To rule-in, or not to falsely rule-out, that is the question: evaluation of hs-cTnT EQA performance in light of the ESC-2020 guideline

OBJECTIVES

To accurately evaluate non-ST-elevated acute cardiac syndrome (NSTE-ACS), the quality of high-sensitive cardiac troponin (hs-cTn) assays is of vital importance. The 2020 revision of the NSTE-ACS guideline includes clinical decision-limits (CDL's) to both rule-in and rule-out NSTE-ACS for most commercially available platforms, providing both 0/1 h and 0/2 h delta limits. Our study evaluated whether laboratories are able to meet the analytical performance specifications for imprecision (APS) for hs-cTnT.

METHODS

Results from external quality assurance (EQA) in commutable samples were used to evaluate the current and historic performance of analyzers. The performance of analyzers that either passed or failed to comply with 0/1 h-APS were used on a real-world dataset of first hs-cTnT-values to simulate 10.000 samples of t=0, t=1 and t=2 h values with multiple delta's for all relevant CDL's. We compared the simulated values to the input values to obtain the percentage of aberrant results simulated.

RESULTS

The majority of analyzers complies with APS for rule-in in 2022 (0/1 h: 90.4 % and 0/2 h: 100 %), compliance for the 0/1 h rule-out is still far from optimal (0/1 h: 30.7 %, 0/2 h: 75.4 %), with improving compliance over the past years (rule-in p=<0.0001, rule-out p=0.011, χ2). Whilst 0/1 h-APS-passing analyzers have a minute risk to falsely rule-out patients whom should be ruled-in (0.0001 %), failing performance increases this risk to 2.1 % upon using 0/1 h CDL's. Here, adopting 0/2 h CDL's is favorable (0.01 %).

CONCLUSIONS

Laboratories that fail to meet hs-cTnT 0/1 h-APS should improve their performance to the required and achievable level. Until performance is reached clinics should adopt the 0/2 h CDL's.

The use of cardiac troponins and B-type natriuretic peptide in COVID-19

Coronavirus disease 2019 (COVID-19) is still challenging health care systems worldwide. Over time, it has become clear that respiratory disease is not the only important entity as critically ill patients are also more prone to develop complications, such as acute cardiac injury. Despite extensive research, the mainstay of treatment still relies on supportive care and targeted therapy of these complications. The development of a prognostic model which helps clinicians to diverge patients to an appropriate level of care is thus crucial. As a result, several prognostic markers have been studied in the past few months. Among them are the cardiac biomarkers, especially cardiac troponins T/I and brain natriuretic peptide, which seem to have important prognostic values as several reports have confirmed their strong association with adverse clinical outcomes and death. The use of these biomarkers as part of a prognostic tool could potentially result in more precise risk stratification of COVID-19 patients and divergence to an adequate level of care. However, several caveats persist causing international guidelines to still recommend in favour of a more conservative approach to cardiac biomarker testing for prognostic purposes.

Dexamethasone is associated with early deaths in light chain amyloidosis patients with severe cardiac involvement

Background

Cardiac light chain amyloidosis (AL-CA) patients often die within three months of starting chemotherapy. Chemotherapy for non-immunoglobulin M gammopathy with AL-CA frequently includes bortezomib (Bor), cyclophosphamide (Cy), and dexamethasone (D). We previously reported that NT-ProBNP levels can double within 24h of dexamethasone administration, suggesting a deleterious impact on cardiac function. In this study, we evaluate the role of dexamethasone in early cardiovascular mortality during treatment.

Methods and findings

We retrospectively assessed 100 de novo cardiac AL patients (62% male, mean age 68 years) treated at our institute between 2009 and 2018 following three chemotherapy regimens: CyBorDComb (all initiated on day 1; 34 patients), DCyBorSeq (D, day 1; Cy, day 8; Bor, day 15; 17 patients), and CyBorDSeq (Cy, day 1; Bor, day 8; D, day 15; 49 patients). The primary endpoint was cardiovascular mortality and cardiac transplantation at days 22 and 455. At day 22, mortality was 20.6% with CyBorDComb, 23.5% with DCyBorSeq, and 0% with CyBorDSeq (p = 0.003). At day 455, mortality was not significantly different between regimens (p = 0.195). Acute toxicity of dexamethasone was evaluated on myocardial function using a rat model of isolated perfused heart. Administration of dexamethasone induced a decrease in left ventricular myocardium contractility and relaxation (p<0.05), supporting a potential negative inotropic effect of dexamethasone in AL-CA patients with severe cardiac involvement.

