Development and validation of a decision support tool for the diagnosis of acute heart failure: systematic review, meta-analysis, and modelling study.

OBJECTIVES: To evaluate the diagnostic performance of N-terminal pro-B-type natriuretic peptide (NT-proBNP) thresholds for acute heart failure and to develop and validate a decision support tool that combines NT-proBNP concentrations with clinical characteristics. DESIGN: Individual patient level data meta-analysis and modelling study. SETTING: Fourteen studies from 13 countries, including randomised controlled trials and prospective observational studies. PARTICIPANTS: Individual patient level data for 10 369 patients with suspected acute heart failure were pooled for the meta-analysis to evaluate NT-proBNP thresholds. A decision support tool (Collaboration for the Diagnosis and Evaluation of Heart Failure (CoDE-HF)) that combines NT-proBNP with clinical variables to report the probability of acute heart failure for an individual patient was developed and validated. MAIN OUTCOME MEASURE: Adjudicated diagnosis of acute heart failure. RESULTS: Overall, 43.9% (4549/10 369) of patients had an adjudicated diagnosis of acute heart failure (73.3% (2286/3119) and 29.0% (1802/6208) in those with and without previous heart failure, respectively). The negative predictive value of the guideline recommended rule-out threshold of 300 pg/mL was 94.6% (95% confidence interval 91.9% to 96.4%); despite use of age specific rule-in thresholds, the positive predictive value varied at 61.0% (55.3% to 66.4%), 73.5% (62.3% to 82.3%), and 80.2% (70.9% to 87.1%), in patients aged <50 years, 50-75 years, and >75 years, respectively. Performance varied in most subgroups, particularly patients with obesity, renal impairment, or previous heart failure. CoDE-HF was well calibrated, with excellent discrimination in patients with and without previous heart failure (area under the receiver operator curve 0.846 (0.830 to 0.862) and 0.925 (0.919 to 0.932) and Brier scores of 0.130 and 0.099, respectively). In patients without previous heart failure, the diagnostic performance was consistent across all subgroups, with 40.3% (2502/6208) identified at low probability (negative predictive value of 98.6%, 97.8% to 99.1%) and 28.0% (1737/6208) at high probability (positive predictive value of 75.0%, 65.7% to 82.5%) of having acute heart failure. CONCLUSIONS: In an international, collaborative evaluation of the diagnostic performance of NT-proBNP, guideline recommended thresholds to diagnose acute heart failure varied substantially in important patient subgroups. The CoDE-HF decision support tool incorporating NT-proBNP as a continuous measure and other clinical variables provides a more consistent, accurate, and individualised approach. STUDY REGISTRATION: PROSPERO CRD42019159407.

Diagnostic and prognostic accuracy of galectin-3 and soluble ST2 for acute heart failure.

BACKGROUND: We aimed to compare head-to-head the diagnostic and prognostic capabilities of galectin-3, soluble ST2 (sST2) and B-type natriuretic peptide (BNP) for heart failure (HF) in an emergency setting. METHODS: We studied 251 consecutive patients with dyspnoea as a chief compliant presenting to an emergency department. The diagnosis of HF was based on the Framingham score for HF plus echocardiographic evidence of systolic or diastolic dysfunction. All-cause mortality was assessed at one year. Plasma concentrations of galectin-3 and BNP were measured with two commercially available assays from Abbott Diagnostics, plasma concentrations of sST2 were quantified with the Presage ST2 assay. The diagnostic and prognostic accuracies of galectin-3, sST2 and BNP were assessed by receiver operating characteristic (ROC) curve analysis. RESULTS: Of the 251 patients, 137 had dyspnoea attributable to acute HF and 114 had dyspnoea attributable to other reasons. BNP had a higher area under the curve (AUC) for the diagnosis of HF (0.92; 95% CI, 0.87-0.95) than galectin-3 (0.57; 95% CI, 0.51-0.64) and sST2 (0.63; 95% CI, 0.56-0.69). Of the 137 patients with acute HF, 41 died and 96 survived during follow up. The AUC of BNP for the prediction of one-year all-cause mortality in HF patients (0.72; 95% CI, 0.63-0.79) was not different from the AUCs of galectin-3 (0.70; 95% CI, 0.62-0.78) and sST2 (0.75; 95% CI, 0.67-0.82). CONCLUSIONS: In this study, galectin-3, sST2 and BNP were equally useful for the prediction of one-year all-cause mortality in patients with acute HF. However, in contrast to BNP, galectin-3 and sST2 were not useful as an aid in the diagnosis of acute HF in short of breath patients presenting to an emergency department.

