Plasma atrial natriuretic peptide (ANP) fragments proANP (1-30) and proANP (31-67) measurements in chronic heart failure: a useful index for heart transplantation?

Effect of adrenaline on serum mid-regional pro-atrial natriuretic peptide and central blood volume

New Findings

What is the central question in this study?

Atrial natriuretic peptide (ANP) is secreted in response to atrial wall distension and thus allows for evaluation, albeit indirect, of the central blood volume. Adrenaline has chronotropic and inotropic effects. We evaluated whether the chronotropic and inotropic effects of adrenaline were reflected in mid‐regional proANP.

What is the main finding and its importance?

Central blood volume remained stable with infusion of adrenaline and yet mid‐regional proANP increased. Thus, the chronotropic and inotropic state of the heart or adrenaline directly induces release of ANP variants from the myocytes.

Abstract

Atrial natriuretic peptide (ANP) has vasodilatory, natriuretic and diuretic properties. It is secreted in response to atrial wall distension and thereby provides an indirect evaluation of central blood volume (CBV). Adrenaline has chronotropic and inotropic effects that increase cardiac output. In the present study, we evaluated whether these effects were influenced by an increase in CBV and reflected in mid‐regional proANP (MR‐proANP) concentrations in the circulation, a stable proxy marker of bioactive ANP. Changes in CBV were evaluated by thoracic electrical admittance and haemodynamic variables monitored by pulse‐contour analysis during two intervals with graded infusion of adrenaline. Adrenaline infusion increased heart rate (by 33 ± 18%) and stroke volume (by 6 ± 13%), hence cardiac output (by 42 ± 23%; all P < 0.05). The increase in cardiac output did not result from an increase in CBV, because thoracic electrical admittance remained stable (−3 ± 17%; P = 0.230). Serum MR‐proANP concentrations were increased (by 26 ± 25%; P < 0.001) by adrenaline infusion and remained elevated 60 min postinfusion. We conclude that MR‐proANP in the circulation is affected not only by CBV, but also by increased chronotropy/inotropy of the heart, or that adrenaline directly induces release of ANP variants from the myocytes.

Cardiovascular Biomarkers: Lessons of the Past and Prospects for the Future

Cardiovascular diseases (CVDs) are a major healthcare burden on the population worldwide. Early detection of this disease is important in prevention and treatment to minimise morbidity and mortality. Biomarkers are a critical tool to either diagnose, screen, or provide prognostic information for pathological conditions. This review discusses the historical cardiac biomarkers used to detect these conditions, discussing their application and their limitations. Identification of new biomarkers have since replaced these and are now in use in routine clinical practice, but still do not detect all disease. Future cardiac biomarkers are showing promise in early studies, but further studies are required to show their value in improving detection of CVD above the current biomarkers. Additionally, the analytical platforms that would allow them to be adopted in healthcare are yet to be established. There is also the need to identify whether these biomarkers can be used for diagnostic, prognostic, or screening purposes, which will impact their implementation in routine clinical practice.

Elevated MR-proANP plasma concentrations are associated with sepsis and predict mortality in critically ill patients

Background and aims

Mid-regional pro atrial natriuretic peptide (MR-proANP) is an established biomarker for heart failure, based on its key role in regulating homeostasis of water balance and blood pressure. The aim of the study was to determine the value of MR-proANP as a clinical biomarker in critical illness and/or sepsis. Upon admission to the medical intensive care unit (ICU), we investigated MR-proANP plasma concentrations in 217 critically ill patients (144 with sepsis, 73 without sepsis). Results were compared with 65 healthy controls.

Results

MR-proANP plasma levels were significantly elevated in critically ill patients, when compared to healthy controls. Notably, MR-proANP levels were significantly higher in ICU patients with sepsis. MR-proANP levels were not associated with metabolic comorbidities like diabetes or obesity. In critically ill patients, MR-proANP plasma concentrations correlated with inflammatory cytokines, markers of organ dysfunction and several adipocytokines, such as resistin, retinol-binding protein 4 (RBP4) and adiponectin. Importantly, high MR-proANP plasma levels were associated with mortality, as MR-proANP levels above 227.0 pmol/l indicated a particularly increased mortality risk in ICU patients. The association between MR-proANP and mortality was independent of single organ failure and inflammation markers.

Conclusion

Our study emphasizes the role of circulating MR-proANP as a biomarker in critically ill patients, in which high MR-proANP indicates organ dysfunction, sepsis and mortality risk. The association between high MR-proANP and inflammatory as well as adipose tissue-derived endocrine mediators warrants further pathophysiological investigations.

