Evaluation of a new, rapid bedside test for quantitative determination of b-type natriuretic peptide.Congestive heart failure congestive heart failure, inability of the heart to expel sufficient blood to keep pace with the metabolic demands of the body. In the healthy individual the heart can tolerate large increases of workload for a considerable length of time. (CHF CHF
In currencies, this is the abbreviation for the Swiss Franc.
The currency market, also known as the Foreign Exchange market, is the largest financial market in the world, with a daily average volume of over US $1 trillion. ) is among the most frequently encountered cardiac diagnoses, with an estimated prevalence of 1% (1). Plasma concentrations of B-type natriuretic peptide (BNP BNP B-type natriuretic peptide, brain natriuretic peptide Physiology A 32-residue peptide hormone produced predominantly in the ventricles, secreted in response to fluid overload–eg, CHF. See Atrial natriuretic peptide. ) and its precursor, N-terminal pro-BNP (NT pro-BNP), are increased in patients with CHF and have been shown to accurately predict clinical severity and left ventricular ejection fraction (LVEF LVEF Left ventricular ejection fraction. See Ejection fraction. ) as well as morbidity and mortality Morbidity and Mortality can refer to:
1. pertaining to, characterized by, or promoting natriuresis.
2. an agent that promotes natriuresis.
adj. peptides is the time-consuming nature of analytical techniques, e.g., extraction procedures, long incubation times, or radioactive labeling (4-8). A rapid bedside test for determination of BNP was introduced recently (Triage BNP; Biosite Diagnostics, San Diego, CA). We evaluated the assay and compared it, in samples from patients with suspected CHF, with other assay systems for determination of either BNP (Shionoria BNP; CIS Cis (sĭs), same as Kish (1.)
(1) (CompuServe Information Service) See CompuServe.
(2) (Card Information S Diagnostics) or NT pro-BNP (Roche Diagnostics, Tutzing, Germany).
The Triage BNP test is an immunofluorometric assay for quantitative determination of BNP in EDTA-anticoagulated whole blood or plasma (9,10). A murine recombinant polyclonal antibody is bound to the fluorescent label, and a murine monoclonal antibody against the disulfide di·sul·fide
A chemical compound containing two sulfur atoms combined with other elements or radicals. Also called bisulfide. bond-mediated ring structure of BNP 32 is bound to the solid phase.
Briefly, after the addition of 250 [micro]L of EDTA-anticoagulated whole blood, the plasma is separated and allowed to react with fluorescent antibody conjugates within a reaction chamber. After an incubation period, complexes of the analyte and fluorescent antibody conjugates are captured on a detection lane. The concentration of BNP in the specimen is proportional to the fluorescence bound to the detection lane, which is determined quantitatively by a handheld fluorescence instrument (Triage Meter) as described in detail elsewhere (11). The time from application of the sample until the result is reported is ~15 min.
The Shionoria BNP test is a one-step immunoradiometric assay that uses two different monoclonal antibodies that recognize the C-terminal structure and the disulfide bond-mediated ring structure of BNP 32, respectively. This test requires ~20 h. NT pro-BNP(1-76) was determined by a recently developed research enzyme immunoassay that uses a polyclonal antibody specific for the N-terminal sequence (amino acids 1-21) of NT pro-BNP as well as a polyclonal antibody specific for the middle sequence (amino acids 30-38) of NT pro-BNP. The assay time is ~2 h, and no extraction is required. Both assays have been described in detail elsewhere (6,12-14).
The within-run (n = 11) and between-day (n = 11 days) imprecision of the Triage BNP assay were determined at three different concentrations that were prepared by mixing patient samples with high and low BNP concentrations. Within-run and between-day studies used EDTA-anticoagulated whole blood and EDTA EDTA: see chelating agents. plasma, respectively, each with a single assay lot and unchanged calibration.
For determination of the detection limit, defined as the lowest concentration that could be differentiated from zero (mean + 3 SD), a zero calibrator calibrator
an instrument for dilating a tubular structure or for determining the caliber of such a structure. was measured 20 times with four lots of reagents on 5 consecutive days.
Plasma samples from 50 apparently healthy individuals (30 males, 20 females; age range, 20-60 years) were measured, and the median and 97.5th percentile concentrations were calculated.
