Plasma proatrial natriuretic factor (1-98) concentration after myocardial infarction: relation to indices of cardiac and renal function

Clinical significance of brain natriuretic peptide in patients with postmyocardial infarction

BACKGROUND

Risk stratification after acute myocardial infarction (AMI) includes the evaluation of left ventricular (LV) function. Natriuretic peptides, and particularly brain natriuretic peptide (BNP), emerged as a potential marker of ventricular function and prognosis after AMI.

HYPOTHESIS

Brain natriuretic peptide levels are related to ventricular function, either systolic or isolated diastolic, and can give prognostic information in patients surviving AMI.

METHODS

In all, 101 patients were enrolled. An echocardiographic (M-mode, two-dimensional, and pulsed Doppler) evaluation was performed and blood samples for BNP measurement were obtained. Clinical events were recorded during 12 months of follow-up.

RESULTS

A negative correlation between BNP and LV ejection fraction was observed (r = -0.38; p < 0.001). The BNP levels were higher among patients with LV systolic dysfunction than in patients with isolated diastolic dysfunction (339.1 +/- 249.9 vs. 168.0 +/- 110.5 pg/ml, p = 0.001). The latter had higher levels of BNP than those with normal LV function (68.3 +/- 72.6 pg/ml, p < 0.001). The BNP accuracy to detect LV systolic dysfunction was good (area under the ROC curve [AUC] = 0.83) and increased when isolated diastolic dysfunction was also considered (AUC = 0.87). Brain natriuretic peptide had a very good accuracy in the prediction of death (AUC = 0.95) and the development of heart failure (AUC = 0.90).

CONCLUSION

These results extend previous evidence relating BNP to systolic function after AMI. Furthermore, a relationship between BNP levels and diastolic function was found. Brain natriuretic peptide had a very good performance in detecting the occurrence of an adverse event. We conclude that BNP can detect high-risk patients and help select patients for more aggressive approaches.

Midregional pro-atrial natriuretic peptide is a useful indicator for the detection of impaired left ventricular function in patients with coronary artery disease

AIMS

We compared the diagnostic performance of N-terminal pro-brain natriuretic peptide (NT-proBNP) with a newly developed assay for the midregional part of pro-atrial natriuretic peptide (MR-proANP) concerning the detection of impaired left ventricular ejection function (LVEF) among patients with coronary artery disease (CAD).

METHODS AND RESULTS

Plasma levels of MR-proANP and NT-proBNP were determined in 102 consecutive patients with a history of ST-elevation myocardial infarction. Plasma levels of both markers were measured during a mean follow-up period of 687 days after acute myocardial infarction. Univariate analyses revealed inverse correlations between MR-proANP levels and LVEF (r=-0.39; p<0.001), NT-proBNP levels and LVEF (r=-0.39; p<0.001) and a positive correlation between MR-proANP and NT-proBNP (r=0.75; p<0.001). After adjustment for traditional risk factors, MR-proANP was the strongest predictor for LVEF (p=0.001) in multivariate analysis, being even superior to NT-proBNP. The area under the ROC curve (AUC) indicated moderate performance (AUC=0.73; p<0.01) of MR-proANP regarding the detection of a reduced LVEF<50%. The AUC of NT-proBNP for detection of impaired LVEF<50% was 0.68 (p=0.019). The negative predictive values of both markers were 86% for MR-proANP at a cut-off >135 pmol/L and NT-proBNP at a cut-off >560 pmol/L. At these cut-offs, the specificity of MR-proANP was 90%, and the specificity of NT-proBNP was 84%.

CONCLUSIONS

MR-proANP is a useful indicator for the exclusion of a preserved left ventricular function in patients with coronary artery disease. The study demonstrates that the diagnostic performance of MR-proANP is comparable to the "gold standard" NT-proBNP.

Correlation between levels of N-terminal pro-B-type natriuretic peptide and degrees of heart failure

BACKGROUND

The N-terminal fragment of pro Brain Natriuretic Peptide (NT-pro BNP) is a neuro-hormone synthesized in the cardiac ventricles in response to increased wall tension. The purpose of this study was to assess the correlation between the NT-pro BNP levels and the New York Heart Association function class (NYHA Fc) of dyspnea and echocardiographic findings for the patients who visited our cardiology departments.

