NT-proBNP Assay Research Articles

A-020 Evaluation of the QuidelOrtho Diagnostics Vitros NT-proBNP II Assay

Abstract Background N-terminal-proBNP (NT-proBNP), a short peptide originating from the cleavage of proBNP by Corin, can be used as a diagnostic test in individuals presenting with signs and symptoms consistent with heart failure (HF). QuidelOrtho Diagnostics released its latest reformulation of its NT-proBNP assay, the Vitros NT-proBNP II assay. The analytical performance of this assay was evaluated. Methods Repeatability, reproducibility, and carryover were assessed using quality control material. The analytical measuring range and clinical reportable range (AMR and CRR) were assessed using commercially available material and diluted patient samples. Accuracy was assessed by comparing results from the Vitros NT-proBNP II assay and results from the Vitros NT-proBNP assay. Instrument-to-instrument comparison was performed by comparing results from the NT-proBNP II assay from two different Vitros 5600 chemistry analyzers. Paired heparin and EDTA plasma samples were assessed for specimen type comparison. Results Repeatability and reproducibility were <=10% CV and no carryover was observed. The AMR was 20 - 30,000 pg/mL and the CRR extended the range to 600,000 pg/mL. Passing-Bablok analysis showed a significant proportional bias with a slope of 1.34 for samples up to 12,000 pg/mL (Vitros NT-proBNP). Vendor-performed comparison studies showed no significant proportional bias with a slope of 1.06 using unweighted Deming analysis for samples up to 20,700 pg/mL (Vitros NT-proBNP). Instrument-to-instrument and heparin-to-EDTA plasma comparisons showed no significant biases. Conclusions The NTproBNP II assay showed acceptable repeatability, reproducibility, and no carryover. The AMR analysis verified the measuring range in the IFU of the assay and the CRR is extended to 600,000 pg/mL. Results were very comparable between two different Vitros 5600s and between paired heparin and EDTA plasma specimens. Comparison between the Vitros NT-proBNP and Vitros NT-proBNP II assays showed a very significant proportional bias (slope of 1.34) for specimens up to 12,000 pg/mL measured on the Vitros NT-proBNP assay, but the proportional bias is less significant at higher NT-proBNP values (>20,000 pg/mL, Vitros NT-proBNP) are included in the analysis. There may be a significant matrix effect or interference at lower NT-proBNP concentrations with the reformulated reagent, which may be less prominent when NT-proBNP is present at much higher concentrations.

Newborn Screening for High-Risk Congenital Heart Disease by Dried Blood Spot Biomarker Analysis

Congenital heart disease (CHD) is the most common human organ malformation, affecting approximately 1 of 125 newborns globally. Assessing the performance of 2 diagnostic tests using minimal amounts of dried blood spots (DBS) to identify high-risk CHD compared with controls in a Swedish cohort of neonates. This diagnostic study took place in Sweden between 2019 and 2023 and enrolled full-term babies born between 2005 and 2023. All cases were identified through centralized pediatric cardiothoracic surgical services in Lund and Gothenburg, Sweden. Controls were followed up for 1 year to ensure no late presentations of high-risk CHD occurred. Cases were verified through surgical records and echocardiography. High-risk CHD, defined as cases requiring cardiac surgical management during infancy due to evolving signs of heart failure or types in which the postnatal circulation depends on patency of the arterial duct. Using 3-μL DBS samples, automated quantitative tests for NT-proBNP and interleukin 1 receptor-like 1 (IL-1 RL1; formerly known as soluble ST2) were compared against established CHD screening methods. Performance of DBS tests to detect high-risk CHD using receiver operating characteristic curves; Bland-Altman and Pearson correlation analyses to compare IL-1 RL1 DBS with plasma blood levels. A total of 313 newborns were included (mean [SD] gestational age, 39.4 [1.3] weeks; 181 [57.8%] male). Mean (SD) birthweight was 3495 (483) grams. Analyzed DBS samples included 217 CHD cases and 96 controls. Among the CHD cases, 188 participants (89.3%) were high-risk types, of which 73 (38.8%) were suspected prenatally. Of the 188 high-risk cases, 94 (50.0%) passed pulse oximetry screening and 36 (19.1%) were initially discharged after birth without diagnoses. Combining NT-proBNP and IL-1 RL1 tests performed well in comparison with existing screening methods and enabled additional identification of asymptomatic babies with receiver operating characteristic area under the curve 0.95 (95% CI, 0.93-0.98). In this diagnostic study, NT-proBNP and IL-1 RL1 DBS assays identified high-risk CHD in a timely manner, including in asymptomatic newborns, and improved overall screening performance in this cohort from Sweden. Prospective evaluation of this novel approach is warranted.

