Association of ischemia-modified albumin and melatonin in patients with ST-elevation myocardial infarction

Diagnostic Accuracy of Ischemia-Modified Albumin for Acute Coronary Syndrome: A Systematic Review and Meta-Analysis

The diagnostic usefulness of ischemia-modified albumin in acute coronary syndrome (ACS) has been questioned. The goal of this systematic review and meta-analysis was to see how accurate ischemia-modified albumin (IMA) was in diagnosing ACS in patients admitted to emergency departments (EDs). We searched for relevant literature in databases such as MEDLINE, EMBASE, and the Cochrane Library. Primary studies that reliably reported on patients with symptoms suggestive of ACS and evaluated IMA on admission to emergency departments were included. The QUADAS-2 tool was used to assess the risk of bias in the included research. A total of 4,761 patients from 19 studies were included in this systematic review. The sensitivity and specificity were 0.74 and 0.40, respectively, when the data were pooled. The area under the curve value for IMA for the diagnosis of ACS was 0.75, and the pooled diagnostic odds ratio value was 3.72. Furthermore, ACS patients with unstable angina had greater serum IMA levels than those with non-ischemic chest pain. In contrast to prior meta-analyses, our findings suggest that determining whether serum IMA levels are effective for diagnosing ACS in the emergency department is difficult. However, the accuracy of these findings cannot be ascertained due to high heterogeneity between studies.

Novel Combined Antioxidant Strategy against Hypertension, Acute Myocardial Infarction and Postoperative Atrial Fibrillation

Reactive oxygen species (ROS) play a physiological role in the modulation of several functions of the vascular wall; however, increased ROS have detrimental effects. Hence, oxidative stress has pathophysiological impacts on the control of the vascular tone and cardiac functions. Recent experimental studies reported the involvement of increased ROS in the mechanism of hypertension, as this disorder associates with increased production of pro-oxidants and decreased bioavailability of antioxidants. In addition, increased ROS exposure is found in ischemia-reperfusion, occurring in acute myocardial infarction and cardiac surgery with extracorporeal circulation, among other settings. Although these effects cause major heart damage, at present, there is no available treatment. Therefore, it should be expected that antioxidants counteract the oxidative processes, thereby being suitable against cardiovascular disease. Nevertheless, although numerous experimental studies agree with this notion, interventional trials have provided mixed results. A better knowledge of ROS modulation and their specific interaction with the molecular targets should contribute to the development of novel multitarget antioxidant effective therapeutic strategies. The complex multifactorial nature of hypertension, acute myocardial infarction, and postoperative atrial fibrillation needs a multitarget antioxidant strategy, which may give rise to additive or synergic protective effects to achieve optimal cardioprotection.

Melatonin and Cardioprotection in Humans: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Myocardial ischemia/reperfusion (IR) injury represents a critical problem associated with interventional approaches for coronary reperfusion. Pharmacological cardioprotective interventions are advocated to ameliorate IR injury. Melatonin is an anti-inflammatory and antioxidant agent with a wide range of therapeutic properties that may contribute to its cardioprotective effects. No systematic review or meta-analysis has compared melatonin vs. placebo as a cardioprotective agent in humans. The present study, based on a systematic review and meta-analysis, was carried out to assess melatonin's efficacy as a cardioprotective treatment. We performed a systematic review of the available literature. Randomized controlled trials (RCTs) were identified and information was extracted using predefined data extraction forms. The primary outcomes were (a) left ventricular ejection fraction (LVEF) and (b) blood troponin levels in patients who underwent myocardial revascularization and were randomized to melatonin or placebo. The inverse-variance random-effects method was used to pool the estimates. Heterogeneity and publication bias were assessed. Weighted mean differences or standardized mean differences were calculated. A total of 283 records were screened and seven RCTs met all the inclusion criteria. After the pooled analysis, the results on LVEF were consistent across all studies, and a significant heterogeneity was found in the results on troponin levels. The melatonin-treated patients had on average higher LVEF than the placebo-treated individuals with a weighted mean difference = 3.1% (95% CI 0.6-5.5, p = 0.01). Five works compared the levels of troponin after melatonin or placebo treatment. The melatonin-treated patients had lower levels of troponin with a standardized mean difference = -1.76 (95% CI -2.85 to -0.67, p = 0.002). The findings of this meta-analysis revealed that melatonin administration in humans as a cardioprotective agent attenuated heart dysfunction with a favorable effect on the LVEF.

