Development of a novel, N-Terminal-proBNP (NT-proBNP) assay with a low detection limit

Associations between muscle quality and N-terminal pro-B-type natriuretic peptide (NT-proBNP): The multi-ethnic study of atherosclerosis

INTRODUCTION

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is widely used in clinical settings to identify cardiac stress, diagnose, and manage heart failure (HF). We explored the associations between NT-proBNP and both muscle area and density.

METHODS

A cross-sectional analysis including 1,489 participants from the MESA. Plasma NT-proBNP concentrations and inflammatory biomarkers and health history questionnaires were analyzed. Computed tomography quantified abdominal body composition. Separate multivariable linear regression models were used to assess the associations between both muscle (MA) area and density (MD) and NT-proBNP.

RESULTS

In models adjusted for sociodemographic characteristics, risk factors for cardiovascular disease, anthropometric variables, and subcutaneous and visceral adiposity, NT-proBNP was inversely associated with total abdominal and psoas MAs. Adjustment for inflammatory markers and MD attenuated these associations to the null. Stabilization MA and NT-proBNP were not significantly associated. Analyses per quartiles of MA confirmed lack of a consistent association between stabilization and total abdominal MAs and NT-proBNP. While the third and fourth quartiles of psoas MA were inversely associated with NT-proBNP, adding inflammation biomarkers and MD to the model attenuated the association to the null. Conversely, after full adjustment, NT-proBNP was inversely and significantly associated with total abdominal, stabilization and psoas MDs. For psoas MD, but not the other muscle density variables, the addition of MA to the model attenuated the association to the null. The quartiles of MD were consistently inversely associated with NT-proBNP, where higher MDs showed larger estimates of the association compared to the lowest quartiles, for all muscle groups investigated.

CONCLUSION

Muscle density is inversely associated with NT-proBNP, while muscle area is not after adjustment for inflammation and muscle density.

Preoperative B-Type Natriuretic Peptides to Predict Postoperative Atrial Fibrillation in Cardiac Surgery: A Systematic Review and Meta-Analysis

BACKGROUND

Post-operative atrial fibrillation (AF) is the most common complication following cardiac surgery. There has been extensive exploration of clinical variables, imaging, and biomarkers to predict its occurrence after cardiac surgery. In this study, we examine the emerging biomarkers B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) to assess their pre-operative values and correlations with the occurrence of post-operative AF in patients undergoing cardiac surgery.

METHODS

A comprehensive literature search was conducted using PubMed, EMBASE, MEDLINE via Ovid, ClinicalTrials.Gov, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) to identify studies published until March 2023. The studies were included if they reported pre-operative BNP or NT-proBNP values and the development of post-operative AF in cardiac surgery patients. Subsequently, data were extracted, and a meta-analysis was performed using Review Manager 5.4 4 (The Cochrane Collaboration, 2020) and SPSS version 28 (IBM Corp, Armonk, NY, USA) to assess the difference between pre-operative BNP and NT-proBNP levels between patients with post-operative AF (AF group) and those without (No-AF group) using a random-effect model. Further analysis was performed in three subgroups: isolated coronary artery bypass grafting, isolated valve, and combined/mixed surgery group.

RESULT

A total of 20 studies, including 9,079 participants were identified and included in the systematic review and meta-analysis. Pre-operative BNP levels were reported in 11 studies, and NT-proBNP levels were reported in 10 studies, of which one study reported both BNP and NT-proBNP levels. There is an overall significant difference between pre-operative levels of BNP (p=0.03, I2=95%) and NT-proBNP (p<0.001, I2=65%) when compared between AF and No-AF groups. Nonetheless, subgroup analysis showed there is no significant difference in pre-operative BNP levels, except in isolated valve surgery (p<0.001), whereas all subgroups showed significantly different pre-operative levels of NT-proBNP.

CONCLUSIONS

Elevated levels of both BNP and NT-proBNP were observed in patients who developed post-operative AF after undergoing cardiac surgery. In particular, pre-operative NT-proBNP levels were elevated in all patients irrespective of the type of surgical procedure, but elevated pre-operative BNP was only seen in valve surgery patients. These findings suggest the potential usefulness of NT-proBNP as a promising biomarker for predicting the occurrence of post-operative AF following cardiac surgery.

Selenium and coenzyme Q10 improve the systemic redox status while reducing cardiovascular mortality in elderly population-based individuals

BACKGROUND

Serum sulfhydryl groups (R-SH, free thiols) reflect the systemic redox status in health and disease, and may be amenable to therapeutic modulation. Since R-SH are readily oxidized by reactive species, oxidative stress is characterized by reduced serum R-SH levels. Selenium and coenzyme Q₁₀ supplementation may improve the systemic redox status. This study aimed to evaluate the effect of supplementation with selenium and coenzyme Q₁₀ on serum free thiols and to study associations with the risk of cardiovascular mortality in elderly community-dwelling individuals.

METHODS

In this randomized, double-blind, placebo-controlled trial, serum R-SH were measured colorimetrically and adjusted for albumin in 434 individuals at baseline and after 48 months of intervention. Selenium yeast (200 μg/day) and coenzyme Q₁₀ (200 mg/day) or placebo were provided as dietary supplements.

RESULTS

After 48 months of intervention, participants receiving combined selenium and coenzyme Q₁₀ supplementation demonstrated increased levels of serum R-SH compared to placebo (P = 0.002). In prospective association analysis, the highest rate of cardiovascular mortality after a median follow-up of 10 years (IQR: 6.8-10.5) was observed in the lowest quartile (Q1) of R-SH levels. Baseline albumin-adjusted serum R-SH were significantly associated with the risk of cardiovascular mortality, even after adjustment for potential confounding factors (hazard ratio [HR] 1.98 per SD, 95% CI: 1.34-2.91, P < 0.001).

CONCLUSION

Supplementation with selenium and coenzyme Q₁₀ to an elderly community-dwelling population low on the two substances, significantly improved serum R-SH levels, supporting a reduction in systemic oxidative stress. Low serum R-SH levels were significantly associated with an increased risk of cardiovascular mortality in elderly individuals.

Sensitive detection of heart-failure biomarkers natriuretic peptides using multi-photon laser wave-mixing spectroscopy

Nonlinear laser wave-mixing spectroscopy is demonstrated as a fast and sensitive detection method for heart-failure biomarkers, pro-atrial natriuretic peptide (proANP) and brain natriuretic peptide (BNP). Wave mixing is an ultrasensitive optical absorption-based method and analytes can be detected in their native form or labeled with fluorophore and chromophore labels. In this study, we utilized Chromeo P540 dye to label the peptides for wave-mixing detection. The wave-mixing signal is created from the diffraction of incoming photons by the thermal grating at the capillary analyte cell. The signal beam is strong, collimated, and coherent (laser-like) and it is collected using a simple photodetector with an excellent signal-to-noise ratio. We demonstrated advantages of this technique over conventional assays including shorter analysis times, smaller sample requirements, and higher throughput. To enhance detection selectivity and sensitivity levels, wave mixing is effectively coupled to capillary zone electrophoresis (CZE) and field-amplified sample stacking (FASS) methods. We determined detection limits of 7.4 × 10^-10 M or 55 zmol and 6.8 × 10^-10 M or 51 zmol for proANP and BNP, respectively, and separated and detected both peptides within 2 min. Due to the challenges in the confirmatory diagnoses of heart failure, wave-mixing serves as a potentially beneficial screening tool in addition to the commonly used echocardiographic tests.

Pulmonary transit time of cardiovascular magnetic resonance perfusion scans for quantification of cardiopulmonary haemodynamics

AIMS

Pulmonary transit time (PTT) is the time blood takes to pass from the right ventricle to the left ventricle via pulmonary circulation. We aimed to quantify PTT in routine cardiovascular magnetic resonance imaging perfusion sequences. PTT may help in the diagnostic assessment and characterization of patients with unclear dyspnoea or heart failure (HF).

METHODS AND RESULTS

We evaluated routine stress perfusion cardiovascular magnetic resonance scans in 352 patients, including an assessment of PTT. Eighty-six of these patients also had simultaneous quantification of N-terminal pro-brain natriuretic peptide (NTproBNP). NT-proBNP is an established blood biomarker for quantifying ventricular filling pressure in patients with presumed HF. Manually assessed PTT demonstrated low inter-rater variability with a correlation between raters >0.98. PTT was obtained automatically and correctly in 266 patients using artificial intelligence. The median PTT of 182 patients with both left and right ventricular ejection fraction >50% amounted to 6.8 s (Pulmonary transit time: 5.9-7.9 s). PTT was significantly higher in patients with reduced left ventricular ejection fraction (<40%; P < 0.001) and right ventricular ejection fraction (<40%; P < 0.0001). The area under the receiver operating characteristics curve (AUC) of PTT for exclusion of HF (NT-proBNP <125 ng/L) was 0.73 (P < 0.001) with a specificity of 77% and sensitivity of 70%. The AUC of PTT for the inclusion of HF (NT-proBNP >600 ng/L) was 0.70 (P < 0.001) with a specificity of 78% and sensitivity of 61%.

CONCLUSION

PTT as an easily, even automatically obtainable and robust non-invasive biomarker of haemodynamics might help in the evaluation of patients with dyspnoea and HF.

