Periodic verification of results' comparability between several analyzers: experience in the application of the EP31-A-IR guideline.

OBJECTIVES: To assess the usefulness of the EP31-A-IR guideline published by the Clinical and Laboratory Standards Institute (CLSI) to perform the periodic verification of results' comparability between several analyzers. METHODS: Twenty-four biochemistry parameters that could be measured in different analyzers were included: albumin, alkaline phosphatase, alanine aminotransferase, amylase, aspartate aminotransferase, calcium, chloride, C-reactive protein, creatine kinase, creatinine, direct bilirubin, gamma glutamyl transferase, glucose, lactate dehydrogenase, magnesium, phosphate, potassium, sodium, total bilirubin, total cholesterol, total protein, triglycerides, urea and uric acid. In accordance with the EP31-A-IR guideline: (1) Patient samples were selected considering the concentration or activity of interest. (2) Acceptance criteria were established specifically for each concentration or activity level. A quality specification based on biological variation or on state of the art was selected, considering the analytical performance of the available technology. (3) Maximum allowable differences (MAD) between analyzers were calculated. (4) Measurements were performed as stated in appendix B of the guideline. (5) Maximum differences between analyzers were calculated. Results were considered comparable when the maximum difference was less than or equal to the MAD. RESULTS: For the 24 parameters evaluated, any difference between analyzers exceeded the MAD. CONCLUSIONS: The EP31-A-IR guideline proved to be useful for periodic verification of results' comparability. However, it must be considered that, to be practicable, it may require to adjust the acceptance criteria in accordance to the analytical performance of the available technology; as well as the number of analytical measurements conforming to the laboratory resources.

Cardiac dysfunction and remodeling regulated by anti-angiogenic environment in patients with preeclampsia: the ANGIOCOR prospective cohort study protocol.

BACKGROUND: Cardiovascular diseases (CVD) are cause of increased morbidity and mortality in spite of advances for diagnosis and treatment. Changes during pregnancy affect importantly the maternal CV system. Pregnant women that develop preeclampsia (PE) have higher risk (up to 4 times) of clinical CVD in the short- and long-term. Predominance of an anti-angiogenic environment during pregnancy is known as main cause of PE, but its relationship with CV complications is still under research. We hypothesize that angiogenic factors are associated to maternal cardiac dysfunction/remodeling and that these may be detected by new cardiac biomarkers and maternal echocardiography. METHODS: Prospective cohort study of pregnant women with high-risk of PE in first trimester screening, established diagnosis of PE during gestation, and healthy pregnant women (total intended sample size n = 440). Placental biochemical and biophysical cardiovascular markers will be assessed in the first and third trimesters of pregnancy, along with maternal echocardiographic parameters. Fetal cardiac function at third trimester of pregnancy will be also evaluated and correlated with maternal variables. Maternal cardiac function assessment will be determined 12 months after delivery, and correlation with CV and PE risk variables obtained during pregnancy will be evaluated. DISCUSSION: The study will contribute to characterize the relationship between anti-angiogenic environment and maternal CV dysfunction/remodeling, during and after pregnancy, as well as its impact on future CVD risk in patients with PE. The ultimate goal is to improve CV health of women with high-risk or previous PE, and thus, reduce the burden of the disease. TRIAL REGISTRATION: NCT04162236.

Quality assurance of add-on testing in plasma samples: stability limit for 29 biochemical analytes.