Targeting Host Defense System and Rescuing Compromised Mitochondria to Increase Tolerance against Pathogens by Melatonin May Impact Outcome of Deadly Virus Infection Pertinent to COVID-19

Fighting infectious diseases, particularly viral infections, is a demanding task for human health. Targeting the pathogens or targeting the host are different strategies, but with an identical purpose, i.e., to curb the pathogen's spreading and cure the illness. It appears that targeting a host to increase tolerance against pathogens can be of substantial advantage and is a strategy used in evolution. Practically, it has a broader protective spectrum than that of only targeting the specific pathogens, which differ in terms of susceptibility. Methods for host targeting applied in one pandemic can even be effective for upcoming pandemics with different pathogens. This is even more urgent if we consider the possible concomitance of two respiratory diseases with potential multi-organ afflictions such as Coronavirus disease 2019 (COVID-19) and seasonal flu. Melatonin is a molecule that can enhance the host's tolerance against pathogen invasions. Due to its antioxidant, anti-inflammatory, and immunoregulatory activities, melatonin has the capacity to reduce the severity and mortality of deadly virus infections including COVID-19. Melatonin is synthesized and functions in mitochondria, which play a critical role in viral infections. Not surprisingly, melatonin synthesis can become a target of viral strategies that manipulate the mitochondrial status. For example, a viral infection can switch energy metabolism from respiration to widely anaerobic glycolysis even if plenty of oxygen is available (the Warburg effect) when the host cell cannot generate acetyl-coenzyme A, a metabolite required for melatonin biosynthesis. Under some conditions, including aging, gender, predisposed health conditions, already compromised mitochondria, when exposed to further viral challenges, lose their capacity for producing sufficient amounts of melatonin. This leads to a reduced support of mitochondrial functions and makes these individuals more vulnerable to infectious diseases. Thus, the maintenance of mitochondrial function by melatonin supplementation can be expected to generate beneficial effects on the outcome of viral infectious diseases, particularly COVID-19.

Melatonin Plays a Critical Protective Role in Nicotine-Related Abdominal Aortic Aneurysm

Aim: Smoking is a major risk factor for abdominal aortic aneurysm (AAA). Among the components of smoke, nicotine is known to exert pro-atherosclerotic, prothrombotic, and proangiogenic effects on vascular smooth muscle cells (VSMCs). The current study was designed to investigate the mechanisms through which nicotine induces vascular wall dysfunction and to examine whether melatonin protects against nicotine-related AAA. Methods: In this study, an enzyme-linked immunosorbent assay (ELISA) was used to measure melatonin and TNF-α levels, as well as total antioxidant status (TAS), in patients with AAA. We established a nicotine-related AAA model and explored the mechanisms underlying the therapeutic effects of melatonin. Tissue histopathology was used to assess vascular function, while western blotting (WB) and immunofluorescence staining were performed to detect protein expression. Results: We observed melatonin insufficiency in the serum from patients with AAA, particularly smokers. Moreover, melatonin level was positively correlated with antioxidant capacity. In the in vivo model, nicotine accelerated AAA expansion and destroyed vascular structure. Furthermore, OPN, LC3II, p62, matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), NF-κB p65, TNF-α, phosphorylated AKT, and phosphorylated mTOR levels were increased, in vivo, following nicotine treatment, while SM22α and α-SMA levels were reduced. Additionally, melatonin attenuated the effects of nicotine on AAA and reversed changes in protein expression. Moreover, melatonin lost its protective effects following bafilomycin A1-mediated inhibition of autophagy. Conclusion: Based on our data, melatonin exerts a beneficial effect on rats with nicotine-related AAA by downregulating the AKT-mTOR signaling pathway, improving autophagy dysfunction, and restoring the VSMC phenotype.

Ischemia modified albumin (IMA) in acute coronary syndrome (ACS) and left bundle branch block (LBBB). Does it make the difference?

BACKGROUND

Management of patients with a suspected ACS and LBBB is a challenge to the clinician.

AIM

To detect the ability of IMA to exclude myocardial ischemia in suspected patients with ACS and LBBB.