Shape dependency of gold nanorods through TMB2+-mediated etching for the visual detection of NT-proBNP

Heart failure (HF) is a major public health problem triggered by heart circulation disorders. Early detection and diagnosis are conducive to the prevention and treatment of HF. Hence, it is necessary to establish a simple and sensitive method to monitor the diagnostic biomarkers of HF. The N-terminal B-type natriuretic peptide precursor (NT-proBNP) is acknowledged as a sensitive biomarker. In this study, a visual detection method for NT-proBNP was developed based on the oxidized 3,3′,5,5′-tetramethylbenzidine (TMB²⁺)-mediated etching of gold nanorods (AuNRs) and double-antibody-sandwich ELISA. The etching color for different amounts of NT-proBNP was obvious and significant differences could be ascertained based on the blue-shift of the longitudinal localized surface plasmon resonance (LLSPR) of the AuNRs. The results could be observed by the naked eye. The constructed system showed a concentration range from 6 to 100 ng mL⁻¹ and a low detection limit of 6 ng mL⁻¹. This method exhibited negligible cross-reactivity toward other proteins, and the recoveries of the samples ranged from 79.99% to 88.99%. These results demonstrated that the established method is suitable for the simple and convenient detection of NT-proBNP.

Visual detection of NT-proBNP based on the principle of HRP-catalyzed TMB conversion into TMB²⁺ to mediate gold nanorods etching and an ELISA system.

Secondhand tobacco smoke exposure, urine cotinine, and risk of incident atrial fibrillation: The multi-ethnic study of atherosclerosis

BACKGROUND

Secondhand tobacco smoke (SHS) exposure may reduce heart rate variability and lead to atrial fibrillation (AF); however prior study findings have not been confirmed using objective measures for both SHS and AF events.

METHODS

We prospectively examined the association between SHS exposure and incident AF in 5731 participants, ages of 45-84 years and free of known AF and other cardiovascular diseases (CVD) at baseline (2000-2002), who were followed through 2015 in the Multi-Ethnic Study of Atherosclerosis (MESA). SHS weekly exposure time was identified by self-report. Urine cotinine was collected in a cohort subset of 3237 current non-smoking cohort participants. AF events were identified using Medicare claims, hospital records, and 12‑lead electrocardiographic findings. A multivariable Cox proportional hazards regression analysis was used with simultaneous adjustment for demographic factors, educational level, health insurance status, active smoking status, tobacco pack-years, traditional CVD risk factors, depressive symptoms and medications.

RESULTS

During a median follow-up of 14.0 years, 856 and 452 AF events were identified in the overall and the cohort subset, respectively. No association of SHS exposure time or urine cotinine with incident AF was observed. However, a higher AF risk with greater urine cotinine (8.53-442.0 ng/mL) compared with lower urine cotinine (≤7.07 ng/mL) was observed in never smokers [hazard ratios (HR) and 95% confidence intervals: 1.60 (1.16, 2.19)], but not in former smokers [HR: 0.88 (0.63, 1.23)] (p-value for multiplicative interaction: 0.009 and for additive interaction: 0.017, respectively).

CONCLUSION

Objectively measured greater SHS exposure expressed by urine cotinine might be associated with 1.6-fold higher risk of incident AF in never smokers.

Higher galectin-3 levels are independently associated with lower anxiety in patients with risk factors for heart failure

Background

Galectin-3 promotes the proliferation of neural progenitor cells and is engaged in cell-cell adhesion, cell-matrix interactions, and macrophage activation. In addition, in patients with heart failure this carbohydrate-binding protein is a known prognostic marker for cardiovascular mortality. However, its association with psychological variables has not been investigated so far.

Methods

Using data from the multicenter, observational Diast-CHF (Diagnostic Trial on Prevalence and Clinical Course of Diastolic Dysfunction and Heart Failure) trial, we studied in participants with cardiovascular risk factors (n = 1260, age 66.7 ± 8.0 years, males 51%, left ventricular ejection fraction 60.0 ± 8.1%) the relationship between serum concentrations of galectin-3 and anxiety. Galectin-3 levels were measured by means of a sandwich enzyme-linked immunosorbent assay, and anxiety was assessed using the Hospital Anxiety and Depression Scale (HADS).

Results

In univariate analysis, there was a weak but significant inverse correlation between galectin-3 and HADS anxiety (rho = − 0.076; p = 0.008). Linear regression models adjusted for sex, age, body-mass index, estimated glomerular filtration rate, left ventricular ejection fraction, 6-min walking distance, the 36-item Short-Form Health Survey (SF-36) subscale physical functioning, and known biomarkers for heart failure confirmed that serum galectin-3 significantly and independently predicted self-rated anxiety (B = -2.413; 95%CI = -2.413–-4.422; p = 0.019).

Conclusion

In patients with cardiovascular risk factors, serum concentrations of galectin-3 showed an inverse association with anxiety, which was independent of both the severity of physical impairment and established risk factors for the progression of heart failure.

B-Type Natriuretic Peptide as a Significant Brain Biomarker for Stroke Triaging Using a Bedside Point-of-Care Monitoring Biosensor

Stroke is a widespread condition that causes 7 million deaths globally. Survivors suffer from a range of disabilities that affect their everyday life. It is a complex condition and there is a need to monitor the different signals that are associated with it. Stroke patients need to be rapidly diagnosed in the emergency department in order to allow the admission of the time-limited treatment of tissue plasminogen activator (tPA). Stroke diagnostics show the use of sophisticated technologies; however, they still contain limitations. The hidden information and technological advancements behind the utilization of biomarkers for stroke triaging are significant. Stroke biomarkers can revolutionize the way stroke patients are diagnosed, monitored, and how they recover. Different biomarkers indicate different cascades and exhibit unique expression patterns which are connected to certain pathologies in the human body. Over the past decades, B-type natriuretic peptide (BNP) and its derivative N-terminal fragment (NT-proBNP) have been increasingly investigated and highlighted as significant cardiovascular biomarkers. This work reviews the recent studies that have reported on the usefulness of BNP and NT-proBNP for stroke triaging. Their classification association is also presented, with increased mortality in stroke, correlation with cardioembolic stroke, and an indication of a second stroke recurrence. Moreover, recent scientific efforts conducted for the technological advancement of a bedside point-of-care (POC) device for BNP and NT-proBNP measurements are discussed. The conclusions presented in this review may hopefully assist in the major efforts that are currently being conducted in order to improve the care of stroke patients.

Change in NT-proBNP (N-Terminal Pro-B-Type Natriuretic Peptide) Level and Risk of Dementia in Multi-Ethnic Study of Atherosclerosis (MESA)

Cross-sectionally measured NT-proBNP (N-terminal pro-B-type natriuretic peptide) is related to incident dementia. However, data linking changes in NT-proBNP to risk of future dementia are lacking. We aimed to examine the association of change in NT-proBNP over 3.2 years with incident dementia. We included 4563 participants in MESA (Multi-Ethnic Study of Atherosclerosis) prospective cohort who were free of cardiovascular disease at enrollment, had NT-proBNP level measured at MESA exams 1 (baseline, 2000-2002) and 3 (2004-2005), and had no diagnosis of dementia before exam 3. The association of change in NT-proBNP level between MESA exams 1 through 3 and all-cause hospitalized dementia (by International Classification of Diseases, Ninth Revision, codes) after MESA exam 3 (2004-2005) through 2015 was assessed using competing-risks Cox proportional hazard regression analysis. During 45 522 person-years of follow-up, 223 dementia cases were documented. Increase in log-NT-proBNP from MESA exams 1 through 3 was positively associated with incidence of dementia (multivariable hazard ratio, 1.28 [95% CI, 1.001-1.64]; P=0.049). An increase of at least 25% in NT-proBNP level from MESA exam 1 through 3 was associated with a 55% (P=0.02) increase in the risk of dementia in multivariable analysis. Addition of temporal NT-proBNP change to a model including risk factors and baseline NT-proBNP improved the prediction of dementia (Harrell C statistic from 0.85 to 0.87, P=0.049). Increase in NT-proBNP is independently associated with future all-cause hospitalized dementia and offers a moderately better predictive performance for risk of dementia compared with risk factors and baseline NT-proBNP. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT00005487.

B-Type Natriuretic Peptides and Cardiac Troponins for Diagnosis and Risk-Stratification of Syncope

BACKGROUND

The utility of BNP (B-type natriuretic peptide), NT-proBNP (N-terminal proBNP), and hs-cTn (high-sensitivity cardiac troponin) concentrations for diagnosis and risk-stratification of syncope is incompletely understood.

METHODS

We evaluated the diagnostic and prognostic accuracy of BNP, NT-proBNP, hs-cTnT, and hs-cTnI concentrations, alone and against those of clinical assessments, in patients >45-years old presenting with syncope to the emergency department in a prospective diagnostic multicenter study. BNP, NT-proBNP, hs-cTnT and hs-cTnI concentrations were measured in a blinded fashion. Cardiac syncope, as adjudicated by 2 physicians based on all information available including cardiac work-up and 1-year follow-up, was the diagnostic end point. EGSYS (Evaluation of Guidelines in Syncope Study), a syncope-specific diagnostic score, served as the diagnostic comparator. Death and major adverse cardiac events at 30 and 720 days were the prognostic end points. Major adverse cardiac events were defined as death, cardiopulmonary resuscitation, life-threatening arrhythmia, implantation of pacemaker/implantable cardioverter defibrillator, acute myocardial infarction, pulmonary embolism, stroke/transient ischemic attack, intracranial bleeding, or valvular surgery. ROSE (Risk Stratification of Syncope in the Emergency Department), OESIL (Osservatorio Epidemiologico della Sincope nel Lazio), SFSR (San Fransisco Syncope Rule), and CSRS (Canadian Syncope Risk Score) served as the prognostic comparators.