Introduction: Clinical laboratories should guarantee sample stability in specific storage conditions for further analysis. The aim of this study is to evaluate the stability of plasma samples under refrigeration for 29 common biochemical analytes usually ordered within an emergency context, in order to determine the maximum allowable period for conducting add-on testing. Materials and methods: A total of 20 patient samples were collected in lithium heparin tubes without gel separator. All analyses were performed using Alinity systems (Abbott Laboratories, Abbott Park, USA) and samples were stored at 2-8 °C. Measurements were conducted in primary plasma tubes at specific time points up to 48 hours, with an additional stability study in plasma aliquots extending the time storage up to 96 hours. The stability limit was estimated considering the total limit of change criteria. Results: Of the 29 studied parameters, 24 demonstrated stabilities within a 48-hour storage period in primary plasma tubes. However, five analytes: aspartate aminotransferase, glucose, lactate dehydrogenase, inorganic phosphate and potassium evidenced instability at different time points (7.9 hours, 2.7 hours, 2.9 hours, 6.2 hours and 4.7 hours, respectively). The stability study in plasma aliquots showed that all parameters remained stable for 96 hours, except lactate dehydrogenase, with a stability limit of 63 hours. Conclusions: A reduced stability of primary plasma samples was observed for five common biochemical analytes ordered in an emergency context. To ensure the quality of add-on testing for these samples, plasma aliquots provide stability for a longer period.

Impact of Angiogenic and Cardiovascular Biomarkers for Prediction of Placental Dysfunction in the First Trimester of Pregnancy.

Algorithms for first-trimester prediction of pre-eclampsia usually include maternal risk factors, blood pressure, placental growth factor (PlGF), and uterine artery Doppler pulsatility index. However, these models lack sensitivity for the prediction of late-onset pre-eclampsia and other placental complications of pregnancy, such as small for gestational age infants or preterm birth. The aim of this study was to assess the screening performance of PlGF, soluble fms-like tyrosine kinase-1 (sFlt-1), N-terminal pro-brain natriuretic peptide (NT-proBNP), uric acid, and high-sensitivity cardiac troponin T (hs-TnT) in the prediction of adverse obstetric outcomes related to placental insufficiency. This retrospective case-control study was based on a cohort of 1390 pregnant women, among which 210 presented pre-eclampsia, small for gestational age infants, or preterm birth. Two hundred and eight women with healthy pregnancies were selected as controls. Serum samples were collected between weeks 9 and 13 of gestation, and maternal serum concentrations of PlGF, sFlt-1, NT-proBNP, uric acid, and hs-TnT were measured. Multivariate regression analysis was used to generate predictive models combining maternal factors with the above-mentioned biomarkers. Women with placental dysfunction had lower median concentrations of PlGF (25.77 vs. 32.00 pg/mL; p < 0.001), sFlt-1 (1212.0 vs. 1363.5 pg/mL; p = 0.001), and NT-proBNP (51.22 vs. 68.71 ng/L; p < 0.001) and higher levels of uric acid (193.66 µmol/L vs. 177.40 µmol/L; p = 0.001). There was no significant difference between groups regarding the sFlt-1/PlGF ratio. Hs-TnT was not detected in 70% of the maternal serums analyzed. Altered biomarker concentrations increased the risk of the analyzed complications both in univariate and multivariate analyses. The addition of PlGF, sFlt-1, and NT-proBNP to maternal variables improved the prediction of pre-eclampsia, small for gestational age infants, and preterm birth (area under the curve: 0.710, 0.697, 0.727, and 0.697 vs. 0.668, respectively). Reclassification improvement was greater in maternal factors plus the PlGF model and maternal factors plus the NT-p roBNP model (net reclassification index, NRI: 42.2% and 53.5%, respectively). PlGF, sFlt-1, NT-proBNP, and uric acid measurements in the first trimester of pregnancy, combined with maternal factors, can improve the prediction of adverse perinatal outcomes related to placental dysfunction. In addition to PlGF, uric acid and NT-proBNP are two promising predictive biomarkers for placental dysfunction in the first trimester of pregnancy.

Predictive Model for Preeclampsia Combining sFlt-1, PlGF, NT-proBNP, and Uric Acid as Biomarkers.

