B Type natriuretic peptide: a good omen in myocardial ischaemia?

Brain Natriuretic Peptide Protects Cardiomyocytes from Apoptosis and Stimulates Their Cell Cycle Re-Entry in Mouse Infarcted Hearts

Brain Natriuretic Peptide (BNP) supplementation after infarction increases heart function and decreases heart remodeling. BNP receptors, NPR-A and NPR-B are expressed on adult cardiomyocytes (CMs). We investigated whether a part of the BNP cardioprotective effect in infarcted and unmanipulated hearts is due to modulation of the CM fate. For this purpose, infarcted adult male mice were intraperitoneally injected every two days during 2 weeks with BNP or saline. Mice were sacrificed 1 and 14 days after surgery. BNP or saline was also injected intraperitoneally every two days into neonatal pups (3 days after birth) for 10 days and in unmanipulated 8-week-old male mice for 2 weeks. At sacrifice, CMs were isolated, counted, measured, and characterized by qRT-PCR. The proportion of mononucleated CMs was determined. Immunostainings aimed to detect CM re-entry in the cell cycle were performed on the different hearts. Finally, the signaling pathway activated by BNP treatment was identified in in vitro BNP-treated adult CMs and in CMs isolated from BNP-treated hearts. An increased number of CMs was detected in the hypoxic area of infarcted hearts, and in unmanipulated neonatal and adult hearts after BNP treatment. Accordingly, Troponin T plasma concentration was significantly reduced 1 and 3 days after infarction in BNP-treated mice, demonstrating less CM death. Furthermore, higher number of small, dedifferentiated and mononucleated CMs were identified in adult BNP-treated hearts when compared to saline-treated hearts. BNP-treated CMs express higher levels of mRNAs coding for hif1 alpha and for the different cyclins than CMs isolated from saline-treated hearts. Higher percentages of CMs undergoing DNA synthesis, expressing Ki67, phospho histone3 and Aurora B were detected in all BNP-treated hearts, demonstrating that CMs re-enter into the cell cycle. BNP effect on adult CMs in vivo is mediated by NPR-A binding and activation of the ERK MAP kinase pathway. Interestingly, an increased number of CMs was also detected in adult infarcted hearts treated with LCZ696, an inhibitor of the natriuretic peptide degradation. Altogether, our results identified BNP and all therapies aimed to increase BNP's bioavailability as new cardioprotective targets as BNP treatment leads to an increased number of CMs in neonatal, adult unmanipulated and infarcted hearts.

Association of Systemic Trimethyllysine With Heart Failure With Preserved Ejection Fraction and Cardiovascular Events

CONTEXT

Carnitine has been associated with cardiac energy metabolism and heart failure, but the association between its precursors-trimethyllysine (TML) and γ-butyrobetaine (GBB)-and heart failure with preserved ejection fraction (HFpEF) remains unclear.

OBJECTIVE

To evaluate the relationship between TML-related metabolites and HFpEF in an Asian population.

METHODS

The cross-sectional component of this study examined the association between plasma TML-related metabolites and HFpEF, while a prospective cohort design was applied to examine the association with incident cardiovascular events in HFpEF. Included in the study were 1000 individuals who did not have heart failure (non-HF) and 1413 patients with HFpEF. Liquid chromatography mass spectrometry was used to assess plasma carnitine, GBB, TML and trimethylamine-N-oxide (TMAO) concentrations.

RESULTS

Plasma GBB and TML were both elevated in patients with HFpEF. After adjusting for traditional risk factors and renal function, TML, but not GBB, was significantly associated with HFpEF. The odds ratio (OR) for the fourth vs first quartile of TML was 1.57 (95% CI 1.09-2.27; P-trend < .01). The OR for each SD increment of log-TML was 1.26 (95% CI 1.08-1.47). Plasma TMAO (P-interaction = 0.024) and estimated glomerular filtration rate (P-interaction = 0.024) modified the TML-HFpEF association. The addition of TML improved the diagnostic value under the multivariable model. In the prospective study of patients with HFpEF, higher plasma TML was associated with increased risk of cardiovascular events.

CONCLUSION

Plasma TML concentrations are positively associated with HFpEF, and higher plasma TML indicates increased risk of cardiovascular events.

Comparison of ANP and BNP Granular Density in Atria of Rats After Physiological and Pathological Hypertrophy

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are cardiac hormones located in atria granules. Both peptides respond to cardiac pressure and volume dynamics and accordingly serve as translation biomarkers for the clinical treatment of heart failure. Serum ANP and BNP play central secretary roles in blood pressure and cardiac output regulation and have proven utility as differential biomarkers of cardiovascular proficiency and drug-induced maladaptation, yet both peptides are impervious to exercise-induced hypertrophy. We employed immunoelectron microscopy to examine the effects of 28 days of chronic swim exercise or administration of a PPARγ agonist on atrial granules and their stored natriuretic peptides in Sprague Dawley rats. Chronic swimming and drug treatment both resulted in a 15% increase in heart weight compared with controls, with no treatment effects on perinuclear granule area in the left atria (LAs). Drug treatment resulted in larger size granules with greater BNP density in the right atria. Comparing swimming and PPARγ agonist treatment effects on ANP:BNP granule density ratios between atrial chambers revealed a shift toward a greater proportion of ANP than BNP in LAs of swim-trained rats. These data suggest a distinction in the population of ANP and BNP after chronic swim or PPARγ that makes it a novel metric for the differentiation of pathological and physiological hypertrophy.