Screening for cardiac amyloidosis in patients with tenosynovial red flags: A collaboration between family medicine and cardiology

BackgroundAmyloid deposition in tenosynovial structures precedes cardiac involvement up to 20 years. Therefore, a cardiological screening in patients with a history of tenosynovial manifestations of cardiac amyloidosis (CA) could lead to an increased number of early diagnoses. MethodsPatients with tenosynovial manifestations of CA (carpal tunnel syndrome, atraumatic biceps tendon rupture, lumbar spinal stenosis) have been identified by general practitioners and evaluated in a Referral Center for CA. Patients with a high suspicion of CA underwent the CA diagnostic pathway. ResultsAmong 50 General Practitioners (GP) contacted, 10 (20%) agreed to participate in the study for a total of 5615 patients ≥60 years. One hundred forty-five patients met the inclusion criteria, 2 of them already had a diagnosis of CA, and 57 agreed to undergo a cardiological evaluation (electrocardiography, echocardiography, NTproBNP assay). The median age was 73 [67–80] years and 31 (54%) were women. Eight patients were suggested to start the CA diagnostic pathway, five of them underwent a complete diagnostic evaluation for CA, three refused to complete the diagnostic exams and no new diagnoses were made. ConclusionA screening program for CA in patients with tenosynovial manifestations identified by general practitioners is feasible, but may not yield a high rate of new diagnosis. In this study, we identified two patients who already had a diagnosis of CA, and among patients at high risk for CA, 37% refused to complete the diagnostic pathway. Increased awareness of CA among patients might increase participation and diagnostic yield in screening studies. Further validation of this protocol is needed to evaluate its diagnostic performance.

A-020 Evaluation of the Analytical Performance of BNP and NT-proBNP Assays on the Atellica CI 1900 Analyzer

Abstract Background The Atellica® CI 1900 Analyzer is an automated, high-throughput integrated chemistry and immunoassay analyzer employing both Atellica CH and Atellica IM assays. This study was designed to evaluate the analytical performance of the Atellica IM B-type Natriuretic Peptide (BNP) and NT-proBNP (PBNP) assays* on the Atellica CI 1900 Analyzer. Methods The Atellica CI 1900 BNP and PBNP assays use the same reagents and calibrators as the Atellica IM assays. Precision and method comparison were used as performance indicators for the Atellica CI 1900 Analyzer. Precision studies were performed according to CLSI EP05-A3 and method comparison according to CLSI EP09-A3 using native and contrived human plasma (BNP) and serum (PBNP) samples. One aliquot of each sample pool was tested in duplicate in two runs per day >2 h apart on each analyzer for >20 days. BNP and PBNP were evaluated with one reagent lot on two systems. For the method comparison, individual native and contrived human plasma samples (BNP) or native human serum samples (PBNP) were analyzed using the Atellica IM BNP and PBNP assays on both the Atellica IM and Atellica CI 1900 Analyzers. Results Representative precision and MC results for each assay are listed in the table. For the two assays tested, repeatability and within-lab %CVs were <2.5% and <3.0%, respectively. Slopes determined by the Deming linear regression model were approximately equal to 1. Conclusion Evaluation of the Atellica IM BNP and PBNP assays using the Atellica CI 1900 Analyzer demonstrated acceptable precision and equivalent performance compared to the same assays on the Atellica IM Analyzer.

Evaluation of a New Aptamer-Based Array for Soluble Suppressor of Tumorgenicity (ST2) and N-terminal Pro-B-Type Natriuretic Peptide (NTproBNP) in Heart Failure Patients.

Recent advances in multi-marker platforms offer faster data generation, but the fidelity of these methods compared to the ELISA is not established. We tested the correlation and predictive performance of SOMAscan vs. ELISA methods for NTproBNP and ST2. Patients ≥ 18years with heart failure and ejection fraction < 50% were enrolled. We tested the correlation between SOMA and ELISA for each biomarker and their association with outcomes. There was good correlation of SOMA vs. ELISA for ST2 (ρ = 0.71) and excellent correlation for NTproBNP (ρ = 0.94). The two versions of both markers were not significantly different regarding survival association. The two ST2 assays and NTproBNP assays were similarly associated with all-cause mortality and cardiovascular mortality. These associations remained statistically significant when adjusted for MAGGIC risk score (all p < 0.05). SOMAscan quantifications of ST2 and NTproBNP correlate to ELISA versions and carry similar prognosis.

Low Toxicity and Disease Responses in Systemic AL-Amyloidosis Using an Yttrium-90 Labelled Anti-CD66 Monoclonal Antibody TLX66 As the Only Conditioning Prior to Autologous Stem Cell Transplantation