N-terminal pro-brain natriuretic peptide (NT-proBNP) and uric acid are elevated in pregnancies with preeclampsia (PE). Short-term prediction of PE using angiogenic factors has many false-positive results. Our objective was to validate a machine-learning model (MLM) to predict PE in patients with clinical suspicion, and evaluate if the model performed better than the sFlt-1/PlGF ratio alone. A multicentric cohort study of pregnancies with suspected PE between 24+0 and 36+6 weeks was used. The MLM included six predictors: gestational age, chronic hypertension, sFlt-1, PlGF, NT-proBNP, and uric acid. A total of 936 serum samples from 597 women were included. The PPV of the MLM for PE following 6 weeks was 83.1% (95% CI 78.5−88.2) compared to 72.8% (95% CI 67.4−78.4) for the sFlt-1/PlGF ratio. The specificity of the model was better; 94.9% vs. 91%, respectively. The AUC was significantly improved compared to the ratio alone [0.941 (95% CI 0.926−0.956) vs. 0.901 (95% CI 0.880−0.921), p < 0.05]. For prediction of preterm PE within 1 week, the AUC of the MLM was 0.954 (95% CI 0.937−0.968); significantly greater than the ratio alone [0.914 (95% CI 0.890−0.934), p < 0.01]. To conclude, an MLM combining the sFlt-1/PlGF ratio, NT-proBNP, and uric acid performs better to predict preterm PE compared to the sFlt-1/PlGF ratio alone, potentially increasing clinical precision.

Characterization of add-on testing before and after automation at a core laboratory.

Objectives: Add-on testing refers to the process that occurs in clinical laboratories when clinicians request that additional tests be performed on a previously analysed specimen. This is a common but inefficient procedure, highly time-consuming, especially at core laboratories and could be optimised by automating these procedures. The aims of this study are: 1) To describe patterns of add-on testing at a core laboratory at a tertiary hospital, 2) To evaluate turnaround time (TAT) before and after automation of the pre-, post- and analytical phases. Methods: Retrospective, observational study conducted at the biochemistry area of a core laboratory of all add-on orders received in two different months (pre-automation and post-automation). Results: A total of 2464 add-on orders were analysed, representing around 5 % of total requests. Most orders were for either one (>50 %) or two (≈20 %) tests. Most orders were received during the week (from Monday to Friday), particularly during the morning shift (>50 %). More than 50 % of requests were made by the Emergency Department. The two most common add-on parameters were C-reactive protein and N-terminal pro-brain natriuretic peptide. After automation, the median TAT decreased by 42.3 % (from 52 to 22 min). The largest decreases in TAT were observed for routine samples (58.89 %) and fully automated analyses (56.86 %). Conclusions: Automation of our core laboratory substantially reduced turnaround time for add-on testing, indicating an increase in efficiency. Automation eliminated several manual steps in the process, leading to a mean reduction of 15 work hours per day (more than 2 full-time equivalents).

The Relevance of Implementing the Systematic Screening of Perioperative Myocardial Injury in Noncardiac Surgery Patients.

Perioperative myocardial injury (PMI) is a common cardiac complication. Recent guidelines recommend its systematic screening using high-sensitivity cardiac troponin (hs-cTn). However, there is limited evidence of local screening programs. We conducted a prospective, single-center study aimed at assessing the feasibility and outcomes of implementing systematic PMI screening. Hs-cTn concentrations were measured before and after surgery. PMI was defined as a postoperative hs-cTnT of ≥14 ng/L, exceeding the preoperative value by 50%. All patients were followed-up during the hospitalization, at one month and one year after surgery. The primary outcome was the incidence of death and major cardiovascular and cerebrovascular events (MACCE). The secondary outcomes focused on the individual components of MACCE. We included two-thirds of all eligible high-risk patients and achieved almost complete compliance with follow-ups. The prevalence of PMI was 15.7%, suggesting a higher presence of cardiovascular (CV) antecedents, increased perioperative CV complications, and higher preoperative hs-cTnT values. The all-cause death rate was 1.7% in the first month, increasing up to 11.2% at one year. The incidence of MACCE was 9.5% and 8.6% at the same time points. Given the observed elevated frequencies of PMI and MACCE, implementing systematic PMI screening is recommendable, particularly in patients with increased cardiovascular risk. However, it is important to acknowledge that achieving optimal screening implementation comes with various challenges and complexities.