Analytical and clinical evaluation of a rapid quantitative lateral flow immunoassay for measurement of soluble ST2 in human plasma.

BACKGROUND: Soluble ST2 (sST2) is gaining growing interest as a biomarker in heart failure. So far, the ELISA-format is widely used for commercially available ST2 assays, which hampers their use in clinical routine. Recently, a rapid quantitative lateral flow immunoassay for the measurement of sST2 in human plasma has been developed. METHODS: We evaluated precision and linearity of the ASPECT-PLUS ST2 test, and performed an analytical and clinical assay comparison with the MBL and the PRESAGE ST2 ELISAs. We measured sST2 with these three assays in a clinical cohort of 251 consecutive patients with acute dyspnea as the chief compliant (i.e., 137 patients with dyspnea attributable to heart failure and 114 patients with dyspnea attributable to other reasons). RESULTS: Within-run and total coefficients of variation of the ASPECT-PLUS ST2 test were < 17% and the assay was linear across its measurement range. We found a constant and proportional bias between the MBL ST2 assay, the PRESAGE ST2 assay and the ASPECT-PLUS ST2 test, respectively. However, at the proposed cut-off of 35 ng/mL, sST2 results obtained with the PRESAGE ST2 assay and the ASPECT-PLUS ST2 test were similar. Testing clinically, the three assays deemed equally useful for the diagnosis of heart failure (AUC, 0.670 for the MBL ST2 assay vs. 0.626 for the PRESAGE ST2 assay vs. 0.630 for the ASPECT-PLUS ST2 test) and for the prediction of 1-year mortality in dyspnoeic patients (AUC, 0.743 for the MBL assay vs. 0.742 for the PRESAGE ST2 assay vs. 0.752 for the ASPECT-PLUS ST2 test). CONCLUSION: The ASPECT-PLUS test meets the analytical requirements for point-of-care testing. Test results of the ASPECT-PLUS ST2 and the PRESAGE ST2 methods were comparable at the proposed cut-off, and the diagnostic/prognostic capabilities of the three methods were similar.

Plasma concentrations of novel cardiac biomarkers before and after hemodialysis session.

OBJECTIVES: Biomarkers are useful for establishing disease severity or prognosis in patients with chronic kidney disease. The aim of our study was to determine the plasma concentrations of novel cardiovascular biomarkers in patients on chronic hemodialysis in the context of published upper reference limits (URL) of these biomarkers; and to compare the plasma concentrations of those same analytes before and after hemodialysis session. DESIGN AND METHODS: Plasma concentrations of N-terminal pro-B-type natriuretic peptide (NT-proBNP), mid-regional pro-A-type natriuretic peptide (MR-proANP), mid-regional pro-adrenomedullin (MR-proADM), C-terminal pro-endothelin-1 (CT-proET-1), C-terminal pro-arginine vasopressin (CT-proAVP, also known as Copeptin) and soluble ST2 (sST2) were measured in 28 patients before and after dialysis session. Of the 28 patients with conventional hemodialysis, 24 had low-flux hemofiltration and 4 had high-flux hemodiafiltration. RESULTS: Median plasma concentrations of the biomarkers obtained before hemodialysis were as follows: NT-proBNP, 11,307ng/L (URL, 500ng/L); MR-proANP, 778pmol/L (URL, 250pmol/L); MR-proADM, 2.57nmol/L (URL, 0.52nmol/L); median CT-proET-1, 252pmol/L (URL, 75pmol/L); median CT-proAVP, 142pmol/L (URL, 19pmol/L); and median sST2, 27ng/mL (URL, 50ng/mL). Median relative analyte changes after low-flux vs. high-flux dialysis compared to predialysis values were +19% vs. -43% for NT-proBNP; +7% vs. -45% for MR-proANP; -2% vs. -63% for MR-proADM; -19% vs. -61% for CT-proET-1; +13% vs. -64% for CT-proAVP; and +2% vs. +3% for sST2. CONCLUSIONS: Plasma concentrations of the investigated biomarkers were markedly increased in chronic hemodialysis patients (with the exception of sST2). After hemodialysis session, analyte concentrations (with the exception of sST2) decreased significantly using a high-flux membrane but not if using a low-flux membrane.

