Saenger, Amy K.

Abstract Background Concerns exist regarding how the 99th percentile upper reference limit (URL) of cardiac troponin (cTn) is determined and whether it should be derived from normal healthy individuals. Content The 99th percentile URL of cTn is an important criterion to standardize the diagnosis of myocardial infarction (MI) for clinical, research, and regulatory purposes. Statistical heterogeneity in its calculation exists but recommendations have been proposed. Some negativity has resulted from the fact that with some high-sensitivity (hs) cTn assays, a greater number of increases above the 99th percentile are observed when transitioning from a contemporary assay. Increases reflect acute or chronic myocardial injury and provide valuable diagnostic and prognostic information. The etiology of increases can sometimes be difficult to determine, making a specific treatment approach challenging. For those reasons, some advocate higher cutoff concentrations. This approach can contribute to missed diagnoses. Contrary to claims, neither clinical or laboratory guidelines have shifted away from the 99th percentile. To support the diagnosis of acute MI, the 99th percentile URL remains the best-established approach given the absence of cTn assay standardization. Importantly, risk stratification algorithms using hs-cTn assays predict the possibility of MI diagnoses established using the 99th percentile. Summary The 99th percentile of cTn remains the best-established criterion for the diagnosis of acute MI. While not perfect, it is analytically and clinically evidence-based. Until there are robust data to suggest some other approach, staying with the 99th percentile, a threshold that has served the field well for the past 20 years, appears prudent.

Abstract The use of soluble cardiac biomarkers such as NT-proBNP and troponin has revolutionized prognostication for patients with AL amyloidosis and led to their use in the Mayo 2004 and 2012 staging systems. Novel soluble markers with different phenotypic targets may further improve this approach. Soluble ST2 (sST2), which is the circulating form of the IL-33 receptor, has been shown to be a marker of cardiac remodelling and fibrosis, is predictive of mortality in patients with congestive heart failure, and is predictive of risk of GVHD and GVHD mortality. Samples of blood of patients with AL amyloidosis collected and frozen at -20C under a biobank IRB protocol were retrieved and sST2 measured. Patients were eligible for present study if they had a research sample collected within 90 days of their AL amyloidosis diagnosis. We have validated that values do not change significantly with storage at -20C over a 90 day period. Concentrations of sST2 were determined using a novel high-sensitivity sandwich immunoassay (Presagew ST2; Critical Diagnostics, San Diego, CA, USA). The sST2 assay had within-run and total coefficients of variation of <7.5% and 13.0% across its measurement range. Samples from 273 consecutive patients meeting diagnostic criteria for AL amyloidosis seen at our institution from 1/9/2010 to 12/22/2011 were evaluated. Median age was 63. 58% were male. One hundred and thirty have died over 33.9 months. Correlation between sST2 and the other biomarkers was modest with correlation coefficients of 0.48 and 0.20 for NT-proBNP and Troponin T, respectively. Patients with sST2 above and below the median of 27.2 ng/mL (6.3-596) had significant differences in 2 year overall survival: 71.2% to 39% (figure). In multivariate modeling sST2’s prognostic value was independent of the Mayo 2004 and the Mayo 2012 cardiac biomarker staging systems, the latter of which also includes prognostic information relating to plasma cell burden. In these multivariate models, sST2 median had a RR of 2.4, (95%CI 1.6, 3.6 p<0.001) with the Mayo 2004 Staging system (RR of 2.9, 95%CI 2.1, 4.1p<0.001); and sST2 median had a RR of 2.2 (95%CI 1.5, 3.4, p<0.001) with the Mayo 2012 staging system (RR 1.9, 95%CI 1.6, 2.3, p<0.001). A larger cohort including patients with longer follow up will be presented at the meeting as will gender specific cut off values and a comparison of our values with those previously used to prognosticate in patients with heart failure. sST2 appears to be a novel powerful prognostic factor for patients with AL amyloidosis. Because sST2 functions as a decoy receptor, which neutralizes the benefits of IL-33, it may play a role in the deleterious phenotype seen in patients with AL, i.e. myocardial hypertrophy and reduction of contractility. Disclosures: Saenger: Critical Diagnostics : Research Funding; Roche: Research Funding. Jaffe:Critical Diagnostics: Consultancy, Research Funding; Roche: Consultancy.