Non-invasive electromechanical assessment during atrial fibrillation identifies underlying atrial myopathy alterations with early prognostic value.

Electromechanical characterization during atrial fibrillation (AF) remains a significant gap in the understanding of AF-related atrial myopathy. This study reports mechanistic insights into the electromechanical remodeling process associated with AF progression and further demonstrates its prognostic value in the clinic. In pigs, sequential electromechanical assessment during AF progression shows a progressive decrease in mechanical activity and early dissociation from its electrical counterpart. Atrial tissue samples from animals with AF reveal an abnormal increase in cardiomyocytes death and alterations in calcium handling proteins. High-throughput quantitative proteomics and immunoblotting analyses at different stages of AF progression identify downregulation of contractile proteins and progressive increase in atrial fibrosis. Moreover, advanced optical mapping techniques, applied to whole heart preparations during AF, demonstrate that AF-related remodeling decreases the frequency threshold for dissociation between transmembrane voltage signals and intracellular calcium transients compared to healthy controls. Single cell simulations of human atrial cardiomyocytes also confirm the experimental results. In patients, non-invasive assessment of the atrial electromechanical relationship further demonstrate that atrial electromechanical dissociation is an early prognostic indicator for acute and long-term rhythm control.

Risk Assessment after ST-Segment Elevation Myocardial Infarction: Can Biomarkers Improve the Performance of Clinical Variables?

INTRODUCTION: Myocardial infarction with ST-segment elevation (STEMI) is the coronary artery disease associated with the highest risk of morbimortality; however, this risk is heterogeneous, usually being evaluated by clinical scores. Risk assessment is a key factor in personalized clinical management of patients with this disease. AIM: The aim of this study was to assess whether some new cardiac biomarkers considered alone, combined in a multibiomarker model or in association with clinical variables, improve the short- and long-term risk stratification of STEMI patients. MATERIALS AND METHODS: This was a retrospective observational study of 253 patients with STEMI. Blood samples were obtained before or during the angiography. The assessed biomarkers were C-terminal fragment of insulin-like growth factor binding protein-4 (CT-IGFBP4), high sensitive cardiac troponin T (hs-cTnT), N-terminal fragment of probrain natriuretic peptide (NT-proBNP), and growth differentiation factor 15 (GDF-15); they reflect different cardiovascular (CV) physiopathological pathways and underlying pathologies. We registered in-hospital and follow-up mortalities and their causes (cardiovascular and all-cause) and major adverse cardiac events (MACE) during a two year follow-up. Discrimination, survival analysis, model calibration, and reclassification of the biomarkers were comprehensively evaluated. RESULTS AND DISCUSSION: In total, 55 patients (21.7%) died, 33 in-hospital and 22 during the follow-up, most of them (69.1%) from CV causes; 37 MACE occurred during follow-up. Biomarkers showed good prognostic ability to predict mortality, alone and combined with the multibiomarker model. A predictive clinical model based on age, Killip-Kimball class, estimated glomerular filtration rate (eGFR), and heart rate was derived by multivariate analysis. GDF-15 and NT-proBNP significantly improved risk assessment of the clinical model, as shown by discrimination, calibration, and reclassification of all the end-points except for all-cause mortality. The combination of NT-proBNP and hs-cTnT improved CV mortality prediction. CONCLUSIONS: GDF-15 and NT-proBNP added value to the usual risk assessment of STEMI patients.

Electrophysiological and histological characterization of atrial scarring in a model of isolated atrial myocardial infarction.