Conclusion

Delaying dexamethasone during the first chemotherapy cycle reduces the number of early deaths without extending survival. It is clear that dexamethasone is beneficial in the long-term treatment of patients with AL-CA. However, the initial introduction of dexamethasone during treatment is critical, but may be associated with early cardiac deaths in severe CA. Thus, it is important to consider the dosage and timing of dexamethasone introduction on a patient-severity basis. The impact of dexamethasone in the treatment of AL-CA needs further investigation.

No difference in biomarkers of ischemic heart injury and heart failure in patients with COVID-19 who received treatment with chloroquine phosphate and those who did not

Background

Chloroquine was promoted as a COVID-19 therapeutic early in the pandemic. Most countries have since discontinued the use of chloroquine due to lack of evidence of any benefit and the risk of severe adverse events. The primary aim of this study was to examine if administering chloroquine during COVID-19 imposed an increased risk of ischemic heart injury or heart failure.

Methods

Medical records, laboratory findings, and electrocardiograms of patients with COVID-19 who were treated with 500 mg chloroquine phosphate daily and controls not treated with chloroquine were reviewed retrospectively. Controls were matched in age and severity of disease.

Results

We included 20 patients receiving chloroquine (500 mg twice daily) for an average of five days, and 40 controls. The groups were comparable regarding demographics and biochemical analyses including C-reactive protein, thrombocytes, and creatinine. There were no statistically significant differences in cardiac biomarkers or in electrocardiograms. Median troponin T was 10,8 ng/L in the study group and 17.9 ng/L in the control group, whereas median NT-proBNP was 399 ng/L in patients receiving chloroquine and 349 ng/L in the controls.

Conclusions

We found no increased risk of ischemic heart injury or heart failure as a result of administering chloroquine. However, the use of chloroquine to treat COVID-19 outside of clinical trials is not recommended, considering the lack of evidence of its effectiveness, as well as the elevated risk of fatal arrythmias.

Undetectable High-Sensitivity Troponin T as a Gatekeeper for Coronary Computed Tomography Angiography in Patients Suspected of Acute Coronary Syndrome

OBJECTIVES

The aim of this study was to characterize the safety and efficiency of a strategy employing the limit of detection (LoD) of high-sensitivity troponin T (hs-TnT) as a gatekeeper for coronary computed tomography angiography (CCTA) in suspected acute coronary syndrome (ACS) patients in the emergency department (ED).

METHODS

We included suspected ACS patients who underwent CCTA and were evaluated with hs-TnT. Patients were categorized as below the LoD and at or above the LoD. The primary outcome was 30-day major adverse cardiac events (MACEs), defined as all-cause mortality, ACS, or coronary revascularization.

RESULTS

The study population consisted of 177 patients (mean age 55 ± 10 years, 50.3% women), and 16 (9.0%) patients reached the primary outcome. None of the patients died, while 13 had an adjudicated diagnosis of ACS, and 3 underwent elective coronary revascularization. There were 77 patients (44%) with an hs-TnT value below the LoD (MACEs; n = 1 [1.3%]) and 100 (56%) with at or above the LoD levels (MACEs; n = 15 [15%]). None of 67 patients with an hs-TnT value below the LoD and <50% stenosis on CCTA experienced MACEs. Out of the 10 patients with an hs-TnT value below the LoD and ≥50% stenosis on CCTA, 1 patient underwent elective percutaneous coronary revascularization. In patients with an hs-TnT value at or above the LoD, 74 patients had <50% stenosis on CCTA, and 2 patients (3%) were diagnosed with myocardial infarction without obstructive coronary artery disease confirmed on invasive angiography. Thirteen (50%) patients with an hs-TnT value at or above the LoD and ≥50% stenosis on CCTA experienced MACEs (11 ACS and 2 elective percutaneous coronary revascularizations).