Centella asiatica (L.) Urb. Prevents Hypertension and Protects the Heart in Chronic Nitric Oxide Deficiency Rat Model

Background: Hypertension is a major risk factor for cardiovascular disease (CVD), which is the number one cause of global mortality. The potential use of natural products to alleviate high blood pressure has been demonstrated to exert a cardioprotective effect. Centella asiatica (L.) Urb. belongs to the plant family Apiaceae (Umbelliferae). It contains a high amount of triterpenoid and flavonoid that have antioxidant properties and are involved in the renin-angiotensin-aldosterone system which is an important hormonal system for blood pressure regulation. Objective: This study aimed to investigate the effects of C. asiatica ethanolic extract on blood pressure and heart in a hypertensive rat model, which was induced using oral N(G)-nitro-l-arginine methyl ester (l-NAME). Methods: Male Sprague-Dawley rats were divided into five groups and were given different treatments for 8 weeks. Group 1 only received deionized water. Groups 2, 4, and 5 were given l-NAME (40 mg/kg, orally). Groups 4 and 5 concurrently received C. asiatica extract (500 mg/kg, orally) and captopril (5 mg/kg, orally), respectively. Group 3 only received C. asiatica extract (500 mg/kg body weight, orally). Systolic blood pressure (SBP) was measured at weeks 0, 4, and 8, while serum nitric oxide (NO) was measured at weeks 0 and 8. At necropsy, cardiac and aortic malondialdehyde (MDA) contents, cardiac angiotensin-converting enzyme (ACE) activity, and serum level of brain natriuretic peptide (BNP) were measured. Results: After 8 weeks, the administrations of C. asiatica extract and captopril showed significant (p < 0.05) effects on preventing the elevation of SBP, reducing the serum nitric oxide level, as well as increasing the cardiac and aortic MDA content, cardiac ACE activity, and serum brain natriuretic peptide level. Conclusion: C. asiatica extract can prevent the development of hypertension and cardiac damage induced by l-NAME, and these effects were comparable to captopril.

Integration of imaging and circulating biomarkers in heart failure: a consensus document by the Biomarkers and Imaging Study Groups of the Heart Failure Association of the European Society of Cardiology

Circulating biomarkers and imaging techniques provide independent and complementary information to guide management of heart failure (HF). This consensus document by the Heart Failure Association (HFA) of the European Society of Cardiology (ESC) presents current evidence-based indications relevant to integration of imaging techniques and biomarkers in HF. The document first focuses on application of circulating biomarkers together with imaging findings, in the broad domains of screening, diagnosis, risk stratification, guidance of treatment and monitoring, and then discusses specific challenging settings. In each section we crystallize clinically relevant recommendations and identify directions for future research. The target readership of this document includes cardiologists, internal medicine specialists and other clinicians dealing with HF patients.

cGMP and mitochondrial K+ channels-Compartmentalized but closely connected in cardioprotection

The 3',5'-cGMP pathway triggers cytoprotective responses and improves cardiomyocyte survival during myocardial ischaemia and reperfusion (I/R) injury. These beneficial effects were attributed to NO-sensitive GC induced cGMP production leading to activation of cGMP-dependent protein kinase I (cGKI). cGKI in turn phosphorylates many substrates, which eventually facilitate opening of mitochondrial ATP-sensitive potassium channels (mitoK_ATP ) and Ca²⁺ -activated potassium channels of the BK type (mitoBK). Accordingly, agents activating mitoK_ATP or mitoBK provide protection against I/R-induced damages. Here, we provide an up-to-date summary of the infarct-limiting actions exhibited by the GC/cGMP axis and discuss how mitoK_ATP and mitoBK, which are present at the inner mitochondrial membrane, confer mito- and cytoprotective effects on cardiomyocytes exposed to I/R injury. In view of this, we believe that the functional connection between the cGMP cascade and mitoK⁺ channels should be exploited further as adjunct to reperfusion therapy in myocardial infarction.

Adaptive response triggered by the repeated SCUBA diving is reflected in cardiovascular, muscular, and immune biomarkers

It has been shown that one recreational SCUBA (rSCUBA) diving session is sufficient to cause changes in plasma level of cardiovascular (CV) and muscular biomarkers. To explore whether repetitive rSCUBA diving triggers an adaptive response of the CV, muscular, and immune system, we measured the cardiac damage (NT-proBNP, hs-TnI, and CK-MB), muscle damage (myoglobin (Mb), galectin-3, CK, and LDH), vascular endothelial activation (ET-1 and VEGF), and inflammatory (leukocyte count (Lkc), CRP, and IL-6) biomarkers. A longitudinal intervention study included divers (N = 14) who conducted one dive per week over 5 weeks at the depth of 20-30 m for 30 min after a non-dive period of 5 months. The blood samples were collected before and after the first, third, and fifth dives and specific biomarkers were measured in plasma or serum by the standard laboratory methods. The concentrations of the majority of measured biomarkers increased after every single dive; the exception was ET-1 concentration that decreased. The cumulative effect of five dives has been reflected in diminishing changes in hs-TnI, Mb, galectin-3, ET-1, VEGF, and IL-6 levels, and more pronounced increases in NT-proBNP and hs-CRP levels. The median values of all measured biomarkers in all time points, except Mb, remained within the corresponding reference range. Repeatedly performed rSCUBA diving activates an adaptive response of the CV, muscular, and immune system that is reflected in changes in the specific biomarker concentration.

Increasing heart vascularisation after myocardial infarction using brain natriuretic peptide stimulation of endothelial and WT1+ epicardial cells

Brain natriuretic peptide (BNP) treatment increases heart function and decreases heart dilation after myocardial infarction (MI). Here, we investigated whether part of the cardioprotective effect of BNP in infarcted hearts related to improved neovascularisation. Infarcted mice were treated with saline or BNP for 10 days. BNP treatment increased vascularisation and the number of endothelial cells in all areas of infarcted hearts. Endothelial cell lineage tracing showed that BNP directly stimulated the proliferation of resident endothelial cells via NPR-A binding and p38 MAP kinase activation. BNP also stimulated the proliferation of WT1⁺ epicardium-derived cells but only in the hypoxic area of infarcted hearts. Our results demonstrated that these immature cells have a natural capacity to differentiate into endothelial cells in infarcted hearts. BNP treatment increased their proliferation but not their differentiation capacity. We identified new roles for BNP that hold potential for new therapeutic strategies to improve recovery and clinical outcome after MI.

N-terminal pro-brain natriuretic peptide is related with coronary flow velocity reserve and diastolic dysfunction in patients with asymmetric hypertrophic cardiomyopathy

BACKGROUND

The relations of elevated N-terminal pro-brain natriuretic peptide (NT-pro-BNP) and cardiac ischemia in hypertrophic cardiomyopathy (HCM) patients is uncertain. Therefore we designed the study with the following aims: (1) to analyze plasma concentrations of NT-pro-BNP in various subsets of HCM patients; (2) to reveal the correlations of NT-pro-BNP, myocardial ischemia, and diastolic dysfunction; (3) to assess predictors of the elevated plasma levels of NT-pro-BNP.