Despite the introduction of new therapies Systemic AL-amyloidosis (AL) remains incurable and the majority of patients will relapse. Autologous stem cell transplantation (ASCT) remains an important treatment option with improvement of organ function and survival in responding patients, however the toxicity of ASCT using conventional chemotherapy results in high morbidity and mortality limiting the application in this vulnerable patient group. We tested the use of a monoclonal anti-CD66 radiolabelled with yttrium-90, TLX66 (90Y-besilesomab) as the sole conditioning agent prior to ASCT in a phase I study in patients with AL. The study had full ethical and regulatory approvals (EudraCT 2015-002231-18; ISRCTN 13400668). The study consisted of three radiation activity levels, 30, 40 and 45 Mega Becquerels (MBq) per kg body weight with 3 patients treated at each activity level. Patients entered the study after fulfilling entry requirements and with informed consent. Prior to receiving the 90Y-besilesomab organ dosimetry and biodistribution were determined using the same anti-CD66 radiolabelled with indium-111 (111In-anti-CD66) with sequential gamma camera imaging. Estimated absorbed radiation to critical organs was determined from an established dosimetry model, organ radiation dose expressed in Gray (Gy). Radiation dose limits of 45Gy for the bone marrow and 15Gy for the liver were used as safety measures. Table 1 summarises patient details. The median previous lines of treatment were 2 (range 1-5) including three who had previous ASCT using high dose melphalan. The primary end-point was treatment related toxicity as determined using CTCAE v4.0. Haematological toxicities (cytopenia) were excluded as adverse events (AEs) unless considered life-threatening. Secondary end-points: Disease response determined by changes in clonal free light chain assay (FLCa), malignant plasma cell percentage in BM as determined by multi-colour flow cytometry; cardiac toxicity from NT-proBNP assay; overall survival and time to disease progression; biodistribution and dosimetry SPECT-CT imaging; engraftment using the European Blood and Marrow Transplant (EBMT) criteria for neutrophil and platelet engraftment. Results: Ten patients underwent dosimetry with 111In-anti-CD66, 9 received the 90Y-besilesomabwith infused activity determined by study cohort and patient body weight; one patient failed dosimetry with excessive hepatic uptake, two received reduced activity to keep the marrow dose within the 45Gy limit. There were no serious adverse events (SAE's) in the trial. There were 3 grade 4 AE's (mainly cytopenias during transplantation) and no SUSAR's were reported. A total of 41 grade 1-4 AE's were recorded. There were no transplant related deaths. All patients became profoundly cytopenic consistent with bone marrow suppression due to the targeted radiation. All patients engrafted with median neutrophils recovery by D+13 and platelets by D+11. Importantly, no patients experienced any mucositis or therapy related diarrhoea. All maintained oral nutrition. Only two patients experienced a fever post-transplant, neither were life-threatening. Table 2 summarises the estimated absorbed radiation dose to critical organs and disease responses. Of the 9 patients treated with 90Y-besilesomaband ASCT 7 had haematologic responses with 2 complete responses (CR), 5 partial responses (PR), 1 stable disease (SD) and 1 progressive disease (PD) as determined. Six of 8 evaluable patients showed a reduction in percentage of malignant plasma cells in the BM. The study collected data up to D+100 post-transplant but 2 patients showed continuing slow reduction in clonal FLCa beyond D+100 with 1 achieving a CR 5 months post-transplant. No radiation dose limiting toxicity was seen. No consistent changes were seen in NT-proBNP. Importantly no cardiac AEs were recorded. All patients are alive. The long term follow up data will be presented. Acknowledgement: The native anti CD66 MAb (Besilesomab) was provided by Telix Pharmaceuticals. TLX66 (90Y-besilesomab) was acquired by Telix Pharmaceuticals in 2021. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Assays Specific for BNP1-32 and NT-proBNP Exhibit a Similar Performance to Two Widely Used Assays in the Diagnosis of Heart Failure.

Secretion of cardioprotective B-type natriuretic peptide 1-32 (BNP1-32) is increased proportionately with cardiac dysfunction, but its measurement in plasma is difficult. Therefore, less specific BNP and amino-terminal proBNP (NT-proBNP) assays that detect the precursor molecule proBNP alongside BNP or NT-proBNP metabolites were developed to reflect BNP1-32 secretion and are now mandated in the diagnosis of heart failure (HF). We compared the diagnostic performance of 2 widely used clinical assays: the Roche proBNPII assay, and Abbott BNP assay, against our recently developed in-house assays that measure either intact BNP1-32 or NT-proBNP. EDTA plasma samples obtained from patients presenting with breathlessness (n = 195, 60 [31%] with clinically adjudicated HF) were assayed using the Roche NT-proBNP and our specific in-house BNP1-32 and NTBNP assays. A subset (n = 75) were also assessed with the Abbott BNP assay. Roche NT-proBNP was highly correlated with BNP1-32 and NTBNP (Spearman rho = 0.92 and 0.90, respectively, both Ps < 0.001), and all 3 assays similarly discriminated acute HF from other causes of breathlessness (ROC analysis areas under the curve 0.85-0.89). The Abbott BNP assay performed similarly to the other assays. Roche NT-proBNP and BNP1-32 assays had similar sensitivity (83% and 80%), specificity (83% and 84%), positive (70% and 71%) and negative (91% and 90%) predictive values, and accuracy (both 83%) at their optimal cutoffs of 1536 and 12 ng/L, respectively. Since all assays exhibited similar performance in the diagnosis of HF, currently mandated assays provide a reliable proxy for circulating concentrations of active BNP1-32 in HF diagnosis.

Circulating cardiac biomarkers improve risk stratification for incident cardiovascular disease in community dwelling populations.

SummaryBackgroundPlasma cardiac markers may assist in prediction of incident cardiovascular disease.MethodsThe incremental value of cardiac Troponins (T and I) and NT-proBNP added to risk factors in the PREDICT score for incident cardiovascular disease (CVD) in primary care, was assessed in 4102 asymptomatic participants in a randomised controlled trial of Vitamin D (ViDA). Findings were corroborated in 2528 participants in a separate community-based observational registry of CVD-free volunteers (HVOLS).FindingsHazard ratios for first cardiovascular events adjusted for PREDICT risk factors, comparing fifth to first quintiles of marker plasma concentrations, were 2.57 (95% CI 1.47-4.49); 3.01 (1.66-5.48) and 3.38 (2.04-5.60) for hs-cTnI, hs-cTnT and NT-proBNP respectively. The C statistic for discrimination of the primary endpoint increased from 0.755 to 0.771 (+0.016, p = 0.01). Cardiac marker data correctly reclassified risk upwards in 6.7% of patients and downwards in 3.3%. These findings were corroborated by results from HVOLS.InterpretationIncrements in plasma cardiac biomarkers robustly and reproducibly predicted increased hazard of incident CVD, independent of established risk factors, in two community-dwelling populations. Cardiac markers may augment risk assessment for onset of CVD in primary care.FundingViDA was funded by the Health Research Council of New Zealand (grant 10/400) and the Accident Compensation Corporation. HVOLS was funded by the Health Research Council of NZ Programme Grants (grants 02/152 and 08/070) and by grants from the Heart Foundation of NZ and the Christchurch Heart Institute Trust. Roche Diagnostics provided in-kind support for NT-proBNP and hs-cTnT assays and Abbott Laboratories for hs-cTnI assays.