MATERIAL AND METHODS

A total of 68 patients with suspected ACS and LBBB (group I) and another twenty patients age and sex matched known to have LBBB with normal coronary angiography (group II) were included in this study and subjected to: routine laboratory tests, 12 lead ECG, echocardiography, and measurement of serum troponin I (TnI) and IMA (measured by ELISA). Diagnostic coronary angiography was performed on all patients and scored by severity and modified Gensini scores.

RESULTS

IMA and TnI levels are significantly increased in group I compared to group II (P value <0.001). IMA with a cutoff value >95 could predict significant CAD (lesions >50%) with AUC of 0.923, sensitivity of 88%, specificity of 83.33%, PPV of 93.6%, NPV of 71.4% and accuracy 86.76%. Moreover, by using both simple and multiple logistic regression analyses IMA could also independently detect significant CAD. The combined use of IMA and TnI significantly improved the sensitivity and the negative predictive value to 98% and 90.9% respectively.

CONCLUSION

There was a distinct advantage of measuring IMA in patients presenting to the emergency department with acute chest pain and LBBB to rule out a final diagnosis of ACS.

Evaluation of Oxidative Stress in Women with Polycystic Ovarian Syndrome as Represented by Serum Ischemia Modified Albumin and Its Correlation with Testosterone and Insulin Resistance

Objective Ischemia-mediated oxidative stress and inflammation have been reported to be important contributors to the pathogenesis of polycystic ovary syndrome (PCOS). Ischemia-modified albumin (IMA) is a novel marker generated under ischemic and oxidative conditions and may reflect disease activity in distinct disease states. Therefore, we investigated whether the serum IMA levels are affected in infertile PCOS patients. Methods Forty-six patients with infertile PCOS, 30 patients with unexplained infertility, and 31 age- and body mass index (BMI)-matched controls were included in this cross-sectional study. Biochemical parameters, serum IMA levels, and their correlations with serum testosterone and insulin resistance were determined for each subject. Results In patients with infertile PCOS, the serum IMA levels were significantly elevated (p=0.003) compared with unexplained infertility patients and controls. A correlation analysis suggested that the IMA levels only correlated with the serum free testosterone levels in PCOS patients (r=0.43, p=0.028). Conclusion Elevations in the serum IMA levels in infertile PCOS patients may suggest a possible additional role of oxidative stress mechanisms in disease pathophysiology. Moreover, correlation between serum IMA and testosterone levels may influence the quality of oocytes via alterations in the balance of critical follicular fluid factors in the follicular microenvironment.

Melatonin as a preventive and curative therapy against pulmonary hypertension

Pulmonary hypertension (PH) is characterized by elevated pulmonary arterial pressure, which leads to right ventricular (RV) hypertrophy and failure. The pathophysiological mechanisms of PH remain unclear but oxidative stress is believed to contribute to RV dysfunction. Melatonin is a powerful antioxidant and is cardioprotective against ischemia-reperfusion injury and hypertension. Therefore, we hypothesized that a chronic treatment with melatonin, given as a curative or preventive therapy, may confer cardiovascular benefits in PH. PH was induced in Long Evans rats (n ≥ 6 per group), with a single subcutaneous injection of monocrotaline (MCT, 80 mg/kg). Melatonin was given daily in the drinking water, with the treatment starting either on the day of the injection of MCT (dose testing: melatonin 75 ng/L and 6 mg/kg), 14 days after the injection of MCT (curative treatment: 6 mg/kg), or 5 days before the injection (preventive treatment: 6 mg/kg). The development of PH was assessed by measuring RV hypertrophy, RV function, cardiac interstitial fibrosis, and plasma oxidative stress. Compared with controls, MCT-treated rats displayed RV hypertrophy and dysfunction, increased interstitial fibrosis, and elevated plasma oxidative stress. A chronic melatonin treatment (75 ng/L or 6 mg/kg) reduced RV hypertrophy, improved RV function and reduced plasma oxidative stress. Curative and preventive treatment improved RV functional and plasma oxidative stress parameters and reduced cardiac interstitial fibrosis. Our data demonstrate that melatonin confers cardioprotection in this model of PH. As melatonin is an inexpensive and safe drug, we propose that clinical investigation of the effects of melatonin on RV function in patients with PH should be considered.