METHODS AND RESULTS

In 61 patients (mean age 48.9±16.3 years; 26 male) with asymmetric HCM plasma levels of NT-pro-BNP were obtained. Standard transthoracic examination, tissue Doppler echocardiography with measurement of transthoracic coronary flow velocity reserve (CFVR) in left anterior descending artery (LAD) was done. Mean natural logarithm value of NT-pro-BNP was 7.11±0.95pg/ml [median value 1133 (interquartile range 561-2442)pg/ml]. NT-pro-BNP was significantly higher in patients with higher NYHA class, in obstructive HCM, more severe mitral regurgitation, increased left atrial volume index (LAVI), presence of calcified mitral annulus, elevated left ventricular (LV) filling pressure and in decreased CFVR. Levels of NT-pro-BNP significantly correlated with the ratio of E/e' (r=0.534, p<0.001), LV outflow tract gradient (r=0.503, p=0.024), LAVI (r=0.443, p<0.001), while inversely correlated with CFVR LAD (r=-0.569, p<0.001). When multivariate analysis was done only CFVR LAD and E/e' emerged as independent predictors of NT-pro-BNP.

CONCLUSION

Plasma levels of NT-pro-BNP were significantly higher in HCM patients with more advanced disease. Elevated NT-pro-BNP not only reflects the diastolic impairment of the LV, but it might also be the result of cardiac ischemia in patients with HCM.

Lebetin 2, a Snake Venom-Derived Natriuretic Peptide, Attenuates Acute Myocardial Ischemic Injury through the Modulation of Mitochondrial Permeability Transition Pore at the Time of Reperfusion

Cardiac ischemia is one of the leading causes of death worldwide. It is now well established that natriuretic peptides can attenuate the development of irreversible ischemic injury during myocardial infarction. Lebetin 2 (L2) is a new discovered peptide isolated from Macrovipera lebetina venom with structural similarity to B-type natriuretic peptide (BNP). Our objectives were to define the acute cardioprotective actions of L2 in isolated Langendorff-perfused rat hearts after regional or global ischemia-reperfusion (IR). We studied infarct size, left ventricular contractile recovery, survival protein kinases and mitochondrial permeability transition pore (mPTP) opening in injured myocardium. L2 dosage was determined by preliminary experiments at its ability to induce cyclic guanosine monophosphate (cGMP) release without changing hemodynamic effects in normoxic hearts. L2 was found to be as effective as BNP in reducing infarct size after the induction of either regional or global IR. Both peptides equally improved contractile recovery after regional IR, but only L2 increased coronary flow and reduced severe contractile dysfunction after global ischemia. Cardioprotection afforded by L2 was abolished after isatin or 5-hydroxydecanote pretreatment suggesting the involvement of natriuretic peptide receptors and mitochondrial K_ATP (mitoK_ATP) channels in the L2-induced effects. L2 also increased survival protein expression in the reperfused myocardium as evidenced by phosphorylation of signaling pathways PKCε/ERK/GSK3β and PI3K/Akt/eNOS. IR induced mitochondrial pore opening, but this effect was markedly prevented by L2 treatment. These data show that L2 has strong cardioprotective effect in acute ischemia through stimulation of natriuretic peptide receptors. These beneficial effects are mediated, at least in part, by mitoK_ATP channel opening and downstream activated survival kinases, thus delaying mPTP opening and improving IR-induced mitochondrial dysfunction.

The Effects of Exercise on Natriuretic Peptides in Individuals without Heart Failure

Cardiac natriuretic peptides (NPs) play an important role in the regulation of energy expenditure in skeletal muscle and adipose tissue. A systematic review on the effects of exercise on NPs in patients with heart failure reported that aerobic and resistance training reduced NPs; however, the effects of exercise on NPs and the underlying mechanism of exercise-induced NP secretion in subjects without heart failure remain unknown. In athletes and young, healthy subjects, the NP concentration at rest is not elevated, but strenuous endurance exercise significantly increases NPs. The exercise-induced increase in NPs may be caused by transient myocardial wall stress, cardiomyocyte metabolic changes, or neuroendocrinological response, which may have cytoprotective and growth-regulating effects on the heart. On the other hand, in elderly, overweight/obese subjects, and patients with hypertension, NP concentrations also increase during exercise; however, NP secretion may be more susceptible to cardiac stress compared to young, healthy individuals. Recent studies have shown that NPs are associated with thermogenesis in fat tissue and oxidative capacity in skeletal muscles. NPs may also have a protective role for skeletal muscle in humans, although further studies are warranted to elucidate the physiological mechanism of exercise-induced NP secretion.

Pharmacological Therapy in the Heart as an Alternative to Cellular Therapy: A Place for the Brain Natriuretic Peptide?

The discovery that stem cells isolated from different organs have the ability to differentiate into mature beating cardiomyocytes has fostered considerable interest in developing cellular regenerative therapies to treat cardiac diseases associated with the loss of viable myocardium. Clinical studies evaluating the potential of stem cells (from heart, blood, bone marrow, skeletal muscle, and fat) to regenerate the myocardium and improve its functional status indicated that although the method appeared generally safe, its overall efficacy has remained modest. Several issues raised by these studies were notably related to the nature and number of injected cells, as well as the route and timing of their administration, to cite only a few. Besides the direct administration of cardiac precursor cells, a distinct approach to cardiac regeneration could be based upon the stimulation of the heart's natural ability to regenerate, using pharmacological approaches. Indeed, differentiation and/or proliferation of cardiac precursor cells is controlled by various endogenous mediators, such as growth factors and cytokines, which could thus be used as pharmacological agents to promote regeneration. To illustrate such approach, we present recent results showing that the exogenous administration of the natriuretic peptide BNP triggers “endogenous” cardiac regeneration, following experimental myocardial infarction.