METHODS

From October, 2002 to April, 2003, serum NT-pro BNP levels were measured in 348 patients who visited the Samsung Medical Center and the Jong Koo Lee Heart Clinic.

RESULTS

The NT-pro BNP levels were increased with the progression of NYHA Fc of dyspnea (p < 0.001 by ANOVA), the increase in the systolic left ventricular internal dimension (p < 0.05), and the decrease in the ejection fraction (p < 0.01). For the NYHA Fc I patients, the NT-pro BNP levels were positively correlated with age (0 < 0.001) and left atrial size (p < 0.001). For the patients with ischemic heart disease, the NT-pro BNP levels were also positively correlated with the NYHA Fc (p < 0.001 by ANOVA). The NT-pro BNP levels were increased with the increase in the systolic (p < 0.001) and diastolic pressure (p = 0.017), the left ventricular internal dimension as well as the decrease in the ejection fraction (p < 0.001). The area under the receiver operating characteristic (ROC) curve for the NT-pro BNP levels was 0.994 (95% confidence interval, 0.979-0.999), and the most reliable cut-off level for the NT-pro BNP was 293.6 pg/mL.

CONCLUSION

The NT-pro BNP levels were positively correlated with the NYHA Fc of dyspnea and the systolic dysfunction for the patients who visited our cardiology departments. A 300 pg/mL value for the NT-pro BNP cut-off point appears to be a sensitive level to differentiate dyspnea originating from an ailing heart or not for the patients who visited our cardiology departments.

In patients with severe systolic dysfunction, only brain natriuretic peptide is related to diastolic restrictive pattern

BACKGROUND

In patients with severe systolic dysfunction the relationship between diastolic dysfunction and plasma levels of atrial and brain natriuretic peptide (ANP, BNP), catecholamines, renin, and aldosterone in patients with chronic heart failure (CHF) has never been investigated.

OBJECTIVES

The aim of this study was to evaluate in clinically stable patients with severe systolic dysfunction whether the presence of diastolic restrictive pattern modifies neurohormonal plasma levels.

METHODS

Of 82 consecutive patients with stable CHF, 36 were in sinus rhythm, had an adequate ultrasound window and an ejection fraction <30%, and gave their written consent. Plasma levels of ANP, BNP, aldosterone, renin, epinephrine, and norepinephrine were assessed, and the diastolic function was evaluated by Doppler transmitral flow velocity curves.

RESULTS

Except for aldosterone, plasma levels of the other hormones were above normal range in most patients. Patients with restrictive pattern (22%) had BNP plasma levels significantly higher than patients with nonrestrictive pattern (78%): 251 +/- 196 versus 44 +/- 35 ng/L (P=.02). A BNP value of 72.6 ng/L had a sensitivity of 88%, with a specificity of 89% for detecting restrictive pattern in our population.

CONCLUSION

In clinically stable patients with CHF and severe systolic dysfunction, BNP is the only neurohormone sensitive to the concomitant presence of a restrictive pattern.

Diagnostic and prognostic usefulness of natriuretic peptides in emergency department patients with dyspnea

More than 4.5 million Americans have congestive heart failure (CHF), close to 550,000 new cases are diagnosed each year, and one third of known patients with CHF are annually admitted to the hospital. Emergency department diagnosis of CHF is often based on history and physical examination findings along with results of ancillary tests, such as chest radiography and ECG. Although signs and symptoms of fluid overload, such as lower extremity edema and dyspnea, raise the suspicion of CHF, their lack of sensitivity makes them poor screening tools. The natriuretic peptides are promising markers of myocardial dysfunction and heart failure. Because of their relationship to myocardial pressure and stretching, natriuretic peptides have been investigated over the past 5 decades as both diagnostic and prognostic markers in acute coronary syndromes and CHF. This article discusses each of the natriuretic peptides and attempts to delineate their potential diagnostic and prognostic roles in the ED.