A preliminary study on the relationships between diurnal melatonin secretion profile and sleep variables in patients emergently admitted to the coronary care unit

To clarify the significance of melatonin secretion under intensive care conditions, we investigated melatonin secretion profiles and sleep parameters of 23 patients just after admission to the coronary care unit (CCU) and 19 age-matched controls. Sleep parameters were evaluated by actigraphy, and melatonin secretion was assessed by measuring the urinary 6-sulphatoxy melatonin (6-SMT). 6-SMT secretion was lower and nocturnal sleep parameters were less satisfactory in the subjects than those in the controls, and there were positive correlations between these variables, particularly in the subject patients. The lowered melatonin secretion might be involved in the mechanism of insomnia in CCU patients.

A review of melatonin as a suitable antioxidant against myocardial ischemia-reperfusion injury and clinical heart diseases

Cardiac tissue loss is one of the most important factors leading to the unsatisfactory recovery even after treatment of ischemic heart disease. Melatonin, a circadian molecule with marked antioxidant properties, protects against ischemia-reperfusion (IR) injury. In particular, the myocardial protection of melatonin is substantial. We initially focus on the cardioprotective effects of melatonin in myocardial IR. These studies showed how melatonin preserves the microstructure of the cardiomyocyte and reduces myocardial IR injury. Thereafter, downstream signaling pathways of melatonin were summarized including Janus kinase 2/signal transducers and activators of transcription 3, nitric oxide-synthase, and nuclear factor erythroid 2 related factor 2. Herein, we propose the clinical applications of melatonin in several ischemic heart diseases. Collectively, the information summarized in this review (based on in vitro, animal, and human studies) should serve as a comprehensive reference for the action of melatonin in cardioprotection and hopefully will contribute to the design of future experimental research.

ST elevation myocardial infarction: recent advances and updates

ST elevation myocardial infarction (STEMI) remains a leading cause of morbidity, mortality and disability worldwide. Statistically, a trend towards improvements in morbidity and mortality has been consistent over the years, which is attributed primarily to the modification of risk factors, healthier lifestyles, treatment advances and better management of door-to-balloon times via STEMI systems. However, a major challenge in the coming years will be the baby boomers (born between the years 1946 and 1964) coming into old age. The first baby boomers turned 65 in year 2011. As the baby boomers age in the coming years, the incidence of coronary heart disease is likely to increase, and so there will be a greater need to have major advances in the management of coronary heart disease in order to deal with this additional incidence. The scope of this article is to review recent advances in the management of STEMI and to provide an updated overview.

Alterations in the time course of expression of the Nox family in the brain in a rat experimental cerebral ischemia and reperfusion model: effects of melatonin

Ischemia-reperfusion (I/R) injury induces the generation of reactive oxygen species (ROS), which results in a poor prognosis for ischemic stroke patients. This study was designed to evaluate the time course of expression of the Nox family, a major source of ROS, and whether melatonin, a potent scavenger of ROS, influences these parameters in a rat model of cerebral I/R caused by middle cerebral artery occlusion (MCAO). After 2-hr occlusion, the filament was withdrawn to allow reperfusion. At 0, 3, 6, 12, 24, and 48 hr after reperfusion, brain tissue samples were obtained for assays. Among the Nox family, the mRNA and protein levels of Nox2 and Nox4 were increased both in the ischemic hemisphere and contralateral counterpart in the experimental I/R rats at 0 hr after reperfusion, peaked at 3 hr, and then returned to the basal level at 24 hr. Double-immunofluorescence staining further confirmed the expressions of Nox2 and Nox4 in three major types of brain cells, including neurons, astrocytes, and endothelial cells. In addition, melatonin (5 mg/kg) or its vehicle was injected intraperitoneally at 0.5 hr before MCAO. Compared with I/R + vehicle group, melatonin pretreatment diminished the increased expression of Nox2 and Nox4, reduced ROS levels, and inhibited cell apoptosis. Our findings suggested that the inhibition of Nox2 and Nox4 expressions by melatonin may essentially contribute to its antioxidant and anti-apoptotic effects during brain I/R.