Attenuation of monocyte chemotaxis--a novel anti-inflammatory mechanism of action for the cardio-protective hormone B-type natriuretic peptide

B-type natriuretic peptide (BNP) is a prognostic and diagnostic marker for heart failure (HF). An anti-inflammatory, cardio-protective role for BNP was proposed. In cardiovascular diseases including pressure overload-induced HF, perivascular inflammation and cardiac fibrosis are, in part, mediated by monocyte chemoattractant protein (MCP)1-driven monocyte migration. We aimed to determine the role of BNP in monocyte motility to MCP1. A functional BNP receptor, natriuretic peptide receptor-A (NPRA) was identified in human monocytes. BNP treatment inhibited MCP1-induced THP1 (monocytic leukemia cells) and primary monocyte chemotaxis (70 and 50 %, respectively). BNP did not interfere with MCP1 receptor expression or with calcium. BNP inhibited activation of the cytoskeletal protein RhoA in MCP1-stimulated THP1 (70 %). Finally, BNP failed to inhibit MCP1-directed motility of monocytes from patients with hypertension (n = 10) and HF (n = 6) suggesting attenuation of this anti-inflammatory mechanism in chronic heart disease. We provide novel evidence for a direct role of BNP/NPRA in opposing human monocyte migration and support a role for BNP as a cardio-protective hormone up-regulated as part of an adaptive compensatory response to combat excess inflammation.

Troponin T, B-type natriuretic peptide, C-reactive protein, and cause-specific mortality

PURPOSE

We sought to evaluate the associations of high-sensitivity troponin T (Hs-TnT), N-terminal pro-brain natriuretic peptide (NT-proBNP), and high sensitivity C-reactive protein (Hs-CRP) with mortality from any cause, cardiovascular disease (CVD), coronary heart disease (CHD), stroke, cancer, and respiratory disease in the Atherosclerosis Risk in Communities cohort.

METHODS

We included 11,193 participants aged 54 to 74 years, initially free of the conditions being studied, and who had biomarkers measured. Participants were followed for a mean of 9.9 years.

RESULTS

Hazard ratios (HR), adjusted for multiple risk factors, for mortality in participants in the highest Hs-TnT category compared with those with undetectable levels were: Total 3.42 (95% confidence interval [CI], 2.75-4.26); CVD, 7.34 (95% CI, 4.64-11.6); CHD, 6.06 (95% CI, 2.91-12.6); stroke, 3.31 (95% CI, 1.26-8.66); cancer, 1.60 (95% CI, 1.08-2.38); and respiratory, 3.85 (95% CI, 1.39-10.7). Comparing the highest NT-proBNP quintile with those in the lowest quintile, the adjusted HRs for mortality were: Total, 3.05 (95% CI, 2.46-3.77); CVD, 7.48 (95% CI, 4.67-12.0); CHD, 4.07 (95% CI, 2.07-7.98); and stroke, 10.4 (95% CI, 2.26-47.7). Comparing extreme Hs-CRP quintiles, the adjusted HRs for mortality were: Total, 1.61 (95% CI, 1.32-1.97); CVD, 1.76 (95% CI, 1.19-2.62); and respiratory, 3.36 (95% CI, 1.34-8.45). Having multiple markers elevated simultaneously greatly increased cause-specific mortality risks.

CONCLUSIONS

Greater levels of Hs-TnT, NT-proBNP and Hs-CRP are associated with increased risk of death, not just from CVD, but also from some noncardiovascular causes.

Natriuretic Peptide testing in primary care

The incidence, as well as the morbidity and mortality associated with heart failure (HF) continue to rise despite advances in diagnostics and therapeutics. A recent advance in the diagnostic and therapeutic approach to HF is the use of natriuretic peptide (NP) testing, including both B-type natriuretic peptide (BNP) and its amino terminal cleavage equivalent (NT-proBNP). NPs may be elevated at an early stage among those with symptoms as well among those without. The optimal approach for applying NP testing in general populations is to select the target population and optimal cut off values carefully. Superior diagnostic performance is observed among those with higher baseline risk (such as hypertensives or diabetics). As well, unlike for acute HF, the cut off value for outpatient testing for BNP is 20-40 pg/mL and for NTproBNP it is 100-150 ng/L. In symptomatic primary care patients, both BNP and NT-proBNP serve as excellent tools for excluding HF based on their excellent negative predictive values and their use may be cost effective. Among those with established HF, it is logical to assume that titration of treatment to achieve lower NPs levels may be advantageous. There are several ongoing trials looking at that prospect.

Meta-analysis of B-type natriuretic peptide's ability to identify stress induced myocardial ischemia

Studies in victims of sudden cardiac death and those surviving a cardiac arrest have confirmed that extent of coronary artery disease is similar in those with and without angina, suggesting that it is the presence of myocardial ischemia rather than associated symptoms that determine the prognosis. Experimental models show that hypoxic myocardial tissue results in production of extra B-type natriuretic peptide (BNP), suggesting that BNP could potentially serve as a biomarker of myocardial ischemia. We performed a meta-analysis of the studies that link BNP to inducible myocardial ischemia as indicated by noninvasive stress tests. Values of true positive, false positive, true negative, and false negative were calculated from the reported sensitivity, specificity, disease prevalence, and total number of patients studied. Sixteen studies reporting data on 2,784 patients across 14 study populations were included in the final analysis. Mean age of participants was 55 to 69 years and 55% to 90% were men. Pooled sensitivity and specificity of BNP for detection of stress-induced myocardial ischemia were 71% (95% confidence interval [CI] 68 to 74) and 52% (95% CI 52 to 54), respectively. Pooled diagnostic odds ratio was 3.5 (95% CI 2.46 to 5.04) and summary receiver operating characteristic curve revealed an area under the curve of 0.71 ± 0.02 (mean ± SE). In conclusion, this meta-analysis suggests that an increased BNP level can identify inducible ischemia as detected by standard noninvasive stress tests. This raises the possibility of a whole new role for BNP in the diagnosis and management of myocardial ischemia.

NT-proBNP and circulating inflammation markers in prediction of a normal myocardial scintigraphy in patients with symptoms of coronary artery disease

BACKGROUND

Myocardial perfusion imaging (MPI) can detect myocardial perfusion abnormalities but many examinations are without pathological findings. This study examines whether circulating biomarkers can be used as screening modality prior to MPI.