RESULTS

Among 1538 patients eligible for diagnostic assessment, cardiac syncope was the adjudicated diagnosis in 234 patients (15.2%). BNP, NT-proBNP, hs-cTnT, and hs-cTnI were significantly higher in cardiac syncope versus other causes (P<0.01). The diagnostic accuracy for cardiac syncope, as quantified by the area under the curve, was 0.77 to 0.78 (95% CI, 0.74-0.81) for all 4 biomarkers, and superior to EGSYS (area under the curve, 0.68 [95%-CI 0.65-0.71], P<0.001). Combining BNP/NT-proBNP with hs-cTnT/hs-cTnI further improved diagnostic accuracy to an area under the curve of 0.81 (P<0.01). BNP, NT-proBNP, hs-cTnT, and hs-cTnI cut-offs, achieving predefined thresholds for sensitivity and specificity (95%), allowed for rule-in or rule-out of ≈30% of all patients. A total of 450 major adverse cardiac events occurred during follow-up. The prognostic accuracy of BNP, NT-proBNP, hs-cTnI, and hs-cTnT for major adverse cardiac events was moderate-to-good (area under the curve, 0.75-0.79), superior to ROSE, OESIL, and SFSR, and inferior to CSRS.

CONCLUSIONS

BNP, NT-proBNP, hs-cTnT, and hs-cTnI concentrations provide useful diagnostic and prognostic information in emergency department patients with syncope.

CLINICAL TRIAL REGISTRATION

URL: https://www.

CLINICALTRIALS

gov. Unique identifier: NCT01548352.

Simultaneous detection of multiple NT-proBNP clinical samples utilizing an aptamer-based sandwich assay on an integrated microfluidic system

Although cardiovascular diseases such as heart failure (HF) affect 30 million people globally, the early detection of HF has, until recently, been difficult and prone to misdiagnoses. Monitoring the circulatory levels of a relatively new biomarker, the N-terminal prohormone of a B-type natriuretic peptide, could be used for early risk evaluation of HF. Therefore, we developed a pneumatically-driven, automatic integrated microfluidic platform equipped with micromixers, micropumps, and microvalves for the simultaneous detection of NT-proBNP in up to six clinical samples within 25 min by using a novel aptamer-based sandwich assay, and the limit of detection was only 1.53 pg mL-1; given that the chip is 64% more compact than those developed in our prior works and requires only 5 μL of sample input, it may serve as a promising tool for early diagnosis of HF.

Association Between 3-Iodothyronamine (T1am) Concentrations and Left Ventricular Function in Chronic Heart Failure

CONTEXT

Thyroid hormone metabolites might affect the heart. The endogenous aminergic metabolite 3-iodothyronamine (T1am) reduces left ventricular ejection fraction (LVEF) in rodents.

OBJECTIVE

To investigate concentration of T1am and its association with LVEF and biomarkers of heart function in patients with chronic heart failure (CHF) without thyroid disease, including patients with cardiac cachexia (nonedematous weight loss >5% over 6 months).

METHODS

Cross-sectional study. CHF was characterized by LVEF <45% and symptoms. Three groups were included (n = 19 in each group, matched on age, sex, and kidney function): patients with cachexia (CAC), patients without (non-CAC), and control (C) patients with prior myocardial infarction and LVEF >45%. T1am was measured by a monoclonal antibody-based chemiluminescence immunoassay. N-amino terminal pro-BNP (NT-proBNP) concentrations were also analyzed.

RESULTS

Mean (SD) LVEF: CAC, 32 ± 9%; non-CAC, 38 ± 8%; and C, 60 ± 8% (P < 0.0001). TSH, T4, and T3 levels did not differ between groups and did not correlate to T1am. Serum T1am (nmol/L) concentrations were higher in CHF: CAC (mean ± SD), 12.4 ± 6.6; non-CAC, 9.1 ± 5; and C, 7.3 ± 2.9. A negative association between T1am and LVEF was present after adjusting for sex, age, T3, and estimated glomerular filtration rate (P = 0.03). Further, serum T1am levels tended to be associated with NT-proBNP (P = 0.053).

CONCLUSION

Serum T1am levels were increased in patients with CHF and numerically highest (although nonsignificant) in patients with cardiac cachexia. Increasing T1am concentrations were independently associated with reduced LVEF, suggesting a direct effect on the human heart.

Higher plasma levels of CT-proAVP are linked to less anxiety in men but not women with cardiovascular risk factors: Results from the observational Diast-CHF study

AIM

Using data from the multicenter, observational Diast-CHF (Diagnostic Trial on Prevalence and Clinical Course of Diastolic Dysfunction and Heart Failure) study, this post-hoc analysis aimed at assessing the association between serum concentrations of C-terminal pro-arginine vasopressin (CT-proAVP) and anxiety in patients with cardiovascular risk factors.

BACKGROUND

Animal studies have demonstrated that centrally released AVP is involved in the development of anxiety-like behaviors, however, it is unknown whether, also in humans, CT-proAVP used as a proxy for the co-secreted AVP is associated with self-reported anxiety.

METHODS

In 1463 study participants with cardiovascular risk factors (mean age 66.7 ± 8.1 years, 51.3% males, mean left ventricular ejection fraction 59.8 ± 8.3%), serum concentrations of CT-proAVP were measured by means of an ELISA assay, and anxiety was assessed using the Hospital Anxiety and Depression Scale (HADS).

RESULTS

Data showed that there was a significant and inverse correlation between HADS anxiety and CT-proAVP (rho = -0.074; p = 0.005). Serum CT-proAVP and the HADS anxiety differed between the two sexes: men displayed lower anxiety (4.7 ± 3.5 versus 5.5 ± 3.7) and had higher CT-proAVP levels (5.8 pmol/L, interquartile range 3.5-9.9 pmol/L versus 3.0 pmol/L, interquartile range 2.0-4.7) than women (both, p < 0.001). Using univariate ANOVA adjusted for age, body-mass index, estimated glomerular filtration rate, left ventricular ejection fraction, 6-minute walking distance, SF-36 physical functioning, and the natriuretic peptides NT-proBNP and MR-proANP, the interaction term sex*CT-proAVP was significantly associated with anxiety (p = 0.006). Further analysis showed that CT-proAVP was inversely related to anxiety only in men (B = -0.991; 95%CI = -1.650 to -0.331; p = 0.003), but not in women (p = 0.335).

CONCLUSION

In male study participants with cardiovascular risk factors, serum concentrations of CT-proAVP showed an inverse association with anxiety, which was independent from the severity of physical impairment.

Development and Evaluation of Up-Converting Phosphor Technology-Based Lateral Flow Assay for Quantitative Detection of NT-proBNP in Blood

A newly assay, up-converting phosphor technology-based lateral flow (UPT-LF) assay, was developed for rapid and quantitative detection of N-terminal fragment of B-type natriuretic peptide precursor (NT-proBNP), one of the most important serum molecular maker of heat failure, in plasma samples as a point of care testing (POCT) method for diagnosis of acute heart failure. Human plasma from 197 patients with acute heart failure and 200 healthy controls was assessed using the UPT-LF assay, in a comparison with a Roche Elecsys assay. The limit of detection of the UPT-LF assay, with a coefficient of variation (CV) of less than 15%, was 116 ng/L, which is lower than the clinical diagnosis cutoff (150 ng/mL). The linear range was 50-35,000 ng/L. The CVs were less than 10% for both UPT-LF and Roche Elecsys assays for plasma samples under different storages, demonstrating the good stability and reproducibility. There are certain linear correlations between the results of UPT-LF and Roche Elecsys assay for EDTA-K2 and heparin-anticoagulated plasma, as well as for serum samples. For UPT-LF assay, there is a significant correlation between the values derived from analysis of EDTA-K2 and heparin-anticoagulated plasma samples (R = 0.995). No statistically significant difference was found between serum and plasma samples for UPT-LF assay. Our results demonstrate that NT-proBNP levels in healthy adults are elevated with age and had a relationship with sex, and with the age increase the NT-proBNP levels of females are significantly higher than those of males (p<0.01). The UPT-LF assay has a high reproducibility, stability, sensitivity, specificity, and is consistent with Roche Elecsys assay, and therefore it could be used as a POCT method for the quantitative detection of NT-proBNP in blood for clinical diagnosis and research of acute heart failure.

Cost savings with a new screening algorithm for pulmonary arterial hypertension in systemic sclerosis

BACKGROUND

Screening for pulmonary arterial hypertension (PAH) in systemic sclerosis (SSc) is now standard care in this disease. The existing Australian Scleroderma Interest Group algorithm (ASIGSTANDARD ) is based on transthoracic echocardiography (TTE) and pulmonary function tests (PFT). Recently, ASIG has derived and validated a new screening algorithm (ASIGPROPOSED ) that incorporates N-terminal pro-B-type natriuretic peptide level together with PFT in order to decrease reliance on TTE, which has some limitations. Right heart catheterisation (RHC) remains the gold standard for the diagnosis of PAH in patients who screen 'positive'.

AIM

To compare the cost of PAH screening in SSc with ASIGSTANDARD and ASIGPROPOSED algorithms.

METHODS

We applied both ASIGSTANDARD and ASIGPROPOSED algorithms to 643 screen-naïve SSc patients from the Australian Scleroderma Cohort Study (ASCS), assuming a PAH prevalence of 10%. We compared the costs of screening, the number of TTE required and both the total number of RHC required and the number of RHC needed to diagnose one case of PAH, and costs, according to each algorithm. We then extrapolated the costs to the estimated total Australian SSc population.

