Age and the European Society of Cardiology 0/1-hour high sensitivity troponin T algorithm for the evaluation of patients with possible acute myocardial infarction: results from the STOP-CP study

Background

The European Society of Cardiology (ESC) 0/1-hour high sensitivity troponin (hs-cTn) algorithm is widely used in the evaluation of patients presenting to the Emergency Department (ED) with symptoms suspicious for non ST-segment elevation myocardial infarction (NSTEMI). The effect of increasing patient age with its use has not been studied in any detail.

Purpose

The objective of this secondary analysis of the STOP-CP (High Sensitivity Cardiac Troponin T to Optimize Chest Pain Risk Stratification) United States (US) multicenter study was to evaluate the efficacy and safety of use of the ESC 0/1-hour hs-cTnT algorithm in younger, middle-aged, and older patients.

Methods

Patients (≥21 years old) presenting to the (ED) with symptoms suggestive of NSTEMI were enrolled (1/25/2017–9/6/2018) at 8 US medical centers. The ESC hs-cTnT 0/1-hour hs-cTnT algorithm was used to place patients into rule-out, observe, and rule-in NSTEMI zones. Algorithm performance for rapid NSTEMI rule-out and 30-day adverse outcomes was studied in 3 patient age (years) intervals: younger (21–45). middle aged (46–64) and older (≥65). Major adverse cardiovascular events (MACE) consisted of cardiac death, myocardial infarction, or coronary revascularization at 30-days. Fisher's exact tests were used to compare NSTEMI ruled out and MACE rates between patient age intervals. Negative likelihood ratios (NLR) with 95% confidence interval (CI) were calculated for 30-day MACE.

Results

Overall 1430 participants were enrolled with 15.7% (224/1430) young, 57.4% (821/1430) middle-aged, and 26.9% (385/1430) being older. The ESC 0/1 hour hs-cTnT algorithm NSTEMI rule-out rates were 79.9% (179/224), 62.1% (510/821) and 35.6% (137/385) respectively for these age groups (p<0.0001). The overall 30-day MACE rate was 14.2% (203/1430) with interval age rates of 7.1% (16/224) in younger, 13.1% (108/821) middle aged and 20.5% (79/385) older patients. Amongst NSTEMI ruled-out patients MACE occurred in 1.1% (2/179) of younger, 3.3% (17/510) middle aged and 2.9% (4/137) older individuals (p=0.320). NLR for 30-day MACE was 0.15 (95% CI 0.04, −0.54) in younger, 0.23 (95% CI 0.15–0.35) middle aged and 0.12 (95% CI 0.04–0.31) for older patients.

Conclusions

With increasing age ED patients were less often rapidly ruled out for NSTEMI during their initial cardiac evaluations. The STOP-CP US study demonstrated that older age interval alone was not an independent variable that increased the risk for 30-day MACE in patients ruled out for NSTEMI using the ESC 0/1 hour hs-cTnT algorithm. Our report suggests that cardiac risk stratification scores using age as an independent variable for predicting 30-day MACE in these patients require reevaluation.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Roche, Basel, Switzerland

Patients with known coronary artery disease who are ruled out for acute myocardial infarction using a high sensitivity troponin T 0/1-hour algorithm have increased 30-day major adverse cardiac events

Background

The European Society of Cardiology (ESC) 0/1-hour high sensitivity troponin (hs-cTn) algorithm is widely used in the evaluation of patients presenting to the Emergency Department (ED) with symptoms suspicious for non ST-segment elevation myocardial infarction (NSTEMI). There is limited data available for the use of this algorithm comparing NSTEMI rule-out rates and 30-day adverse outcomes in patients with and without known coronary artery disease (CA), defined as prior myocardial infarction [MI], coronary revascularization, or ≥70% coronary stenosis.

Purpose

The objective of this secondary analysis of the STOP-CP (High Sensitivity Cardiac Troponin T to Optimize Chest Pain Risk Stratification) United States (US) multicenter study was to compare the ESC 0/1-hour algorithm for rapid NSTEMI rule-out and 30-day adverse outcomes in patients with and without known CAD.

Methods

Patients (≥21 years old) presenting to the (ED) with symptoms suggestive of NSTEMI were enrolled (1/25/2017–9/6/2018) at 8 US medical centers. The ESC hs-cTnT 0/1-hour hs-cTnT algorithm was used to stratify patients into rule-out, observe, and rule-in zones. Algorithm performance for 30-day adverse outcomes was analyzed in patients with or without known CAD. Major adverse cardiovascular events (MACE) consisted of cardiac death, MI, or coronary revascularization. Fisher's exact tests were used to compare NSTEMI rule-out and 30-day MACE rates in patients with and without known CAD. Negative likelihood ratios (NLR) with a 95% confidence interval (CI) were calculated for 30-day MACE.