METHODOLOGY/PRINCIPAL FINDINGS

243 patients with an intermediate risk of CAD or with known CAD with renewed suspicion of ischemia were referred to MPI. Blood samples were analyzed for N-terminal fragment of the prohormone brain natriuretic peptide (NT-proBNP), YKL-40, IL-6, matrix metalloproteinase 9 (MMP-9) and high sensitive C-reactive protein (hsCRP). Patients with myocardial perfusion defects had elevated levels of NT-proBNP (p<0.0001), YKL-40 (p = 0.03) and IL-6 (p = 0.03) but not of hsCRP (p = 0.58) nor of MMP-9 (p = 0.14). The NT-proBNP increase was observed in both genders (p<0.0001), whereas YKL-40 (p = 0.005) and IL-6 (p = 0.02) were elevated only in men. A NT-proBNP cut off-concentration at 25 ng/l predicted a normal MPI with a negative predictive value >95% regardless of existing CAD.

CONCLUSIONS

20-25% of patients suspected of CAD could have been spared a MPI by using a NT-proBNP cut-off concentration at 25 ng/l with a negative predictive value >95%. NT-proBNP has the potential use of being a screening marker of CAD before referral of the patient to MPI.

Randomized comparison between clinical evaluation plus N-terminal pro-B-type natriuretic peptide versus exercise testing for decision making in acute chest pain of uncertain origin

BACKGROUND

Exercise testing constitutes the usual tool for decision making in chest pain units. This policy implies logistical constrains. Our aim was to evaluate a new strategy, combining a clinical risk score and N-terminal pro-B-type natriuretic peptide (NT-proBNP), in patients presenting to the emergency department with chest pain, without ischemic electrocardiogram changes or troponin elevation.

METHODS

A total of 320 patients were randomized to either usual management, involving exercise testing, or a new strategy combining a clinical risk score and NT-proBNP without exercise testing. In the usual management, discharge decision was guided by the result of exercise test. In the new strategy, those patients with low clinical risk score and NT-proBNP were directly discharged. The primary outcome was hospitalization at the index episode. Secondary outcomes were cardiac events at 1 year.

RESULTS

A total of 110 patients (69%) were hospitalized using usual management in comparison with 90 (56%) in the new strategy (P = .03). There were no differences in death or myocardial infarction (n = 11, 6.9% vs n = 6, 3.8%, P = .3) or cardiac events (n = 38, 24% vs n = 28, 18%, P = .2). Revascularizations at the index episode were more frequent under usual management (18% vs 8%, P = .01), although the new strategy was associated with higher rate of planned postdischarge revascularizations (0.6% vs 5%, P = .04).

CONCLUSIONS

A strategy combining clinical history and NT-proBNP is simpler and reduced initial emergency hospitalizations in patients with chest pain, in comparison with the usual strategy involving exercise testing. Larger studies to assess its impact on long-term hard end points are needed.

Clinical and Laboratory Diagnostics of Cardiovascular Disease: Focus on Natriuretic Peptides and Cardiac Ischemia

Chest pain is the most common clinical presentation of acute ischemic heart disease, but only one third of these patients are ultimately found to have an acute coronary syndrome. Initial assessment of the patient presenting with chest pain includes a careful history, physical examination, an initial electrocardiogram (ECG) and measurement of biochemical markers of myocardial injury. The natriuretic peptide system is activated in a broad spectrum of cardiovascular diseases, including acute coronary syndromes and stable coronary disease. A strong relation between plasma levels of B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) obtained in the subacute phase, and long-term, all-cause mortality, as well as the rate of re-admissions for heart failure after myocardial infarction, has been documented. Persistently elevated NT-proBNP levels during the first 72 hours following admission for an acute coronary syndrome have recently been associated with the presence of refractory ischemia and high risk of short-term recurrent ischemic events. Patients with signs of exercise-induced ischemia by dobutamine stress echocardiography have been reported to have higher baseline BNP values. Moreover, BNP and NT-proBNP levels are increased acutely in proportion to the magnitude of the inducible perfusion defect observed during stress testing, suggesting that BNP and NT-proBNP are markers of acute ischemia. Recently, a relationship between circulating levels of BNP and NT-proBNP and long-term all cause mortality in patients with stable coronary artery disease has been documented.

Role of B-type natriuretic peptide in epoxyeicosatrienoic acid-mediated improved post-ischaemic recovery of heart contractile function

AIMS

This study examined the functional role of B-type natriuretic peptide (BNP) in epoxyeicosatrienoic acid (EET)-mediated cardioprotection in mice with targeted disruption of the sEH or Ephx2 gene (sEH null).

METHODS AND RESULTS

Isolated mouse hearts were perfused in the Langendorff mode and subjected to global no-flow ischaemia followed by reperfusion. Hearts were analysed for recovery of left ventricular developed pressure (LVDP), mRNA levels, and protein expression. Naïve hearts from sEH null mice had similar expression of preproBNP (Nppb) mRNA compared with wild-type (WT) hearts. However, significant increases in Nppb mRNA and BNP protein expression occurred during post-ischaemic reperfusion and correlated with improved post-ischaemic recovery of LVDP. Perfusion with the putative EET receptor antagonist 14,15-epoxyeicosa-5(Z)-enoic acid prior to ischaemia reduced the preproBNP mRNA in sEH null hearts. Inhibitor studies demonstrated that perfusion with the natriuretic peptide receptor type-A (NPR-A) antagonist, A71915, limited the improved recovery in recombinant full-length mouse BNP (rBNP)- and 11,12-EET-perfused hearts as well as in sEH null mice. Increased expression of phosphorylated protein kinase C epsilon and Akt were found in WT hearts perfused with either 11,12-EET or rBNP, while mitochondrial glycogen synthase kinase-3beta was significantly lower in the same samples. Furthermore, treatment with the phosphoinositide 3-kinase (PI3K) inhibitor wortmannin abolished improved LVDP recovery in 11,12-EET-treated hearts but not did significantly inhibit recovery of rBNP-treated hearts.

CONCLUSION

Taken together, these data indicate that EET-mediated cardioprotection involves BNP and PI3K signalling events.

