels in patients with metabolic syndrome (MS).

METHODS

Seventy-eight men (mean age, 57 years) with chest pain and angiographically normal coronary arteries were included in the study. Patients with coronary spastic angina were excluded. Changes in coronary artery diameter and coronary blood flow (CBF) in response to acetylcholine (ACh) were determined using quantitative coronary angiography and Doppler velocity measurements. Coronary flow reserve was calculated as the ratio of coronary blood velocity after adenosine triphosphate infusion relative to baseline values. Patients were divided into two groups based on the presence or absence of MS.

RESULTS

There were 24 patients in the MS group (31%). The increase in CBF in response to ACh infusion was impaired in the MS group (P < 0.0001) compared to the non-MS group, whereas changes in coronary artery diameter in response to ACh infusion did not differ between the two groups. Multivariate regression analysis revealed that MS was a significant factor associated with the lesser change in CBF induced by ACh infusion at 30 μg/min (P < 0.0001, r(2) = 0.46).

CONCLUSION

Coronary endothelial dysfunction was present at the level of resistance vessels but not conduit vessels in the MS patients included in our study.

Stenting for left main coronary artery occlusion in adolescent: A case report

Acute total or subtotal occlusion of left main coronary artery (LMCA) is a catastrophic and mostly fatal event. Patients may present with cardiogenic shock and die whenever this event occurs. Survival is strongly dependent on the presence of collateral blood flow to the left coronary artery or a dominant right coronary artery, and emergency intervention for preserving the left ventricular function. Here, we present a case of a 14-year-old boy with subtotal occlusion of the LMCA accompanying acute myocardial infarction probably caused by congenital syphilis according to his positive serum syphilis antibody. His survival was closely associated with a dominant right coronary artery and timely thrombolytic therapy. Finally, he was treated with angioplasty and paclitaxel-eluting stent implantation. He was followed up after stenting and was doing quite well at the time when we wrote this paper.

Clinical importance of aspirin and clopidogrel resistance

Aspirin and clopidogrel are important components of medical therapy for patients with acute coronary syndromes, for those who received coronary artery stents and in the secondary prevention of ischaemic stroke. Despite their use, a significant number of patients experience recurrent adverse ischaemic events. Interindividual variability of platelet aggregation in response to these antiplatelet agents may be an explanation for some of these recurrent events, and small trials have linked "aspirin and/or clopidogrel resistance", as measured by platelet function tests, to adverse events. We systematically reviewed all available evidence on the prevalence of aspirin/clopidogrel resistance, their possible risk factors and their association with clinical outcomes. We also identified articles showing possible treatments. After analyzing the data on different laboratory methods, we found that aspirin/clopidogrel resistance seems to be associated with poor clinical outcomes and there is currently no standardized or widely accepted definition of clopidogrel resistance. Therefore, we conclude that specific treatment recommendations are not established for patients who exhibit high platelet reactivity during aspirin/clopidogrel therapy or who have poor platelet inhibition by clopidogrel.

Myocardial perfusion imaging and infarct characterization using multidetector cardiac computed tomography

Until recently, computed tomography coronary angiography was restricted to the anatomical assessment of coronary stenosis, whereas the functional significance of coronary lesions remained outside of its scope. Nevertheless, the kinetics of iodinated contrast is similar to gadolinium-diethylenetriamine pentaacetic acid used in contrast-enhanced magnetic resonance imaging, allowing assessment of myocardial perfusion and viability by cardiac computed tomography.