Background: Characterization of atrial myocardial infarction is hampered by the frequent concurrence of ventricular infarction. Theoretically, atrial infarct scarring could be recognized by multifrequency tissue impedance, like in ventricular infarction, but this remains to be proven. Objective: This study aimed at developing a model of atrial infarction to assess the potential of multifrequency impedance to recognize areas of atrial infarct scar. Methods: Seven anesthetized pigs were submitted to transcatheter occlusion of atrial coronary branches arising from the left coronary circumflex artery. Six weeks later the animals were anesthetized and underwent atrial voltage mapping and multifrequency impedance recordings. The hearts were thereafter extracted for anatomopathological study. Two additional pigs not submitted to atrial branch occlusion were used as controls. Results: Selective occlusion of the atrial branches induced areas of healed infarction in the left atrium in 6 of the 7 cases. Endocardial mapping of the left atrium showed reduced multi-frequency impedance (Phase angle at 307 kHz: from -17.1° ± 5.0° to -8.9° ± 2.6°, p < .01) and low-voltage of bipolar electrograms (.2 ± 0.1 mV vs. 1.9 ± 1.5 mV vs., p < .01) in areas affected by the infarction. Data variability of the impedance phase angle was lower than that of bipolar voltage (coefficient of variability of phase angle at307 kHz vs. bipolar voltage: .30 vs. .77). Histological analysis excluded the presence of ventricular infarction. Conclusion: Selective occlusion of atrial coronary branches permits to set up a model of selective atrial infarction. Atrial multifrequency impedance mapping allowed recognition of atrial infarct scarring with lesser data variability than local bipolar voltage mapping. Our model may have potential applicability on the study of atrial arrhythmia mechanisms.

Renal Function Impact in the Prognostic Value of Galectin-3 in Acute Heart Failure.

Introduction: Galectin-3 (Gal-3) is an inflammatory marker associated with the development and progression of heart failure (HF). A close relationship between Gal-3 levels and renal function has been observed, but data on their interaction in patients with acute HF (AHF) are scarce. We aim to assess the prognostic relationship between renal function and Gal-3 during an AHF episode. Materials and Methods: This is an observational, prospective, multicenter registry of patients hospitalized for AHF. Patients were divided into two groups according to estimated glomerular filtration rate (eGFR): preserved renal function (eGFR ≥ 60 mL/min/1.73 m2) and renal dysfunction (eGFR <60 mL/min/1.73 m2). Cox regression analysis was performed to evaluate the association between Gal-3 and 12-month mortality. Results: We included 1,201 patients in whom Gal-3 values were assessed at admission. The median value of Gal-3 in our population was 23.2 ng/mL (17.3-32.1). Gal-3 showed a negative correlation with eGFR (rho = -0.51; p < 0.001). Gal-3 concentrations were associated with higher mortality risk in the multivariate analysis after adjusting for eGFR and other prognostic variables [HR = 1.010 (95%-CI: 1.001-1.018); p = 0.038]. However, the prognostic value of Gal-3 was restricted to patients with renal dysfunction [HR = 1.010 (95%-CI: 1.001-1.019), p = 0.033] with optimal cutoff point of 31.5 ng/mL, with no prognostic value in the group with preserved renal function [HR = 0.990 (95%-CI: 0.964-1.017); p = 0.472]. Conclusions: Gal-3 is a marker of high mortality in patients with acute HF and renal dysfunction. Renal function influences the prognostic value of Gal-3 levels, which should be adjusted by eGFR for a correct interpretation.

Changes in the Composition and Function of Lipoproteins after Bariatric Surgery in Patients with Severe Obesity.

The effect of bariatric surgery on lipid profile and the qualitative characteristics of lipoproteins was analyzed in morbidly obese subjects. Thirteen obese patients underwent bariatric surgery. Plasma samples were obtained before surgery and at 6 and 12 months after the intervention. Thirteen healthy subjects comprised the control group. Lipid profile, hsCRP, and the composition and functional characteristics of VLDL, LDL, and HDL were assessed. At baseline, plasma from subjects with obesity had more triglycerides, VLDLc, and hsCRP, and less HDLc than the control group. These levels progressively normalized after surgery, although triglyceride and hsCRP levels remained higher than those in the controls. The main differences in lipoprotein composition between the obese subjects and the controls were increased apoE in VLDL, and decreased cholesterol and apoJ and increased apoC-III content in HDL. The pro-/anti-atherogenic properties of LDL and HDL were altered in the subjects with obesity at baseline compared with the controls, presenting smaller LDL particles that are more susceptible to modification and smaller HDL particles with decreased antioxidant capacity. Bariatric surgery normalized the composition of lipoproteins and improved the qualitative characteristics of LDL and HDL. In summary, patients with obesity present multiple alterations in the qualitative properties of lipoproteins compared with healthy subjects. Bariatric surgery reverted most of these alterations.