Biomarkers in Acute Coronary Syndrome

BACKGROUND: Evaluation of patients who present to the hospital with acute undifferentiated chest pain or other symptoms and signs suggestive of Acute Coronary Syndrome (ACS) is often a clinical challenge. The initial assessment, requiring a focused history (including risk factors analysis), a physical examination, an electrocardiogram (EKG) and serum cardiac marker determination, is time-consuming and troublesome. Recent investigations have indicated that increases in biomarkers of necrosis, inflammation, ischemia and myocardial stretch may provide earlier assessment of overall patient risk, help in identifying the adequate diagnostic and therapeutic management for each patient and allow for prevention of substantial numbers of new events. APPROACH AND CONTENT: The purpose of this review is to provide an overview of the characteristics of several biomarkers that may have potential clinical utility to identify ACS patients. Patho-physiology, analytical and clinical characteristics have been evaluated for each marker, underlying the properties for potential routine clinical use. SUMMARY: The biomarkers discussed in this review are promising and might lead to improved diagnosis and risk stratification of patients with ACS, however their clinical application requires further studies. It is important to define their clinical role as diagnostic markers, their predictive value and the specificity, standardization and detection limits of the assays.

Natriuretic peptides in vascular physiology and pathology

Four major natriuretic peptides have been isolated: atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), C-type natriuretic peptide (CNP), and Dendroaspis-type natriuretic peptide (DNP). Natriuretic peptides play an important role in the regulation of cardiovascular homeostasis maintaining blood pressure and extracellular fluid volume. The classical endocrine effects of natriuretic peptides to modulate fluid and electrolyte balance and vascular smooth muscle tone are complemented by autocrine and paracrine actions that include regulation of coronary blood flow and, therefore, myocardial perfusion; modulation of proliferative responses during myocardial and vascular remodeling; and cytoprotective anti-ischemic effects. The actions of natriuretic peptides are mediated by the specific binding of these peptides to three cell surface receptors: type A natriuretic peptide receptor (NPR-A), type B natriuretic peptide receptor (NPR-B), and type C natriuretic peptide receptor (NPR-C). NPR-A and NPR-B are guanylyl cyclase receptors that increase intracellular cGMP concentration and activate cGMP-dependent protein kinases. NPR-C has been presented as a clearance receptor and its activation also results in inhibition of adenylyl cyclase activity. The wide range of effects of natriuretic peptides might be the base for the development of new therapeutic strategies of great benefit in patients with cardiovascular problems including coronary artery disease or heart failure. This review summarizes current literature concerning natriuretic peptides, their receptors and their effects on fluid/electrolyte balance, and vascular and cardiac physiology and pathology, including primary hypertension and myocardial infarction. In addition, we will attempt to provide an update on important issues regarding natriuretic peptides in congestive heart failure.

Efecto de la atorvastatina sobre los valores del propéptido natriurético cerebral N-terminal en pacientes con hipercolesterolemia con hipertensión arterial y sin ella

BACKGROUND AND OBJECTIVE

N-terminal pro-brain natriuretic peptide (NT-proBNP) is a useful predictor of cardiovascular events in patients without clinical evidence of cardiovascular disease. It is unknown if the cardiovascular risk factors control can modify these levels. We studied if atorvastatin treatment decrease NT-proBNP levels in hypercholesterolemic subjects, with and without hypertension.

PATIENTS AND METHOD

It was an open, prospective study in 39 patients with hypercholesterolemia without clinical evidence of cardiovascular disease. 15 (38.5%) had hypertension. Blood samples were collected initially and 12 and 24 weeks after beginning treatment with 20 mg of atorvastatin.

RESULTS

The median age was 54 years, and 41% were males. NT-proBNP (pg/ml) values were: 193 (294) at baseline; 141 (211) (p < 0.05) after 12 weeks therapy, and 89 (130) (p < 0.01) at 24 weeks. In hypertensive patients value changed from: 275 (388) at baseline, 196 (290) (p < 0.05) and 112 (124) (p < 0.001) after 12 and 24 weeks treatment. And the levels in normotensives patients were: 137 (198) at baseline, 103 (129) (p = NS), and 74 (135) (p < 0.001) at 12 and 24 weeks after treatment with atorvastatin. We didn't find any correlations between the percentage decrease in NT-proBNP levels, and change of total cholesterol, systolic blood pressure, C reactive protein, or nitrites/nitrates blood levels, at 12, and 24 weeks compared to baseline levels.

CONCLUSIONS

In middle-aged hypercholesterolemic patients, without evidence of cardiovascular disease, atorvastatin therapy decrease NT-proBNP blood levels, in both hypertensive and normotensives subjects.

Presence and severity of coronary artery disease and changes in B-type natriuretic peptide levels in patients with a normal systolic function

B-type brain natriuretic peptide (BNP) levels increase during myocardial ischemia. Here, the authors undertook to evaluate the correlation between changes in plasma BNP levels during exercise and the presence and severity of coronary artery disease (CAD). The study subjects consisted of 159 hospitalized patients with a normal systolic function. Patients were allocated to a control group (N = 101, comprising patients with coronary artery stenosis of < 50%) or to a CAD group (N = 58, comprising patients with stenosis of > or = 50% or a greater coronary artery lesion). In addition, the CAD group was further subdivided into a single-vessel disease (VD) subgroup (N = 31) and a multi-VD subgroup (N = 27). All 159 study subjects underwent coronary angiography (CAG), and plasma BNP levels were measured before and immediately after exercise. A comparative study of BNP levels in the control and CAD groups before and after exercise revealed that BNP levels in the CAD group were significantly higher [22.4 (5.0-28.5) vs. 54.3 (13.1-74.6), P = 0.000; 35.0 (6.2-37.6) vs. 82.5 (23.2-102.8) pg/mL, P = 0.002, respectively]. Changes in BNP levels during exercise in the CAD group tended to be greater than in the control group, but without significance [12.6 (0-13.6) vs. 28.3 (2.8-25.5) pg/mL; P = 0.083]. Subgroup analysis showed that BNP levels tended to be positively related to the proportion of disease vessels, but statistical significance was only found between the control and multi-VD subgroup. Summarizing, this study shows that BNP level changes caused by exercise are closely related with the presence of CAD in patients with a normal systolic function. However, the relationship between these level changes and CAD severity requires further evaluation.