Abstract Abstract 2887 Introduction: Cardiac involvement is the major cause of death in patients with immunoglobulin light chain amyloidosis (AL). Detection of cardiac involvement and risk stratification has been facilitated by cardiac biomarkers like troponin T (cTnT) and N-terminal brain natriuretic peptide (NT-proBNP). A novel high sensitivity cTnT (hs-cTnT) assay has been developed, and we evaluated its diagnostic use with three questions in mind: 1) How do the cTnT and hs-cTnT perform in the AL amyloid staging system? 2) Does higher sensitivity add significant additional value in terms of prognosticating outcomes for patients with AL amyloidosis? 3) Can the current AL amyloidosis staging system be further improved upon? Methods: Stored serum samples (-20°C) from 224 pts with AL were analyzed for concentrations of hsTnT, TnT, and NT-proBNP on the E170 Modular analyzer (Roche Diagnostics, Penzberg, Germany). 99th percentile reference limits were <0.014 and <0.010 mcg/L for hsTnT and TnT, respectively. Results: Median values for hsTnT, TnT, and NT-proBNP were 38 ng/L (range 0–075.4), 0.017 mcg/L (<0.0–0.904), and 1230 ng/L (0–32, 226), respectively. The correlation coefficient between hsTnT and TnT was 0.972. Those classified by echocardiographic parameters as having (n=143) or not having (n=81) cardiac involvement had TnT concentrations of 0.04 and 0.01 mcg/L and hsTnT levels of 52.2 and 15.6 ng/L, respectively. The direct numeric result from the hs-cTnT result CANNOT merely be substituted for a cTnT result in the Mayo AL staging system since 14% of patients would be misclassified. The performance of the receiver operation curve derived hs-cTnT cut-point of 54 ng/L is a slight improvement over the direct substitution of 35 ng/L if replacement of one assay for another is required. An alternate staging option using hs-cTnT alone—using the two thresholds14 ng/L and 54 ng/L (figure)—performs as well as either the original Mayo AL staging system or a derivative system incorporating hs-cTnT with respective relative risks of death (95%CI) of 3.6 (2.3, 5.7), 3.8 (2.5, 5.9), and 3.3 (2.2, .50). On multivariate analysis, our newly described alternate 3 level, hs-cTnT alone staging system is independent of other factors including period of diagnosis, type of therapy, and NT-proBNP value, the last of which dropped out of the model. Alternate models using NT-proBNP and cTnT were explored, but none performed better than the original staging system or the new hs-cTnT system. Conclusion: The direct numeric result from the hs-cTnT result cannot merely be substituted for a cTnT result in the Mayo amyloid staging system. Consideration could be made for AL staging systems using hs-cTnT alone and relegating the NT-proBNP for measuring cardiac response. Disclosures: Jaffe: Roche: Consultancy.

Abstract Abstract 3209 Background: The red blood cell folate (RCF) assay has historically been recommended as a more reliable indicator of tissue folate stores compared to the serum folate (SF) assay, as it is not affected by recent ingestion of food. However, the RCF assay suffers from inherent problems with imprecision and accuracy, which are not encountered with SF measurements. Furthermore, following the advent of required folic acid supplementation of many foods by the Food and Drug Administration (FDA) in 1992, folate deficiency is increasingly rare. Very few studies have looked at the value of the RCF versus the SF. We undertook a 10 year retrospective analysis of RCF and SF results to determine the clinical utility of RCF beyond that of SF. Methods: We retrieved all RCF and SF results from the laboratory information system at Mayo Clinic (Rochester, MN) ordered on inpatients and outpatients between 1999–2009. Data for patients who had concurrent orders for SF and RCF were analyzed and chart reviews were conducted on those patients with normal SF but low RCF. Abnormal values were defined by the National Health and Nutrition Examination Surveys (NHANES)/Center for Disease Control (CDC) criteria for folate deficiency (SF< 3.0 ng/ml, RCF < 140 ng/ml). Results: A total of 152,166 SF and 15,708 RCF were performed over the decade of the study. The prevalence of folate deficiency using only SF values was 0.39% and 0.27% using only RCF values. There were 1082 patients in which SFA and RCFA were ordered concurrently (Table 1). Only 1 patient (0.09%) had both abnormal SF and RCF. Chart reviews of the 4 patients with a normal SF but low RCF were as follows: 1) a 6 year old (yo). male with known folic acid transporter deficiency treated with Leucovorin. 2) a 58 yo male with history of gout, hypertension, psoriasis, and hyperlipidemia with normal hemoglobin (Hb) and MCV. 3) a 65 yo male with chronic diarrhea and suspected alcohol abuse; slight macrocytosis (MCV=100.3 fL) but normal Hb. 4) a 51 yo male with multifactorial gait disorder and alcohol abuse. There was a previous history of vitamin B12 deficiency but B12 levels were normal at this time. The CBC was notable for macrocytosis (MCV=115.1 fL) without anemia. Only in patient 4 did the RCF value result in the institution of folic acid supplementation. Conclusions: The RCF provides no additional information beyond that provided by the SF in virtually all situations. Thus SF alone is sufficient for assessment of folate stores. However, there is no evidence to support routine ordering of either SF or RCF, as true folate deficiency in the current era of FDA mandated folic acid supplementation is exceedingly rare. Disclosures: No relevant conflicts of interest to declare.