Role of brain natriuretic peptide in the diagnosis and management of heart failure: current concepts

BACKGROUND

Progression of heart failure is related to ventricular remodeling, a process associated to neurohormonal activation. Brain natriuretic peptide (BNP), a member of the natriuretic peptide family, has recently emerged as an important neurohormone in the pathophysiology of heart failure.

METHODS

In this update, some of the recent advances on the role of BNP in heart failure are summarized. In particular, the role of BNP in diagnosis of heart disease, as a prognostic marker of cardiovascular events and as a possible guide to optimize heart failure therapy is discussed.

RESULTS

Recent results from 4,300 patients enrolled in the Valsartan Heart Failure Trial (Val-HeFT) confirmed that BNP is the strongest predictor of outcome in heart failure, when compared to other neurohormones and clinical markers. The current use of BNP in the screening and diagnosis of heart failure and its possible future roles are presented.

CONCLUSION

In recent years, there has been an impressive accumulation of data supporting an important role of BNP as a diagnostic and prognostic marker of heart failure. Development of rapid, accurate and affordable diagnostic methods will allow the routine monitoring of BNP in a wide spectrum of settings, from general practice to controlled clinical trials.

Neurohormonal activation in heart failure after acute myocardial infarction treated with beta-receptor antagonists

BACKGROUND

Few studies have described how neurohormonal activation is influenced by treatment with beta-receptor antagonists in patients with heart failure after acute myocardial infarction. The aims were to describe neurohormonal activity in relation to other variables and to investigate treatment effects of a beta(1) receptor-antagonist compared to a partial beta(1) receptor-agonist.

METHODS

Double-blind, randomized comparison of metoprolol 50-100 mg b.i.d. (n=74), and xamoterol 100-200 mg b.i.d (n=67). Catecholamines, neuropeptide Y-like immunoreactivity (NPY-LI), renin activity, and N-terminal pro-atrial natriuretic factor (N-ANF) were measured in venous plasma before discharge and after 3 months. Clinical and echocardiographic variables were assessed.

RESULTS

N-ANF showed the closest correlations to clinical and echocardiographic measures of heart failure severity, e.g. NYHA functional class, furosemide dose, exercise tolerance, systolic and diastolic function. Plasma norepinephrine, dopamine and renin activity decreased after 3 months on both treatments, in contrast to a small increase in NPY-LI which was greater (by 3.9 pmol/l, 95% CI 1.2-6.6) in the metoprolol group. N-ANF increased on metoprolol, and decreased on xamoterol (difference: 408 pmol/l, 95% CI 209-607). Increase above median of NPY-LI (>25.2 pmol/l, odds ratio 2.8, P=0.0050) and N-ANF (>1043 pmol/l, odds ratio 2.8, P=0.0055) were related to long term (mean follow-up 6.8 years) cardiovascular mortality.

CONCLUSIONS

Decreased neurohormonal activity, reflecting both the sympathetic nervous system and the renin-angiotensin system, was found 3 months after an acute myocardial infarction with heart failure treated with beta-receptor antagonists. The small increase in NPY-LI may suggest increased sympathetic activity or reduced clearance from plasma. The observed changes of N-ANF may be explained by changes in cardiac preload, renal function, and differences in beta-receptor mediated inhibition of atrial release of N-ANF. NPY-LI, and N-ANF at discharge were related to long term cardiovascular mortality.

Plasma levels of N-terminal proatrial natriuretic peptide in children are dependent on renal function and age

Plasma levels of natriuretic peptides are used as diagnostic markers of heart failure. The aim of this study was to analyse the relation between plasma levels of N-terminal proatrial natriuretic peptide (Nt-proANP) and renal function, and to develop reference values in children. Nt-proANP was measured in the plasma of 86 patients whose glomerular filtration rate (GFR) was determined by use of the X-ray contrast medium iohexol and a fluorescence technique. Blood samples for Nt-proANP were also collected in 399 reference children, aged 0 - 15 years. The relationship between Nt-proANP and GFR was examined using a multiple regression analysis. The mean value of Nt-proANP was markedly higher in children with heart failure than in children with malignant or urologic diseases (p<0.001). The variability in plasma levels of Nt-proANP was mainly (adjusted R2=0.81) explained by the following four variables: presence of heart failure, GFR, age and previous treatment with anthracyclins. Plasma levels of the peptide are raised at birth, but fall rapidly to adult levels. We conclude that the plasma levels of Nt-proANP are age-dependent. Moderately elevated values were registered in children with severe renal impairment. Heart failure is regularly associated with excessive elevation of Nt-proANP in plasma. Our findings suggest that the influence of heart failure on levels of this peptide in children greatly exceeds the influence of renal dysfunction.