Novel therapeutic strategies for cardioprotection

The morbidity and mortality from ischemic heart disease (IHD) remain significant worldwide. The treatment for acute myocardial infarction has improved over the past decades, including early reperfusion of occluded coronary arteries. Although it is essential to re-open the artery as soon as possible, paradoxically this leads to additional myocardial injury, called acute ischemia-reperfusion injury (IRI), for which currently no effective therapy is available. Therefore, novel therapeutic strategies are required to protect the heart from acute IRI in order to reduce myocardial infarction size, preserve cardiac function and improve clinical outcomes in patients with IHD. In this review article, we will first outline the pathophysiology of acute IRI and review promising therapeutic strategies for cardioprotection. These include novel aspects of mitochondrial function, epigenetics, circadian clocks, the immune system, microvesicles, growth factors, stem cell therapy and gene therapy. We discuss the therapeutic potential of these novel cardioprotective strategies in terms of pharmacological targeting and clinical application.

Urine 6-sulfatoxymelatonin levels are inversely associated with arterial stiffness in post-menopausal women

OBJECT

The secretion of melatonin, a pleiotropic hormone mainly synthesized by the pineal gland, typically decreases with age and may be associated with the development of aging-related pathologic conditions such as cardiovascular disease. Atherosclerosis is an aging-related disease, the pathogenesis of which involves chronic inflammation and increased oxidative stress. Since melatonin has both anti-oxidant and anti-inflammatory properties, it may be associated with atherosclerosis. Therefore, we investigated the relationship between urine concentrations of 6-sulfatoxymelatonin (aMT6s) and arterial stiffness in post-menopausal women.

METHODS

A total of 66 post-menopausal women participated in the study. Melatonin secretion was estimated by measuring aMT6s levels in first morning urine samples. The cardio-ankle vascular index (CAVI) was used as an indicator of arterial stiffness.

RESULTS

Estimated mean CAVI decreased gradually with increasing aMT6s quartiles. The multivariate logistic regression analysis showed that the fourth aMT6s quartile was associated with a high CAVI with an adjusted odds ratio of 0.03 (95% confidence interval, 0.01-0.47).

CONCLUSION

Our study revealed an inverse relationship between urine aMT6s and arterial stiffness as determined by CAVI. Although it is impossible to determine causality, our results suggest that melatonin may have a beneficial role in the pathogenesis of atherosclerosis. Further prospective studies are required to establish the clinical significance of our study.

Cardioprotection and pharmacological therapies in acute myocardial infarction: Challenges in the current era

In patients with an acute ST-segment elevation myocardial infarction, timely myocardial reperfusion using primary percutaneous coronary intervention is the most effective therapy for limiting myocardial infarct size, preserving left-ventricular systolic function and reducing the onset of heart failure. Within minutes after the restoration of blood flow, however, reperfusion itself results in additional damage, also known as myocardial ischemia-reperfusion injury. An improved understanding of the pathophysiological mechanisms underlying reperfusion injury has resulted in the identification of several promising pharmacological (cyclosporin-A, exenatide, glucose-insulin-potassium, atrial natriuretic peptide, adenosine, abciximab, erythropoietin, metoprolol and melatonin) therapeutic strategies for reducing the severity of myocardial reperfusion injury. Many of these agents have shown promise in initial proof-of-principle clinical studies. In this article, we review the pathophysiology underlying myocardial reperfusion injury and highlight the potential pharmacological interventions which could be used in the future to prevent reperfusion injury and improve clinical outcomes in patients with coronary heart disease.

Melatonin ameliorates angiotensin II-induced vascular endothelial damage via its antioxidative properties

Melatonin is well known to have a beneficial effect on the cardiovascular system, but it remains to be elucidated whether melatonin has a therapeutic effect on the vascular damage induced by the potential vasoactive substance angiotensin II (Ang II). In this study, the effects of melatonin on Ang II-induced vascular endothelial damage were investigated. In cultured vascular endothelial cells, Ang II stimulation increased ROS generation and inhibited eNOS phosphorylation (Ser1177), both of which were clearly restored by pretreatment with melatonin. The translocation of p47(phox) subunit of NADPH oxidase from the cytosol to plasma membrane was promoted in Ang II-treated vascular endothelial cells, which was canceled by melatonin pretreatment. In Ang II-infused rats, increased ROS generation in the aortic wall and impaired endothelial function of the aortic ring were observed, which were rescued by coadministration of melatonin. In vasculature, melatonin receptor agonist ramelteon had the antioxidative effect in the same manner as melatonin by itself. These findings suggest that melatonin directly ameliorates Ang II-induced vascular endothelial damage partly via its antioxidative properties, providing with us the potential rationale for clinical application of melatonin to the prevention from cardiovascular diseases.