The study population consisted of 100 patients with underlying cardiac disease and suspected CHF. Clinical severity was characterized according to the functional classification system of the New York Heart Association (NYHA NYHA New York Heart Association ) in stages I to IV (15). The LVEF was evaluated with biplane biplane, aircraft, typically of early design, having two sets of wings fixed at different levels, especially in a vertical stack with the fuselage included between them. See airplane. transthoracic echocardiography by the modified Simpson rule using second harmonic imaging (16). Five patients were excluded because of insufficient sample material or missing clinical data. A total of 95 patients remained in the study group (Table 1). All patients gave informed consent. The study was approved by the local ethics committee.
On the day of echocardiography Echocardiography Definition
Echocardiography is a diagnostic test that uses ultrasound waves to create an image of the heart muscle. Ultrasound waves that rebound or echo off the heart can show the size, shape, and movement of the heart's valves and , peripheral venous blood was collected into sampling tubes containing EDTA as the anticoagulant. Within 20 min after venipuncture venipuncture /veni·punc·ture/ (ven?i-pungk´chur) surgical puncture of a vein.
ve·ni·punc·ture or ve·ne·punc·ture
n. , BNP concentrations were determined by the Triage system. The remaining sample material was centrifuged, and EDTA plasma was frozen at -80[degrees]C until further determination.
Correlation of BNP Triage with Shionoria BNP and NT pro-BNP was evaluated by the statistical procedure by Passing and Bablok (17). For calculation of assay comparison, results of the 95 study patients and the 50 healthy subjects were included (n = 145). Results of ROC analysis are expressed as areas under the individual ROC curves, including the 95% confidence interval. The diagnostic sensitivity of each assay was calculated as the number of test results with a BNP or NT pro-BNP value equal to or higher than a specific cutoff value among all patients with an LVEF [less than or equal to]50%, whereas diagnostic specificity was defined as the number of test results below the cutoff value among all patients with an LVEF >50%.
For imprecision, the within-run CVs of the Triage BNP assay were 9.4%, 13%, and 15% at 40, 450, and 800 ng/L, respectively. At the same mean concentrations, the between-day CVs were 11%, 13%, and 16%, respectively. The detection limit was 6 ng/L. The 97.5th percentile of the healthy subjects was 82 ng/L for the Triage BNP assay, 64 ng/L for the Shionoria BNP, and 57 pmol/L for the NT pro-BNP ELISA ELISA (e-li´sah) Enzyme-Linked Immuno-Sorbent Assay; any enzyme immunoassay using an enzyme-labeled immunoreactant and an immunosorbent.
Comparison of results by regression analysis (Fig. 1) revealed the following: Triage BNP = 1.579(Shionoria BNP) - 2.947 (r = 0.963); Triage BNP = 1.198(NT proBNP) + 1.419 (r = 0.947); NT pro-BNP = 1.309(Shionoria BNP) - 3.780 (r = 0.948). The 95% confidence intervals for slope and intercept were as follows: Triage BNP vs Shionoria BNP, 1.490-1.659 and -4.909 to -1.884; Triage BNP vs NT pro-BNP, 1.136-1.270 and -0.664 to 3.500; NT pro-BNP vs Shionoria BNP, 1.251-1.388 and -6.493 to -1.004. Comparison of BNP and NT pro-BNP concentrations with NYHA classes revealed only moderate correlations for all assays: [r.sub.s] = 0.689 (Triage BNP), 0.667 (Shionoria BNP) and 0.632 (NT pro-BNP); P <0.001; n = 95. Nevertheless, BNP and NT pro-BNP values showed a strong inverse correlation with LVEF: [r.sub.s] = -0.816 (Triage BNP), -0.762 (Shionoria BNP), and -0.718 (NT pro-BNP); P <0.001; n = 95.
ROC analysis regarding impaired ventricular function, defined as LVEF [less than or equal to] 50%, revealed areas under the ROC curve (95% confidence interval) of 0.91 (0.83-0.98) for Triage BNP, 0.88 (0.80-0.95) for Shionogi BNP, and 0.86 (0.77-0.94) for NT pro-BNP, respectively. At a cutoff value of 130 ng/L, the Triage assay had a sensitivity of 93% and a specificity of 79% to detect patients with impaired LVER LVER Local Veteran's Employment Representative Similar results were obtained for the other assays: for the Shionogi BNP, at a cutoff of 100 ng/L, the sensitivity was 80% and the specificity was 79%; for the NT pro-BNP assay, at a cutoff of 100 pmol/L, the sensitivity was 90% and the specificity was 66%.
