B-type natriuretic peptide is related to left ventricular mass in hypertensive patients but not in athletes

Metformin modulates microbiota and improves blood pressure and cardiac remodeling in a rat model of hypertension

AIMS

Metformin has been attributed to cardiovascular protection even in the absence of diabetes. Recent observations suggest that metformin influences the gut microbiome. We aimed to investigate the influence of metformin on the gut microbiota and hypertensive target organ damage in hypertensive rats.

METHODS

Male double transgenic rats overexpressing the human renin and angiotensinogen genes (dTGR), a model of angiotensin II-dependent hypertension, were treated with metformin (300 mg/kg/day) or vehicle from 4 to 7 weeks of age. We assessed gut microbiome composition and function using shotgun metagenomic sequencing and measured blood pressure via radiotelemetry. Cardiac and renal organ damage and inflammation were evaluated by echocardiography, histology, and flow cytometry.

RESULTS

Metformin treatment increased the production of short-chain fatty acids (SCFA) acetate and propionate in feces without altering microbial composition and diversity. It significantly reduced systolic and diastolic blood pressure and improved cardiac function, as measured by end-diastolic volume, E/A, and stroke volume despite increased cardiac hypertrophy. Metformin reduced cardiac inflammation by lowering macrophage infiltration and shifting macrophage subpopulations towards a less inflammatory phenotype. The observed improvements in blood pressure, cardiac function, and inflammation correlated with fecal SCFA levels in dTGR. In vitro, acetate and propionate altered M1-like gene expression in macrophages, reinforcing anti-inflammatory effects. Metformin did not affect hypertensive renal damage or microvascular structure.

CONCLUSION

Metformin modulated the gut microbiome, increased SCFA production, and ameliorated blood pressure and cardiac remodeling in dTGR. Our findings confirm the protective effects of metformin in the absence of diabetes, highlighting SCFA as a potential mediators.

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.

Cardiac Biomarkers Following Marathon Running: Is Running Time a Factor for Biomarker Change?

PURPOSE

Plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) and cardiac troponin T levels show a transient increase after marathon running. The aim of this study was to investigate whether running duration influences the patterns of changes in cardiac biomarkers.

METHODS

Twenty participants with fast and slow finishing times were included in the study. Blood samples were taken before the marathon race, immediately after, and 24 hours after the race. Samples were analyzed for NT-proBNP and cardiac troponin T concentration. Furthermore, a complete blood cell count was performed.

RESULTS

After the marathon race, the fast and slow runners showed similar changes of NT-proBNP and cardiac troponin T (ie, a transient increase). Curve estimation regression analysis showed a curvilinear relationship (quadratic model) between running times and NT-proBNP increments immediately after the race, with less of an increase in the very fast and the very slow runners (r2 = .359, P = .023). NT-proBNP increments immediately after the race were correlated to the decline 24 hours after the marathon (r = -.612, P = .004).

CONCLUSIONS

This study indicates that NT-proBNP release immediately after marathon running varies in a curvilinear fashion with running time. It is speculated that low NT-proBNP release is associated with training adaptation in most elite runners and the relatively low cardiac stress in the slowest (but experienced) runners. The combination of less adaptation and relatively large cardiac wall and metabolic stress may explain the highest NT-proBNP values in runners with average running times. In addition, NT-proBNP decrements 24 hours after the race depend primarily on the values reached after the marathon and not on running time.