Prognostic value of established and novel biomarkers in patients with shortness of breath attending an emergency department.

OBJECTIVES: Acute dyspnea is a common cause for emergency department visits. The aim of this study was to evaluate the prognostic value of established and novel biomarkers in patients with acute dyspnea. DESIGN AND METHODS: We measured 10 biomarkers [B-type natriuretic peptide (BNP), midregional pro-A-type natriuretic peptide (MR-proANP), midregional-proadrenomedullin (MR-proADM), copeptin, C-terminal endothelin-1 precursor fragment (CT-proET-1), soluble ST2 (sST2), chromogranin A (CgA), adiponectin, proguanylin, and prouroguanylin] in 251 consecutive patients with acute dyspnea presenting to the emergency department of a tertiary care hospital. Outcome measure was all-cause mortality at 1 year. RESULTS: At baseline decedents (n=62) had significantly higher median plasma concentrations of all 10 biomarkers than survivors (n=189). Applying univariate Cox proportional-hazard regression analyses, all biomarkers were significant outcome predictors displaying risk ratios (RR) from 1.4 to 2.4 (per 1 SD increase in log transformed values). In multivariate Cox proportional-hazard regression analysis, however, only MR-proANP (RR 1.6; 95% CI, 1.1-2.2; p=0.008), sST2 (RR 1.7; 95% CI, 1.3-2.3; p<0.001), and CgA (RR 1.5; 95% CI, 1.2-1.9, p<0.001) were independently associated with 1-year mortality. We provide a possible explanation for the complementary prognostic value of those three biomarkers in our cohort, where coincidence of heart failure and inflammatory pulmonary disease was common and also related to worse outcome. CONCLUSIONS: Our evaluation of biomarkers in patients with acute dyspnea suggests that MR-proANP, sST2, and CgA are strong, independent and complementary outcome predictors. MR-proANP is considered a specific marker of cardiac stretch, sST2 might reflect both inflammation and cardiac stretch, and CgA obviously indicates neuroendocrine activation in various diseases.

Prognostic value of increased adiponectin plasma concentrations in patients with acute destabilized heart failure.

OBJECTIVES: To evaluate the prognostic value of adiponectin in patients with acute destabilized heart failure. DESIGN AND METHODS: Adiponectin was measured in 137 consecutive heart failure patients attending an emergency department. The endpoint was 1-year all-cause mortality. RESULTS: In Cox proportional-hazards regression, an adiponectin plasma concentration>24.1 mg/L had a risk ratio of 2.46 (95% CI, 1.24-4.87), independently of classical risk factors and B-type natriuretic peptide. CONCLUSIONS: Adiponectin predicts mortality in patients with acute destabilized heart failure.

Chromogranin A and C-terminal endothelin-1 precursor fragment add independent prognostic information to amino-terminal proBNP in patients with acute destabilized heart failure.