RAAS and adrenergic genes in heart failure: Function, predisposition and survival implications

It is well appreciated that several neurohormones and signaling cascades are activated that promote long-term deterioration of cardiac function and structure. Activation of the renin-angiotensin-aldosterone system (RAAS) and the adrenergic system is closely related to heart failure. Common gene variants that encode neurohormonal, adrenergic and intracellular proteins have been demonstrated to modulate the course and consequences of heart failure. However, the literature is replete with conflicting results and it remains uncertain as to whether particular gene variants predispose heart failure. Therefore, the main purpose of this review was to discuss the effects of single nucleotide polymorphisms (SNPs) that are located in genes encoding elements of the RAAS and the adrenergic system on the predisposition to and survival from heart failure. Most studies indicate that common SNPs encoding elements of the RAAS and the adrenergic system do not predispose individuals to heart failure. Conversely, it has been demonstrated that ARB1 Arg389Gly, GRK5 Gln41Leu, ACE I/D, CYP11B2 C-344T and AGTR1 A+1166C modulate pharmacological responses and have a considerable impact on cardiac-related survival. It should not be expected, however, that a single polymorphism determines survival, given that multiple gene products and environmental factors contribute to the pathogenesis of heart failure. Therefore, future studies should consider the interaction effects of multiple genes in populations that are as homogeneous as possible with respect to environmental characteristics.

Two-dimensional speckle tracking echocardiography for the assessment of atrial function

Echocardiography is the most common diagnostic method for assessing atrial function but the technique has some limitations. Traditionally, assessment of left atrial function has been performed by measuring volumes with 2D echocardiography. Additionally, it can be assessed with transmitral Doppler and pulmonary vein Doppler. Recently, an alternative method has been incorporated, namely, measurement of myocardial deformation with color tissue Doppler-derived strain. However, this method has several limitations, such as suboptimal reproducibility, angle-dependence, signal artifacts and the fact that it only measures regional strain and does not obtain information about the curved portion of the atrial roof. To overcome these limitations in the quantification of atrial function, the use of speckle tracking echocardiography (STE) strain has been proposed. This technique is not derived from Doppler but rather from 2D echocardiography; it is angle-independent and allows one to measure global as well as regional atrial strain. In this editorial, we describe the physical and pathophysiological concepts of STE and underline the clinical usefulness of this new technique.

Coronary heart disease: Significance of liver X receptor α genomics

Crosstalk between lipid peroxidation and inflammation is known to be a pathognomonic feature for the development of coronary heart disease (CHD). In this regard ligand activated liver X receptor (LXR)-α has emerged as a key molecular switch by its inherent ability to modulate an array of genes involved in these two fundamental cellular processes. In addition, LXR-α has also been found to play a role in hepatic lipogenesis and innate immunity. Although several lines of evidence in experimental model systems have established the atheroprotective nature of LXR-α, human subjects have been reported to possess a paradoxical situation in which increased blood cellular LXR-α gene expression is always accompanied by increased coronary occlusion. This apparent paradox was resolved recently by the finding that CHD patients possess a deregulated LXR-α transcriptome due to impaired ligand-receptor interaction. This blood cellular mutated LXR-α gene expression correlated specifically with the extent of coronary occlusion and hence need is felt to devise new synthetic ligands that could restore the function of this mutated LXR-α protein in order to modulate genes involved in reverse cholesterol transport and suppression of the inflammatory response leading to the effective treatment of CHD.

Alternatives to clopidogrel for acute coronary syndromes: Prasugrel or ticagrelor?

Clopidogrel is a mainstay in the treatment of patients with acute coronary syndromes or those receiving endovascular prostheses. However, its efficacy has been challenged in the recent past by studies suggesting variable individual responsiveness and by new, more potent competitors, such as prasugrel and ticagrelor. But what is the actual body of evidence in support of clopidogrel? Is there any dark side of the moon? What is the role of prasugrel, which has already been approved in Europe and in the United States? And what will be the future role of ticagrelor, when approved for routine clinical practice? We hereby concisely summarize the scope of this clinical choice, providing arguments in favor and against each of the three antiplatelet agents: clopidogrel, prasugrel, and ticagrelor.

Profound thrombocytopenia induced by clopidogrel with a prior history of long-term safe administration

Clopidogrel has shown an excellent safety, tolerability and efficacy ever since its marketing. However, here we report a rare case with profound thrombocytopenia following clopidogrel administration previously safely exposed to this same drug. This reminds us that thrombocytopenia might be induced by clopidogrel even with a prior, safe history of long-term administration.