Enzyme immunoassays for fragments (epitopes) of human proatrial natriuretic peptides

Several peptides derived from the N-terminal sequence of pro-atrial natriuretic peptide (proANP) have been tested successfully as markers of heart disease. We have developed specific and sensitive competitive enzyme immunoassays for fragments [1-30] and [31-67] of proANP. Antisera were raised in sheep against synthetic peptides predicted to be highly immunogenic. Binding specificity was determined by epitope mapping. Microtiter plates were coated with antibody specific for the Fc region of sheep IgG to capture the affinity-purified specific anti-proANP antibodies in an oriented and reproducible form. Synthetic proANP calibrators or diluted samples were incubated simultaneously with biotinylated peptide and binding was quantitated using streptavidin-peroxidase and TMB. Immunoreactive proANP could be measured in diluted plasma, serum and urine. The detection limits of the proANP[1-30] and proANP[31-67] assays were 2.5 and 10 pmol/l respectively. The linearity of samples diluted beyond the recommended assay conditions was good. Recoveries of added standard peptides ranged from 102 to 112%. Circulating concentrations of immunoreactive proANP in 115 healthy subjects ranged from 0.11 to 0.47 nmol/l proANP[1-30] and 0.18 to 0.79 nmol/l proANP[31-67]. In patients with cardiac disease, proANP levels were increased significantly. The reference interval of proANP[31-67] in urine was 0.09 to 1.7 nmol/l, several-fold higher than proANP[1-30] (<O.03 to 1.1 nmol/l). After storage for 6 months at -20 degrees C there was no detectable decrease in immunoreactivity.

N-terminal proatrial natriuretic peptide correlates with systolic dysfunction and left ventricular filling pattern in patients with idiopathic dilated cardiomyopathy

OBJECTIVE

To investigate the diastolic Doppler filling pattern in patients with idiopathic dilated cardiomyopathy and its relation to N-terminal pro-atrial natriuretic peptide (NT-pro-ANP).

METHODS

32 patients (26 male, six female) with idiopathic dilated cardiomyopathy were investigated. All were in sinus rhythm. Conventional M mode echocardiography and Doppler echocardiography was done in each patient. Pulsed wave Doppler inflow signals were obtained and the following variables were measured: maximum E wave, maximum A wave, E/A ratio, E wave deceleration time, A wave deceleration time. NT-pro-ANP was measured using radioimmunoassay.

RESULTS

Mean (SD) left ventricular ejection fraction was 34 (7)% and mean left ventricular end diastolic diameter on M mode echocardiography was 69 (7) mm. Left ventricular filling indices were as follows: maximum E wave velocity, 0.86 (0.22) m/s; maximum A wave velocity, 0.71 (0.24) m/s; E/A ratio, 1.41 (0.65). Mean E wave deceleration time was 140 (50) ms; mean A wave deceleration time was 100 (20) ms. In a stepwise forward regression model, NT-pro-ANP correlated significantly with left atrial diameter (r = 0.603; p < 0. 001), left ventricular ejection fraction (r = -0.758; p < 0.001), and Doppler derived E/A ratio (r = 0.740; p < 0.001).

CONCLUSIONS

In patients with idiopathic dilated cardiomyopathy there is a relation between NT-pro-ANP and both systolic and diastolic variables. In a multivariate model NT-pro-ANP correlated with left atrial diameter, left ventricular ejection fraction, and Doppler derived E/A ratio on transmitral inflow.