RESULTS

In screen-naïve patients from the ASCS, ASIGPROPOSED resulted in 64% fewer TTE and 10% fewer RHC compared with ASIGSTANDARD , with $1936 (15%) saved for each case of PAH diagnosed. When the costs were extrapolated to the entire Australian SSc population, there was an estimated screening cost saving of $946 000 per annum with ASIGPROPOSED , with a cost saving of $851 400 in each subsequent year of screening.

CONCLUSIONS

ASIGPROPOSED substantially reduces the number of TTE and RHC required and results in substantial cost savings in SSc-PAH screening compared with ASIGSTANDARD .

Prognostic Value of Lymphocyte G Protein-Coupled Receptor Kinase-2 Protein Levels in Patients With Heart Failure

RATIONALE

Sympathetic nervous system hyperactivity is associated with poor prognosis in patients with heart failure (HF), yet routine assessment of sympathetic nervous system activation is not recommended for clinical practice. Myocardial G protein-coupled receptor kinase-2 (GRK2) is upregulated in HF patients, causing dysfunctional β-adrenergic receptor signaling. Importantly, myocardial GRK2 levels correlate with levels found in peripheral lymphocytes of HF patients.

OBJECTIVE

The independent prognostic value of blood GRK2 measurements in HF patients has never been investigated; thus, the purpose of this study was to evaluate whether lymphocyte GRK2 levels predict clinical outcome in HF patients.

METHODS AND RESULTS

We prospectively studied 257 HF patients with mean left ventricular ejection fraction of 31.4±8.5%. At the time of enrollment, plasma norepinephrine, serum NT-proBNP, and lymphocyte GRK2 levels, as well as clinical and instrumental variables were measured. The prognostic value of GRK2 to predict cardiovascular (CV) death and all-cause mortality was assessed using the Cox proportional hazard model including demographic, clinical, instrumental, and laboratory data. Over a mean follow-up period of 37.5±20.2 months (range, 3-60 months), there were 102 CV deaths. Age, left ventricular ejection fraction, New York Heart Association class, chronic obstructive pulmonary disease, chronic kidney disease, N-terminal-pro brain natriuretic peptide, and lymphocyte GRK2 protein levels were independent predictors of CV mortality in HF patients. GRK2 levels showed an additional prognostic and clinical value over demographic and clinical variables. The independent prognostic value of lymphocyte GRK2 levels was also confirmed for all-cause mortality.

CONCLUSIONS

Lymphocyte GRK2 protein levels can independently predict prognosis in patients with HF.

The association between N-terminal pro B-type natriuretic peptide and lipoprotein particle concentration plateaus at higher N-terminal pro B-type natriuretic peptide values: Multi-Ethnic Study on Atherosclerosis

BACKGROUND

The association between N-terminal pro B-type natriuretic peptide (NT-proBNP) and blood levels of small and large LDL- and HDL- particle (P) concentration may not be linear throughout the whole range of NT-proBNP values.

METHODS

Linear spline regression analysis between NT-proBNP and lipoprotein particle concentrations was performed cross-sectionally in 5597 individuals from the Multi-Ethnic Study of Atherosclerosis adjusted for age, race, sex, body mass index, % of energy from saturated fats, intentional exercise, statin use, antihypertensive medication use, diabetes, IL-6 and estimated glomerular filtration rate. Spline knots were selected as the point at which the linear slope changed in these associations.

RESULTS

NT-proBNP was positively associated with large LDL-P and HDL-P, but inversely associated with small LDL-P and HDL-P, but only for NT-proBNP values below the knot (range: 100-200 pg/mL).

CONCLUSION

These results suggest the presence of two distinct biological mechanisms above and below the knot determining the association between NT-proBNP and lipoprotein particle concentrations.

Changes in N-terminal pro-B-type natriuretic peptide and incidence of diabetes: The Multi-Ethnic Study of Atherosclerosis (MESA)

AIMS

This study looked at whether the inverse association of circulating N-terminal pro-B-type natriuretic peptide (NT-proBNP) with incident diabetes is modified by changes in NT-proBNP (ΔNT-proBNP) levels.

METHODS

Plasma NT-proBNP was assayed at baseline and 3.2 years later (visit 3) in the Multi-Ethnic Study of Atherosclerosis (MESA). ΔNT-proBNP was calculated as NT-proBNP visit3-NT-proBNP baseline. A Poisson distribution was fitted to determine the incidence density of diabetes, adjusted for age, race, gender, educational attainment, antihypertensive medication, total intentional exercise and plasma IL-6 levels. In the primary analysis (n=3236 without diabetes up to visit 3, followed for a mean of 6.3 years), incidence density was regressed for the following categories of baseline NT-proBNP: (1)<54.4 pg/mL; (2) 54.4-85.9 pg/mL; and (3) 86-54.2 pg/mL. This was crossed with categories of ΔNT-proBNP as medians (ranges): (1) -6.2 (-131-11.7) pg/mL; (2) 19.8 (11.8-30.1) pg/mL; (3) 44.0 (30.2-67.9) pg/mL; and (4) 111.2 (68.0-3749.9) pg/mL.

RESULTS

The incidence density of diabetes followed a U-shaped association across categories of ΔNT-proBNP within categories of baseline NT-proBNP after adjusting for other covariates (P=0.02). At each level of baseline NT-proBNP, the incidence density of diabetes was lowest for small-to-moderate increases in NT-proBNP.

CONCLUSION

This analysis suggests that NT-proBNP has a biphasic association with diabetes in which the risk of incident diabetes decreases within a 'physiological range' of ΔNT-proBNP, and plateaus or increases as NT-proBNP concentrations increase, probably in response to pathophysiological conditions leading to high levels of NT-proBNP.

Addition of N-terminal pro-B-type natriuretic peptide levels to electrocardiography criteria for detection of left ventricular hypertrophy: the ARIRANG study

The utility of electrocardiography (ECG) in screening for left ventricular hypertrophy (LVH) in general populations is limited mainly because its low sensitivity. B-type natriuretic peptide (BNP) is released due to the remodeling processes of LVH and could improve the diagnostic accuracy for the ECG criteria for LVH. We hypothesized that addition of BNP levels to ECG criteria could aid LVH detection compared with ECG alone in a general population. We enrolled consecutive 343 subjects from a community-based cohort. LVH was defined as LV mass index > 95 g/m(2) for females and > 115 g/m(2) for males according to echocardiography. The area under the receiver operator characteristic (ROC) curve to detect LVH was 0.55 (95% confidence interval [CI], 0.50-0.61) in Sokolow-Lyon criteria and 0.53 (0.47-0.59) in the Cornell voltage criteria. After addition of N-terminal-proBNP levels to the model, the corresponding areas under the ROC were 0.63 (0.58-0.69) and 0.64 (0.59-0.69), respectively. P values for the comparison in areas under the ROC for models with and without N-terminal-proBNP levels were < 0.001. These data suggest that addition of N-terminal-proBNP levels to ECG criteria could significantly improve the diagnostic accuracy of LVH in general populations.

Cardiac natriuretic peptides in plasma increase after dietary induced weight loss in obesity

Background

Cardiac natriuretic peptides are established biomarkers in heart disease, but are also affected by body mass index (BMI). The purpose of the present study was to examine the impact of weight loss and changes in body composition following dietary intervention on plasma concentrations of the prohormones to A- and B-type natriuretic peptides (proANP and proBNP) and adrenomedullin (proADM).

Results

A total of 52 healthy obese subjects, 47 women and 5 men (BMI 36.5 ± 5.6 kg/m²) were randomised to either an intensive weight reduction programme using a combination of very low calorie diet (810 kcal/day) and conventional hypo-energetic diet (1200 kcal/day) for 52 weeks, or to a control group that was offered diet-related counselling. N-terminal proBNP (NT-proBNP), mid-regional proANP (MR-proANP) and proADM (MR-proADM) and body composition using dual-energy x-ray absorptiometry (DEXA) scanning were determined at baseline and after 52 weeks. Comparisons between groups were analysed using t-tests. Changes from the baseline within the groups were analysed with paired tests. Changes in the variables, delta (∆), were calculated as 52 weeks minus the baseline.

In the intervention group, BMI decreased by almost 20% (31.6 ± 6.2 vs. 37.1 ± 6.1 kg/m²; P <0.001) with a loss of body fat of 23.5 ± 15.5% (P < 0.001). Plasma concentrations of NT-proBNP and MR-proANP increased (from 55 ± 31 to 97 ± 55 pg/ml; P < 0.001, and from 59 ± 21 to 74 ± 26 pmol/L; P < 0.001), whereas MR-proADM decreased (from 573 ± 153 to 534 ± 173 pmol/L; P <0.001). Changes (Δ) in MR-proANP correlated with Δfat mass (r = −0.359; P = 0.011) and Δglucose (r = −0.495; P <0.001), while increases in NT-proBNP were primarily associated with reduced plasma glucose (r = −0.462; P <0.001). A modest but significant weight loss of 6% (P < 0.001) was found in the control group with no changes in plasma concentrations of NT-proBNP or MR-proANP, and a minor change in MR-proADM.

Conclusions

Plasma NT-proBNP and MR-proANP concentrations increase and MR-proADM concentration decreases during weight loss, underlining the dynamic impact of BMI, body composition and glucose metabolism on these cardiovascular biomarkers.