CONCLUSION

Our findings support that implementing the LoD of hs-TnT as a gatekeeper may reduce the need for CCTA in suspected ACS patients in the ED.

Fluorescent hollow ZrO2@CdTe nanoparticles-based lateral flow assay for simultaneous detection of C-reactive protein and troponin T

Highly fluorescent hollow ZrO₂@CdTe nanoparticles (NPs) were synthesized efficiently via the hydrothermal method. By changing the hydrothermal time of ZrO₂@CdTe NP, the peaks of fluorescence spectra measured at fluorescent excitation of 330 nm were at 540 nm, 590 nm, and 640 nm, respectively. Hollow ZrO₂ NPs have a uniform core-shell structure with the size of 178 ± 10 nm and shell of 19 ± 4 nm. The as-prepared yellow-ZrO₂@CdTe NPs were used to develop lateral flow assay (LFA) for the sensitive and qualitative detection of C-reactive protein (CRP). The visual limit of detection of the LFA for the CRP antigen was 1 μg/L within 20 min, which is 1000-fold lower than that of colloidal gold-based LFA. In addition, a multiplex lateral flow assay (mLFA) was developed using the as-prepared green and red-ZrO₂@CdTe NPs for the simultaneous, specific, sensitive, and qualitative detection of CRP and troponin T (cTnT). The visual limits of detection of CRP and cTnT in mLFA were 10 μg/L and 0.1 mg/L, respectively. The excellent performance of ZrO₂@CdTe NPs should facilitate their application in point-of-care technology for the detection of other biomarkers.

Intraoperative blood loss may be associated with myocardial injury after non-cardiac surgery

BACKGROUND

This study aimed to evaluate the association between intraoperative blood loss and myocardial injury after non-cardiac surgery (MINS), which is a severe and common postoperative complication.

METHODS

We compared the incidence of MINS based on significant intraoperative bleeding, defined as an absolute hemoglobin level < 7 g/dL, a relative hemoglobin level less than 50% of the preoperative measurement, or need for packed red cell transfusion. We also estimated a threshold for intraoperative hemoglobin level associated with MINS.

RESULTS

We stratified a total of 15,926 non-cardiac surgical patients with intraoperative hemoglobin and postoperative cardiac troponin (cTn) measurements according to the occurrence of significant intraoperative bleeding; 13,416 (84.2%) had no significant bleeding while 2,510 (15.8%) did have significant bleeding. After an adjustment with inverse probability weighting, the incidence of MINS was higher in the significant bleeding group (35.2% vs. 16.4%; odds ratio, 1.58; 95% confidence interval, 1.43-1.75; p < 0.001). The threshold of intraoperative hemoglobin associated with MINS was estimated to be 9.9 g/dL with an area under the curve of 0.643.

CONCLUSION

Intraoperative blood loss appeared to be associated with MINS. Further studies are needed to confirm these findings.

CLINICAL REGISTRATION

The cohort was registered before patient enrollment at https://cris.nih.go.kr (KCT0004244).

Optimizing the Use of High-Sensitivity Troponin Assays for the Early Rule-out of Myocardial Infarction in Patients Presenting with Chest Pain: A Systematic Review

BACKGROUND

We assessed the accuracy and clinical effectiveness of high-sensitivity cardiac troponin (hs-cTn) assays for early rule-out of non-ST-segment elevation myocardial infarction (NSTEMI) in adults presenting with acute chest pain.

METHODS

Sixteen databases were searched to September 2019. Review methods followed published guidelines. The bivariate model was used to estimate summary sensitivity and specificity with 95% confidence intervals for meta-analyses involving 4 or more studies, otherwise random-effects logistic regression was used.