Paper Biosensor for the Detection of NT-proBNP Using Silver Nanodisks as Electrochemical Labels.

We report on the use of silver nanodisks (AgNDs), having a diameter of 50 ± 8 nm and a thickness of 8 ± 2 nm, as electrochemical labels for the detection of a model metalloimmunoassay for the heart failure biomarker NT-proBNP. The detection method is based on an electrochemically activated galvanic exchange (GE) followed by the detection of Ag using anodic stripping voltammetry (ASV). The AgNDs labels are superior to Ag nanocubes and Ag nanospheres in terms of the dynamic range for both the model and NT-proBNP metalloimmunoassays. The linear dynamic range for the model composite is 1.5 to 30.0 pM AgNDs. When AgND labels are used for the NT-proBNP assay, the dynamic range is 0.03–4.0 nM NT-proBNP. The latter range fully overlaps the risk stratification range for heart failure from 53 pM to 590 pM. The performance improvement of the AgNDs is a result of the specific GE mechanism for nanodisks. Specifically, GE is complete across the face of the AgNDs, leaving behind an incompletely exchanged ring structure composed of both Ag and Au.

Detection Efficiency of Ag Nanoparticle Labels for a Heart Failure Marker Using Linear and Square-Wave Anodic Stripping Voltammetry.

In this article, we compare linear sweep anodic stripping voltammetry (LASV) and square-wave anodic stripping voltammetry (SWASV) for detection of a nano metalloimmunoassay. Two separate immunoassays were examined: a model assay, based on interactions between antibodies, and a sandwich assay for the heart failure marker NT-proBNP. In both cases, one antibody is linked to a magnetic microbead, and one is linked to a spherical Ag nanoparticle label. Electrochemical detection is carried out on a paper device. The three analytical figures of merit studied were the precision of the measurements, the calibration sensitivity, and the limit of detection (LOD). For the NT-proBNP assay, the results show that after optimization of the pulse amplitude and frequency of the potential input for SWASV, the detection efficiency is substantially higher compared to LASV. Specifically, the calibration sensitivity increased by up to ~40 fold, the average coefficient of variation decreased by ~40%, and the (LOD) decreased to 300.0 pM. Finally, for a model immunoassay, a ~10-fold decrease in the LOD was observed for SWASV compared to LASV.

Analytical validation of a novel point-of-care immunoassay for canine N-terminal pro-brain natriuretic peptide analysis.

BackgroundN‐terminal pro‐brain natriuretic peptide (NT‐proBNP) is a widely used point‐of‐care (POC) cardiac biomarker in human medicine. Canine NT‐proBNP is used less in veterinary medicine, possibly due to the lack of a POC canine NT‐proBNP assay resulting in temporal delay, increased degradation in transport, and high reported variability in the available assay. A new quantitative POC analyzer allows fast, onsite measurement of NT‐proBNP, minimizing preanalytical error and reducing variability.ObjectiveWe aimed to analytically validate an NT‐proBNP assay (Vcheck) according to American Society of Veterinary Clinical Pathology (ASVCP) and Clinical Laboratory Improvement Amendments (CLIA) specifications.MethodsArchived and prospective plasma and serum samples were collected from male and female, client‐owned dogs of various breeds with cardiac abnormalities (n = 81) and a healthy control population (n = 225). Precision, accuracy, analytical sensitivity, and specificity, and other statistical analyses were performed.ResultsImprecision was considered acceptable with a coefficient of variation ranging from 9% at 4000 pmol/L to 20% at 600 pmol/L. The lower limit of quantitation was 650 pmol/L based on repetitive measures evaluation. Comparison of the Vcheck assay with the Cardiopet NT‐proBNP assay revealed an excellent correlation with minimal bias when preanalytical factors were controlled. Significant degradation of NT‐proBNP occurred when current methods were used at refrigerated and room temperatures, which could change diagnostic and prognostic decision‐making. Age‐partitioned reference intervals have high reference values of 750 pmol/L and 1280 pmol/L for juvenile and adult dogs, respectively.ConclusionsThe Vcheck NT‐ProBNP assay provides analytically acceptable results. Onsite testing can minimize variability related to preanalytical error and provide clinically useful contemporaneous results. Samples should be centrifuged immediately and analyzed within 2 hours of collection.

Do more specific assays for B-type natriuretic peptides better predict heart failure in breathless patients than the currently used assays?