The effect of coenzyme Q10 on morbidity and mortality in chronic heart failure: results from Q-SYMBIO: a randomized double-blind trial

OBJECTIVES

This randomized controlled multicenter trial evaluated coenzyme Q10 (CoQ10) as adjunctive treatment in chronic heart failure (HF).

BACKGROUND

CoQ10 is an essential cofactor for energy production and is also a powerful antioxidant. A low level of myocardial CoQ10 is related to the severity of HF. Previous randomized controlled trials of CoQ10 in HF were underpowered to address major clinical endpoints.

METHODS

Patients with moderate to severe HF were randomly assigned in a 2-year prospective trial to either CoQ10 100 mg 3 times daily or placebo, in addition to standard therapy. The primary short-term endpoints at 16 weeks were changes in New York Heart Association (NYHA) functional classification, 6-min walk test, and levels of N-terminal pro-B type natriuretic peptide. The primary long-term endpoint at 2 years was composite major adverse cardiovascular events as determined by a time to first event analysis.

RESULTS

A total of 420 patients were enrolled. There were no significant changes in short-term endpoints. The primary long-term endpoint was reached by 15% of the patients in the CoQ10 group versus 26% in the placebo group (hazard ratio: 0.50; 95% confidence interval: 0.32 to 0.80; p = 0.003) by intention-to-treat analysis. The following secondary endpoints were significantly lower in the CoQ10 group compared with the placebo group: cardiovascular mortality (9% vs. 16%, p = 0.026), all-cause mortality (10% vs. 18%, p = 0.018), and incidence of hospital stays for HF (p = 0.033). In addition, a significant improvement of NYHA class was found in the CoQ10 group after 2 years (p = 0.028).

CONCLUSIONS

Long-term CoQ10 treatment of patients with chronic HF is safe, improves symptoms, and reduces major adverse cardiovascular events. (Coenzyme Q10 as adjunctive treatment of chronic heart failure: a randomised, double-blind, multicentre trial with focus on SYMptoms, BIomarker status [Brain-Natriuretic Peptide (BNP)], and long-term Outcome [hospitalisations/mortality]; ISRCTN94506234).

Risk stratification in emergency patients by copeptin

BACKGROUND

Rapid risk stratification is a core task in emergency medicine. Identifying patients at high and low risk shortly after admission could help clinical decision-making regarding treatment, level of observation, allocation of resources and post discharge follow-up. The purpose of the present study was to determine short-, mid- and long-term mortality by plasma measurement of copeptin in unselected admitted patients.

METHOD

Consecutive patients >40-years-old admitted to an inner-city hospital were included. Within the first 24 hours after admission, a structured medical interview was conducted and self-reported medical history was recorded. All patients underwent a clinical examination, an echocardiographic evaluation and collection of blood for later measurement of risk markers.

RESULTS

Plasma for copeptin measurement was available from 1,320 patients (average age 70.5 years, 59.4% women). Median follow-up time was 11.5 years (range 11.0 to 12.0 years). Copeptin was elevated (that is, above the 97.5 percentile in healthy individuals).Mortality within the first week was 2.7% (17/627) for patients with elevated copeptin (above the 97.5 percentile, that is, >11.3 pmol/L) compared to 0.1% (1/693) for patients with normal copeptin concentrations (that is, ≤11.3 pmol/L) (P <0.01). Three-month mortality was 14.5% (91/627) for patients with elevated copeptin compared to 3.2% (22/693) for patients with normal copeptin. Similar figures for one-year mortality and for the entire observation period were 27.6% (173/627) versus 8.7% (60/693) and 82.9% (520/527) versus 57.5% (398/693) (P <0.01 for both), respectively.Using multivariable Cox regression analyses shows that elevated copeptin was significantly and independently related to short-, mid- and long-term mortality. Adjusted hazard ratios were 2.4 for three-month mortality, 1.9 for one-year mortality and 1.4 for mortality in the entire observation period.

CONCLUSIONS

In patients admitted to an inner-city hospital, copeptin was strongly associated with short-, mid- and long-term mortality. The results suggest that rapid copeptin measurement could be a useful tool for both disposition in an emergency department and for mid- and long-term risk assessment.

Proinsulin and IGFBP-1 predicts mortality in an elderly population

BACKGROUND

High IGFBP-1 in elderly subjects is related to all-cause and cardiovascular (CV) mortality. We studied the relation of IGFBP-1 to cardiometabolic risk factors and cardiovascular and all-cause mortality, and also the impact of proinsulin and insulin on this association in an unselected elderly primary health care population.

HYPOTHESIS

Our hypothesis was that proinsulin and insulin may have an impact on the association of high IGFBP-1 levels with all-cause and CV-mortality in elderly.

DESIGN, SETTING AND PARTICIPANTS

A cross-sectional and prospective study was carried out in a rural Swedish population. 851 persons aged 66-81 years were evaluated by medical history, clinical examination, electrocardiography, echocardiography, and fasting plasma samples, and were followed prospectively for up to 12 years.

RESULTS

At baseline, in a multivariate analysis, IGFBP-1 was associated with gender, N-terminal proBNP (NT pro-BNP), blood glucose, body mass index (BMI), insulin and proinsulin, estimated glomerular filtration rate (eGFR) and haemoglobin (Hb). During the follow-up period there were 230 deaths (27%), of which 134 (16%) were due to CV mortality. When divided into tertiles there was a significant difference for CV mortality and all-cause mortality between tertiles of IGFBP-1 and proinsulin. For insulin there was a significant difference only for all-cause mortality. After adjustment for well-known risks factors, proinsulin and IGFBP-1 had significant impact on all-cause mortality but only proinsulin on CV mortality.

CONCLUSION

Only proinsulin is an independent predictor for both all-cause mortality and CV mortality when comparing IGFBP-1, insulin, and proinsulin as prognostic biomarkers for CV and all-cause mortality in an elderly population.

Body mass index in chronic heart failure: association with biomarkers of neurohormonal activation, inflammation and endothelial dysfunction

BACKGROUND

Low body mass index (BMI) is associated with a poor outcome in chronic heart failure (CHF). An inverse association between BMI and adiponectin and N-terminal pro-B-type natriuretic peptide (NT-proBNP) has been reported. The aim of the present study was to investigate whether novel markers of neurohormonal activation, inflammation, and endothelial dysfunction are associated with BMI in CHF.

METHODS

In a cross-sectional study including 171 patients with CHF and a left ventricular ejection fraction (LVEF) ≤45% the impact of BMI on circulating plasma concentrations of adiponectin, α-defensins, high sensitivity C-reactive protein (hsCRP), copeptin, mid-regional pro-adrenomedullin (MR-proADM), NT-proBNP, and mid-regional pro-A-type natriuretic peptide (MR-proANP) were evaluated.

RESULTS

In multivariable linear regression analysis including age, sex, LVEF, New York Heart Association functional classification (NYHA), estimated glomerular filtration rate (eGFR), and diabetes, only NT-proBNP (β = -0.32) and adiponectin (β = -0.39) remained independently associated with BMI. MR-proANP was associated with BMI but adjusting for age attenuated the relation being no longer significant.

CONCLUSIONS

Among biomarkers typically increased in patients with CHF only adiponectin and NT-proBNP demonstrated independent inverse associations with BMI. This indicates a direct effect of these two biomarkers enhancing the wasting process seen in CHF.

MicroRNA-150: a novel marker of left ventricular remodeling after acute myocardial infarction

BACKGROUND

Left ventricular (LV) remodeling after acute myocardial infarction is associated with adverse prognosis. MicroRNAs (miRNAs) regulate the expression of several genes involved in LV remodeling. Our aim was to identify miRNAs associated with LV remodeling after acute myocardial infarction.

METHODS AND RESULTS

We studied 90 patients after first ST-segment-elevation acute myocardial infarction. A derivation cohort consisted of 60 patients characterized by echocardiography predischarge and at 6-month follow-up. Thirty patients characterized by magnetic resonance imaging predischarge and at 4-month follow-up were the validation cohort. Remodeling was defined as an increase in LV end-diastolic volume (ΔEDV>0) between discharge and follow-up. Circulating miRNAs were measured by microarrays and polymerase chain reaction. Using a systems-based approach, we identified several miRNAs potentially involved in LV remodeling. In the derivation cohort, one of these miRNAs, miR-150, was downregulated in patients with remodeling (ΔEDV>0) compared with patients without remodeling (ΔEDV≤0). In the validation cohort, patients with remodeling had 2-fold lower levels of miR-150 than those without (P=0.03). miR-150 outperformed N-terminal pro-brain natriuretic peptide to predict remodeling (area under the receiver-operating characteristic curve of 0.74 and 0.60, respectively). miR-150 reclassified 54% (95% confidence interval, 5-102; P=0.03) of patients misclassified by N-terminal pro-brain natriuretic peptide and 59% (95% confidence interval, 9-108; P=0.02) of patients misclassified by a multiparameter clinical model, including age, sex, and admission levels of troponin I, creatine kinase, and N-terminal pro-brain natriuretic peptide.

CONCLUSIONS

Low circulating levels of miR-150 are associated with LV remodeling after first ST-segment-elevation acute myocardial infarction. miR-150 has potential as a novel biomarker in this setting.

The benefits of using a heart failure management programme in Swedish primary healthcare

AIM

Heart failure (HF) is a common condition with which high mortality, morbidity, and poor quality of life are associated. It has previously been shown that use of HF management programmes (HFMPs) in HF clinics can be beneficial. The purpose of this study was to evaluate if the use of HFMPs also has beneficial effects on HF patients in primary healthcare (PHC).