Endurance Exercise Training Attenuates Natriuretic Peptide Release During Maximal Effort Exercise: Biochemical Correlates of the "Athlete's Heart"

Endurance exercise training (ET) stimulates eccentric left ventricular hypertrophy (LVH) with left atrial dilation. To date, the biochemical correlates of exercise-induced cardiac remodelling (EICR) remain incompletely understood. Collegiate male rowers (n = 9) were studied with echocardiography and maximal-effort cardiopulmonary exercise testing (MECPET) before and after 90 days of ET intensification. Mid-regional pro-atrial natriuretic peptide (MR-proANP), N-terminal pro B-type natriuretic peptide (NT-proBNP), and high-sensitivity troponin T (hscTn) were measured at rest, peak MECPET, and 60 minutes post-MECPET at both study time points. ET resulted in eccentric LVH (LV mass = 102 ± 8 vs. 110 ± 11 g/m², p=0.001; relative wall thickness = 0.36 ± 0.04 vs. 0.37 ± 0.04, p=0.103), left atrial dilation (74 ± 18 vs. 84 ± 15 mL, p<0.001), and increased exercise capacity (peak VO₂ = 53.0 ± 5.9 vs. 67.3 ± 8.2 ml/kg/min, p<0.001). LV remodelling was characterized by an approximate 7% increase in LV wall thickness but only a 3% increase in LV chamber radius. The magnitude of natriuretic peptide release, examined as percent change from rest to peak exercise, was significantly lower for both MR-proANP (115 [95, 127]% vs. 78 [59, 87]%, p=0.04) and NT-proBNP (46 [31, 70]% vs. 27 [25, 37]%, p=0.02) after ET. Rowing-based ET and corollary EICR appear to result in an attenuated natriuretic peptide response to maximal effort exercise. This may occur as a function of decreased cardiac wall stress after ET as seen by disproportionally higher ventricular wall thickening compared to chamber dilation.

Plasma NT-proBNP and Cell-Free DNA Concentrations after Prolonged Strenuous Exercise in Working Farm Dogs

BACKGROUND

Plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration is increased in dogs with myocardial dysfunction, and cell-free DNA (cfDNA) increases in numerous disease states. In humans, both of these biomarkers can be altered after endurance exercise.

OBJECTIVE

To investigate the effect of prolonged strenuous exercise on circulating NT-proBNP and cfDNA concentrations in working farm dogs.

ANIMALS

Six healthy, privately owned working farm dogs (4 Huntaways and 2 heading dogs) from the same hill country farm in New Zealand.

METHODS

Prospective, nonrandomised cohort study. Venous blood samples were collected before and after the dogs worked over 4 days. Plasma NT-proBNP concentrations were measured by a commercially available ELISA assay and cfDNA concentrations were determined by fluorometry without prior DNA extraction.

RESULTS

The baseline (before work, Day 1) median plasma NT-proBNP concentration was 664 pmol/L. A linear mixed-effects model showed that work increased plasma NT-proBNP concentrations by 101 ± 9% (P < 0.001), but with each consecutive day of work, NT-proBNP concentrations declined by 16 ± 4% (P < 0.001). The baseline median plasma cfDNA concentration was 653 ng/mL, and plasma cfDNA concentrations increased by 138 ± 45 ng/mL after work (P = 0.004).

CONCLUSIONS AND CLINICAL IMPORTANCE

The plasma concentration of NT-proBNP in healthy Huntaways and heading dogs after work can exceed the upper limit of the reference range. Results in dogs sampled on the day of prolonged strenuous exercise should be interpreted with caution. Plasma concentrations of cfDNA also increase with exercise, but further studies are needed to establish reference ranges in healthy dogs.

The effects of preceding exercise on myocardial damage in rats

[Purpose] The purpose of this study was to investigate the effects of exercise on myocardial injury in male Sprague-Dawley rats. Two groups of rats were trained with either moderate- or high-intensity treadmill running for four weeks. Subsequently, the concentrations of cardiac troponin and the N-terminal of prohormone brain natriuretic peptide (NT-proBNP) were examined following a single bout of prolonged intensive exercise (lasting 3 h). [Subjects and Methods] The study included 40 six-week-old male Sprague-Dawley rats weighing 150-180 g each. The aerobic exercise group was divided into high-intensity (28 m/min) and moderate-intensity (15 m/min) subgroups. Both subgroups were trained for 35 min daily for six days per week (excluding Sunday) over a four-week period. Following training, the high- and moderate-intensity exercise groups and a nonexercise group performed one bout of prolonged treadmill exercise for 3 h at a speed of 15 m/min. [Results] The cardiac troponin and NT-proBNP levels differed significantly between the groups. [Conclusion] The exercise groups showed lower levels of cardiac troponin and NT-proBNP than the nonexercise group after the bout of prolonged intensive exercise.