The Capacity of APOB-Depleted Plasma in Inducing ATP-Binding Cassette A1/G1-Mediated Macrophage Cholesterol Efflux-But Not Gut Microbial-Derived Metabolites-Is Independently Associated with Mortality in Patients with ST-Segment Elevation Myocardial Infarction.

Impaired HDL-mediated macrophage cholesterol efflux and higher circulating concentrations of trimethylamine N-oxide (TMAO) levels are independent risk factors for cardiovascular mortality. The TMAO precursors, γ-butyrobetaine (γBB) and Trimethyllysine (TML), have also been recently associated with cardiovascular death, but their interactions with HDL-mediated cholesterol efflux remain unclear. We aimed to determine the associations between APOB depleted plasma-mediated macrophage cholesterol efflux and plasma TMAO, γBB, and TML concentrations and explore their association with two-year follow-up mortality in patients with acute ST-elevation myocardial infarction (STEMI) and unstable angina (UA). Baseline and ATP-binding cassette transporter ABCA1 and ABCG1 (ABCA1/G1)-mediated macrophage cholesterol efflux to APOB-depleted plasma was decreased in patients with STEMI, and the latter was further impaired in those who died during follow-up. Moreover, the circulating concentrations of TMAO, γBB, and TML were higher in the deceased STEMI patients when compared with the STEMI survivors or UA patients. However, after statistical adjustment, only ABCA1/G1-mediated macrophage cholesterol efflux remained significantly associated with mortality. Furthermore, neither the TMAO, γBB, nor TML levels altered the HDL-mediated macrophage cholesterol efflux in vitro. We conclude that impaired ABCA1/G1-mediated macrophage cholesterol efflux is independently associated with mortality at follow-up in STEMI patients.

A 3-Biomarker 2-Point-Based Risk Stratification Strategy in Acute Heart Failure.

Introduction and Objectives: Most multi-biomarker strategies in acute heart failure (HF) have only measured biomarkers in a single-point time. This study aimed to evaluate the prognostic yielding of NT-proBNP, hsTnT, Cys-C, hs-CRP, GDF15, and GAL-3 in HF patients both at admission and discharge. Methods: We included 830 patients enrolled consecutively in a prospective multicenter registry. Primary outcome was 12-month mortality. The gain in the C-index, calibration, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) was calculated after adding each individual biomarker value or their combination on top of the best clinical model developed in this study (C-index 0.752, 0.715-0.789) and also on top of 4 currently used scores (MAGGIC, GWTG-HF, Redin-SCORE, BCN-bioHF). Results: After 12-month, death occurred in 154 (18.5%) cases. On top of the best clinical model, the addition of NT-proBNP, hs-CRP, and GDF-15 above the respective cutoff point at admission and discharge and their delta during compensation improved the C-index to 0.782 (0.747-0.817), IDI by 5% (p < 0.001), and NRI by 57% (p < 0.001) for 12-month mortality. A 4-risk grading categories for 12-month mortality (11.7, 19.2, 26.7, and 39.4%, respectively; p < 0.001) were obtained using combination of these biomarkers. Conclusion: A model including NT-proBNP, hs-CRP, and GDF-15 measured at admission and discharge afforded a mortality risk prediction greater than our clinical model and also better than the most currently used scores. In addition, this 3-biomarker panel defined 4-risk categories for 12-month mortality.

Growth differentiation factor 15 as mortality predictor in heart failure patients with non-reduced ejection fraction.