The clinical assessment of ischaemia modified albumin and troponin I in the early diagnosis of the acute coronary syndrome

BACKGROUND

An early identification of the patients with the Acute Coronary Syndrome (ACS) is of prime importance, due to the associated very high mortality. Only about 22% of the patients who present at the emergency cardiology care centres with chest pain, have coronary disease. Ischaemia modified albumin has already been licensed by the US Food and Drug Administration for the diagnosis of suspected myocardial ischaemia.

AIM

The goal of the present study was to assess the diagnostic value of serum ischaemia modified albumin and to compare it with sensitive cardiac troponin I in patients with the acute coronary syndromes like unstable angina and acute myocardial infarction.

METHODS

A diagnostic case control study was conducted on 102 patients who presented to the Emergency Department within 6 hrs of having acute chest pain and on 110 healthy age and sex matched volunteers who formed the control group. The serum Ischaemia Modified Albumin level was estimated by the albumin cobalt binding test by using a digital spectrophotometer, while Troponin I was measured by doing an immunofluroscence assay. A receiver operating characteristic curve was established for ischaemia modified albumin, to determine the cut-off point. The sensitivity and the specificity of ischaemia modified albumin and troponin I for the detection of acute coronary syndromes, were analyzed. The results of ischaemia modified albumin and troponin I alone and in combination, were correlated.

RESULTS

The ischaemia modified albumin (p<0.05) and the troponin I (p<0.001) concentrations were significantly higher in acute myocardial infarction and in unstable angina than in the healthy controls. The sensitivity and the specificity of ischaemia modified albumin for the detection of acute coronary syndromes was 88% and 93% as compared to 87% and 75% respectively for troponin I. The combined use of ischaemia modified albumin and troponin I significantly enhanced the sensitivity to 96%. The area which was under the Receiver Operating Characteristic (ROC) curve of ischaemia modified albumin in acute coronary syndromes was 0.90.

CONCLUSION

Ischaemia modified albumin is a useful biochemical marker for the early diagnosis of acute coronary syndrome. The combined use of ischaemia modified albumin and cardiac troponin I enhances the sensitivity and specificity. Hence, a combination of ischaemia modified albumin and cardiac troponin I can be used as a more precise diagnostic marker for Acute Coronary Syndrome.

Decreased level of melatonin in serum predicts left ventricular remodelling after acute myocardial infarction

As experimental studies suggest that melatonin is cardioprotective after myocardial infarction (MI), this study sought to investigate the relationships between circulating levels of melatonin and left ventricular (LV) remodelling in patients after acute MI. This prospective study included 161 patients (age 61±3yr; 78% men) undergoing primary percutaneous coronary intervention who were assessed echocardiographically at hospital discharge (day 3-7) and at 12 months. LV remodelling was defined as >20% increase in LV end-diastolic volume at 12-month follow-up compared with baseline. Serum melatonin concentrations were measured at admission, during the light period. Twenty-four patients showed LV remodelling, and 137 had no evidence of LV remodelling. Patients with LV remodelling had lower levels of melatonin at study entry [9.96 (8.28-11.03) versus 16.74 (13.77-19.59) pg/mL, respectively; P <0.0001]. Multivariate analysis showed that melatonin levels (OR=2.10, CI 95% 1.547-2.870, P<0.001) were an independent predictor of LV remodelling at 12-month follow-up. Receiver operating characteristic (ROC) analysis showed an area under the curve of 0.959 (CI 95% 0.93-0.98; P<0.0001). To our knowledge, this is the first study to show the relationship between melatonin and LV remodelling during the chronic phase post-MI.

Cardiovascular effects of melatonin receptor agonists

INTRODUCTION

Melatonin synchronizes circadian rhythms with light/dark period and it was demonstrated to correct chronodisruption. Several melatonin receptor agonists with improved pharmacokinetics or increased receptor affinity are being developed, three of them are already in clinical use. However, the actions of melatonin extend beyond chronobiology to cardiovascular and metabolic systems as well. Given the high prevalence of cardiovascular disease and their common occurrence with chronodisruption, it is of utmost importance to classify the cardiometabolic effects of the newly approved and putative melatoninergic drugs.