Results

Overall 1430 patients were enrolled. Of these 31.4% (449/1430) had known CAD while 14.2% (203 /1430) experienced 30-day MACE. Using the ESC 0/1-hour hs-cTnT algorithm 39.6% (178/449) of patients with known CAD were placed in the rule-out zone compared to 66.1% (648/981) without CAD (p<0.0001). Of patients with known CAD 23.2% (104/449) had 30-day MACE compared to 10.1% (99/981) of those without known CAD (p<0.0001). Additionally, amongst those patients placed in the rule-out zone, 30-day MACE occurred in 7.9% (14/178) of individuals with known CAD and 1.4% (9/648) of those without known CAD (p<0.0001). NLR for 30-day MACE was 0.28 (95% CI 0.17–0.47) in patients with known CAD and 0.13 (95% CI 0.07–0.23) in those without CAD.

Conclusions

In the multicenter US STOP-CP study patients with known CAD were less often rapidly ruled out for NSTEMI and had higher 30-day MACE rates than those without known CAD. Patients with known CAD who were rapidly ruled out for NSTEMI had a higher 30-day MACE rate compared to those without known CAD. Our analysis suggests that patients with known CAD require further cardiac reevaluations whether they are ruled out for NSTEMI by the ESC 0/1 hour hs-cTnT algorithm or not.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Roche, Basel, Switzerland

The influence of patient size on the overall uncertainty in radiographic dose audit

The aim of this work was to investigate the effect of patient and cohort size on the overall uncertainty associated with dose audit using radiography of the abdomen as the exemplar. Water equivalent diameterDwwas used as the surrogate for patient size and its distribution (σ(Dw)) was used to quantify the effect of sample size. The more precise the kerma area product calibration, the more patients are required in the cohort to have the same impact on the overall uncertainty. Patient sample sizes of 300-400 will result in expanded uncertainties approaching the theoretical limit of double the measurement uncertainty when audits are performed with instruments having measurement uncertainties equal to ±7%, ±10% or ±12.5%. By way of example, for a field instrument with a measurement uncertainty of ±10%, a minimum sample size of 350 is required to achieve a total expanded uncertainty of ±21%. In the case of instruments with associated measurement uncertainty of ±3.5%, patient sample sizes of 300-400 will result in expanded uncertainties of approximately ±10%. From review of the literature and comparison with the results obtained here, it is conjectured that for radiographic dose audits of all parts of the trunk the contribution to overall uncertainty due to patient and sample size could be predicted using an indicative value forσ(Dw) of 3.4 where local data is not available.

Preclinical development of AMG 139, a human antibody specifically targeting IL-23

BACKGROUND AND PURPOSE

AMG 139 is a human anti-IL-23 antibody currently in a phase II trial for treating Crohn's disease. To support its clinical development in humans, in vitro assays and in vivo studies were conducted in cynomolgus monkeys to determine the pharmacology, preclinical characteristics and safety of this monoclonal antibody.

EXPERIMENTAL APPROACH

The in vitro pharmacology, pharmacokinetics (PK), pharmacodynamics and toxicology of AMG 139, after single or weekly i.v. or s.c. administration for up to 26 weeks, were evaluated in cynomolgus monkeys.

KEY RESULTS

AMG 139 bound with high affinity to both human and cynomolgus monkey IL-23 and specifically neutralized the biological activity of IL-23 without binding or blocking IL-12. After a single dose, linear PK with s.c. bioavailability of 81% and mean half-life of 8.4-13 days were observed. After weekly s.c. dosing for 3 or 6 months, AMG 139 exposure increased approximately dose-proportionally from 30 to 300 mg·kg(-1) and mean accumulation between the first and last dose ranged from 2- to 3.5-fold. Peripheral blood immunophenotyping, T-cell-dependent antigen responses and bone formation markers were not different between AMG 139 and vehicle treatment. No adverse clinical signs, effects on body weight, vital signs, ophthalmic parameters, clinical pathology, ECG, organ weights or histopathology were observed in the monkeys with the highest dose of AMG 139 tested (300 mg·kg(-1) s.c. or i.v.).

CONCLUSIONS AND IMPLICATIONS

The in vitro pharmacology, PK, immunogenicity and safety characteristics of AMG 139 in cynomolgus monkeys support its continued clinical development for the treatment of various inflammatory diseases.