AIMS: The prognostic value of biomarkers in patients with heart failure (HF) and mid-range (HFmrEF) or preserved ejection fraction (HFpEF) has not been widely addressed. The aim of this study was to assess whether the prognostic value of growth differentiation factor 15 (GDF-15) is superior to that of N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with HFmrEF or HFpEF. METHODS AND RESULTS: Heart failure patients with either HFpEF or HFmrEF were included in the study. During their first visit to the HF unit, serum samples were obtained and stored for later assessment of GDF-15 and NT-proBNP concentrations. Patients were followed up by the HF unit. The main endpoint was all-cause mortality. A total of 311 patients, 90 (29%) HFmrEF and 221 (71%) HFpEF, were included. Mean age was 72 ± 13 years, and 136 (44%) were women. No differences were found in GDF-15 or NT-proBNP concentrations between both HF groups. During a median follow-up of 15 months (Q1-Q3: 9-30 months), 98 patients (32%) died, most (71%) of cardiovascular causes. Patients who died had higher median concentrations of GDF-15 (4085 vs. 2270 ng/L, P < 0.0001) and NT-proBNP (1984 vs. 1095 ng/L, P < 0.0001). A Cox multivariable model identified New York Heart Association Functional Class III (P = 0.04), systolic blood pressure (P = 0.01), left atrial diameter (P = 0.03), age >65 years (P < 0.0001), and GDF-15 concentrations (P = 0.01) but not NT-proBNP as independent predictors of all-cause mortality. The area under the curve was 0.797 for the basic model including NT-proBNP, and the area under the curve comparing the overall model was 0.819, P = 0.016 (DeLong's test). Integrated discrimination improvement index after the inclusion of GDF-15 in the model with the mortality risk factors was 0.033; that is, the ability to predict death increased by 3.3% (P = 0.004). Net reclassification improvement was 0.548 (P < 0.001); that is, the capacity to improve the classification of the event (mortality) was 54.8%. GDF-15 concentrations were divided in tertiles (<1625, 1625-4330, and >4330 ng/L), and survival curves were evaluated using the Kaplan-Meier technique. Patients in the highest tertile had the poorest 5 year survival, at 16%, whereas the lowest tertile had the best survival, of 78% (P < 0.001). CONCLUSIONS: Growth differentiation factor 15 was superior to NT-proBNP for assessing prognosis in patients with HFpEF and HFmrEF. GDF-15 emerges as a strong, independent biomarker for identifying HFmrEF and HFpEF patients with worse prognosis.

Long-term prognostic value of growth differentiation factor-15 in acute coronary syndromes.

BACKGROUND: Growth Differentiation Factor-15 (GDF-15) predicts death and cardiovascular events in acute coronary syndromes (ACS). We aimed to assess the long-term prognostic value of GDF-15 in ACS. METHODS: We included 358 patients with ACS who underwent coronary angiography. Plasma GDF-15 was measured and clinical data and long-term events were registered. Incremental value of GDF-15 for prognosing all-cause death above a clinical model including GRACE score, left ventricular ejection fraction <40%, prior myocardial infarction and age was assessed. RESULTS: GDF-15 concentrations >1800 ng/L were associated with an increased prevalence of cardiovascular risk factors. During 6.5 years of follow-up 56 patients died, 7 had values of GDF-15 < 1200 ng/L, 7 between 1200 and 1800 ng/L and 42 > 1800 ng/L. After adjustment for potential confounders, GDF-15 > 1800 ng/L were independently associated with all-cause death (HR 4.09; 95% CI 1.57-10.71; p = .004) and the composite of major adverse cardiovascular events (MACE) (HR 2.48; 95% CI 1.41-4.34; p = .001). For long-term all-cause death a significant increase of ROC curve was seen after addition of GDF-15 to a clinical model 0.876 (95% CI 0.823-0.928; p = .014). Same improvements were found for net reclassification improvement (0.776; 95% CI 0.494-1.037; p < .001) and integrated discrimination improvement (0.112; 95% CI 0.055-0.169; p < .001). Multivariate competing risk model showed a significant association between GDF-15 > 1800 ng/L and the incidence of heart failure but not of myocardial infarction. CONCLUSIONS: In the setting of ACS, GDF-15 is associated with long-term all-cause death, MACE and heart failure and provides incremental prognostic value beyond traditional risks factor.