METHODS AND RESULTS

This is a randomized, prospective, open-label study including 160 patients from five PHC centres with systolic HF and a mean age of 75 years (standard deviation 7.8). In the intervention group, an intensive follow-up was performed by HF nurses and physicians providing information and education about HF and the optimization of HF treatment according to recognized guidelines. There was a significant improvement of composite endpoints in the intervention group. Significantly more patients with reduced N-terminal pro brain natriuretic peptide (P = 0.012), improved cardiac function (P = 0.03), fewer healthcare contacts (P = 0.04), and fewer emergency room visits and admittances (P = 0.0002 and P = 0.03, respectively) could be seen in the intervention group when compared with the control group.

CONCLUSIONS

The use of a HFMP in a PHC setting was found to have beneficial effects in terms of reducing the number of healthcare contacts and hospital admissions, and improving cardiac function in patients with systolic HF, even if the result should be interpreted with caution. It can therefore be recommended that HFMPs should be used in PHC.

Plasma C-terminal pro-endothelin-1 and the natriuretic pro-peptides NT-proBNP and MR-proANP in very preterm infants with patent ductus arteriosus

BACKGROUND

In very preterm infants, clinical decision-making, such as closing a patent ductus arteriosus (PDA), may be aided by measuring circulating natriuretic and endothelial pro-peptides.

OBJECTIVES

To investigate the association between perinatal characteristics, PDA echocardiography and plasma concentrations of stable pro-peptides of B-type natriuretic peptide (NT-proBNP), atrial natriuretic peptide (MR-proANP) and endothelin-1 (CT-proET-1).

METHODS

A prospective, cross-sectional, single-center study was performed in 66 infants who were less than 32 weeks of gestational age. Pro-peptide concentrations were determined at birth and at day 2-3 of life.

RESULTS

Plasma concentrations of all 3 pro-peptides increased on average 2- to 5-fold from birth to day 2-3 of life. NT-proBNP and MR-proANP were closely related at birth and at day 2-3 (Rs 0.902 and 0.897, respectively, p < 0.001), whereas CT-proET-1 was related to NT-proBNP and MR-proANP at birth (Rs 0.478 and 0.460, respectively, p < 0.001) but not at day 2-3. Birth weight was negatively related to all 3 pro-peptides at birth (p < 0.01); however, preeclampsia and compromised placental perfusion were associated with elevated NT-proBNP and MR-proANP concentrations at birth. At day 2-3, MR-proANP and NT-proBNP correlated significantly with the ductal diameter (Rs 0.416 and 0.415, respectively, both p = 0.011), whereas CT-proET-1 correlated with the left atrium/aorta ratio (Rs 0.506, p = 0.027). CT-proET-1 was elevated in infants with treated compared to untreated PDA [median (5-95% range) 388 (272-723) vs. 303 (152-422) pmol/l, p = 0.011], but not NT-proBNP or MR-proANP.

CONCLUSION

CT-proET-1 is a promising predictor in determining the need for PDA intervention.

Reference limits for N-terminal-pro-B-type natriuretic peptide in healthy individuals (from the Framingham Heart Study)

N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) is a commonly measured cardiovascular biomarker in ambulatory and hospital settings. Nonetheless, there are limited data regarding "normal" ranges for NT-pro-BNP in healthy subjects, despite the importance of such information for interpreting natriuretic peptide measurements. In this study, a healthy reference sample free of cardiovascular disease from the Framingham Heart Study Generation 3 cohort was examined; there were 2,285 subjects (mean age 38 years, 56% women). Plasma NT-pro-BNP levels were measured using the Roche Diagnostics Elecsys 2010 assay, and reference values (2.5th, 50th, and 97.5th quantiles) were determined using empiric and quantile regression methods. Gender, age, blood pressure, and body mass index accounted for approximately 33% of the interindividual variability in NT-pro-BNP in the reference sample. NT-pro-BNP values were substantially higher in women compared to men at every age, and levels increased with increasing age for both genders. Using quantile regression, the upper reference values (97.5th quantile) for NT-pro-BNP were 42.5 to 106.4 pg/ml in men (depending on age) and 111.0 to 215.9 pg/ml in women. Intraindividual variability was assessed in an additional 12 healthy subjects, who had serial NT-pro-BNP measurements over 1 month. Intraclass correlation was 0.85, indicating that most of the variability in NT-pro-BNP concentrations was among rather than within subjects. However, the reference change value was 100%, suggesting that small proportional differences in NT-pro-BNP could be attributable to analytic variability. In conclusion, the reference limits obtained from this large, healthy, community-based sample may aid in the evaluation of NT-pro-BNP concentrations measured for clinical and research purposes.

N-terminal pro B-type natriuretic peptide in the early evaluation of suspected acute myocardial infarction

BACKGROUND

Myocardial ischemia is a strong trigger of N-terminal pro-B-type natriuretic peptide (NT-proBNP) release. As ischemia precedes necrosis in acute myocardial infarction, we hypothesized that NT-proBNP might be useful in the early diagnosis and risk stratification of patients with suspected acute myocardial infarction.

METHODS

In a prospective multicenter study, NT-proBNP was measured at presentation in 658 consecutive patients with acute chest pain. The final diagnosis was adjudicated by 2 independent cardiologists. Patients were followed long term regarding mortality.

RESULTS

Acute myocardial infarction was the adjudicated final diagnosis in 117 patients (18%). NT-proBNP levels at presentation were significantly higher in acute myocardial infarction as compared with patients with other final diagnoses (median 886 pg/mL vs 135 pg/mL, P <.001). The diagnostic accuracy of NT-proBNP for acute myocardial infarction as quantified by the area under the receiver operating characteristic curve (AUC) was 0.79 (95% confidence interval [CI], 0.75-0.83). When added to cardiac troponin T, NT-proBNP significantly increased the AUC from 0.89 (95% CI, 0.84-0.93) to 0.91 (95% CI, 0.88-0.94; P=.033). Cumulative 24-month mortality rates were 0% in the first, 1.3% in the second, 8.3% in the third, and 23.3% in the fourth quartile of NT-proBNP (P <.001). NT-proBNP (AUC 0.85, 95% CI, 0.81-0.89) predicted all-cause mortality independently of and more accurately than both cardiac troponin T (AUC 0.66, 95% CI, 0.58-0.74; P <.001) and the Thrombolysis in Myocardial Infarction risk score (AUC 0.79, 95% CI, 0.74-0.84; P <.001). Net reclassification improvement (Thrombolysis in Myocardial Infarction vs additionally NT-proBNP) was 0.188 (P <.009), and integrated discrimination improvement was 0.100 (P <.001).

CONCLUSIONS

Use of NT-proBNP improves the early diagnosis and risk stratification of patients with suspected acute myocardial infarction.

Characterization of Molecular Forms of N-Terminal B-Type Natriuretic Peptide In Vitro

BACKGROUND

The heterogeneity of circulating peptides may influence the interpretation of results from N-terminal profragment of BNP (NT-proBNP) assays. Our objective was to characterize the heterogeneity for better usability of the assays.

METHODS

Endogenous proBNP was purified from patient samples and treated with trifluoromethanesulfonic acid (chemical deglycosylation). The human proBNP gene was introduced into rat hearts by adenoviral transfer. Cell lysates and plasma samples containing proBNP-derived peptides were analyzed by chromatography. The fate of exogenous recombinant NT-proBNP added to fresh whole blood samples was followed by immunoassays and chromatography. The main NT-proBNP components were isolated and identified by mass spectrometry.

RESULTS

Immunoreactive NT-proBNP in human plasma comprised several molecular forms, as did circulating immunoreactive human NT-proBNP after adenoviral transfer of human proBNP cDNA into rat ventricular myocardium. Incubation of recombinant NT-proBNP1–76 in human plasma or serum resulted in multiple components with the 2 major components identified as NT-proBNP1–36 and NT-proBNP1–62/64. Profiling by different antisera and chromatography indicated masking of the non–mid-region epitopes likely due to formation of oligomers. More than 75% of the original immunoreactivity in the mid-region epitope was retained after 3-week storage of plasma samples at room temperature.

CONCLUSIONS

There is marked heterogeneity in immunoreactive NT-proBNP in plasma not related to glycosylation. The mid-region epitope of NT-proBNP is stable even in harsh storage conditions. Careful choice of antibody epitopes can yield extraordinarily robust assays.

C-terminal provasopressin (copeptin) is a strong prognostic marker in patients with heart failure after an acute myocardial infarction: results from the OPTIMAAL study

AIMS

The aim of the present study was to compare the prognostic value of a novel and promising marker, copeptin, with B-type natriuretic peptide (BNP), and N-terminal pro-BNP (NT-proBNP), on death or a composite cardiovascular endpoint in patients who developed heart failure after an acute myocardial infarction (AMI).