NT-proBNP and Echocardiographic Parameters in Patients with Acute Heart Failure

Aim. The aim of this study was to analyse the relation between clinical, haemodynamic and X-ray parameters and plasma NT-proBNP level in pts with symptoms of left ventricular dysfunction. Methods. The plasma NT-proBNP levels, chest x-ray, transthoracic 2-d and Doppler echocardiography were performed at the time of admission in a group of 96 consecutive patients (mean age 68 ± 11 years) with symptoms of acute heart failure. NT-proBNP levels were assessed with the use of commercial tests (Roche Diagnostics). Results. All patients have significant increase in NT-proBNP (8 000 ± 9 000 pg/mL vs. controls 90 ± 80 pg/mL, p < 0.001). The group of all patients has shown a significant increase in cardiothoracic ratio (CTR, 0.6 ± 0.1, vs. 0.4 ± 0.1, p <0.001), left atrium diameter (LAD, 4.4 ± 0.8 cm, vs.3.5 ± 0.4 cm, p <0.01). Left ventricular ejection fraction (LVEF) was decreased (37 ± 15%, vs. 64 ± 5%, p <0.001). In patients with acute heart failure, NT-proBNP significantly correlated with end-systolic and end-diastolic left ventricle diameters, ejection fraction, vena cava inferior diameter and plasma creatinine levels. Conclusion. Increased plasma NT-proBNP level is influenced by the clinical severity of acute heart failure and correlates with LVEF and IVCD. NT-proBNP can serve as a marker for the clinical severity of the disease.

Comparison of midregional pro-atrial natriuretic peptide with N-terminal pro-B-type natriuretic peptide in the diagnosis of heart failure

OBJECTIVES

The concentration of atrial natriuretic peptide (ANP) in the circulation is approximately 10- to 50- fold higher than B-type natriuretic peptide (BNP). We sought to compare the accuracy of midregional pro-atrial natriuretic peptide (MRproANP) measured with a novel sandwich immunoassay with N-terminal pro-B-type natriuretic peptide (NTproBNP) in the diagnosis of heart failure.

DESIGN

The diagnosis of heart failure was adjudicated by two independent cardiologists using all available clinical data (including BNP levels) in 287 consecutive patients presenting with dyspnoea to the emergency department (ED). MRproANP and NTproBNP levels were determined at presentation in a blinded fashion.

RESULTS

Heart failure was the adjudicated final diagnosis in 154 patients (54%). Median MRproANP was significantly higher in patients with heart failure as compared to patients with other causes of dyspnoea (400 vs. 92 pmol L(-1), P < 0.001). The diagnostic accuracy of MRproANP was very high with an area under the receiver operating characteristic curve of 0.92 and was comparable with that of NTproBNP (0.92, P = 0.791). Moreover, MRproANP provided incremental diagnostic information to BNP and NTproBNP in patients presenting with BNP levels in the grey zone between 100 and 500 pg mL(-1).

CONCLUSION

Midregional pro-atrial natriuretic peptide is as accurate in the diagnosis of heart failure as NTproBNP. MRproANP seems to provide incremental information on top of BNP or NT-proBNP in some subgroups and should be further investigated in other studies.

Midregional pro-atrial natriuretic peptide as a prognostic marker in pneumonia

OBJECTIVE

To evaluate the usefulness of midregional pro-atrial natriuretic peptide (MR-proANP) measurement in the stratification of severity in community-acquired pneumonia.

METHODS

The population studied was three hundred patients admitted to Emergency Department of a tertiary university hospital presenting clinical signs of lower respiratory tract infection, a new infiltrate on the chest radiograph and a confirmed pneumonia by clinical evolution. Patients were stratified by the Pneumonia Severity Index (PSI), by CURB-65 score and by the development of complications. Serum samples were obtained at the moment of admission and prior to antibiotic therapy, and stored until analysis. MR-proANP was measured by B.R.A.H.M.S MR-proANP KRYPTOR.

RESULTS

Serum levels of MR-proANP increased with the severity of pneumonia, according to PSI score and CURB-65 score. Median MR-proANP levels were significantly higher (p<0.0001) in patients with high PSI risk class (IV-V) than in those with low PSI risk class (I-III). MR-proANP levels were also significantly higher (p=0.029) in those patients that developed complications or died. There was no association between MR-proANP and etiology of pneumonia and the radiographic extent.

CONCLUSION

We can conclude that MR-proANP measurement was helpful for individual risk assessment in patients with pneumonia admitted to the emergency department.

Use of pro-atrial natriuretic peptide in the detection of myocardial ischaemia

BACKGROUND

Because of its unique storage and release mechanisms allowing a very rapid response to haemodynamic changes, pro-atrial natriuretic peptide (proANP) may be a helpful cardiac marker in the detection of myocardial ischaemia.

MATERIALS AND METHODS

A total of 260 consecutive patients with suspected myocardial ischaemia referred for rest/ergometry myocardial perfusion single-photon emission computed tomography (SPECT) were enrolled. Levels of plasma proANP were determined before and 1 min after maximal exercise.