Are There Deleterious Cardiac Effects of Acute and Chronic Endurance Exercise?

Multiple epidemiological studies document that habitual physical activity reduces the risk of atherosclerotic cardiovascular disease (ASCVD), and most demonstrate progressively lower rates of ASCVD with progressively more physical activity. Few studies have included individuals performing high-intensity, lifelong endurance exercise, however, and recent reports suggest that prodigious amounts of exercise may increase markers for, and even the incidence of, cardiovascular disease. This review examines the evidence that extremes of endurance exercise may increase cardiovascular disease risk by reviewing the causes and incidence of exercise-related cardiac events, and the acute effects of exercise on cardiovascular function, the effect of exercise on cardiac biomarkers, including "myocardial" creatine kinase, cardiac troponins, and cardiac natriuretic peptides. This review also examines the effect of exercise on coronary atherosclerosis and calcification, the frequency of atrial fibrillation in aging athletes, and the possibility that exercise may be deleterious in individuals genetically predisposed to such cardiac abnormalities as long QT syndrome, right ventricular cardiomyopathy, and hypertrophic cardiomyopathy. This review is to our knowledge unique because it addresses all known potentially adverse cardiovascular effects of endurance exercise. The best evidence remains that physical activity and exercise training benefit the population, but it is possible that prolonged exercise and exercise training can adversely affect cardiac function in some individuals. This hypothesis warrants further examination.

Natriuretic Peptides as Cardiovascular Safety Biomarkers in Rats: Comparison With Blood Pressure, Heart Rate, and Heart Weight

Cardiovascular (CV) toxicity is an important cause of failure during drug development. Blood-based biomarkers can be used to detect CV toxicity during preclinical development and prioritize compounds at lower risk of causing such toxicities. Evidence of myocardial degeneration can be detected by measuring concentrations of biomarkers such as cardiac troponin I and creatine kinase in blood; however, detection of functional changes in the CV system, such as blood pressure, generally requires studies in animals with surgically implanted pressure transducers. This is a significant limitation because sustained changes in blood pressure are often accompanied by changes in heart rate and together can lead to cardiac hypertrophy and myocardial degeneration in animals, and major adverse cardiovascular events (MACE) in humans. Increased concentrations of NPs in blood correlate with higher risk of cardiac mortality, all-cause mortality, and MACE in humans. Their utility as biomarkers of CV function and toxicity in rodents was investigated by exploring the relationships between plasma concentrations of NTproANP and NTproBNP, blood pressure, heart rate, and heart weight in Sprague Dawley rats administered compounds that caused hypotension or hypertension, including nifedipine, fluprostenol, minoxidil, L-NAME, L-thyroxine, or sunitinib for 1-2 weeks. Changes in NTproANP and/or NTproBNP concentrations were inversely correlated with changes in blood pressure. NTproANP and NTproBNP concentrations were inconsistently correlated with relative heart weights. In addition, increased heart rate was associated with increased heart weights. These studies support the use of natriuretic peptides and heart rate to detect changes in blood pressure and cardiac hypertrophy in short-duration rat studies.