Plasma vasoactive peptides after acute myocardial infarction in relation to left ventricular dysfunction

We measured plasma concentrations of vasoactive peptides in 32 patients with acute myocardial infarction and evaluated their value as markers of left ventricular dysfunction. Plasma levels of atrial natriuretic peptide (ANP), the N-terminal fragment of proANP (NT-proANP), B-type natriuretic peptide (BNP) and endothelin-1 were measured serially by radioimmunoassays. The infarct size was estimated from the creatine kinase MB release curve. Coronary angiography and left ventricular cineangiography were performed in all patients during hospitalization and 6 months later in 15 patients. Myocardial infarction caused an increase in vasoactive peptides, the highest values for ANP (36.5+/-6.79 pmol/l), NT-proANP (1130+/-170 pmol/l) and endothelin-1 (9.72+/-0.68 pmol/l) being found on admission and those for BNP (56.0+/-7.13 pmol/l) on Day 2. Plasma levels of natriuretic peptides were dependent on infarct size, its location and degree of myocardial dysfunction and that of BNP also on infarct artery patency. Plasma endothelin-1 level was higher in patients with TIMI 3 than TIMI 0-2 flow. Plasma vasoactive peptides remained elevated during the 6-month follow-up period and they were dependent on the degree of myocardial dysfunction. BNP measured on any day of hospitalization showed the best correlation with ejection fraction measured during the acute phase of infarction or at 6 months. The results show that BNP is the best indicator of left ventricular dysfunction after myocardial infarction and its reliability is not dependent on the time point of measurement.

Atrial natriuretic peptide and the development of congestive heart failure in the oldest old: a seven-year prospective study

BACKGROUND

Atrial natriuretic peptide (ANP) levels are elevated in symptomatic heart failure and correlate with invasively measured left heart pressures.

OBJECTIVE

To examine the association between plasma ANP level and the subsequent development of congestive heart failure (CHF) in older subjects with no history of CHF.

DESIGN

A 7-year, prospective, blinded, cohort study.

SETTING

A life care facility in Boston, Massachusetts.

PARTICIPANTS

Two hundred fifty-six frail older subjects (mean age 88 +/- 7) with no history of CHF at study entry.

MAIN OUTCOME MEASURE

Clinical episodes of CHF with confirmatory chest roentgenogram findings. Cox proportional hazard analyses were performed to examine the relationship between ANP levels and the development of CHF while controlling for 19 clinical, physical, and laboratory parameters. A Kaplan-Meier estimator (log-rank test) was used to determine if the development of CHF differed by tertile of ANP.

RESULTS

During the follow-up period, 32% of the cohort developed CHF. The mean ANP level in the CHF group was 95 pmol/L +/- 11 pmol/L versus 60 pmol/L +/- 5 pmol/L in the no CHF group (two tailed t test P = .005). On multivariate analysis, a high ANP level was found to be associated significantly (P = .01) with the development of CHF.

CONCLUSIONS

There is a statistically significant association between ANP level and the subsequent development of CHF in frail older individuals with no history of CHF.

Plasma N-terminal atrial natriuretic peptide predicts hospitalization in patients with heart failure

The plasma concentration of N-terminal atrial natriuretic peptide (N-ANP) has been shown to be predictive of both clinical status and survival in patients with heart failure. In this analysis the relationship between N-ANP, morbidity and hospitalization time was evaluated in 417 patients with stable, congestive heart failure recruited from an active, outpatient heart failure registry. Hospital admissions along with the duration of stay occurring after the initial N-ANP sampling during the period of data collection were recorded. A total of 755 admissions occurred, accounting for 7917 days' hospitalization. Relative hospitalization times (in-hospital days/observation period) per N-ANP quartiles I-IV were: 1.2 (+/- 2.7)%, 5.5 (+/- 12.2)%, 10.0 (+/- 21.5)% and 20.8 (+/- 34.3)%, respectively. Although N-ANP levels were correlated with age (r = 0.234, p < 0.0001), division by age quartiles did not significantly predict relative hospitalization times. These data indicate that the degree of cardiac endocrine activation and subsequent N-ANP release is related to morbidity in patients with heart failure and that moderate elevation in N-ANP levels is associated with a substantially increased hospitalization time. N-ANP sampling should be of value as a supplement to clinical evaluation in the assessment of the individual patient with this common syndrome.