AREAS COVERED

In the present review, the available (although very sparse) data on such effects, in particular by the approved (circadin, ramelteon, agomelatine) or clinically advanced (tasimelteon, piromelatine = Neu-P11, TIK-301) compounds are summarized. The authors have searched for an association with blood pressure, vascular reactivity, ischemia, myocardial and vascular remodeling and metabolic syndrome.

EXPERT OPINION

The data suggest that cardiovascular effects of melatonin are at least partly mediated via MT(1)/MT(2) receptors and associated with its chronobiotic action. Therefore, despite the sparse direct evidence, it is believed that these effects will be shared by melatonin analogs as well. With the expected approval of novel melatoninergic compounds, it is suggested that the investigation of their cardiovascular effects should no longer be neglected.

Usefulness of intraplatelet melatonin levels to predict angiographic no-reflow after primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction

Platelet aggregates appear to have a pathogenic role in the no-reflow phenomenon, which is associated with impaired clinical outcome in patients with ST-segment elevation myocardial infarction (STEMI). Melatonin, a hormone that plays a major role in biological circadian rhythms, is present in human platelets. Lowered circulating melatonin levels predict poor outcome in patients with STEMI undergoing primary percutaneous coronary intervention (PPCI). We investigated whether intraplatelet melatonin levels correlate with angiographic no-reflow after PPCI in patients with STEMI. We studied 180 consecutive patients with a first STEMI who underwent PPCI within 6 hours from onset of symptoms. Intraplatelet melatonin levels were measured in platelet-rich plasma using an enzymatic immunoassay method. After PPCI, angiographic no-reflow (defined as Thrombolysis In Myocardial Infarction grade < 2 flow) was observed in 63 patients (35%). Patients with angiographic no-reflow had lower intraplatelet melatonin levels compared to patients without no-reflow (12.32 ± 3.64 vs 18.62 ± 3.88 ng/100,000 platelets, p < 0.0001). After adjusting by potential confounders, binary logistic regression analysis showed that intraplatelet melatonin levels were the only significant predictor of angiographic no-reflow (odds ratio 1.58, 95% confidence interval 1.37 to 1.82, p < 0.0001). In conclusion, low intraplatelet melatonin concentration predicts angiographic no-reflow after PPCI in patients with STEMI.

Current role of ischemia-modified albumin in routine clinical practice

BACKGROUND

Ischemia-modified albumin has been proposed as a useful rule-out marker for the diagnosis of acute coronary syndrome in the emergency department.

OBJECTIVE

To perform a review of ischemia-modified albumin use in the clinical practice.

METHODS

We performed a comprehensive literature search by using electronic bibliographic databases.

CONCLUSION

Although the main limitation of ischemia-modified albumin at present is its low specificity, it may be a useful test to rule out acute coronary syndrome from low to moderate pre-test probability conditions with negative cardiac troponins and a negative ECG.

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.

Melatonin and circadian biology in human cardiovascular disease

Diurnal rhythms influence cardiovascular physiology, i.e. heart rate and blood pressure, and they appear to also modulate the incidence of serious adverse cardiac events. Diurnal variations occur also at the molecular level including changes in gene expression in the heart and blood vessels. Moreover, the risk/benefit ratio of some therapeutic strategies and the concentration of circulating cardiovascular system biomarkers may also vary across the 24-hr light/dark cycle. Synchrony between external and internal diurnal rhythms and harmony among molecular rhythms within the cell are essential for normal organ biology. Diurnal variations in the responsiveness of the cardiovascular system to environmental stimuli are mediated by a complex interplay between extracellular (i.e. neurohumoral factors) and intracellular (i.e. specific genes that are differentially light/dark regulated) mechanisms. Neurohormones, which are particularly relevant to the cardiovascular system, such as melatonin, exhibit a diurnal variation and may play a role in the synchronization of molecular circadian clocks in the peripheral tissue and the suprachiasmatic nucleus. Moreover, mounting evidence reveals that the blood melatonin rhythm has a crucial role in several cardiovascular functions, including daily variations in blood pressure. Melatonin has antioxidant, anti-inflammatory, chronobiotic and, possibly, epigenetic regulatory functions. This article reviews current knowledge related to the biological role of melatonin and its circadian rhythm in cardiovascular disease.