METHODS AND RESULTS

From a subset of 224 patients of the OPTIMAAL study, blood samples were drawn at a mean of 3 days after AMI when all patients had signs and/or symptoms of heart failure or a left ventricular ejection fraction <0.35. Endpoints of interest were mortality (primary endpoint of OPTIMAAL) and a composite cardiovascular endpoint, including death, MI, stroke, and/or resuscitated cardiac arrest. Mean age was 67 +/- 10 years, and mean follow-up was 33 +/- 7 months. Using univariable Cox proportional hazards survival analysis, higher levels of copeptin, BNP, and NT-proBNP were all significantly related to both mortality and the composite cardiovascular endpoint (all P < 0.01). In a multivariable Cox proportional hazards model, including all three biomarkers and other relevant covariates, a doubling of copeptin was related to a 1.83 (1.26-2.64) times increased risk of mortality (P < 0.0001) and a 1.35 (1.05-1.72) times increased risk of the composite cardiovascular endpoint (P = 0.018). Receiver operating characteristic curves indicated that copeptin [area under curve (AUC) 0.81] was a stronger predictor of mortality compared with both BNP (AUC 0.66; P = 0.0063 vs. copeptin) and NT-proBNP (AUC 0.67; P = 0.0016 vs. copeptin). Finally, changes of copeptin levels after 1 month significantly added prognostic information to the baseline value.

CONCLUSION

Copeptin is a strong and novel marker for mortality and morbidity in patients with heart failure after AMI. In this population, the predictive value of copeptin was even stronger than BNP and NT-proBNP.

Association between sleep-disordered breathing, aminoterminal pro-brain natriuretic peptide (NT-proBNP) levels and insulin resistance in morbidly obese young women

OBJECTIVE

Sleep-disordered breathing (SDB) is often encountered in morbid obesity (MO) in conjunction with insulin resistance (IR) and several cardio-vascular risk factors. Aminoterminal pro-brain natriuretic peptide (NT-proBNP) is a promising marker for left ventricular dysfunction (LVD) in MO. The aim of this study was to look for possible correlations between SDB, IR, heart structure and function indexes and NT-proBNP levels in MO female subjects.

MATERIALS AND METHODS

Cross-sectional study involving 110 MO (44.5+/-0.7 kg m(-2)) apparently healthy, young (37.8+/-1.0 y.o.) female patients. NT-proBNP was measured using an ELISA kit (Roche). Echo-cardiograms were performed to quantify left ventricular ejection fraction values (LVEF), cardiac output (CO), left ventricular mass (LVM), left atria size (LA) and left ventricular filling pressures (the E/Em ratio). The Berlin Questionnaire (BQ) was used to assess the risk of SDB. IR and sensitivity were assessed using the HOMA index and adiponectin measurements, respectively.

RESULTS

All patients had a normal LVEF (>50%). Hypertension and Type 2 diabetes mellitus prevalences were 34.5 and 4.5% (respectively). Log-transformed NT-proBNP levels correlated with BQ categories (P<0.0005), creatinine (P<0.001), age (P<0.05), LVM (P<0.001), CO (P<0.001), LA (P<0.0005) and E/Em (P<0.01). NT-proBNP levels, LVD and LVM increased significantly along with BQ scores (P<0.0001). Stepwise multiple regression analysis identified BQ and log-transformed HOMA as independent variables predicting as much as 48.0% of log-transformed NT-proBNP's variability (dependent variable).

CONCLUSIONS

NT-proBNP levels are independently predicted by SDB and IR in asymptomatic MO women. Additionally, SDB worsens along with LVH and diastolic dysfunction. Larger prospective studies are warranted.

Cystatin C and NT-proBNP, a powerful combination of biomarkers for predicting cardiovascular mortality in elderly patients with heart failure: results from a 10-year study in primary care

AIMS

Heart failure (HF) is common among the elderly patients. It is essential to identify those at high risk in order to optimize the use of resources. We aimed to evaluate whether a combination of two biomarkers might give better prognostic information about the risk of cardiovascular (CV) mortality in patients with symptoms associated with HF, compared with only one biomarker.

METHODS AND RESULTS

Four hundred and sixty-four primary health-care patients (mean age 73 years, range 65-87) with symptoms of HF were examined. All patients were evaluated using Doppler echocardiography and blood samples, including measurement of cystatin C and NT-proBNP. The patients were followed over a 10-year period. Patients with serum cystatin C levels within the highest quartile had almost three times the risk (HR: 2.92; 95% CI: 1.23-4.90) of CV mortality compared with those patients who had levels within the first, second, or third quartiles. If, at the same time, the patient had a plasma concentration of NT-proBNP within the highest quartile, the risk increased to >13 times (HR: 13.61; 95% CI: 2.56-72.24) during 10 years of follow-up or >17 times (HR: 17.04; 95% CI: 1.80-163.39) after 5 years of follow-up.

CONCLUSION

Combined analysis of cystatin C and NT-proBNP could provide important prognostic information among elderly patients in the community with symptoms of HF.

Heart murmur and N-terminal pro-brain natriuretic peptide as predictors of death in 2977 consecutive hospitalized patients

BACKGROUND

Little is known about the prognostic importance of murmur in unselected patients. It is difficult to distinguish between innocent and significant murmurs. N-terminal pro-brain natriuretic peptide (NT-pro-BNP) and BNP have recently been shown to be useful in small series of patients with valvular heart disease. We wanted to test whether murmur predicts mortality in unselected patients admitted to the hospital and whether NT-pro-BNP is capable of distinguishing between innocent and significant murmurs.

METHODS

Consecutive patients (n = 2977) older than 40 years admitted to a local hospital were studied. Auscultation, echocardiography were performed and levels of natriuretic peptides were measured.

RESULTS

A total of 21.8% of the 2977 patients had a murmur. After adjusting for sex and age there was a significant difference in the one-year mortality of patients with and without murmur (OR = 1.57, 95% CI = 1.27-1.94). NT-pro-BNP gave additional prognostic information for both patients with and without murmurs. Presence of a murmur was an independent predictor of 1-year mortality (OR = 1.36, 95% CI = 1.03-1.80) in a multivariate analysis. In patients with a murmur but normal NT-pro-BNP, discovery of valvular heart disease by echocardiography yielded no additional prognostic information.

CONCLUSIONS

Detection of a cardiac murmur during routine medical examination of hospitalized patients is associated with increased risk of death within a year. A blood test for NT-pro-BNP gives significant additional prognostic information of a murmur and could obviate the need for echocardiography in selected patients with a murmur and normal NT-pro-BNP for whom surgery is not feasible.

The diagnostic value of serum and urinary NT-proBNP for heart failure

Background

Serum B-type natriuretic peptide (BNP) and the amino-terminal cleavage product of the prohormone (NT-proBNP) have been shown to be valuable parameters for the diagnosis of heart failure (HF) in the general population. Urinary BNP and NT-proBNP have also been suggested for diagnosis of HF. The present study investigated the diagnostic value of both serum and urinary NT-proBNP in selected groups of controls and patients diagnosed with HF.

Methods

Creatinine clearance and serum and urinary NT-proBNP were measured in 76 controls and in 47 patients diagnosed with HF (NYHA III and IV). Echocardiography was used to exclude cardiac dysfunction in the control population by the combined normality of left ventricular ejection fraction (LVEF), E/A ratio (echocardiographic early [E] and late, or atrial [A] phases of ventricular filling), deceleration time and LV mass index. All patients diagnosed with HF had LVEF <40%.

Results

NT-proBNP measurements in urine samples are subject to high variability. Receiver-operating characteristic area under the curve (AUC) for serum, urinary NT-proBNP and their products were 0.94, 0.72 and 0.93, respectively. Correction of urinary NT-proBNP for urinary creatinine content improved the AUC from 0.72 to 0.80. Negative predictive values for ruling out HF were 0.94, 0.67 and 0.89, respectively. Linear regression analysis revealed that creatinine clearance was more important in determining serum NT-proBNP concentrations than age.

Conclusions

Serum NT-proBNP is the best parameter to rule out HF. The product of the serum and urinary concentrations has equal value. Urinary NT-proBNP alone performs rather poorly. Renal function influences NT-proBNP concentrations more than age in this selected population.

Can NT-proBNP predict risk of cardiovascular mortality within 10 years? Results from an epidemiological study of elderly patients with symptoms of heart failure

BACKGROUND

Heart failure has a serious prognosis. However, among elderly patients the panorama of concomitant diseases makes it difficult to implement the results from epidemiological studies. The aim of this study was to evaluate the influence of different clinical variables on cardiovascular mortality during a long-term follow-up.

METHODS AND RESULTS

In all, 474 elderly patients (age 65-82 years) in primary health care were evaluated and followed during a 10 year period. All patients had symptoms associated with heart failure and were examined by a cardiologist. Blood samples including NT-proBNP were analyzed, and ECG and Doppler echocardiography were assessed. Both the systolic and diastolic function was evaluated. Functional capacity was evaluated according to the NYHA classification. During the 10 years of follow-up those with the highest quartile of plasma concentration of NT-proBNP had almost four times increased risk of cardiovascular mortality. Impaired systolic function, diabetes and reduced functional capacity were all markers of increased risk of cardiovascular mortality. All variables were also evaluated after 5 years, with higher risk ratios for a majority of variables.

CONCLUSION

In this study 474 patients with symptoms of heart failure were followed during 10 years. High plasma concentration of NT-proBNP could predict almost four times increased risk of cardiovascular mortality up to 10 years. Also, impaired cardiac function according to echocardiography, and reduced functional capacity as well as diabetes all had influence on risk of cardiovascular mortality up to 10 years.