Abstract Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Heart Foundation of New Zealand Health Research Council of New Zealand Introduction The cardioprotective B-type natriuretic peptide (BNP1-32) and its inactive congener N-terminal proBNP1-76 (NTBNP1-76) are produced from their precursor peptide proBNP, proportionate to cardiac dysfunction, underpinning their now-universal endorsement as markers for heart failure (HF) diagnosis. ProBNP concentrations are also increased in patients with HF. BNP1-32 is difficult to measure in plasma due to its low concentration and short half-life. Thus, less specific BNP and NT-proBNP assays are routinely used in the diagnosis and prognosis of HF. However, these assays also variably detect proBNP, BNP metabolites, and glycosylated proBNP or glycosylated NT-proBNP. How well these assays compare to highly specific assays that only detect BNP1-32 or NTBNP1-76 has not been assessed. Purpose We will compare the performance of assays specific for BNP1-32 and NTBNP1-76 only with that of a less specific commercially available NT-proBNP assay that is widely used for the diagnosis of heart failure. Methods Plasma samples obtained from patients presenting to the Emergency Department with breathlessness (n = 195) were assayed using a commercially available NT-proBNP assay and our specific in-house BNP1-32 (1) and NTBNP1-76 (2) assays. The diagnostic performance for clinically adjudicated acute HF (AHF, 60/195 patients, 31%) was assessed for each assay using receiver operator curve (ROC) analysis. Results Median (IQR) concentrations (n = 195) of NT-proBNP (101.7 [29.7, 353] pmol/L) and NTBNP1-76 (108.6 [25, 442] pmol/L) were markedly higher than BNP1-32 concentrations (1.9 [0.3-6.6] pmol/L) (p &amp;lt; 0.001 for both comparisons). Peptide concentrations were higher in patients with heart failure (n = 60) than those without heart failure for NT-proBNP (559 [247,1097] vs 46 [16,123] pmol/L), NTBNP1-76 (441.9 [155,1205] vs 37.9 [15,131] pmol/L) and BNP1-32 (7.8 [4,17] vs 0.5 [0.2,2.4] pmol/L) (all P &amp;lt; 0.001). NT-proBNP assay results were highly correlated with our specific NTBNP1-76 and BNP1-32 assays (Spearman’s rho = 0.91 and 0.92, respectively, both P &amp;lt; 0.001, n = 195). NT-proBNP, NTBNP1-76 and BNP1-32 assays performed similarly in the diagnosis of AHF (AUC [95%CI] = 0.88 [0.84-0.93], 0.85 [0.79-0.91] and 0.89 [0.84-0.94] respectively (all p &amp;lt; 0.001). Discussion Despite the differences in assay specificity all 3 assays performed similarly in the diagnosis of AHF in patients presenting with breathlessness. Conclusions All three assays diagnosed heart failure similarly, providing evidence that the widely used NT-proBNP assay can reliably be used as a proxy for active BNP1-32 in the diagnosis of acute heart failure. Whether this less specific NT-proBNP assay and our specific NTBNP1-76 and BNP1-32 assays (i) offer similar prognostic information and whether (ii) their marker performance is differentially altered by common confounders including age, renal dysfunction, obesity and atrial fibrillation, remain to be ascertained.

N-Terminal Fragment of the Type-B Natriuretic Peptide (NT-proBNP) Is an Independent Prognostic Factor for Overall Survival in Patients with Monoclonal Gammopathy of Undetermined Significance (MGUS)

Background: The prognostic role of cardiac biomarker NT-proBNP was evaluated in different conditions. In presence of a MGUS, an increased value of NT-proBNP could rise the suspicion of cardiac AL amyloidosis in absence of any other cardiologic disease. Our group recently showed that the addition of NT-proBNP to a simple frailty score based on performance status and age, had a prognostic impact in patients with newly diagnosed multiple myeloma (Milani et al AJH, 2016). Aim of our study was to determine the role of NT-proBNP, a well-established cardiovascular risk biomarker, as a prognostic marker in patients with MGUS in an unselected cohort of patients.Methods: Patients were eligible for this retrospective study if they were seen at the Mayo Clinic, Rochester, MN with a diagnosis of MGUS during the interval between 1/1/2000 and 12/31/2000. As part of the Mayo Clinic registration, all patients underwent a complete clinical assessment of their past medical history and symptoms. Data from that first visit was abstracted and used to calculate a Charlson comorbidity index (CCI). We excluded all patients with a concomitant diagnosis of multiple myeloma, light-chain AL amyloidosis and other plasma cell dyscrasias. We excluded also all patients that had a concomitant diagnosis of any other hematologic malignancies. NT-proBNP concentration was measured in frozen sera collected within 30 days of diagnosis. NT-proBNP assay was run on the E170 Modular analyzer (Roche Diagnostics, Penzberg, Germany). We evaluated the prognostic role of NT-proBNP and these indices on OS using the Kaplan-Meier method.Results: Among the 394 consecutive patients satisfying entry criteria, median age was 70 years [interquartile range (IQR) 60-77], 16% were ≥80 years, and 55% were male. Fourteen patients had a subsequent diagnosis of a plasma cell dyscrasia (7 multiple myeloma, 3 smoldering MM, 1 AL amyloidosis, 2 Waldenstrom's macroglobulinemia and 1 LCDD), 7% had a creatinine ≥2 mg/dL, 33% had CCI ≥2, 29% had an history of hypertension and 6% had atrial fibrillation. The median value of NT-proBNP was 158 ng/L (IQR: 53-477 ng/L). Median overall survival (OS) was 7.6 years. The best cutoff of NT-proBNP predicting OS at two year was 400 ng/L (sensitivity: 78%, specificity: 63%; AUC=0.74) and distinguished two groups with different OS (median 146 vs. 36 months, P<0.001). In the subset of patients with age <70 years, NT-proBNP was able to distinguish two different groups (median survival 182 months vs. 35 months, P<0.001) as well as in the subset of patients older than 70 years of age (median survival 92 vs. 36 months, P<0.001). Variables predictive for OS are shown in the Table and included age, CCI, NT-proBNP. On multivariate analysis age≥70, CCI≥2 NT-proBNP≥400 ng/L were independent predictors of survival. Patients were assigned a score of 1 for each of these variables, creating stages I to IV with scores of 0 to 3 points, respectively. The median OS from diagnosis was 182, 91, 54 and 32 months, respectively.Conclusions: In this unselected cohort of patients with MGUS, NT-proBNP was a useful predictor of survival independent of age and comorbidities score. The threshold of 400 ng/L is similar to the well-established cutoff for heart failure of 300 ng/L and pour proposed cutoff for frailty for patients affected by multiple myeloma. NT-proBNP is a widely available biomarker, could raise the suspicion of concomitant cardiac AL amyloidosis and we believe that could be added to the workup of patients with MGUS. [Display omitted] DisclosuresGertz:Celgene, Novartis, Smith-Kline, Prothena, Ionis, Amgen: Honoraria; Millennium: Consultancy, Honoraria. Palladini:Celgene: Other: Travel grants; Prothena: Honoraria, Other: Travel grant; Jannsen-Cilag: Membership on an entity's Board of Directors or advisory committees. Kumar:Celgene, Millennium/Takeda, Onyx, AbbVie, Janssen, Sanofi, Novartis, Amgen, Genentech, Merck, Oncopeptides, Roche, Skyline Diagnostics: Research Funding; Celgene, Millennium, BMS, Onyx, Janssen, Noxxon, AbbVie, Amgen, Merck, Oncopeptides, Skyline Diagnostics, Takeda: Consultancy; Skyline: Honoraria. Dingli:Karyopharm Therapeutics: Research Funding; Janssen: Consultancy; Alexion Pharmaceuticals: Consultancy; Millenium: Consultancy; Takeda: Consultancy. Kapoor:Takeda, Celgene and Amgen: Research Funding. Dispenzieri:Celgene, Millenium, Pfizer, Janssen: Research Funding.