Abstract The IFCC Committee on Clinical Applications of Cardiac Bio-Markers (C-CB) has directives and initiatives focused on providing evidence-based educational resources to aid and improve understanding around key analytical and clinical aspects of cardiac biomarkers used in clinical practice and the research setting. As a task force, we have previously published position statements and recommendations focused on use and analytical aspects of high-sensitivity cardiac troponin assays. The current educational document is the first from the C-CB highlighting important biochemical, analytical, and clinical aspects as they relate to the natriuretic peptides (NPs), including B-type natriuretic peptide (BNP) and N-terminal pro–B-type natriuretic peptide (NT-proBNP), with a focus on heart failure.

AbstractBACKGROUNDB-type natriuretic peptides (BNPs) are used clinically to diagnose and monitor heart failure and are present in the circulation as multiple proBNP-derived fragments. We investigated the specificity of BNP immunoassays with glycosylated and nonglycosylated BNP, N-terminal proBNP (NT-proBNP), and proBNP peptides to probe the cross-reactivity of each assay.METHODSNine B-type natriuretic peptides were studied,including synthetic and recombinant BNP (Shionogi, Scios, Mayo), human and synthetic glycosylated and nonglycosylated NT-proBNP (HyTest, Roche Diagnostics), and human glycosylated and nonglycosylated proBNP (HyTest, Scios). Five BNP [Abbott, Abbott POC, Alere, Beckman Coulter, Siemens (Centaur)], 9 NT-proBNP [Ortho-Clinical Diagnostics, Roche, Response, bioMerieux, Siemens (Dimension, Immulite, Stratus CS), Mitsubishi] and 3 research-use-only proBNP immunoassays [Biosite (Alere), Bio-Rad, Goetze] were evaluated. Specificity was assessed by calculating the recovery between baseline and peptide-spiked human plasma pools at target concentrations of 100 ng/L BNP, 300 ng/L proBNP, or 450 ng/L NT-proBNP. All assays were performed in duplicate.RESULTSBNP and NT-proBNP assays demonstrated substantial cross-reactivity with proBNP peptides. NT-proBNP assays do not detect glycosylated forms of either NT-proBNP or proBNP. proBNP assays preferentially detect the BNP 1–32 peptide and have minimal cross-reactivity with BNP peptides and glycosylated proBNP.CONCLUSIONSBNP or NT-proBNP results are not transferable among the current existing immunoassays owing to their differences in cross-reactivity and ability to detect various glycosylated forms of proBNP-derived fragments. Opportunities remain to standardize and harmonize BNP and NT-proBNP assays, as well as to develop specific proBNP assays, to widen their clinical scope of use.