BACKGROUND: The aim of this study was to evaluate the prognostic value of chromogranin A (CgA) and C-terminal endothelin-1 precursor fragment (CT-proET-1) in patients with acute destabilized heart failure. METHODS: 137 consecutive patients with acute destabilized heart failure attending the emergency department of a tertiary care hospital were prospectively enrolled. Plasma concentrations of CgA, CT-proET-1, and amino-terminal proBNP (NT-proBNP) were measured at baseline. The endpoint was defined as all-cause mortality; the study participants were followed up for 365 days. RESULTS: Decedents (n=41) had higher median plasma concentrations of CgA (9.7 vs. 6.0 nmol/L; p=0.002), CT-proET-1 (120 vs. 72 pmol/L; p=0.006), and NT-proBNP (5112 vs. 2610 ng/L; p<0.001) at baseline than survivors (n=96). Applying Cox proportional-hazards regression analyses, increased CgA (>6.6 nmol/L), CT-proET-1 (>79 pmol/L), and NT-proBNP (>3275 ng/L) revealed significant risk ratios of 1.96 (95% CI, 1.04-3.70) for CgA, 2.56 (95% CI, 1.33-4.95) for CT-proET-1, and 2.05 (95% CI, 1.09-3.87) for NT-proBNP. When the cohort was stratified according to median CgA and NT-proBNP concentrations, and to median CT-proET-1 and NT-proBNP concentrations, respectively, Cox proportional-hazards regression analyses showed the highest risk for death in patients with both increased CgA and NT-proBNP (risk ratio, 3.65; 95% CI, 1.44-9.28), and increased CT-proET-1 and NT-proBNP (risk ratio, 4.03; 95% CI, 1.61-8.88). CONCLUSIONS: Our study demonstrates that increased CgA and CT-proET-1 plasma concentrations at the initial presentation of patients with acute destabilized heart failure in the emergency department add independent prognostic information in addition to NT-proBNP measurement.

Increased plasma concentrations of soluble ST2 are predictive for 1-year mortality in patients with acute destabilized heart failure.

BACKGROUND: The soluble isoform of the interleukin-1 receptor family member ST2 (sST2) has been implicated in heart failure. The aim of the present study was to evaluate the capability of sST2 as a prognostic marker in patients with acute destabilized heart failure. METHODS: sST2 plasma concentrations were obtained in 137 patients with acute destabilized heart failure attending the emergency department of a tertiary care hospital. The endpoint was defined as all-cause mortality, and the study participants were followed up for 365 days. RESULTS: Of the 137 patients enrolled, 41 died and 96 survived during follow-up. At baseline the median sST2 plasma concentration was significantly higher in the patients who died than in those who survived (870 vs 342 ng/L, P <0.001). Kaplan-Meier curve analyses demonstrated that the risk ratios for mortality were 2.45 (95% CI, 0.88-6.31; P = 0.086) and 6.63 (95% CI, 2.55-10.89; P <0.001) in the second tercile (sST2, 300-700 ng/L; 11 deaths vs 34 survivors) and third tercile (sST2, >700 ng/L; 25 deaths vs 21 survivors) of sST2 plasma concentrations compared with the first tercile (sST2, < or =300 ng/L; 5 deaths vs 41 survivors). In multivariable Cox proportional-hazards regression analyses, an sST2 plasma concentration in the upper tercile was a strong and independent predictor of all-cause mortality. CONCLUSIONS: Increased sST2 concentrations determined in plasma samples drawn from patients with acute destabilized heart failure at their initial presentation indicate increased risk of future mortality. Increased sST2 plasma concentrations are independently and strongly associated with one-year all-cause mortality in these patients.

Comparative evaluation of B-type natriuretic peptide, mid-regional pro-A-type natriuretic peptide, mid-regional pro-adrenomedullin, and Copeptin to predict 1-year mortality in patients with acute destabilized heart failure.