RESULTS

Thirty-seven studies (124 publications) were included in the review. The hs-cTn test strategies evaluated in the included studies were defined by the combination of 4 factors (assay, number of tests, timing of tests, and threshold concentration or change in concentration between tests). Clinical opinion indicated a minimum acceptable sensitivity of 97%. A single test at presentation using a threshold at or near the assay limit of detection could reliably rule-out NSTEMI for a range of hs-cTn assays. Serial testing strategies, which include an immediate rule-out step, increased the proportion ruled out without loss of sensitivity. Finally, serial testing strategies without an immediate rule-out step had excellent sensitivity and specificity, but at the expense of the option for immediate patient discharge.

CONCLUSION

Test strategies that comprise an initial rule-out step, based on low hs-cTn concentrations at presentation and a minimum symptom duration, and a second step for those not ruled-out that incorporates a small absolute change in hs-cTn at 1, 2, or 3 hours, produce the highest rule-out rates with a very low risk of missed NSTEMI.

PROSPERO REGISTRATION

CRD42019154716.

Type 2 Myocardial Infarction: Evolving Approaches to Diagnosis and Risk-Stratification

BACKGROUND

Type 2 myocardial infarction (T2MI) is frequently encountered in clinical practice and associated with adverse outcomes.

CONTENT

T2MI occurs most frequently due to noncoronary etiologies that alter myocardial oxygen supply and/or demand. The diagnosis of T2MI is often confused with acute nonischemic myocardial injury, in part because of difficulties in delineating the nature of symptoms and misunderstandings about disease categorization. The use of objective features of myocardial ischemia using electrocardiographic (ECG) or imaging abnormalities may facilitate more precise T2MI diagnosis. High-sensitivity cardiac troponin (hs-cTn) assays allow rapid MI diagnosis and risk stratification, yet neither maximum nor delta values facilitate differentiation of T2MI from T1MI. Several investigational biomarkers have been evaluated for T2MI, but none have robust data. There is interest in evaluating risk profiles among patients with T2MI. Clinically, the magnitude of maximum and delta cTn values as well as the presence and magnitude of ischemia on ECG or imaging is used to indicate disease severity. Scoring systems such as GRACE, TIMI, and TARRACO have been evaluated, but all have limited to modest performance, with substantial variation in time intervals used for risk-assessment and endpoints used.

SUMMARY

The diagnosis of T2MI requires biomarker evidence of acute myocardial injury and clear clinical evidence of acute myocardial ischemia without atherothrombosis. T2MIs are most often caused by noncoronary etiologies that alter myocardial oxygen supply and/or demand. They are increasingly encountered in clinical practice and associated with poor short- and long-term outcomes. Clinicians require novel biomarker or imaging approaches to facilitate diagnosis and risk-stratification.

Diagnostic value of copeptin combined with hypersensitive cardiac troponin T detection in early acute myocardial infarction: A protocol of randomized double-blind diagnostic trial

BACKGROUND

The sensitivity and specificity of the routine detection of acute myocardial infarction (AMI) in early diagnosis are not high, which can not meet the clinical needs. Copeptin combined with hypersensitive cardiac troponin T (hs-cTnT) is a new detection scheme, and its value in the early diagnosis of acute myocardial infarction is still unclear. Accordingly, the aim of this study is to evaluate the diagnostic value of copeptin combined with hypersensitive troponin T detection in early acute myocardial infarction.

METHODS

This is a prospective, randomized; double-blind diagnostic trial to investigate the diagnostic value of copeptin combined with hypersensitive troponin T detection in early acute myocardial infarction. Approved by the clinical research ethics of our hospital. Patients were randomly divided into one of 2 test protocols: (A) copeptin combined with hs-cTnT group and (B) cardiac troponin I (cTnI) group. Patients, doctors, nurses, inspectors, and data-gathering assistants were blinded to group allocation. We will focus on the sensitivity comparison of the 2 detection methods at different time periods and the sensitivity and specificity comparison of the two detection methods. Data were analyzed using the statistical software package SPSS version 25.0 (Chicago, IL).