Cardiovascular sequalae in uncomplicated COVID-19 survivors.

BackgroundA high proportion of COVID-19 patients were reported to have cardiac involvements. Data pertaining to cardiac sequalae is of urgent importance to define subsequent cardiac surveillance.MethodsWe performed a systematic cardiac screening for 97 consecutive COVID-19 survivors including electrocardiogram (ECG), echocardiography, serum troponin and NT-proBNP assay 1–4 weeks after hospital discharge. Treadmill exercise test and cardiac magnetic resonance imaging (CMR) were performed according to initial screening results.ResultsThe mean age was 46.5 ± 18.6 years; 53.6% were men. All were classified with non-severe disease without overt cardiac manifestations and did not require intensive care. Median hospitalization stay was 17 days and median duration from discharge to screening was 11 days. Cardiac abnormalities were detected in 42.3% including sinus bradycardia (29.9%), newly detected T-wave abnormality (8.2%), elevated troponin level (6.2%), newly detected atrial fibrillation (1.0%), and newly detected left ventricular systolic dysfunction with elevated NT-proBNP level (1.0%). Significant sinus bradycardia with heart rate below 50 bpm was detected in 7.2% COVID-19 survivors, which appeared to be self-limiting and recovered over time. For COVID-19 survivors with persistent elevation of troponin level after discharge or newly detected T wave abnormality, echocardiography and CMR did not reveal any evidence of infarct, myocarditis, or left ventricular systolic dysfunction.ConclusionCardiac abnormality is common amongst COVID-survivors with mild disease, which is mostly self-limiting. Nonetheless, cardiac surveillance in form of ECG and/or serum biomarkers may be advisable to detect more severe cardiac involvement including atrial fibrillation and left ventricular dysfunction.

Development of an NT-ProBNP Assay Reagent Based on High Specific Activity Alkaline Phosphatase CmAP and an Improved Coupling Method

(1) Background: Chemiluminescent enzyme immunoassay (CLEIA) is an efficient analytical method. Alkaline phosphatase (ALP) with high specific activity is the basis for CLEIA to achieve high sensitivity. In this study, a high specific activity Cobetia marina ALP (CmAP) and an improved coupling method were used to develop an N-terminal pro-B-type natriuretic peptide (NT-proBNP) diagnostic reagent. (2) Methods: The purification method of CmAP was improved and the related enzyme activities were assessed. The enzyme and magnetic beads were coupled only to the Fc region of the detection antibody and the capture antibody, respectively, by using a specially improved method. The NT-proBNP in human serum was assessed. (3) Results: The specific activity of the purified CmAP was found to be 13,133 U/mg. No loss in the enzyme activity was observed after its storage at room temperature for 4 months. The sensitivity of the in vitro diagnostic reagents was found to be 0.58 ng/L. (4) Conclusions: CmAP can be applied as a substitute for the commercial ALP. Analytical parameters indicated that the chemiluminescence diagnostic reagent for NT-proBNP is adequately sensitive and reliable for detecting the serum NT-proBNP, which suggests that both the enzyme and coupling method are suitable for the CLEIA.