Abstract BACKGROUND We assessed the impact of clinical decision support (CDS) rules within the electronic health record for ionized calcium (iCa), serum magnesium (Mg), and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in intensive care unit (ICU) inpatients at a large academic center. METHODS A repeat order for measurement of iCa or Mg placed within 24 (iCa) or 48 (Mg) h of a previously nonactionable result, or additional orders for NT-proBNP beyond 1 within a single hospitalization, triggered a CDS pop-up alert showing the prior result and offering the opportunity to cancel the order or to place the order after entering an indication for repeat testing. The number of tests performed for each of these analytes and incidence of adverse clinical outcomes potentially associated with hypocalcemia or hypomagnesemia were compared between the 90-day period before CDS implementation and two 90-day periods immediately following. RESULTS iCa test volumes decreased by 48%, Mg by 39%, and NT-proBNP by 28% in the 90-day period immediately following implementation and remained decreased by 54%, 49%, and 22%, respectively, during the following 90-day period (all P values &lt;0.0002). Adverse clinical outcomes potentially associated with hypocalcemia or hypomagnesemia did not increase (all P-values &gt;0.17). CONCLUSIONS Implementation of CDS dramatically decreased repeat testing of iCa, Mg, and NT-proBNP without adversely impacting clinical outcomes in the ICU. Expansion of the rules from the ICU units to include the entire hospitalized patient population and expansion to additional analytes is expected to lead to further reductions in testing.

The use of soluble cardiac biomarkers such as N‐terminal pro‐brain natriuretic peptide (NT‐proBNP) and troponin has revolutionized prognostication for patients with AL amyloidosis. Soluble ST2 (sST2) and galectin‐3 have also been reported to have prognostic value in other cardiac patient populations. We identified 502 patients with AL amyloidosis, who provided a research sample and consent to review their medical records between 1/1/2006‐12/31/2010 within 90 days of their diagnosis. Samples were assayed for sST2 and galectin‐3. Within this AL amyloidosis population, overall survival (OS) was 25.5 months (95% CI 18, 35.7 months). Receiver operating curve analyses were done to detect the best cut‐points for sST2 and galectin‐3 to predict both 1‐ and 5‐year OS. The respective cut points for sST2 were 30 and 29.7 ng/mL, while the median sST2 for the entire population was 31 ng/mL (IQR 19.8, 53.6). The respective cut points for galectin‐3 were 11 and 10.4 ng/mL while the median for the entire population was 16.6 ng/mL (IQR 11.5, 24.0). Although on univariate analysis, both sST2 and galectin‐3 were prognostic, upon multivariate analysis, only sST2 was independent of troponin, NT‐proBNP, serum immunoglobulin free light chain, and blood pressure. Not only did sST2 add to previously reported prognostication systems, but a novel prognostication 5‐point system including sST2 was possible. The addition of sST2 – but not galectin‐3 – to existing prognostication systems for patients with AL amyloidosis strengthens the ability to predict for death. Am. J. Hematol. 90:524–528, 2015. © 2015 Wiley Periodicals, Inc.

Abstract BACKGROUND Aggressive LDL cholesterol (LDL-C)-lowering strategies are recommended for primary and secondary prevention of cardiovascular events. A newly derived equation for LDL-C estimation was recently published that addressed limitations in the commonly used Friedewald LDL-C calculation method. The novel method was reported to classify patients with superior concordance to measured LDL-C compared to the Friedewald method, particularly in patients with LDL-C &lt;70 mg/dL. METHODS We evaluated the performance of the novel method within an independent cohort of 23 055 patients with LDL-C measured by the gold standard β-quantification reference method. RESULTS Overall Friedewald underestimated and the novel method overestimated measured LDL-C. Both estimations significantly deviated from the reference method when LDL-C was &lt;70 mg/dL. Overall, the Friedewald and novel calculations correctly classified 77% and 78% of patients, respectively. The largest discrepancy in classification was observed in individuals with measured LDL-C &lt;70 mg/dL. For this group the novel calculation would reclassify 8.7% of patients as &gt;70 mg/dL compared to the Friedewald equation. CONCLUSIONS We compared both novel and Friedewald estimated LDL-C against the LDL-C reference method; in contrast, the prior study relied on validation of a subset of samples by β-quantification to allow the use of the vertical autoprofile method for LDL-C measurement. We conclude that the novel method has some benefits but it is unclear whether improvements over the Friedewald calculation are substantive enough to justify making the change in routine clinical practice and to improve patient outcomes.