Brain natriuretic peptide predicts forced vital capacity of the lungs, oxygen pulse and peak oxygen consumption in physiological condition

Brain natriuretic peptide (NT-pro-BNP) is used as marker of cardiac and pulmonary diseases. However, the predictive value of circulating NT-pro-BNP for cardiac and pulmonary performance is unclear in physiological conditions. Standard echocardiography, tissue Doppler and forced spirometry at rest were used to assess cardiac parameters and forced vital capacity (FVC) in two groups of athletes (16 elite male wrestlers (W), 21 water polo player (WP)), as different stress adaptation models, and 20 sedentary subjects (C) matched for age. Cardiopulmonary test on treadmill (CPET), as acute stress model, was used to measure peak oxygen consumption (peak VO2), maximal heart rate (HRmax) and peak oxygen pulse (peak VO2/HR). NT-pro-BNP was measured by immunoassey sandwich technique 10min before the test - at rest, at the beginning of the test, at maximal effort, at third minute of recovery. FVC was higher in athletes and the highest in W (WP 5.60±0.29 l; W 6.57±1.00 l; C 5.41±0.29 l; p<0.01). Peak VO2 and peak VO2/HR were higher in athletes and the highest in WP. HRmax was not different among groups. In all groups, NT-pro-BNP decreased from rest to the beginning phase, increased in maximal effort and stayed unchanged in recovery. NT-pro-BNP was higher in C than W in all phases; WP had similar values as W and C. On multiple regression analysis, in all three groups together, ΔNT-pro-BNP from rest to the beginning phase independently predicted both peak VO2 and peak VO2/HR (r=0.38, 0.35; B=37.40, 0.19; p=0.007, 0.000, respectively). NT-pro-BNP at rest predicted HRmax (r=-0.32, B=-0.22, p=0.02). Maximal NT-pro-BNP predicted FVC (r=-0.22, B=-0.07, p=0.02). These results show noticeable predictive value of NT-pro-BNP for both cardiac and pulmonary performance in physiological conditions suggesting that NT-pro-BNP could be a common regulatory factor coordinating adaptation of heart and lungs to stress condition.

Competitive sports and the heart: benefit or risk?

BACKGROUND

Controversy surrounds the cardiac effects of competitive sports and the athlete's heart. In this review, we present and discuss the main cardiological findings in competitive athletes.

METHOD

Selective review of pertinent literature retrieved by a search with the keywords "athlete's heart," "ECG," "echocardiography," "endurance exercise," "longevity," and others.

RESULTS

Regular exercise leads to functional and structural adaptations that improve cardiac function. Athlete's heart, which develops rarely, is a typical finding in endurance athletes. This condition is characterized by physiological, harmonically eccentric hypertrophy of all cardiac chambers. The athlete's ECG can be used to distinguish physiological, training-related changes from pathological training-unrelated changes. The athlete's heart function is normal at rest and increases appropriately during exercise. The cardiac markers troponin and B-type natriuretic peptide are within the normal range in healthy athletes at rest, but can temporarily be mildly elevated after exhausting endurance-exercise, without evidence of myocardial damage. The epidemiological data suggest that participation in competitive sports increases life expectancy.

CONCLUSION

Competitive exercise does not induce cardiac damage in individuals with healthy hearts, but does induce physiological functional and structural cardiac adaptations which have positive effects on life expectancy.

Effect of endurance and strength exercise on release of brain natriuretic peptide

Objectives:

The aim of this study was to investigate the effects of 8-week endurance and resistance exercise training on release of brain natriuretic peptide.

Materials and Methods:

Study population was categorized into 4 groups: Group-1 (n = 6) consisted of sedentary individuals who volunteered to complete 8-weeks of endurance exercise; Group-2 (n=6) consisted of sedentary individuals who volunteered to complete 8-weaks of resistance exercise. Three blood samples [for Terminal pro BNP (NT-Pro-BNP)] were taken before, immediately after exercise and after 8 weeks of exercise training.

Results:

NT-Pro BNP was significantly increased immediately after endurance exercise [from 37.9 ± 1.4 pg/ml to 52.1 ±1.5 pg/ml; P = 0.002] and was decreased to 23.2 ± 9.3 pg/ml after 8 weeks of endurance exercise [P = 0.013]. On the other hand, NT-Pro BNP showed no significant changes immediately after resistance exercise [from 26.6 ± 4.9 pg/ml to 24.1 ±4.5 pg/ml; P = 0.553]. In contrast, NT-Pro BNP was significantly increased to 39.5 ±1.6 pg/ml after 8 weeks of resistance exercise [P = 0.012].