Multistate equilibrium unfolding of Escherichia coli dihydrofolate reductase: thermodynamic and spectroscopic description of the native, intermediate, and unfolded ensembles

The thermodynamic and spectroscopic properties of a cysteine-free variant of Escherichia coli dihydrofolate reductase (AS-DHFR) were investigated using the combined effects of urea and temperature as denaturing agents. Circular dichroism (CD), absorption, and fluorescence spectra were recorded during temperature-induced unfolding at different urea concentrations and during urea-induced unfolding at different temperatures. The first three vectors obtained by singular-value decomposition of each set of unfolding spectra were incorporated into a global analysis of a unique thermodynamic model. Although individual unfolding profiles can be described as a two-state process, a simultaneous fit of 99 vectors requires a three-state model as the minimal scheme to describe the unfolding reaction along both perturbation axes. The model, which involves native (N), intermediate (I), and unfolded (U) states, predicts a maximum apparent stability, DeltaG degrees (NU), of 6 kcal mol(-)(1) at 15 degrees C, an apparent m(NU) value of 2 kcal mol(-)(1) M(-)(1), and an apparent heat capacity change, DeltaC(p)()(-NU), of 2.5 kcal mol(-)(1) K(-)(1). The intermediate species has a maximum stability of approximately 2 kcal mol(-)(1) and a compactness closer to that of the native than to that of the unfolded state. The population of the intermediate is maximal ( approximately 70%) around 50 degrees C and falls below the limits of detection of > or =2 M urea or at temperatures of <35 or >65 degrees C. The fluorescence properties of the equilibrium intermediate resemble those of a transient intermediate detected during refolding from the urea-denatured state, suggesting that a tryptophan-containing hydrophobic cluster in the adenosine-binding domain plays a key role in both the equilibrium and kinetic reactions. The CD spectroscopic properties of the native state reveal the presence of two principal isoforms that differ in ligand binding affinities and in the packing of the adenosine-binding domain. The relative populations of these species change slightly with temperature and do not depend on the urea concentration, implying that the two native isoforms are well-structured and compact. Global analysis of data from multiple spectroscopic probes and several methods of unfolding is a powerful tool for revealing structural and thermodynamic properties of partially and fully folded forms of DHFR.

An essential intermediate in the folding of dihydrofolate reductase

The folding of Escherichia coli dihydrofolate reductase was examined at pH 7.8 and 15 degrees C by using stopped-flow fluorescence and absorbance spectroscopies. The formation of a highly fluorescent intermediate occurs with relaxation times ranging between 142 and 343 msec, whereas stopped-flow absorbance spectroscopy using methotrexate binding assays shows a distinct lag phase during these time frames for the native state. The lag in absorbance kinetics and the lack of fast-track folding events indicate that the formation of this ensemble of intermediates is an obligatory step in the folding reaction.

Localized, stereochemically sensitive hydrophobic packing in an early folding intermediate of dihydrofolate reductase from Escherichia coli

Mutational analysis was performed to probe the development of hydrophobic clusters during the early events in the folding of dihydrofolate reductase. Replacements were made in several hydrophobic subdomains to examine the roles of hydrophobicity and stereochemistry in the formation of kinetic intermediates. Amide protons in two of these clusters, including residues I91, I94, and I155, have been shown to be protected against solvent exchange within 13 ms of folding. Additional hydrophobic clusters were probed by substitutions at residues I2, I61, and L112; these residues are not protected from exchange until later in the folding reaction. Valine and leucine replacements at positions I91, I94, and I155 significantly diminish the formation of the burst phase kinetic intermediate, relative to the wild-type protein. In contrast, I2 and I61 are insensitive to these substitutions in the first 5 ms of the folding reaction, as is the replacement of L112 with either isoleucine or valine. These results demonstrate that the tightly packed core of dihydrofolate reductase is acquired in a non-uniform fashion, beginning in the submillisecond time frame. The progressive development of specific side-chain packing in localized hydrophobic clusters may be a common theme for complex protein folding reactions.

A comparison of the antibacterial action of five udder washes

Five commercially available udder washes were tested for antibacterial action. Four contained iodine and one chlorhexidine. Each product was used exclusively for 10 days and its bactericidal action compared with that of water. Bactericidal activity was demonstrated in all five washes but the chlorine based product performed better than the iodine washes. However, the results suggested that the skin of cows' teats can be cleansed with water as effectively as with an added product.