BACKGROUND: The aim of the present study was to evaluate the capability B-type natriuretic peptide (BNP) as a prognostic marker in patients with acute destabilized heart failure in comparison with mid-regional pro-A-type natriuretic peptide (MR-proANP), mid-regional pro-adrenomedullin (MR-proADM), and the C-terminal part of the arginine vasopressin prohormone (Copeptin). METHODS AND RESULTS: BNP, MR-proANP, MR-proADM, and Copeptin plasma concentrations were obtained in 137 patients with acute destabilized heart failure attending a tertiary care hospital. The end point was defined as all-cause mortality, and the study participants were followed for 365 days. Of the 137 patients enrolled, 41 died and 96 survived during follow-up. ROC curve analysis showed that the areas under curve for the prediction of 1-year mortality were similar for BNP (0.716; 95% CI 0.633-0.790), MR-proANP (0.725; 95% CI 0.642-0.798), MR-proADM (0.708; 95% CI 0.624-0.782), and Copeptin (0.688; 95% CI 0.603-0.764). Using tercile approaches, Kaplan-Meier curve analyses demonstrated that the predictive value of all four analytes for survival probability was comparable (log-rank test for trend, P < .001 for each). In multivariable Cox proportional-hazards regression analyses, increased BNP, MR-proANP, MR-proADM, and Copeptin plasma concentrations were the strongest predictors of mortality. CONCLUSION: BNP is considered an established prognostic marker for heart failure patients. The present study provides evidence that MR-proANP, MR-proADM, and Copeptin measurements might have similar predictive properties compared with BNP determinations for one-year all-cause mortality in acute destabilized heart failure.

B-type natriuretic peptide and amino terminal proBNP predict one-year mortality in short of breath patients independently of the baseline diagnosis of acute destabilized heart failure.

BACKGROUND: The aim of the present study was to demonstrate the capability of B-type natriuretic peptide (BNP) and amino terminal proBNP (NT-proBNP) as prognostic markers in patients with dyspnoea as a chief complaint. METHODS: BNP and NT-proBNP plasma concentrations were obtained from 251 short of breath patients presenting to the emergency department of a tertiary care hospital. Patients with acute coronary syndromes or trauma were excluded. The endpoint was defined as all-cause mortality, and the study participants were followed up for 365 days from the time they attended the emergency department. RESULTS: Of the 251 patients, 62 died and 189 stayed alive during follow-up. In the present study, optimal cut off levels for the prediction of survival were 454 ng/L for BNP, and 2060 ng/L for NT-proBNP. Mortality was higher in patients with baseline BNP and NT-proBNP concentrations above these cut off levels (log rank p<0.001; hazard ratios, 0.325 and 0.357, respectively). In multivariate Cox proportional-hazards regression analyses, elevated BNP/NT-proBNP, low systolic blood pressure, and renal dysfunction were predictors of mortality even when the baseline diagnosis of acute destabilized heart failure was factored into the model. CONCLUSIONS: Both BNP and NT-proBNP measures obtained from short of breath patients presenting to an emergency department may be predictive of one-year all-cause mortality independently of the baseline diagnosis of acute destabilized heart failure.

Midregional pro-A-type natriuretic peptide measurements for diagnosis of acute destabilized heart failure in short-of-breath patients: comparison with B-type natriuretic peptide (BNP) and amino-terminal proBNP.

BACKGROUND: The aim of the present study was to assess the utility of amino-terminal pro-A-type natriuretic peptide (NT-proANP) measurements for the emergency diagnosis of acute destabilized heart failure (HF), using a novel sandwich immunoassay covering midregional epitopes (MR-proANP). METHODS: The retrospective analysis comprised 251 consecutive patients presenting to the emergency department of a tertiary care hospital with dyspnea as a chief complaint. The diagnosis of acute destabilized HF was based on the Framingham score for HF plus echocardiographic evidence of systolic or diastolic dysfunction. A commercially available immunoluminometric assay was used for measurement of MR-proANP plasma concentrations. RESULTS: Median MR-proANP plasma concentrations were significantly higher in patients with dyspnea attributable to acute destabilized HF (338 pmol/L; n = 137) than in patients with dyspnea attributable to other reasons (98 pmol/L; n = 114; P <0.001). The area under the curve for MR-proANP was 0.876 (SE = 0.022; 95% confidence interval, 0.829-0.914), and the cutoff concentration with the highest diagnostic accuracy was 169 pmol/L (sensitivity, 89%; specificity, 76%; diagnostic accuracy, 83%). In the setting evaluated, diagnostic information obtained by MR-proANP measurements was similar to that obtained with B-type natriuretic peptide (BNP) and amino-terminal proBNP (NT-proBNP) measurements. CONCLUSIONS: MR-proANP measurements may be useful as an aid in the diagnosis of acute destabilized HF in short-of-breath patients presenting to an emergency department. The diagnostic value of MR-proANP appears to be comparable to that of BNP and NT-proBNP.