Conclusion:

Endurance exercise training reduces circulating NT-Pro BNP concentration, which is likely a marker of reduced ventricular wall tension and improved myocardial function. In contrast, strength exercise induces significant increase in NT-Pro BNP, which could be partially attributed to myocardial damage.

N-terminal pro-atrial natriuretic peptide reflects cardiac remodelling in stage 1 hypertension

Early detection of left ventricular hypertrophy (LVH) is beneficial, since treatment-induced regression of LVH has been unequivocally associated with a better prognosis. Our aim was to study the relation of cardiac remodelling and natriuretic peptides (NPs) in stage 1 hypertension. We studied 175 (46±7 years, 87 women and 88 men) apparently healthy middle-aged that had never been treated for hypertension. Left ventricular and atrial parameters were determined by magnetic resonance imaging. Systolic blood pressure (BP) correlated with left ventricular mass index (LVMI) (r=0.23, P<0.01) and ventricular septum thickness index (IVSI) (r=0.29, P<0.001). N-terminal pro-B-type NP (NT-proBNP) or N-terminal pro-atrial NP (NT-proANP) did not correlate with BP, LVMI or IVSI. NT-proANP correlated with left atrial area index (LAAI) (r=0.38, P<0.001), and subjects with LVH had higher LAAI than subjects with normal left ventricular geometry and no LVH (11.2±0.3 vs 10.0±0.2 cm(2) m(-2), P<0.001). In conclusion, measurement of NT-proBNP or NT-proANP does not appear to discriminate LVH in middle-aged, never treated and apparently healthy hypertensives. NT-proANP, but not NT-proBNP, reflects early cardiac remodelling in hypertensive heart disease.

Hypertension update and cardiovascular risk reduction in physically active individuals and athletes

Hypertension is a prevalent disease worldwide. Its inadequate treatment leads to major cardiovascular complications, such as myocardial infarction, stroke, and heart failure. These conditions decrease life expectancy and are a substantial cost burden to health care systems. Physically active individuals and professional athletes are not risk free for developing this condition. Although the percentage of persons affected is substantially lower than the general population, these individuals still need to be thoroughly evaluated and blood pressure targets monitored to allow safe competitive sports participation. Regarding treatment, lifestyle modification measures should be routinely emphasized to athletes and active individuals with the same importance as for the general population. Medication treatment can be complicated because of restrictions by athletic organizations and possible limitations on maximal exercise performance. In addition, the choice of an antihypertensive drug should be made with consideration for salt and water losses that routinely occur in athletes, as well as preservation of exercise performance and endothelial function. First-line therapies for athletes and physically active individuals may be different from the general population. Some authorities believe that blocking the renin-angiotensin system with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) is more beneficial compared with diuretics because of ACE inhibitors and ARBs being able to avoid salt and water losses. Dihydropyridine calcium channel blockers (CCBs) are another reasonable choice. Despite effects on heart rate, nondihydropyridine CCBs do not appear to impair exercise performance. beta-Blockers are not used as a first-line therapy in athletes because of effects on exercise and prohibition by the National Collegiate Athletic Association and World Anti-Doping Agency in certain sports. In this article, we address the evidence on hypertension and its related treatments in active individuals to provide recommendations that allow the best competitive sports results and reduce cardiovascular risk.

Does cardiac morphology predict plasma brain natriuretic Peptide levels in adolescent athletes?

OBJECTIVE

The purpose of this study was to establish the relationship of plasma levels of brain natriuretic peptide (BNP) to physiologic parameters and cardiac morphologic characteristics in a population of young athletes. Our hypothesis is that physiologic and cardiac morphologic characteristics do not predict BNP levels in adolescent athletes.

DESIGN

Observational study.