Aminoterminal pro-brain natriuretic peptide (NT-proBNP) and sleep-disordered breathing in morbidly obese females: a cross-sectional study

Sleep-disordered breathing (SDB) is often encountered in morbid obesity (MO) in conjunction with insulin resistance (IR). Aminoterminal pro-brain natriuretic peptide (NT-proBNP) is a promising marker for left ventricular dysfunction (LVD) in MO. We sought to explore the factors that may influence the relationships of SDB and IR with NT-proBNP in MO women. We performed a cross-sectional pilot study involving 110 asymptomatic MO (44.5+/-0.7 kg/m2) young women. SDB risk was assessed using a modified version of the Berlin Questionnaire (BQ). IR was assessed using the homeostasis model assessment (HOMA) index and adiponectin levels. LVD was assessed using NT-proBNP and echocardiograms. In this study, NT-proBNP levels and LVD increased significantly along the BQ strata. Multiple regression analysis identified BQ and log-transformed HOMA as the independent variables predicting as much as 48.0% of the variability of logNT-proBNP. In conclusion, NT-pro-BNP levels are independently predicted by SDB and IR in asymptomatic MO women. Larger prospective studies are warranted.

Continuous positive airway pressure improves exercise capacity and heart rate recovery in obstructive sleep apnea

BACKGROUND

There is a relationship between obstructive sleep apnea (OSA) and heart failure (HF). Peak oxygen consumption (peak VO(2)), heart rate recovery, and N-terminal-pro-BNP (NT-proBNP) are strong prognostic predictors in HF. The effects of nasal continuous positive airway pressure (nCPAP) on these parameters in OSA patients are not well defined.

METHODS

Forty patients with newly diagnosed OSA [apnea-hypopnea index (AHI) 37 (20-65) h(-1)] underwent cardiopulmonary exercise testing for assessment of peak VO(2) and heart rate recovery at one (HRR-1) and two (HRR-2) minutes after exercise termination as well as NT-proBNP measurement at baseline and after 7.9+/-1.4 months of effective nCPAP (nightly usage>3.5 h). The effects of nCPAP were compared in patients with mild-to-moderate (AHI<30 h(-1); n=16) vs. severe (AHI>or=30 h(-1); n=24) OSA.

RESULTS

In the group as a whole, peak VO(2) (baseline: 31.9+/-9.3 vs. follow-up: 33.7+/-9.0 ml/kg/min; p=0.02) and HRR-2 [38 (32-43) vs. 42 (32-47) bpm; p=0.01] but not HRR-1 [22 (15-26) vs. 22 (16-27) bpm; p=0.16] improved from baseline to follow-up. The effect on peak VO(2) was mainly driven by a trend towards an increase in patients with mild-to-moderate OSA (31.8+/-10.7 vs. 33.9+/-10.2 ml/kg/min; p=0.08), whereas an effect on HRR-1 [20 (15-23) vs. 21 (16-26) bpm; p=0.03] and HRR-2 [38 (29-42) vs. 42 (33-47) bpm; p=0.004] was observed only in those with severe OSA. NT-proBNP levels remained unchanged [21 (11-45) vs. 26 (5-52) pg/ml; p=0.6].

CONCLUSIONS

Treatment with nCPAP is associated with an improvement in peak VO(2) and heart rate recovery in patients with OSA.

Intravenous iron reduces NT-pro-brain natriuretic peptide in anemic patients with chronic heart failure and renal insufficiency

OBJECTIVES

Our objective was to evaluate in a double-blind, randomized, placebo-controlled study possible modifications in NT-pro-brain natriuretic peptide (NT-proBNP) and C-reactive protein (CRP) levels together with clinical and functional parameters, in a group of anemic patients with chronic heart failure (CHF) and chronic renal failure (CRF) receiving intravenous iron therapy, without recombinant human erythropoietin (rhEPO), versus placebo.

BACKGROUND

Chronic heart failure and CRF associated with absolute or relative iron deficiency anemia is a common problem. This situation is linked with a variable inflammatory status. Both NT-proBNP and CRP are recognized markers for left ventricular dysfunction and inflammatory status, respectively. In this double-blind, randomized, placebo-controlled study, modifications in NT-proBNP and CRP level and clinical and functional parameters, in anemic patients with CHF and CRF receiving intravenous iron therapy, without rhEPO, versus placebo were evaluated.

METHODS

Forty patients with hemoglobin (Hb) <12.5 g/dl, transferrin saturation <20%, ferritin <100 ng/ml, creatinine clearance (CrCl) <90 ml/min, and left ventricular ejection fraction (LVEF) < or =35% were randomized into 2 groups (n = 20 for each). For 5 weeks, group A received isotonic saline solution and group B received iron sucrose complex, 200 mg weekly. Minnesota Living with Heart Failure Questionnaire (MLHFQ) and 6-min walk (6MW) test were performed. NT-pro brain natriuretic peptide and CRP were evaluated throughout the study. No patients received erythroprotein any time.

RESULTS

After 6 months follow-up, group B showed better hematology values and CrCl (p < 0.01) and lower NT-proBNP (117.5 +/- 87.4 pg/ml vs. 450.9 +/- 248.8 pg/ml, p < 0.01) and CRP (2.3 +/- 0.8 mg/l vs. 6.5 +/- 3.7 mg/l, p < 0.01). There was a correlation initially (p < 0.01) between Hb and NT-proBNP (group A: r = -0.94 and group B: r = -0.81) and after 6 months only in group A: r = -0.80. Similar correlations were observed with Hb and CRP. Left ventricular ejection fraction percentage (35.7 +/- 4.7 vs. 28.8 +/- 2.4), MLHFQ score, and 6MW test were all improved in group B (p < 0.01). Additionally, group B had fewer hospitalizations: 0 of 20 versus group A, 5 of 20 (p < 0.01; relative risk = 2.33).

CONCLUSIONS

Intravenous iron therapy without rhEPO substantially reduced NT-proBNP and inflammatory status in anemic patients with CHF and moderate CRF. This situation was associated with an improvement in LVEF, NYHA functional class, exercise capacity, renal function, and better quality of life.

N-terminal pro-B-type natriuretic peptide and functional capacity in patients with obstructive sleep apnea

The obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular abnormalities including left ventricular hypertrophy, left ventricular diastolic dysfunction, and endothelial dysfunction. The present study evaluated whether N-terminal pro-B-type natriuretic peptide (NT-proBNP) and peak oxygen consumption (peak VO(2)), both integral markers of cardiovascular function, are related to OSAS severity. In addition, we tested whether NT-proBNP levels depend on body composition in OSAS patients, similar to what has been reported in patients without OSAS. Eighty-nine patients with untreated OSAS underwent NT-proBNP measurement, dual X-ray absorptiometry, and cardiopulmonary exercise testing. In a representative subgroup (n = 32), transthoracic echocardiography was performed. The severity of OSAS was classified based on apnea-hypopnea index (AHI) values as mild (AHI 5-15 h(-1)), moderate (AHI 15-30 h(-1)), and severe (AHI >30 h(-1)). OSAS was mild in 19 (21%), moderate in 21 (24%), and severe in 49 (55%) patients. NT-proBNP levels did not differ among patients with mild [30 (10-57)], moderate [37 (14-55)], and severe [24 (13-49) pg/ml; p = 0.8] OSAS and were not related to body mass index (r = 0.07; p = 0.5), percent lean body mass (r = -0.17; p = 0.1), and percent fat mass (r = 0.18; p = 0.1). Percent predicted peak VO(2) was on average normal and did not differ among patients with mild (115 +/- 26), moderate (112 +/- 23), and severe OSAS (106 +/- 29%; p = 0.4). Body weight-indexed peak VO(2) did not differ among patients with mild (31.9 +/- 10.3), moderate (32.1 +/- 7.9), and severe OSAS (30.0 +/- 9.9 ml kg(-1) min(-1); p = 0.6) either. Lower NT-proBNP (beta = -0.2; p = 0.02) was independently but weakly associated with higher body weight-indexed peak VO(2). In the echocardiography subgroup, NT-proBNP was not significantly related to left ventricular mass index (r = 0.26; p = 0.2). In conclusion, NT-proBNP and peak VO(2) are not related to OSAS severity, and NT-proBNP poorly reflects left ventricular hypertrophy in OSAS. The lack of a relationship between NT-proBNP and OSAS severity is not due to a significant influence of body composition on NT-proBNP. There is an association between higher NT-proBNP and lower peak VO(2), indicating that NT-proBNP is a marker of cardiorespiratory fitness in patients with OSAS. However, the association is too weak to be clinically useful.

Miniaturized monolithic disks for immunoadsorption of cardiac biomarkers from serum

Immunoadsorbers based on 2.0 x 6.0 mm i.d., epoxy-bearing, methacrylate-based monolithic disks were developed in order to target myoglobin and N-terminal pro-natriuretic peptide (NT-proBNP), two biomarkers involved in cardiovascular disease. In both cases, antibodies were successfully coupled to the polymeric disk material. The developed immunoadsorbers permitted the selective isolation of myoglobin and NT-proBNP from human serum. Myoglobin was successfully isolated and detected from serum samples at concentrations down to 250 fmol microL(-1). However, the affinity of the antibodies was not sufficient for the analysis of low-concentration clinical samples. Frontal analysis of anti-NT-proBNP disks revealed the ability of the immunoadsorber to bind up to 250 pmol NT-proBNP, which is more than sufficient for the analysis of clinical samples. Anti-NT-proBNP disks showed good stability over more than 18 months and excellent batch-to-batch reproducibility. Moreover, anti-NT-proBNP disks permitted the isolation of NT-proBNP at concentrations down to 750 amol microL(-1) in serum, corresponding to concentrations of strongly diseased patients. Using reversed-phase trapping columns, the detection of NT-proBNP eluted from immunoadsorbers by mass spectrometry was achieved for concentrations down to 7.8 fmol microL(-1).