Ultrasensitive quantification of cardiac troponin I by a Single Molecule Counting method: analytical validation and biological features.

AIM: To evaluate analytical and biological characteristics of the Singulex Clarity® cTnI assay, based upon Single Molecule Counting technology. METHODS: Assay's analytical sensitivity, precision, linearity, hook effect, cross-reactivity or interference by endogenous and exogenous substances, stability, 99th reference percentile [p99th] in EDTA plasma were evaluated in single or multi-site studies. RESULTS: Detection limit was 0.12 ng/L. Sensitivity was 0.14 ng/L at 20% CV (functional sensitivity) and 0.53 ng/L at 10% CV. Imprecision was 3.16%-10.0% in a multi-lot, single-site study, and 5.5%-12.0% in a single-lot, multi-site study; assay was linear from 0.08 to 25,000 ng/L. No hook effect was observed; any cross-reactivity/interference exceeded the 10%. Healthy subjects were recruited using clinical history, normal NT-proBNP and eGFR (n = 560) or plasma creatinine (n = 535) as inclusion criteria. cTnI was detectable in 96.8% of healthy subjects. The p99th were 8.01 (eGFR used) and 8.15 ng/L (plasma creatinine); both were measured with ≤5.7% CV. Median cTnI were significantly higher in older and male than in young and female subjects. CONCLUSIONS: The Singulex Clarity cTnI assay show analytical features and % detection in healthy subjects that improve the corresponding values of most of the existing high-sensitivity cTnI assays.

High-Sensitivity Troponin T and Soluble Form of AXL as Long-Term Prognostic Biomarkers after Heart Transplantation.

ANTECEDENTS: Cardiac allograft vasculopathy (CAV) is a frequent complication limiting the long-term (>1 year) survival after heart transplantation (HTx). CAV is initiated by endothelial dysfunction and can lead to severe cardiovascular (CV) complications. Since CAV is often clinically silent, biomarkers could help identifying HTx patients at risk of CAV and their severe complications. AIM: Evaluate the clinical yield of high-sensitivity cardiac troponin T (hs-cTnT), marker of cardiomyocyte damage, and the soluble form of AXL (sAXL), biomarker of endothelial dysfunction, to assess the prognosis of long-term cardiovascular (CV) events occurring after HTx. METHODS: 96 patients were evaluated at least > 1 year after HTx. CAV was evaluated by coronary angiography or multisliced tomography, and hs-cTnT and sAXL measured 6 months before or after CAV evaluation. Patients were followed during 42 ± 15 months for a combined end point including cardiac death, angina or acute myocardial infarction, left ventricular ejection fraction < 50%, or heart failure not due to an acute rejection. RESULTS: 51 patients (53%) presented CAV at evaluation; 21 of them had CV events. Hs-cTnT (56 ± 45 versus 20 ± 18 ng/L; p = 0.04) and sAXL concentrations (98 ± 51 versus 26 ± 26 ng/L; p = 0.01) were significantly higher in patients with CV events. Hs-cTnT (HR 1.03; 95% CI 1.015-1.042, p = 0.0001) and sAXL (HR 1.01; 95% CI 1.001-1.019, p = 0.02) were independent predictors of CV events. A hs-cTnT concentration < 21 ng/L, detected by AUC ROC, predicted the absence of CV events with a predictive value of 91%; sAXL did not add more predictive value to hs-cTnT. Survival free of CV events was 92% in patients with hs-cTnT < 21 ng/L and 57% in those with hs-cTnT > 21 ng/L (p < 0.001). CONCLUSION: Hs-cTnT, but not sAXL, measured during the long-term follow-up of HTx patients appears as a helpful biomarker to identify patients at low risk of adverse CV outcomes.