SETTING

Outpatient hospital.

PARTICIPANTS

Thirty healthy male adolescent high school football players (16.0 +/- 1.1 years).

INTERVENTIONS

Physical exam, electrocardiography, plasma BNP measurement by rapid fluorescent immunoassay, and limited echocardiography.

MAIN OUTCOME MEASURES

Null hypothesis-physiologic parameters and cardiac morphology do not predict plasma BNP levels in healthy adolescent football players. Significance level set at P < 0.05.

RESULTS

Plasma BNP for this population was 11.9 +/- 10.2 pg/mL. There was no correlation between BNP and mean arterial pressure (r = -0.09, P = 0.64), body mass index (r = 0.11, P = 0.57), interventricular septal thickness (r = -0.15, P = 0.44), left ventricular (LV) wall thickness (r = 0.00, P = 0.99), relative wall thickness (r = -0.04, P = 0.84), LV mass (r = 0.05, P = 0.79), or LV mass index (r = 0.11, P = 0.55).

CONCLUSIONS

Plasma BNP levels in healthy adolescent athletes have no correlation to body mass index or LV mass, even when corrected for body surface area.

Diagnostic and prognostic impact of brain natriuretic peptide in cardiac and noncardiac diseases

OBJECTIVE

Cardiac secretion of brain natriuretic peptide (BNP) increases with the progression of congestive heart failure (CHF). The plasma measurement of BNP emerged recently as a useful, cost-effective biomarker for the diagnosis and prognosis of CHF.

METHODS

BNP assay is useful for evaluating patients with acute dyspnea, because a low level can help rule out CHF in primary care settings and reduce the demand for echocardiography. Equally, BNP level can be particularly useful in recognizing heart failure in a patient with acute dyspnea and a history of chronic obstructive pulmonary disease.

RESULTS

However, although the clinical use of BNP as a biomarker in CHF is increasing, the specificity of BNP in CHF is not strong, suggesting that other mechanisms beyond simple ventricular stretch stimulate BNP release. Multiple disorders in the intensive care unit, apart from CHF, cause elevated BNP levels, including cardiovascular disease states such as ischemia, arrhythmias, cardiac hypertrophy, and coronary endothelial dysfunction, as well as disorders of no cardiac origin, such as sepsis, septic shock, and acute respiratory distress syndrome. Moreover, the impact of increased BNP in patients with sepsis is not clear. The relationship between BNP and both left ventricular ejection fraction and left-sided filling pressures is weak, and data on the prognostic impact of high BNP levels in patients with sepsis are conflicting.

CONCLUSION

Nevertheless, this review highlights the potential benefits of BNP in the recognition and management of heart failure, and defines the gray zones of BNP levels; it also identifies conditions influencing BNP levels in relation to a certain heart failure and describes conditions of no cardiac origin with increased BNP.

Cut-off values of B-type natriuretic peptide for the diagnosis of congestive heart failure in patients with dyspnoea visiting emergency departments: a study on Korean patients visiting emergency departments

OBJECTIVES

To determine the optimal cut-off values of B-type natriuretic peptide (BNP) for the diagnosis of congestive heart failure (CHF) in 1040 Korean patients with dyspnoea visiting emergency departments.

METHODS

BNP values were measured for 662 patients without CHF to examine whether significant relationships existed between the BNP values and age, gender or underlying disease. In 378 patients with CHF, a similar analysis was performed in addition to the examination of the relationship between the mean BNP values and CHF severity.

RESULTS

The optimal threshold for the detection of heart failure was a BNP concentration of 296.5 pg/mL, regardless of age, sex and underlying disease among the Korean study population. In the non-CHF patients, women showed significantly higher mean BNP values than did men. Further, in these patients, the mean BNP values of men with underlying disease (hypertension, angina pectoris, chronic renal failure, chronic obstructive pulmonary disease) and those with at least two underlying diseases, one of which was hypertension, was higher than those without underlying disease, whereas no difference was observed between women with and without underlying disease. Based on the New York Heart Association classification, echocardiography findings and mortality rate of the CHF patients, the BNP value was found to be related to both the severity of heart failure and its prognosis.