Impact of cardiac surgery on plasma levels of B-type natriuretic peptide in children with congenital heart disease

OBJECTIVE

To examine prospectively the effect of cardiac surgery on plasma concentration of B-type natriuretic peptide (BNP) in children with congenital heart disease.

SETTING

Tertiary referral center.

METHODS

BNP plasma concentration was measured by sandwich immunoassay (Biosite) in 65 consecutive patients with congenital heart disease (age 4 days to 17.1 years, mean (S.D.) age 3.6 (4.7) years, median age 1.0 years) on the day before and after surgical therapy. BNP levels were compared to perioperative data and to healthy subjects.

RESULTS

BNP increased significantly (p<0.001) after cardiac surgery from median 31 pg/ml (mean 189 pg/ml) to median 453 pg/ml (mean 607 pg/ml) and remained significantly elevated during the first week (p<0.001). After a first peak mean (S.D.) 1.3 (0.7) days after surgery, there was a significant decrease of plasma BNP followed by a second peak 5.1 (1.1) days after surgery. Postoperative BNP plasma concentration was correlated to BNP before surgery (r=0.58, p<0.001), to cardiopulmonary bypass duration (r=0.52, p<0.001) and to serum lactate concentration at the first day after surgery (r=0.49, p<0.001).

CONCLUSIONS

In children with congenital heart defects plasma BNP increased immediately after cardiac surgery despite haemodynamic unloading. The correlation to cardiopulmonary bypass time and serum lactate concentration and the similarity between the pattern of BNP release after surgery and after myocardial ischaemia might be explained by a cytoprotective role for BNP after cardiac surgery.

Release of cardiac biochemical markers after percutaneous myocardial laser or sham procedures

BACKGROUND

Percutaneous myocardial laser (PML) reduces symptoms in patients with intractable angina. PML leads to a certain loss of viable myocardium, we therefore assessed if troponin or cardiac markers release may explain the clinical effect, and furthermore assessed the markers release during percutaneous sham procedures.

METHODS

Eighty-two patients with chronic refractory angina were randomized to either percutaneous myocardial laser or a true sham procedure. Cardiac markers were assessed before the procedure, and (1/2), 2, 4, 6, and 10-12 h postprocedure.

RESULTS

Troponin I increased to median peak levels (range) of 4 (0.6-43) microg/L in the laser group vs. 1.5 (0.1-5.9) microg/L, p=0.001, and creatine kinase MB to 14 (6-357) microg/L vs. 11 (3-40) microg/L, p<0.05, within and between-group comparison, the rise of CK-MB occurred significantly earlier in the sham group, 3.8 vs. 2.5 h. A time-dependent between-group difference was only detected for troponin. 88% of sham and 100% of laser patients had marker levels above reference limits. There was no correlation between the number of laser/sham created channels, biomarker levels postprocedure, and changes in left ventricular ejection fraction or angina improvement during 12 months of follow-up.

CONCLUSIONS

The release of cardiac markers is not related to relief of angina after myocardial laser. The use of intracardiac catheters induces a considerable marker release, which is not caused by acute ischemia.

B-type natriuretic peptide in paediatric patients with congenital heart disease

AIMS

To examine the diagnostic value of B-type natriuretic peptide (BNP) plasma concentration in congenital heart disease.

METHODS AND RESULTS

BNP was measured in 288 consecutive patients (mean age 6.0 +/- 6.4 years) with left-to-right shunt, left or right heart obstruction, tetralogy of Fallot, functionally univentricular heart, or impaired left ventricular function and compared with age- and gender-specific normal values, and to haemodynamic and echocardiographic data. BNP increased with decreasing left ventricular shortening fraction (r = -0.80; P < 0.001). In patients with left-to-right shunt, BNP was increased (mean SDS +1.64; P < 0.001) and positively correlated (P < 0.001) to shunt volume (r = 0.66), systolic right ventricular pressure (r = 0.69), mean pressure of the pulmonary artery (r = 0.66), and pulmonary resistance (r = 0.59). There was no correlation between BNP and invasive pressure gradient or extent of ventricular hypertrophy in patients with left or right heart obstruction. In patients with tetralogy of Fallot, BNP was not significantly increased. Patients with functionally univentricular heart had elevated BNP plasma levels (mean SDS +1.39; P < 0.001) without decrease after volume unloading by cavopulmonary connection.

CONCLUSION

In children with congenital heart defects, plasma BNP correlates closely to ventricular function. BNP plasma levels do not reflect directly the extent of ventricular pressure or volume work, but mirror the impairment of the loaded ventricles. Normal BNP cannot exclude pathology, but reflects a compensated status of the heart.

Independent elevations of N-terminal pro-brain natriuretic peptide and cardiac troponins in endurance athletes after prolonged strenuous exercise

BACKGROUND

Although elevated resting brain natriuretic peptide (BNP) concentrations reflect heart disease, the meaning of exercise-induced increases is poorly understood and has been examined in small groups only. Therefore, the present study aimed to examine the increase in N-terminal pro-brain natriuretic peptide (NT-proBNP) and relations to cardiac troponin I and T (cTnI, cTnT) elevations after prolonged strenuous exercise in a large cohort of athletes.

METHODS

We examined exercise-induced changes in NT-proBNP, cTnI, and cTnT in 105 obviously healthy endurance athletes (40 +/- 8 years) before and after prolonged strenuous exercise. Blood samples were taken before, 15 minutes, and 3 hours after a marathon (n = 46), a 100-km run (n = 14), and a mountain bike marathon (n = 45).

RESULTS

Eighty-one of 105 athletes exceeded the upper reference limit of NT-proBNP (males/females 88:153 ng/L) after exercise. NT-proBNP increased in all 3 events (P < .001) with the highest increase in the 100-km runners (median increase 200 ng/L; 25th/75th percentile 115/770 ng/L), which differed from the increase in the marathon (97 ng/L; 36/254 ng/L) or the mountain bike marathon (78 ng/L; 37/196 ng/L) (P < .01). Cardiac troponin I exceeded 0.04 microg/L in 74%; cTnT exceeded 0.01 microg/L in 47% of athletes after exercise. NT-proBNP was not related to exercise-induced increases in cTnI or cTnT, but correlated with exercise time (r = 0.55, P < .001).