RESULTS

Baseline proANP and peak exercise proANP were significantly higher in patients with myocardial ischaemia as compared to those without ischaemia (median, 82 [IQR, 57-112] vs. 67 [IQR, 50-106] pmol L(-1), P = 0.007; and 89 [IQR, 65-121] vs. 78 [IQR, 57-116] pmol L(-1), P = 0.033). The area under the ROC curve for baseline proANP was 0.597 (95% CI, 0.527-0.667), as compared to 0.577 (95% CI, 0.507-0.648) for peak exercise proANP. Exercise-induced changes in proANP were similar in patients with and without myocardial ischaemia, and showed no correlation with the extent of myocardial ischaemia.

CONCLUSIONS

Baseline proANP and peak exercise proANP are significantly higher in patients with myocardial ischaemia. However, because of considerable overlap in proANP levels between patients with and without myocardial ischaemia, neither measurement seems helpful in the detection of myocardial ischaemia in clinical practice.

Pro-atrial natriuretic peptide is a prognostic marker in sepsis, similar to the APACHE II score: an observational study

Introduction

Additional biomarkers in sepsis are needed to tackle the challenges of determining prognosis and optimizing selection of high-risk patients for application of therapy. In the present study, conducted in a cohort of medical intensive care unit patients, our aim was to compare the prognostic value of mid-regional pro-atrial natriuretic peptide (ANP) levels with those of other biomarkers and physiological scores.

Methods

Blood samples obtained in a prospective observational study conducted in 101 consecutive critically ill patients admitted to the intensive care unit were analyzed. The prognostic value of pro-ANP levels was compared with that of the Acute Physiology and Chronic Health Evaluation (APACHE) II score and with those of various biomarkers (i.e. C-reactive protein, IL-6 and procalcitonin). Mid-regional pro-ANP was detected in EDTA plasma from all patients using a new sandwich immunoassay.

Results

On admission, 53 patients had sepsis, severe sepsis, or septic shock, and 68 had systemic inflammatory response syndrome. The median pro-ANP value in the survivors was 194 pmol/l (range 20–2000 pmol/l), which was significantly lower than in the nonsurvivors (median 853.0 pmol/l, range 100–2000 pmol/l; P < 0.001). On the day of admission, pro-ANP levels, but not levels of other biomarkers, were significantly higher in surviving than in nonsurviving sepsis patients (P = 0.001). In a receiver operating characteristic curve analysis for the survival of patients with sepsis, the area under the curve (AUC) for pro-ANP was 0.88, which was significantly greater than the AUCs for procalcitonin and C-reactive protein, and similar to the AUC for the APACHE II score.

Conclusion

Pro-ANP appears to be a valuable tool for individual risk assessment in sepsis patients and for stratification of high-risk patients in future intervention trials. Further studies are needed to validate our results.

Carcinoid heart disease: the role of urinary 5-hydroxyindoleacetic acid excretion and plasma levels of atrial natriuretic peptide, transforming growth factor-beta and fibroblast growth factor

BACKGROUND

Serotonin excretion plays a role in the development of carcinoid heart disease (CHD), but the exact pathogenesis is not known. In the current study, the authors evaluated 24-hour urinary 5-hydroxyindoleacetic acid (5-HIAA) excretion, as well as plasma levels of transforming growth factor-beta (TGF-beta), fibroblast growth factor (FGF), and atrial natriuretic peptide (ANP) in patients with and without CHD determined by ultrasound examination.

METHODS

Urine and plasma samples were obtained for 37 patients and cardiac ultrasound was performed during follow-up in 1999 and 2000. Median 5-HIAA excretion was calculated for the period between diagnosis and ultrasound examination. CHD was defined as the thickening of the tricuspid valve with additional III-IV/IV tricuspid valve regurgitation.

RESULTS

CHD was found in 9 of 37 patients (24%). No significant differences were found for age, gender, presence, and duration of liver metastases. All CHD patients had symptoms of the carcinoid syndrome compared with 71% of the non-CHD patients (P = 0.159). Median 5-HIAA excretion was significantly higher in the CHD group compared with the non-CHD group: 576 micromol/24 hours versus 233 micromol/24 hours (P = 0.02). No difference in TGF-beta and FGF plasma levels was observed between both groups (P = 0.139 and P = 0.985, respectively), nor was there a correlation with morphology of the tricuspid valve or degree of dilatation of the right atrium/ventricle. However, the CHD group had higher median ANP levels than the non-CHD group: 48 ng/L and 25 ng/L, respectively (P = 0.026).

CONCLUSIONS

High levels of 5-HIAA excretion and plasma ANP were found to be associated with CHD. No significant relation with TGF-beta or FGF was been found.