[FIGURE 1 OMITTED]
The Triage BNP assay seems to be a sensitive screening method to decide which patient with suspected CHF warrants further investigation, particularly when assessment by echocardiography is not readily available. The major advantage of the Triage test system compared with the other investigated assays is its rapid and accurate measurement of BNP from whole blood with 24-h availability in a routine laboratory or at the point of care. Additional time-consuming preparation, centrifugation Centrifugation
A mechanical method of separating immiscible liquids or solids from liquids by the application of centrifugal force. This force can be very great, and separations which proceed slowly by gravity can be speeded up enormously in centrifugal , extraction, and incubation steps can be omitted. Rapid measurement of either BNP or NT pro-BNP seems useful, especially in the triage of patients with suspected CHF presenting to the emergency room, where these results add important information for faster diagnostic evaluation (8,18). It might also be useful in patients admitted with decompensated CHF as a previous study has shown that changes in BNP during treatment are a strong predictor for mortality and early readmission (19). Furthermore, the recently introduced BNP-guided therapy for chronic CHF will require faster determination of the analyte (20). Nevertheless, additional clinical trials need to be designed to clarify the detailed clinical benefit in patients diagnosis, management, and therapy as well as the cost-effectiveness of this marker (8).
We gratefully acknowledge VIVA Diagnostika Germany, Biosite Diagnostics Europe, and Roche Diagnostics Germany for providing reagents free of cost.
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(11.) Apple FS, Christenson RH, Valdes R Jr, Andriak AJ, Berg A, Duh duh
Used to express disdain for something deemed stupid or obvious, especially a self-evident remark.
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Yuriko Fischer, * Karsten Filzmaier,  Hugo Stiegler,  Jurgen Graf,  Simone Fuhs,  Andreas Franke,  Uwe Janssens,  Axel M. Gressner 
( Institut fur Klinische Chemie and Pathobiochemie, and
 Medizinische Klinik I, Universitatsklinikum der RWTH Aachen, Pauwelsstrasse 30, 52074 Aachen, Germany;
* author for correspondence: fax 49-241-8888512, e-mail email@example.com)
Table 1. Patient characteristics according to LVEF (n = 95). LVEF >50% 40-50% n 53 14 Age, mean (range), years 60(19-85) 65 (52-86) M/F 37/16 11/3 NYHA classification (a) I 38 (72%) II 8 (15%) 8 (57%) III 7 (13%) 5 (36%) IV 1 (7%) Underlying cardiac disease (b) CAD (c) 29 (55%) 11 (79%) HTN 5 (9%) 3 (21%) DCM 1 (2%) 1 (7%) ARRH 11 (21%) 2 (14%) VHD 3 (6%) Other (d) 16 (30%) 1 (7%) BNP (e) Triage, ng/L 60 (28-109) 333 (217-616) Shionoria, ng/L 45 (18-83) 186 (92-415) NT pro-BNP, pmol/L 64 (31-104) 277 (106-650) 30-39% <30% n 14 14 Age, mean (range), years 67 (58-76) 61(41-75) M/F 8/6 8/6 NYHA classification (a) I 2 (14%) II 7 (50%) 5 (36%) III 4 (29%) 5 (36%) IV 1 (7%) 4 (28%) Underlying cardiac disease (b) CAD (c) 10 (71%) 2 (21%) HTN 3 (21%) DCM 3 (21%) 8 (57%) ARRH 3 (21%) 3 921%) VHD 2 (14%) 1 (7%) Other (d) 1 (7%) 1 (7%) BNP (e) Triage, ng/L 482 (229-1087) 811 (500-1420) Shionoria, ng/L 242 (121-541) 375 (261-892) NT pro-BNP, pmol/L 321 (195-798) 538 (312-973) (a) Absolute values and percentages given. (b) Suspected or diagnosed underlying cardiac disease in patient population. Absolute values and percentages given, because of comorbidity numbers, may exceed total number of patients. (c) CAD, coronary artery disease; HTN, hypertension; DCM, dilated cardiomyopathy; ARRH, arrhythmias; VHD, valvular heart disease. (d) Myocarditis, pericarditis, pulmonary embolism, pneumonia, chronic obstructive pulmonary disease. (e) Values for BNP and NT pro-BNP are given as median and 25th and 75th percentiles.