CONCLUSIONS

Increases in NT-proBNP can be found in a major part of obviously healthy athletes after prolonged strenuous exercise. The release of BNP during and after exercise may not result from myocardial damage but may have cytoprotective and growth-regulating effects. The different nature of exercise-induced increases in BNP and cardiac troponins has to be elucidated in the future.

N-terminal pro-B-type natriuretic peptide and matrix metalloproteinases in early and late left ventricular remodeling after acute myocardial infarction

N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) is a predictor of left ventricular remodeling. Matrix metalloproteinases (MMPs) contribute to collagen breakdown that is associated with ventricular remodeling after acute myocardial infarction (AMI). We assessed the association between circulating levels of NT-pro-BNP, MMP-2, and MMP-9 and their inhibitor (tissue inhibitor of metalloproteinase-1) early (24 and 72 hours) and late (7 and 30 days) after AMI in 108 patients who had ST-elevation AMI (90 men; mean age 60 years). Serum MMP-2 levels measured 24 and 72 hours after AMI were inversely associated with NT-pro-BNP levels, whereas MMP-9 serum levels were positively related. During late-stage remodeling after AMI, circulating concentrations of tissue inhibitor of metalloproteinase-1 were independently associated with NT-pro-BNP levels 7 and 30 days after AMI. This study shows that, in patients who have ST-elevation AMI, circulating levels of NT-pro-BNP are associated with MMPs in a species-specific and time-dependent manner.

N-terminal pro-B-type natriuretic peptide and long-term mortality in stable coronary heart disease

BACKGROUND

The level of the inactive N-terminal fragment of pro-brain (B-type) natriuretic peptide (BNP) is a strong predictor of mortality among patients with acute coronary syndromes and may be a strong prognostic marker in patients with chronic coronary heart disease as well. We assessed the relationship between N-terminal pro-BNP (NT-pro-BNP) levels and long-term mortality from all causes in a large cohort of patients with stable coronary heart disease.

METHODS

NT-pro-BNP was measured in baseline serum samples from 1034 patients referred for angiography because of symptoms or signs of coronary heart disease. The rate of death from all causes was determined after a median follow-up of nine years.

RESULTS

At follow-up, 288 patients had died. The median NT-pro-BNP level was significantly lower among patients who survived than among those who died (120 pg per milliliter [interquartile range, 50 to 318] vs. 386 pg per milliliter [interquartile range, 146 to 897], P<0.001). Patients with NT-pro-BNP levels in the highest quartile were older, had a lower left ventricular ejection fraction (LVEF) and a lower creatinine clearance rate, and were more likely to have a history of myocardial infarction, clinically significant coronary artery disease, and diabetes than patients with NT-pro-BNP levels in the lowest quartile. In a multivariable Cox regression model, the hazard ratio for death from any cause for the patients with NT-pro-BNP levels in the fourth quartile as compared with those in the first quartile was 2.4 (95 percent confidence interval, 1.5 to 4.0; P<0.001); the NT-pro-BNP level added prognostic information beyond that provided by conventional risk factors, including the patient's age; sex; family history with respect to ischemic heart disease; the presence or absence of a history of myocardial infarction, angina, hypertension, diabetes, or chronic heart failure; creatinine clearance rate; body-mass index; smoking status; plasma lipid levels; LVEF; and the presence or absence of clinically significant coronary artery disease on angiography.

CONCLUSIONS

NT-pro-BNP is a marker of long-term mortality in patients with stable coronary disease and provides prognostic information above and beyond that provided by conventional cardiovascular risk factors and the degree of left ventricular systolic dysfunction.

Autocrine and paracrine actions of natriuretic peptides in the heart

The natriuretic peptides, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP), are a family of polypeptide mediators exerting numerous actions in cardiovascular homeostasis. ANP and BNP are cardiac derived, being secreted and up-regulated in myocardium in response to many pathophysiological stimuli. CNP is an endothelium-derived mediator. The classical endocrine effects of ANP and BNP on fluid homeostasis and blood pressure, especially in conditions characterised by left ventricular dysfunction, are well recognised and extensively researched. However, there is accumulating evidence that, in addition to endocrine actions, ANP and BNP exhibit important autocrine and paracrine functions within the heart and coronary circulation. These include regulation of myocyte growth, inhibition of fibroblast proliferation and extracellular matrix deposition, a cytoprotective anti-ischaemic (preconditioning-like) function, and influences on coronary endothelium and vascular smooth muscle proliferation and contractility. Most if not all of these actions can be ascribed to particulate guanylyl cyclase activation because the ANP/BNP receptor, natriuretic peptide receptor (NPR)-A, has an intracellular guanylyl cyclase domain. Subsequent elevation of the intracellular second messenger cGMP may exert diverse physiological effects through activation of cGMP-dependent protein kinases (cGK), predominantly cGK-I. However, there appear to be other contributory mechanisms in several of these actions, including the augmentation of nitric oxide synthesis. These diverse actions may represent counterregulatory mechanisms in the pathophysiology of many cardiovascular diseases, not just those typified by left ventricular dysfunction. Ultimately, insights from the autocrine/paracrine actions of natriuretic peptides may provide routes to therapeutic application in cardiac diseases of natriuretic peptides and drugs that modify their availability.

B-type natriuretic peptide: a new tool in the armamentarium used to accurately diagnose heart failure

Nearly 5 million Americans have heart failure (HF). Making a correct diagnosis early is an important component in the multifaceted approach to detection and/or treatment of this disease. The US Food and Drug Administration recently approved a point-of-care B-type natriuretic peptide assay to be used in the diagnosis of HF. Nesiritide, a synthetic B-type natriuretic peptide, was also approved for use in decompensated HF. B-type natriuretic peptide is released from the cardiac ventricles in response to increased left ventricular volume and/or pressure. This article reviews the nature of this peptide and its potential as a screening tool for HF. It will also present evidence defining the role of B-type natriuretic peptide in the differential diagnosis of dyspnea, prognosis after cardiac events, and in monitoring HF drug therapy.