CONCLUSIONS

The BNP concentration used for the diagnosis of CHF in Korean people is considerably higher than the normal cut-off value of 100 pg/mL. In the non-CHF patients, the BNP values of women were influenced less by underlying disease. This suggests that the factors that influence BNP values in women are different from those in men.

N-terminal pro brain natriuretic peptide predicts mortality in patients with end-stage renal disease in hemodialysis

Concentrations of N-terminal pro brain natriuretic peptide (NT-proBNP) increase in patients with heart failure and other cardiovascular (CV) diseases and are strong prognostic markers. In patients with end-stage renal disease (ESRD) in hemodialysis (HD), levels of NT-proBNP are almost always raised. In ESRD patients undergoing HD, we aimed at (i) identifying the factors that affect levels of NT-proBNP, (ii) determining the effect of HD on NT-proBNP, and (iii) determining the prognostic impact of NT-proBNP. A total of 109 patients underwent physical examination, electrocardiogram, and echocardiography. Serum NT-proBNP was measured before and after HD (Elecsys 2010). NT-proBNP levels were markedly elevated (pre-HD 4079 pg/ml, post-HD 2759 pg/ml, P<0.001). There was a strong inverse correlation between NT-proBNP and left ventricular ejection fraction (LVEF) (P=0.043), 24-h urine production (P=0.006), and K(t)/V (efficacy of dialysis) (P=0.016) and a positive correlation with left ventricular hypertrophy (LVH) (P=0.014). Patients with higher concentrations, both pre- and post-HD had an increased mortality rate compared to those with lower concentrations (P=0.007, P=0.002). We found age (P=0.009) and NT-proBNP (pre-HD P=0.007, post-HD P=0.001) predictive of death. Our findings demonstrate that CV disease in terms of LVH and reduced LVEF in addition to 24-h urine production and K(t)/V determine NT-proBNP levels. Post-HD levels of NT-proBNP were lower than pre-HD levels; both predictive of mortality.

Usefulness of N-terminal pro-B-type natriuretic peptide levels to predict exercise capacity in hypertrophic cardiomyopathy

Most patients with hypertrophic cardiomyopathy (HC) have reduced maximal oxygen consumption (VO2max) during exercise. The degree of impairment is poorly predicted by the magnitude of hypertrophy, left ventricular (LV) outflow tract obstruction, and other conventional markers of disease severity. The aim of this study was to determine the usefulness of N-terminal-pro-B-type natriuretic peptide (NT-pro-BNP) as a marker of exercise performance in HC. Plasma NT-pro-BNP was measured in 171 consecutive patients (mean age 46 +/- 18 years) who underwent echocardiography and cardiopulmonary exercise testing. The mean log NT-pro-BNP was 2.79 +/- 0.5; log NT-pro-BNP levels were higher in women patients (p = 0.001) and patients with chest pain (p = 0.010), in New York Heart Association class > or = II (p = 0.009), with atrial fibrillation (p < 0.001), with systolic impairment (p = 0.025), and with LV outflow tract obstructions (p < 0.0001). NT-pro-BNP levels were also correlated with maximal wall thickness (r = 0.335, p < 0.0001), left atrial size (r = 0.206, p = 0.007), and the mitral Doppler E/A ratio (r = 0.197, p = 0.012). The mean percent VO2max achieved was 73.8 +/- 22.6%; percent VO2max was smaller in patients with systolic impairment (p = 0.044) and LV outflow tract obstructions (p = 0.025). There were inverse correlations between percent VO2max and NT-pro-BNP (r = -0.352, p = 0.001), LV end-systolic cavity size (r = -0.182, p = 0.031), and left atrial size (r = -0.251, p = 0.003). On multivariate analysis, only NT-pro-BNP was correlated with percent VO2max. A NT-pro-BNP level of 316 ng/L had 78% sensitivity and 44% specificity (area under the curve 0.616) for predicting percent VO2max < 80%. In conclusion, NT-pro-BNP levels correlate with peak oxygen consumption in HC and are more predictive of functional impairment than other conventional markers of disease severity.