Capability of B-type natriuretic peptide (BNP) and amino-terminal proBNP as indicators of cardiac structural disease in asymptomatic patients with systemic arterial hypertension.

BACKGROUND: The aim of the present study was to prospectively evaluate the diagnostic utility of B-type natriuretic peptide (BNP) and amino-terminal proBNP (NT-proBNP) measurements for the detection of cardiac structural disease in asymptomatic patients with systemic arterial hypertension and to test the hypothesis that the 2 analytes are equally useful in this clinical setting. METHODS: We studied a consecutive series of 149 asymptomatic patients referred for echocardiographic evaluation of the cardiac effects of systemic arterial hypertension. Diagnosis of cardiac structural disease was based on the presence of systolic or diastolic dysfunction, left atrial dilatation, left ventricular dilatation or hypertrophy, pulmonary hypertension, and wall motion or valvular abnormalities. Blood concentrations of BNP and NT-proBNP were measured by 2 commercially available assays (Abbott AxSYM and Roche Elecsys, respectively). Diagnostic accuracies of BNP and NT-proBNP were assessed by ROC curve analysis. Areas under the curves were compared by analysis of equivalency. RESULTS: In distinguishing between hypertensive patients with cardiac structural disease (n = 118) and hypertensive patients without (n = 31), areas under the curves were 0.740 (95% confidence interval, 0.662-0.808) for BNP and 0.762 (0.685-0.828) for NT-proBNP and were significantly equivalent (P = 0.015). Cutoff values with a 90% sensitivity for cardiac structural disease were 17 ng/L for BNP and 39 ng/L for NT-proBNP, with 29% and 32% specificity, respectively. CONCLUSIONS: BNP and NT-proBNP have similar capabilities for detecting cardiac structural disease in asymptomatic patients with systemic arterial hypertension. However, in the setting evaluated, a screening strategy relying on measurement of BNP or NT-proBNP may be of limited value because of the low specificity at the selected cutoff values.

Plasma B-type natriuretic peptide in patients with pleural effusions: preliminary observations.

STUDY OBJECTIVES: To address the value of plasma B-type natriuretic peptide (BNP) concentrations as a diagnostic tool for determining the cardiac etiology of pleural effusions, and to determine possible differences of plasma BNP concentrations before and after pleurocentesis in patients with congestive heart failure (CHF). DESIGN: Observational study. SETTING: Tertiary care hospital. PATIENTS: Consecutive series of 64 patients with indications for diagnostic pleurocentesis. The final diagnosis of the underlying disease was assessed by clinical criteria. Seven patients were excluded due to pleural effusions of equivocal origin or due to obvious hemothorax secondary to trauma. INTERVENTION: Pleurocentesis attempting to drain effusions dry. Plasma BNP concentrations were measured directly before pleurocentesis and 24 h after the intervention. During these 24 h, the dosages of patients' medications were held constant. MEASUREMENTS AND RESULTS: In distinguishing between patients with pleural effusions caused by CHF (n = 31) and patients with pleural effusions attributable to other causes (n = 26), the area under the curve was 0.974 (SE, 0.021; 95% confidence interval, 0.892 to 0.997) for plasma BNP. A BNP cutoff concentration of 2,201 ng/L had a sensitivity of 77% and a specificity of 100% in the diagnosis of CHF. The median plasma BNP concentrations in patients with pleural effusions caused by CHF (n = 31) did not change within 24 h after pleurocentesis compared with the concentrations obtained before the procedure (before pleurocentesis, 3,227 ng/L; 24 h after pleurocentesis, 2,759 ng/L; p = 0.189), despite a median removal of 1,100 mL pleural fluid. CONCLUSIONS: Plasma BNP concentrations of patients with pleural effusions of unknown origin may be an aid in the diagnosis of CHF as the underlying cause. If plasma BNP is used as a surrogate marker of global cardiac function, there is no indication of hemodynamic improvement caused by pleurocentesis alone in patients with CHF and pleural effusions.

Factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations are not associated with chronic limb ischemia: the Linz Peripheral Arterial Disease (LIPAD) study.

OBJECTIVE: Factor V G1691A (Leiden), prothrombin G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T mutations are considered risk factors for venous thromboembolism. It remains to be characterized whether the presence of these relatively common mutations poses a risk for peripheral arterial disease (PAD). Therefore, we intended to test, by conducting a case-control study, the hypothesis that PAD was associated with an increased prevalence of factor V G1691A, prothrombin G20210A, and MTHFR C677T mutations. METHODS: The study comprised 433 patients admitted for inpatient diagnostics and treatment of PAD in patients with chronic limb ischemia. Patients with acute ischemia or malignancy were excluded. A total of 433 control subjects matched to the patients with PAD in a 1:1 design by sex, age (+/-2 years), and diabetes mellitus status were recruited. Factor V G1691A, prothrombin G20210A, and MTHFR C677T genotypes were assessed by polymerase chain reaction. RESULTS: For the factor V G1691A polymorphism, the genotype frequencies in PAD patients were 92.8% GG (normal homozygotes = wild type) and 7.2% GA (mutant heterozygotes), and in control subjects they were 94.0% GG and 6.0% GA (chi 2 test; P = .493). The distribution of the prothrombin G20210A genotypes was 96.3% GG (normal homozygotes = wild type) and 3.7% GA (mutant heterozygotes) in PAD patients and was 97.2% GG and 2.8% GA in control subjects (chi 2 test; P = .442). Genotype frequencies for the MTHFR C677T polymorphism were 47.8% CC (normal homozygotes = wild type), 43.4% CT (mutant heterozygotes), and 8.8% TT (mutant homozygotes) in PAD patients, compared with 47.1% CC, 44.1% CT, and 8.8% TT in control subjects (chi 2 test; P = .977). Accordingly, as determined by logistic regression analysis, no significant odds ratios for heterozygous or homozygous genotypes of the three polymorphisms could be observed. CONCLUSIONS: PAD was not associated with an increased prevalence of factor V G1691A, prothrombin G20210A, and MTHFR C677T mutations in the population studied. Thus, there is no indication that of one of these mutations may be a risk factor for chronic limb ischemia. However, the role of these mutations in acute limb ischemia remains to be clarified.

Long-term stability of endogenous B-type natriuretic peptide (BNP) and amino terminal proBNP (NT-proBNP) in frozen plasma samples.

The aim of the present study was to assess the long-term stability of endogenous B-type natriuretic peptide (BNP) and amino terminal proBNP (NT-proBNP) in plasma samples stored at -20 degrees C without addition of protease inhibitors (e.g., aprotinin). Stability of BNP and NT-proBNP was tested in 60 EDTA plasma samples with BNP values between 30 and 420 pg/ml. Initial BNP and NT-proBNP plasma concentrations were determined within four hours after blood collection using the AxSYM BNP and the Elecsys NT-proBNP assays. Subsequently, all samples were stored at -20 degrees C and were thawed for the second BNP and NT-proBNP determination on the two instruments after one day, 30 days, 60 days, 90 days and 120 days, respectively. Mean recovery (i.e., residual immunoreactivity) of BNP and NT-proBNP expressed in percent of the initial value for the given time interval of storage was calculated. Mean recovery of BNP was less than 70% after one day of storage at -20 degrees C and decreased to less than 50% after two to four months of storage (e.g., recovery of endogenous BNP after three months of storage at -20 degrees C ranging from 0% to 71%). In contrast, mean recovery of NT-proBNP was generally greater than 90%, irrespective of the duration of storage at -20 degrees C (e.g., recovery of endogenous NT-proBNP after three months of storage at -20 degrees C ranging from 91% to 112%). In conclusion, the determination of endogenous BNP with the AxSYM assay using frozen plasma samples may not be valid under the conditions tested. In contrast, NT-proBNP as measured by the Elecsys assay may be stored at -20 degrees C for at least four months without a relevant loss of the immunoreactive analyte.