Evaluation of Circulating Cardiovascular Biomarker Levels for Early Detection of Congenital Heart Disease in Newborns in Sweden

Congenital heart disease (CHD) is the most common congenital malformation in humans worldwide. Circulating cardiovascular biomarkers could potentially improve the early detection of CHD, even in asymptomatic newborns. To assess the performance of a dried blood spot (DBS) test to measure the cardiovascular biomarker amino terminal fragment of the prohormone brain-type natriuretic peptide (NT-proBNP) levels in newborns and to compare DBS with standard EDTA analysis in control newborns during the first week of life. This diagnostic study was conducted in a single regional pediatric service in southern Sweden. Healthy, term neonates born between July 1, 2018, and May 31, 2019, were prospectively enrolled and compared against retrospectively identified newborns with CHD born between September 1, 2003, and September 30, 2019. Neonates who required inpatient treatment beyond the standard postnatal care were excluded. New DBS test for NT-proBNP quantification in newborns that used 3 μL of blood vs the current screening standard. Performance of the new test and when combined with pulse oximetry screening was measured by receiver operating characteristic curve analysis. Performance of the new test and EDTA screening was compared using Pearson linear correlation analysis. The DBS samples of 115 neonates (81 control newborns and 34 newborns with CHD, of whom 63 were boys [55%] and the mean [SD] gestational age was 39.6 [1.4] weeks) were analyzed. The new NT-proBNP test alone identified 71% (n = 24 of 34) of all CHD cases and 68% (n = 13 of 19) of critical CHD cases as soon as 2 days after birth. Detection of any CHD type improved to 82% (n = 28 of 34 newborns) and detection of critical CHD improved to 89% (n = 17 of 19 newborns) when combined pulse oximetry screening and NT-proBNP test results were used. Performance of the NT-proBNP test was excellent when control newborns were matched to newborns with CHD born between July 1, 2018, and May 31, 2019 (area under the curve, 0.96; SE, 0.027; 95% CI, 0.908-1.0; asymptotic P < .05). This study found that NT-proBNP assay using minimal DBS samples appears to be timely and accurate in detecting CHD in newborns and to discriminate well between healthy newborns and newborns with various types of CHD. This finding warrants further studies in larger cohorts and highlights the potential of NT-proBNP to improve neonatal CHD screening.

A chemiluminescence immunoassay for the detection of NT-proBNP

BackgroundThe aim of the study was to assess the analytical performance of the HISCL NT-proBNP assay, a newly developed chemiluminescence immunoassay, for the detection of NT-proBNP. MethodsThe within-run and total imprecision of the NT-proBNP assay were determined with HISCL cardiac marker controls. The linear ranges of the NT-proBNP assays were evaluated based on the CLSI EP6-A document using selected serum samples. Two hundred serum samples were evaluated to compare the HISCL NT-proBNP and Elecsys NT-proBNP assays. Five additional high NT-proBNP concentrations serum samples were evaluated to assess if there was high-dose hook effect in the HISCL NT-proBNP assay. ResultsThe total and within-run imprecision values of the HISCL NT-proBNP assay were 5.85%, 0.81%, 2.56% and 0.54% and 6.07%, 0.73%, 2.61% and 0.59% at 6.1, 129.83, 3732.84and39737.33 pg/ml, respectively. The assay was verified to be linear for NT-proBNP levels ranging between 6.1 and 39737.33 pg/ml. The assay comparison showed that HISCL NT-proBNP = 0.9803 × Elecsys NT-proBNP −4.383. The sensitivity of HISCL NT-proBNP was 87.23%, and the specificity was 85.61%. The AUC of HISCL NT-proBNP (0.90 (95% CI, 0.86–0.93)) did not differ from that of Elecsys NT-proBNP(0.89 (95% CI, 0.85–0.93)) (P = 0.638). The results of five high NT-proBNP concentrations samples (44448, 54206, 55634, 55728 and 109406 pg/ml, measured with the Elecsys NT-proBNP assay) tested with HISCL NT-proBNP assay were all displayed with “>40000 pg/ml”. ConclusionsThe HISCL NT-proBNP chemiluminescence immunoassay showed good analytical and diagnostic performance for the detection of NT-proBNP and could be used in routine clinical practice.

Screening for asymptomatic heart failure with preserved ejection fraction in mongolian population at high risk.

Objective The goals of the present study were to assess the prevalence of asymptomatic heart failure with preserved ejection fraction (HFpEF) in subjects at high risk of developing HF and to define the diagnostic accuracy of NT-pro BNP assay compared with echocardiography in this setting.Material and methods This cross-sectional study included subjects aged from 35 to 64 years, with high risk of HF, who had no clinical symptoms of HF. Risk factors of HF were detected by clinical examinations. NT-pro BNP determination was performed using immunoassay analyzer (FIA8000, Getein Bio Medical Inc, China),. The cut-off point for NT-pro BNP was 125 pg/ml. Diagnosis of HFpEF was based on criteria recommended by 2016 ESC heart failure guidelines. Diastolic dysfunction was assessed according to the algorithm proposed in the joint recommendations of the ASE/EACVI.Results 602 patients with risk factors of HF were included in the study, of which 256 (42.5 %) were males and 346 (57.5 %) females. The mean age was 51.71±8.07 years. 83 patients (13.8 %) showed elevated NT-pro BNP levels of ≥125 pg / ml. Our study has shown that NT-pro BNP concentration was positively correlating with age, both systolic and diastolic blood pressure, left ventricular mass and E / e' ratio and negatively correlating with waist circumference, body mass index, left ventricular EF and E / A ratio in asymptomatic population. The likelihood of positive NT-pro BNP test was independently (p&lt;0.05) associated with age, hypertension and diabetes. The diagnosis of asymptomatic HFpEF was confirmed in 12.3 % of studied population. A cutoff value of 125 pg / ml for NT-proBNP concentration showed the following diagnostic re-abilities in identifying asymptomatic HFpEF: sensitivity 85.0 %, specificity 88.6 % and area under curve 0.92 (95 % CI 0.86-0.98).Conclusion Subjects with raised NT-pro BNP level (≥125 pg/ml) were more likely to have a confirmed diagnosis of asymptomatic HFpEF after screening. In summary, in at-risk population, natriuretic peptide based screening combined with echocardiography identifies high prevalence of asymptomatic HFpEF.