Aortic stenosis: An update

Aortic stenosis (AS) is the most common valvular heart disease in the world. It is a disease of the elderly and as our population is getting older in both the developed and the developing world, there has been an increase in the prevalence of AS. It is impacting the mortality and morbidity of our elderly population. It is also causing a huge burden on the healthcare system. There has been tremendous progress in our understanding of AS in recent years. Lately, studies have shown that AS is not just a disease of the aortic valve but it affects the entire systemic vasculature. There are studies looking at more sophisticated measures of disease severity that might better predict the optimal timing of valve replacement. The improvement in our understanding in etiology and pathophysiology of the disease process has led to a number of trials with possible treatment options for AS. In this review, we talk about our understanding of the disease and latest developments in disease assessment and management. We look forward to a time when there will be medical treatment for AS.

Regulatory role of mitochondria in oxidative stress and atherosclerosis

Mitochondrial physiology and biogenesis play a crucial role in the initiation and progression of cardiovascular disease following oxidative stress-induced damage such as atherosclerosis (AST). Dysfunctional mitochondria caused by an increase in mitochondrial reactive oxygen species (ROS) production, accumulation of mitochondrial DNA damage, and respiratory chain deficiency induces death of endothelial/smooth muscle cells and favors plaque formation/rupture via the regulation of mitochondrial biogenesis-related genes such as peroxisome proliferator-activated receptor γ coactivator (PGC-1), although more detailed mechanisms still need further study. Based on the effect of healthy mitochondria produced by mitochondrial biogenesis on decreasing ROS-mediated cell death and the recent finding that the regulation of PGC-1 involves mitochondrial fusion-related protein (mitofusin), we thus infer the regulatory role of mitochondrial fusion/fission balance in AST pathophysiology. In this review, the first section discusses the possible association between AST-inducing factors and the molecular regulatory mechanisms of mitochondrial biogenesis and dynamics, and explains the role of mitochondria-dependent regulation in cell apoptosis during AST development. Furthermore, nitric oxide has the Janus-faced effect by protecting vascular damage caused by AST while being a reactive nitrogen species (RNS) which act together with ROS to damage cells. Therefore, in the second section we discuss mitochondrial ATP-sensitive K(+) channels, which regulate mitochondrial ion transport to maintain mitochondrial physiology, involved in the regulation of ROS/RNS production and their influence on AST/cardiovascular diseases (CVD). Through this review, we can further appreciate the multi-regulatory functions of the mitochondria involved in AST development. The understanding of these related mechanisms will benefit drug development in treating AST/CVD through targeted biofunctions of mitochondria.

Efficacy and safety of valsartan plus hydroclorothiazide for high blood pressure

AIM

To evaluate efficacy and tolerability of the combination valsartan plus hydrochlorothiazide (160 mg and 25 mg daily, respectively) in young-middle aged males with high-normal blood pressure (BP) or first-degree arterial hypertension with evidence of target organ damage.

METHODS

Twenty males with high-normal BP or first-degree hypertension associated with left ventricular concentric remodeling and/or increased aortic stiffness were enrolled. BP at rest and during exercise, and echocardiographic parameters of the left ventricle (LV), were evaluated at baseline and after 3 mo of treatment. The effects of treatment on aortic stiffness, metabolic parameters, renal and erectile function were also assessed.

RESULTS

BP was significantly reduced by treatment both at rest (P < 0.001) and during exercise (P < 0.001), and 85% of patients achieved BP normalization (< 130/85 mmHg). Doppler echocardiography showed a significant reduction of LV mass (P < 0.005). LV hypertrophy was identified in 70% of subjects at baseline and in 5% after 3 mo of treatment. The ratio of early (E) to late (A) trans-mitral diastolic flow velocity increased, (P < 0.05), the relative wall thickness decreased (P < 0.05) and the left ventricular relaxation time shortened (P < 0.005). The left atrial diameter (P < 0.05) and the aortic diameter (P < 0.05) and stiffness (P < 0.005) also decreased.