Amino-terminal proBNP in ovine plasma: evidence for enhanced secretion in response to cardiac overload

We have recently identified a novel amino-terminal fragment of pro-brain natriuretic peptide (NT-proBNP) in the circulation of humans, the concentration of which increases progressively as the left ventricle fails. To clarify the origins of NT-proBNP in experimental animals, we have developed an RIA for NT-proBNP based on residues 52-71 of ovine proBNP-(1-103) and used it to study cardiac processing, secretion, and metabolism of BNP in sheep with cardiac overload induced by coronary artery ligation (CAL) or rapid left ventricular pacing (rLVP). The concentration of NT-proBNP in left atrial plasma extracts drawn from normal control sheep was threefold that of mature BNP. Size-exclusion and reverse-phase HPLC analyses of plasma extracts coupled to RIA revealed a single peak of immunoreactive (ir) NT-proBNP [ approximately 8,000 relative molecular weight (Mr)], quite distinct from a single peak of ir-mature BNP ( approximately 3,000 Mr). In contrast, ovine cardiac tissue contained only a single immunoreactive peak of high-molecular-weight BNP ( approximately 11,000 Mr), consistent in size with proBNP-(1-103). Sampling from the cardiac coronary sinus in normal control sheep (n = 5) and sheep with CAL (n = 5) revealed that the molar ratio of NT-proBNP to mature BNP was similar. There was a significant gradient of both mature and NT-proBNP across the heart in normal sheep, whereas after CAL the gradient was significant for mature BNP only. In both forms of cardiac overload (CAL and rLVP), left atrial plasma levels of NT-proBNP were significantly increased above normal levels, in contrast with mature BNP levels, which were raised only in the rLVP group of animals. Blockade of natriuretic peptide metabolism in sheep with heart failure (induced by rLVP) raised mature BNP levels threefold but did not affect levels of NT-proBNP. In conclusion, these studies show that NT-proBNP is formed from proBNP stores during secretion and, compared with mature BNP, accumulates in plasma because metabolism of NT-proBNP appears to differ from that of mature BNP. Although its function, if any, remains unclear, plasma NT-proBNP may prove to be a sensitive marker of cardiac overload and/or decompensation.

Natriuretic peptides: physiology, therapeutic potential, and risk stratification in ischemic heart disease

BACKGROUND

The natriuretic peptide family consists of four molecules that share significant amino acid sequence homologic characteristics and a looped motif. Atrial natriuretic peptide and brain natriuretic peptide are similar in their ability to promote natriuresis and diuresis, inhibit the renin-angiotensin-aldosterone axis, and act as vasodilators. Understanding of the actions of C-type natriuretic peptide and dendroaspis natriuretic peptide is incomplete, but these two new family members also act as vasodilators. Because of the rapid evolution of information about this peptide family, we reviewed the state of the art with respect to risk stratification and therapeutic ability.

METHODS

English-language papers were identified by a MEDLINE database search covering 1966 through 1997 and supplemented with bibliographic references and texts.

CONCLUSIONS

The natriuretic peptides are counterregulatory hormones with prognostically important levels. They are similarly upregulated in heart failure and counteract neurohormones that induce vasoconstriction and fluid retention. BNP may be the superior prognosticator for risk stratification after myocardial infarction and is independent of left ventricular ejection fraction. Lastly, experimental trials suggest that administration of exogenous natriuretic peptides or inhibitors of their catabolism to patients with ischemic heart disease may be clinically beneficial.

Plasma N-terminal atrial natriuretic factor: a predictor of survival in patients with congestive heart failure

BACKGROUND

Congestive heart failure results in biatrial stretch, which stimulates myocyte release of atrial natriuretic factor (1-126). The N-terminal fragment, proatrial natriuretic factor(1-98), (proANF), is released on an equimolar basis with the C-terminal (99-126) active hormone and may be assayed simply because of prolonged in vitro stability. Proatrial natriuretic factor has been shown to be predictive of clinical status in patients with congestive heart failure. This retrospective analysis was undertaken to evaluate the relationship between N-terminal atrial natriuretic factor(1-98) and survival in patients with stable congestive heart failure.