150 ProBNP glycosylation of threonine 71 is increased with obesity in patients with heart failure

Abstract Funding Acknowledgements The National Heart Foundation of New Zealand Background Heart failure (HF) is a leading cause of morbidity and mortality worldwide. Plasma levels of B-type natriuretic peptide (BNP) or its amino terminal congener (NT-proBNP) are used for HF diagnosis and risk stratification. Circulating levels of both BNP and NT-proBNP are reduced by obesity and this phenomenon is one of the key weaknesses of the diagnostic performance of the natriuretic peptides in HF. Formation of BNP from enzymatic cleavage of proBNP1-108 between residues 76 and 77 by corin and/or furin is influenced by the degree of proBNP glycosylation, therefore we investigated the relationship between proBNP glycosylation, plasma NT-proBNP and body mass index (BMI) in HF patients. Methods Three assays were developed to distinguish between total proBNP (glycosylated plus non-glycosylated proBNP), proBNP not glycosylated at threonine 71 (NG-T71) and proBNP not glycosylated in the central region (NG-C). Intra and inter-assay CVs were &amp;lt;15%, limits of detection were &amp;lt;2 pmol/L and samples diluted in parallel. Results Applying these assays and an NT-proBNP assay to plasma samples from 106 healthy volunteers and 238 patients with HF determined that concentrations (median(IQR)) of proBNP, NG-T71 and NT-proBNP were greater in HF patients compared to controls (24.9 (3.6-55), 9.4 (1.5-21) and 212 (104-409) pmol/L vs 3.0 (1.5-19), 3.0 (1.5-14.5) and 4.7 (2-8) pmol/L respectively, all p &amp;lt; 0.012). NG-C was undetectable in most samples. ProBNP levels in HF patients with BMI above and below 30 kg/m2 were not different (21.9 (2.6-70) pmol/L and 25.7 (3.9-53) pmol/L respectively, p = 0.85), whereas HF patients with BMI &amp;gt; 30 had lower NT-proBNP and NG-T71 levels (121 (64-248) and 3 (1.5-16) pmol/L verse 271 (178-486) and 13.5 (1.5-24.2) pmol/L respectively, p &amp;lt; 0.003) and higher proBNP:NT-proBNP and proBNP:NG-T71 ratios (p = 0.001 and p = 0.02 respectively) than those with BMI &amp;lt; 30. Discussion and Conclusion Using three new assays specific for different glycosylated forms of proBNP we have shown that the processing of proBNP is dysregulated in heart failure compared to controls due to increased glycosylation at threonine 71 of proBNP. Obese patients with HF have even greater dysregulation, demonstrated by decreased concentrations of proBNP that is not glycosylated at T71 (NG-T71), and concomitant decreases in NT-proBNP. Thus, we have shown for the first time that increased BMI is associated with increased proBNP glycosylation at T71 in patients with heart failure. Glycosylation-induced impairment of proBNP processing explains, at least in part, the reduction in plasma concentrations of B-type cardiac natriuretic peptides observed in obesity. Using these assays to evaluate the proBNP profile of larger patient cohorts will further develop understanding of the relationships between BNP production, BMI and heart failure pathogenesis, which would be expected to lead to increased diagnostic performance.

Role of BNP vs NT-proBNP Testing in the Age of New Drug Therapies: Sacubitril-Valsartan

Sacubitril-valsartan (Entresto), a new dual drug therapy that includes an angiotensin receptor neprilysin (NEP)15 inhibitor (sacubitril), is directed at reducing the risk of cardiovascular death and hospitalization for heart failure (HF) in patients with chronic HF (New York Heart Association classes II–IV) and reduced ejection fraction (HFrEF). Since its approval for the treatment of HFrEF, a commonly raised question has been whether treatment with this drug can complicate the interpretation of B-type natriuretic peptide (BNP) testing results compared to those of the N-terminal proBNP assay because Entresto may interfere with BNP clearance. The clinical and analytical studies addressing this issue are limited. Furthermore, the diversity of both BNP and NT-proBNP assays used in clinical laboratory practice have not been adequately evaluated in clinical trials, and studies to provide an evidence-based conclusion regarding the appropriate assays to use when a patient is on Entresto are lacking. In this article, 5 experts from the US and Europe provide their views regarding this issue. Do you think the differences between BNP and NT-proBNP measurements in patients receiving Entresto are only an early phenomenon because they both seem to be reduced over time? James Januzzi: In the PARADIGM-HF trial, NT-proBNP fell acutely after initiation of Entresto and then continued to drop over time until the end of the trial. Both the enalapril and Entresto arms had a slow, gradual drop in NT-proBNP by the end of trial. This drop likely reflects one of 2 possibilities. First, it may be the subtraction of noncompleters by the end of trial led to a perceived further drop in NT-proBNP (sicker patients that withdrew or died who likely had higher NT-proBNP concentrations). Alternatively, longer treatment with either therapy (angiotensin-converting enzyme inhibitor or angiotensin receptor neprilysin inhibitors) led to further stability, resulting in less synthesis and release of …