CONCLUSION

The full-dose combination of valsartan plus hydrochlorothiazide produced optimal BP control with regression of target organ damage, already after 3 mo, without relevant side effects.

Acoustic cardiography to improve detection of coronary artery disease with stress testing

AIM

To assess if performance of 12-lead exercise tolerance testing (ETT) can be improved by simultaneous acoustic cardiography and to compare the diagnostic performances of electrocardiography (ECG) during ETT and acoustic cardiography for detection or exclusion of angiographically proven coronary artery disease (CAD).

METHODS

We conducted an explorative study with retrospective data analysis using a convenience sample of consecutive patients (n = 59, mean age: 62 years) from an outpatient clinic in Switzerland, who were referred for ETT by their general practitioner on suspicion of CAD, and in whom, coronary angiography was carried out. Measurements included sensitivity, specificity, likelihood ratios and receiver operating characteristic curves. A standard, symptom-limited, 12-lead ECG exercise tolerance test was performed by independent persons with simultaneous acoustic cardiography and subsequent cardiac angiography for determination of significant CAD.

RESULTS

Thirty-four of the 59 adult subjects (58%) had a final diagnosis of CAD by angiography, and in 25 subjects, CAD was excluded by angiography. Sensitivity/specificity of ST segment depression in the group was 29%/92%, whereas the most powerful acoustic cardiographic parameter was the strength of the fourth heart sound (S4), with corresponding sensitivity/specificity of 53%/92%. The disjunctive combination of the S4 and ST depression had sensitivity/specificity of 68%/84%.

CONCLUSION

In this preliminary pilot study, the use of acoustic cardiography alone during ETT or disjunctively with ST depression has been shown to be a simple and convenient method for the detection of CAD, which was superior to ST depression on the standardized ECG.

Heart regeneration: Past, present and future

The heart has been considered a post-mitotic organ without regenerative capacity for most of the last century. We review the evidence that led to this hypothesis in the early 1900s and how it was progressively modified, culminating with the report that we renew 50% of our cardiomyocytes during our lifetime. The future of cardiac regenerative therapies is discussed, presenting the difficulties to overcome before repair of the diseased heart can come into clinical practice.

Heart failure in subjects with chronic kidney disease: Best management practices

Renal dysfunction is common in patients with heart failure (HF) and can complicate HF therapy. Treating patients with HF and kidney disease is difficult and requires careful assessment, monitoring and balancing of risk between potential benefits of treatment and adverse impact on renal function. In this review, we address the pathophysiological contexts and management options in this adversarial relation between the heart and the kidney, which exists in a substantial proportion of HF patients. Angiotensin converting enzyme inhibitors and β-blockers are associated with similar reductions in mortality in patients with and without renal insufficiency but usually are less often prescribed in patients with renal insufficiency. Careful monitoring of side effects and renal function should be done in all patients with renal insufficiency and prompt measures should be adopted to prevent further complications.

Percutaneous coronary intervention for acute myocardial infarction in a patient with dextrocardia

Situs inversus with dextrocardia is a rare congenital anomaly. There are limited published case reports of successful percutaneous coronary intervention (PCI) in these patients who have atherosclerotic coronary artery disease, especially when presenting with acute myocardial infarction. PCI is technically difficult because of mirror image dextrocardia. We hereby describe a 48-yr-old female, who had acute inferior wall myocardial infarction and underwent successful emergency primary coronary angioplasty and stenting of a proximally occluded right coronary artery. Technical details about PCI are discussed.