METHODS AND RESULTS

Proatrial natriuretic factor was sampled from 316 patients (mean age, 68 (+/-) 11 years; 71% men) recruited from an outpatient heart failure clinic. The mean ejection fraction was 34 (+/-) 13%. Seventy-three deaths were registered during the period of data collection (42 months). Deaths per proANF quartile (n = 79) were as follows: 2 (2.5%) in quartile I. 13 (16.5%) in quartile II, 21 (26.6%) in quartile III, and 37 (46.8%) in quartile IV. The odds ratio estimates for death adjusted for age and sex were 7.6, 13.9, and 33.9 for the second, third, and fourth quartiles, respectively. Survival curves constructed according to proANF quartiles demonstrate significant differences in mortality rates. The correlation with death was greater for proANF as compared with left ventricular end-diastolic diameter (P < .001), systolic pulmonary artery pressure (P < .005), or ejection fraction (P < .05).

CONCLUSION

These data indicate that the concentration of proANF is related to prognosis in patients with heart failure and that moderate elevation is associated with markedly decreased survival. Analysis should be of practical value in the assessment of prognosis in this heterogeneous population.

A two-site delfia immunoassay for measurements of the N-terminal peptide of pro-atrial natriuretic peptide (nANP)

A rapid, sensitive and reliable two-site immunoassay for measurements of the N-terminal peptide of pro-atrial natriuretic peptide (nANP) is presented. The method uses one monoclonal antibody, directed against the N-terminal part of nANP, as catcher antibody and another monoclonal antibody, directed against the C-terminal part of nANP, as detector antibody. The catcher antibody is biotinylated and is bound to streptavidin pre-coated microtiter strips. The detector antibody is labelled with Europium, which is measured in a Wallac DELFIA time-resolved fluorometer. Blood collected in plain Vacutainer tubes gave same measured amounts of nANP as blood collected in heparinised tubes. Blood collected in tubes containing EDTA gave same measured amounts of nANP as the plain tubes, provided that a 2-step assay protocol was used. Based upon 100 healthy blood donors, a reference interval was calculated to < 450 pmol/L. Within the reference group there was a significant increase of serum nANP with age. Based on 42 patients with different degree of impaired renal function, a significant correlation of nANP and serum creatinine was found. Assay performance, given as total assay variation was 12%, 10% and 9% respectively at serum levels of 140, 970 and 3500 pmol/L. It is concluded that this method is fast, sensitive and reliable for clinical measurements of nANP.

Neuroendocrine activation after myocardial infarction: causes and consequences

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Plasma proatrial natriuretic factor is predictive of clinical status in patients with congestive heart failure

Atrial stretch results in myocyte release of the prohormone atrial natriuretic factor (1-126). The N-terminal (1-98) fragment, proatrial natriuretic factor (proANF) is released on an equimolar basis with the C-terminal (99-126) active hormone and may be assayed simply due to in vitro stability. This study was undertaken to evaluate the relation between proANF and routinely available measures of clinical status. ProANF was sampled from 202 patients (median age 68 years [range 15 to 85], 77% men) recruited from an active outpatient heart failure clinic. Patients were subgrouped according to New York Heart Association functional class, radionuclide ejection fraction (EF), echocardiographic left ventricular (LV) end-diastolic diameter, and Doppler-determined systolic pulmonary arterial pressure. The median proANF (pmol/L) values for patients in New York Heart Association classes I, II, III, IV were 725, 1,527, 1,750, and 5,172, respectively. The proANF value for the group with EF > 40% was 1,534 versus 1,993 for EF < or = 40% (p < 0.05). The value for the group with LV diameter < 60 mm ws 838 versus 1,751 for LV diameter > or = 60 mm (p < 0.01). The value for the group with systolic pulmonary artery pressure < 45 mm Hg was 1,241 versus 2,660 for systolic pulmonary artery pressure > or = 45 mm Hg (p < 0.01). ProANF correlated better than the other variables with New York Heart Association functional class and was more closely associated with noninvasive measurements than New York Heart Association functional class.(ABSTRACT TRUNCATED AT 250 WORDS)