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.

Utility of brain natriuretic peptide (BNP) measurement in cardiovascular disease

Cardiac failure is a prevalent and costly condition in Western society. The ageing of the population, together with current medical options which improve, rather than eradicate heart failure, lead to the projection that this problem will increase substantially in the foreseeable future. The availability of a simple test to assist the diagnosis and effective management of heart failure would greatly assist the clinical approach to this problem. This review examines the physiological basis for the measurement of natriuretic peptides as markers of the presence or risk of heart failure. It considers its use in the hospital and non-hospital setting and examines the cost-effectiveness of current assays. It is possible that in future natriuretic peptides may offer a form of treatment for heart failure, but this is beyond the scope of this review. Nevertheless, the review highlights the potential benefits of this group of tests in the management of heart failure.

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.

Natriuretic Peptides and the Dialysis Patient

The natriuretic peptide family consists of four structurally similar, but genetically distinct molecules with pronounced cardiovascular and renal actions. They are counterregulatory hormones playing an important role in fluid volume homeostasis. Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) cause diuresis, natriuresis, and vasodilatation. C-type natriuretic peptide (CNP) has antimitogenic effects and causes vascular smooth muscle relaxation. Dendroaspis natriuretic peptide (DNP) shares many of the actions of ANP and BNP, but its function in humans is not yet fully understood. Natriuretic peptides have been extensively investigated as biochemical markers of the fluid state. Levels are elevated in disease conditions characterized by fluid overload and are closely related to survival in various cardiac disease states. In the dialysis population, BNP correlates significantly with cardiac function, whereas ANP is sensitive to volume changes during dialysis. However, changes in concentration do not predict achievement of euvolemia, and short half-life, combined with complicated assay techniques, make ANP a less than satisfactory tool for assessing hydration. BNP is a superior prognosticator for risk stratification in dialysis patients, and serial estimations will help in the identification of occult cardiac disease.

Bedside tests of B-type natriuretic peptide in the diagnosis of left ventricular diastolic dysfunction in hypertensive patients

AIMS

To investigate the value of B-type natriuretic peptide (BNP) in diagnosing left ventricular diastolic dysfunction in patients with hypertension.

METHODS

The left ventricular diastolic function and plasma BNP levels were assessed prospectively in 135 hypertensive patients.

RESULTS

The plasma BNP in patients with (n=61) and without (n=74) diastolic dysfunction was 122+/-105 and 18+/-16 pg/ml, respectively (p<0.001). Increased BNP levels were associated with systolic blood pressure (p<0.05), left ventricular mass index (p<0.001), the E/A ratio of transmitral flow (p<0.01) and the isovolumic relaxation time (p<0.01). A receiver-operator characteristic curve showing the sensitivity and specificity of BNP against the echocardiography diagnosis of diastolic dysfunction revealed an area under the curve (accuracy) of 0.904 (p<0.01). Using a cut-off value of >40 pg/ml, the sensitivity and specificity of plasma BNP in diagnosing left ventricular diastolic dysfunction were 79% and 92%, respectively.

CONCLUSIONS

The plasma BNP levels in patients with hypertension are closely related to left ventricular hypertrophy and filling impairment. Plasma BNP may be used to facilitate the diagnosis of left ventricular diastolic dysfunction.

The role and assessment of ventricular peptides in heart failure

Although heart failure may be diagnosed readily in its advanced stages, it may be difficult to diagnose clinically in its early stages.Thus, there is a critical need for an inexpensive, simple, rapid,and objective test for heart failure. This article discusses the role and assessment of ventricular natriuretic peptides and related pep-tides in heart failure.