Percutaneous coronary intervention for unprotected left main coronary artery stenosis

Hemodynamically significant left main coronary artery stenosis (LMCA) is found in around 4% of diagnostic coronary angiograms and is known as unprotected LMCA stenosis if the left coronary artery and left circumflex artery has no previous patent grafts. Previous randomized studies have demonstrated a significant reduction in mortality when revascularization by coronary artery bypass graft (CABG) surgery was undertaken compared with medical treatment. Therefore, current practice guidelines do not recommend percutaneous coronary intervention (PCI) for such a lesion because of the proven benefit of surgery and high rates of restenosis with the use of bare metal stents. However, with the advent of drug-eluting stents (DES), the long term outcomes of PCI with DES to treat unprotected LMCA stenoses have been acceptable. Therefore, apart from the current guidelines, PCI for treatment of unprotected LMCA stenosis is often undertaken in individuals who are at a very high risk of CABG or refuse to undergo a sternotomy. Future randomized studies comparing CABG vs PCI using DES for treatment of unprotected LMCA stenosis would be a great advance in clinical knowledge for the adoption of appropriate treatment.

Impaired diastolic function in naïve untreated human immunodeficiency virus infected patients

AIM

To evaluate cardiac function and structure in untreated human immunodeficiency virus (HIV) patients without clinical evidence of cardiovascular disease.

METHODS

Fifty-three naïve untreated HIV-infected patients and 56 healthy control subjects underwent clinical assessment, electrocardiography (ECG) and echocardiography, including tissue doppler imaging. Moreover, a set of laboratory parameters was obtained from all subjects, including HIV-RNA plasma levels, CD4 cell counts and tumor necrosis factor-α levels.

RESULTS

The two groups showed normal ECG traces and no differences regarding systolic morphologic parameters. In contrast, a higher prevalence of left ventricular diastolic dysfunction (abnormal relaxation or pseudonormal filling pattern) was found in the HIV patients (36% vs 9% in patients and controls, respectively, P <0.001).

CONCLUSION

Subclinical cardiac abnormalities appear in an early stage of the HIV infection, independent of antiretroviral therapy. The data suggest that HIV per se plays a role in the genesis of diastolic dysfunction.

Cardiovascular and metabolic effects of Berberine

Berberine (BBR) is a natural alkaloid isolated from the Coptis Chinensis. While this plant has been used in Ayurvedic and Chinese medicine for more than 2500 years, interest in its effects in metabolic and cardiovascular disease has been growing in the Western world in the last decade. Many papers have been published in these years reporting beneficial effects in carbohydrate and lipid metabolism, endothelial function and the cardiovascular system. In this review, we report a detailed analysis of the scientific literature regarding this topic, describing the effects and the underlying mechanisms of BBR on carbohydrate and lipid metabolism, endothelial function and the cardiovascular system.

Assessment of neovascularization within carotid plaques in patients with ischemic stroke

AIM

To assess neovascularization within human carotid atherosclerotic soft plaques in patients with ischemic stroke.

METHODS

Eighty-one patients with ischemic stroke and 95 patients without stroke who had soft atherosclerotic plaques in the internal carotid artery were studied. The thickest soft plaque in each patient was examined using contrast-enhanced ultrasound. Time-intensity curves were collected from 5 s to 3 min after contrast injection. The neovascularization within the plaques in the internal carotid artery was evaluated using the ACQ software built into the scanner by 2 of the experienced investigators who were blinded to the clinical history of the patients.

RESULTS

Ischemic stroke was present in 7 of 33 patients (21%) with grade I plaque, in 14 of 51 patients (28%) with grade II plaque, in 26 of 43 patients (61%) with grade III plaque, and in 34 of 49 patients (69%) with grade IV plaque (P < 0.001 comparing grade IV plaque with grade I plaque and with grade II plaque and P = 0.001 comparing grade III plaque with grade I plaque and with grade II plaque). Analysis of the time intensity curves revealed that patients with ischemic stroke had a significantly higher intensity of enhancement (IE) than those without ischemic stroke (P < 0.01). The wash-in time (WT) of plaque was significantly shorter in stroke patients (P < 0.05). The sensitivity and specificity for IE in the plaque were 82% and 80%, respectively, and for WT were 68% and 74%, respectively. There was no significant difference in the peak intensity or time to peak between the 2 groups.