Comparison of the automated AxSYM and ADVIA centaur immunoassays for homocysteine determination.

A new fully automated chemiluminescence assay for total homocysteine (tHcy) determination (ADVIA Centaur homocysteine, Bayer) was evaluated in comparison with a previously established fluorescence polarization assay (AxSYM homocysteine, Abbott). Linearity could be demonstrated in a concentration range up to 50 micromol/l for both methods. The detection limit was 0.92 micromol/l for the AxSYM and 0.61 micromol/l for the ADVIA Centaur analyzer. Within-run coefficients of variation (%CV) ranged from 1.7% to 1.8% for the AxSYM, and from 2.2% to 2.7% for the ADVIA Centaur analyzer, total CV ranged from 2.5% to 3.5% for the AxSYM, and from 3.6% to 4.5% for the ADVIA Centaur analyzer. Passing and Bablock regression analysis of 180 samples with the AxSYM assay as reference method revealed an intercept of -0.41 micromol/l (95% CI -1.17 to 0.20 micromol/l) and a slope of 1.11 (95% CI 1.05 to 1.18), the Bland-Altman difference plot showed a mean difference of -0.9 micromol/l between tHcy measurements with wide 95% limits of agreement (-3.6 to 1.7 micromol/l). At thresholds of 10 and 15 micromol/l there was a considerable proportion of discordant classifications of study subjects by the AxSYM and ADVIA Centaur method. When evaluating case-control status for vascular disease both assays showed similar characteristics (i.e., significant difference of tHcy in 71 CAD patients and 109 control subjects, and non-significant odds ratios for tHcy in the multivariate model). In conclusion, both methods are reliable for routine tHcy determination in clinical laboratories, as they are fast and completely automated systems with good accuracy and precision allowing sample random access, automatic dilution and stored calibration capabilities. However, results of both assays may not be used interchangeably since the ADVIA Centaur method tends to overestimate tHcy values compared to the AxSYM method.

Biochemical diagnosis of impaired left ventricular ejection fraction--comparison of the diagnostic accuracy of brain natriuretic peptide (BNP) and amino terminal proBNP (NT-proBNP).

The aim of the present investigation was to evaluate the diagnostic accuracy of brain natriuretic peptide (BNP) and amino terminal proBNP (NT-proBNP) for the detection of mild/moderate and severe impairment of left ventricular ejection fraction (LVEF). In 180 subjects BNP and NT-proBNP were measured by two novel fully automated chemiluminescent assays (Bayer and Roche methods). LVEF as determined by echocardiography was categorized as normal (> 60%), mildly/moderately reduced (35-60%) and severely diminished (< 35%). Discriminating between patients with LVEF< 35% (n = 32) and subjects with LVEF > or = 35% (n = 148), receiver-operating characteristic (ROC) curve analysis revealed an area under the curve (AUC) of 0.912 for BNP and of 0.896 for NT-proBNP (difference 0.016, p = 0.554). In contrast, BNP displayed an AUC of 0.843 and NT-proBNP an AUC of 0.927 (difference of 0.084, p = 0.034) when comparing patients with LVEF 35-60% (n = 37) and individuals with LVEF > 60% (n = 111). Evaluation of discordant false classifications at cut-off levels with the highest diagnostic accuracy showed advantages for BNP in the biochemical diagnosis of LVEF < 35% (4 misclassifications by BNP and 25 by NT-proBNP, p < 0.001) and for NT-proBNP in the detection of LVEF 35-60% (25 misclassifications by BNP and 7 by NT-proBNP, p = 0.002). In conclusion, the present study indicates a different diagnostic accuracy of BNP and NT-proBNP for the detection of mildly/moderately reduced LVEF and severely diminished LVEF. Advantages of BNP may be advocated for the biochemical diagnosis of more severely impaired LVEF, while NT-proBNP might be a more discerning marker of early systolic left ventricular dysfunction.