CONCLUSION

This study shows that the higher the grade of plaque enhancement, the higher the risk of ischemic stroke. The data suggest that the presence of neovascularization is a marker for unstable plaque.

Long term combination treatment for severe idiopathic pulmonary arterial hypertension

We report the long-term follow-up of 3 cases of severe idiopathic pulmonary arterial hypertension, in whom tadalafil plus sitaxentan combination therapy improved the clinical condition and exercise performance without any relevant adverse event.

Heart and HAART: Two sides of the coin for HIV-associated cardiology issues

The introduction of highly active antiretroviral therapy (HAART) has generated a contrast in the cardiac manifestations of acquired immunodeficiency syndrome. In developed countries, we have observed an approximately 30% reduction in the prevalence of human immunodeficiency virus (HIV)-associated cardiomyopathy, possibly related to a reduction of opportunistic infections and myocarditis. In developing countries, however, where the availablity of HAART is limited and the pathogenic impact of nutritional factors is significant, we have observed an approximately 32% increase in the prevalence of HIV-associated cardiomyopathy and a related high mortality rate from congestive heart failure. Also, some HAART regimens in developed countries, especially those including protease inhibitors, have been shown to cause, in a high proportion of HIV-infected patients, an iatrogenic metabolic syndrome (HIV-lipodystrophy syndrome) that is associated with an increased risk of cardiovascular events related to a process of accelerated atherosclerosis, even in young HIV-infected people. Careful cardiac screening is warranted for patients who are being evaluated for, or who are receiving, HAART regimens, particularly for those with known underlying cardiovascular risk factors. A close collaboration between cardiologists and infectious disease specialists is needed for decisions regarding the use of antiretrovirals, for a careful stratification of cardiovascular risk factors, and for cardiovascular monitoring of HIV-infected patients receiving HAART, according the most recent clinical guidelines.

Antithrombotic management of patients on oral anticoagulation undergoing coronary artery stenting

Patients on oral anticoagulation (OAC), who are referred for coronary artery stenting account for about 5% of the whole population undergoing percutaneous coronary intervention (PCI). Although relatively small, this patient subset poses particular problems owing to the need to balance carefully the risk of bleeding against the risk of stent thrombosis and thromboembolism. Triple therapy (TT) of OAC, aspirin and clopidogrel appears as the most effective for prevention of stent thrombosis and thromboembolism. However, an increased incidence of major bleeding is to be expected during follow-up. Therefore, TT should be prolonged for as short a time as possible, and implantation of drug-eluting stents avoided. Frequent monitoring of international normalized ratio is also warranted, and the intensity of OAC should be targeted at the lower limit of the therapeutic range. Gastric protection should also be considered for all patients on medium- to long-term TT, owing to the observed highest incidence of bleeding at the gastrointestinal site. Peri-procedural management is cumbersome, and a substantial incidence of in-hospital major bleeding has been reported. Since this latter is more related to procedural variables than to TT itself, choice of radial access, avoidance of glycoprotein IIb/IIIa inhibitors, and preference for not interrupting effective OAC should be implemented. However, the evidence on which the recommendations for managing this patient subset are based is limited and of relative poor quality. While waiting for the results of ongoing, large prospective studies that are aimed at conclusively determining optimal medium- to long-term antithrombotic treatment, the official recommendations issued by the Working Group on Thrombosis of the European Society of Cardiology on the management of patients on OAC undergoing PCI with stenting should followed.

Need for new materials, biofunctionalization and non-surgical heart valve technology

Transition from non-surgical heart valve defects repair from bench to bedside is a reality. Some biological material-based designs for transcatheter aortic valve implantation are ready for use. Their drawback, however is their unknown functional as well as structural durability. Moreover, research on new non-biological materials is essential to replace classical animal-derived sources of human heart valve prostheses.