DISCUSSION

The purpose of this study is to evaluate the diagnostic value of copeptin combined with hypersensitive cardiac troponin T detection in early acute myocardial infarction. The results of this study will establish clinical evidence for the detection of high sensitivity cardiac troponin T in the early diagnosis of acute myocardial infarction.

ETHICS AND DISSEMINATION

Private information from individuals will not be published. This systematic review also does not involve endangering participant rights. Ethical approval was not required. The results may be published in a peer-reviewed journal or disseminated at relevant conferences.

OSF REGISTRATION NUMBER

DOI 10.17605/OSF.IO/6TE5Z.

Laboratory Findings Associated With Severe Illness and Mortality Among Hospitalized Individuals With Coronavirus Disease 2019 in Eastern Massachusetts

IMPORTANCE

The coronavirus disease 2019 (COVID-19) pandemic has placed unprecedented stress on health systems across the world, and reliable estimates of risk for adverse hospital outcomes are needed.

OBJECTIVE

To quantify admission laboratory and comorbidity features associated with critical illness and mortality risk across 6 Eastern Massachusetts hospitals.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study of all individuals admitted to the hospital who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by polymerase chain reaction across these 6 hospitals through June 5, 2020, using hospital course, prior diagnoses, and laboratory values in emergency department and inpatient settings from 2 academic medical centers and 4 community hospitals. The data were extracted on June 11, 2020, and the analysis was conducted from June to July 2020.

EXPOSURES

SARS-CoV-2.

MAIN OUTCOMES AND MEASURES

Severe illness defined by admission to intensive care unit, mechanical ventilation, or death.

RESULTS

Of 2511 hospitalized individuals who tested positive for SARS-CoV-2 (of whom 50.9% were male, 53.9% White, and 27.0% Hispanic, with a mean [SD ]age of 62.6 [19.0] years), 215 (8.6%) were admitted to the intensive care unit, 164 (6.5%) required mechanical ventilation, and 292 (11.6%) died. L1-regression models developed in 3 of these hospitals yielded an area under the receiver operating characteristic curve of 0.807 for severe illness and 0.847 for mortality in the 3 held-out hospitals. In total, 212 of 292 deaths (72.6%) occurred in the highest-risk mortality quintile.

CONCLUSIONS AND RELEVANCE

In this cohort, specific admission laboratory studies in concert with sociodemographic features and prior diagnosis facilitated risk stratification among individuals hospitalized for COVID-19.

Using the clinical chemistry score in the emergency department to detect adverse cardiac events: a diagnostic accuracy study

BACKGROUND

The ability to rule out or in a major adverse cardiac event (MACE) in patients with suspected acute coronary syndrome at emergency department (ED) presentation would be beneficial to patient care and the health care system. The clinical chemistry score (CCS) was evaluated in this context.

METHODS

This diagnostic accuracy study evaluated 2 different ED cohorts with suspected acute coronary syndrome. For patients in cohort 1, who presented to the ED of 3 hospitals in Hamilton, Ontario, between May and August 2013, retrospective measurements were taken using the Ortho Clinical Diagnostics high-sensitivity cardiac troponin I (hs-cTnI) assay; for patients in cohort 2, who presented to the ED of the same 3 hospitals in Hamilton between November 2012 and February 2013, an ED cardiac presentation blood test panel was performed with the Abbott Diagnostics hs-cTnI assay. The sensitivity and specificity of the CCS (cut-offs of ≥ 1 and 5) and hs-cTnI alone (published cut-offs) were compared for MACE (composite of death, myocardial infarction, unstable angina, revascularization) at 30 days for both cohorts and at 90 days for cohort 2.

RESULTS

The incidence of MACE at 30 days was higher in cohort 1 (n = 1058) (19.4%, 95% confidence interval [CI] 16.8%-22.2%) than in cohort 2 (n = 5974) (14.6%, 95% CI 13.6%-15.6%). In cohort 1, a CCS of 1 or above yielded a sensitivity of 99.5% (95% CI 97.3%-99.9%). The sensitivity with an Ortho hs-cTnI cut-off of 1 ng/L or above was 91.2% (95% CI 86.5%-95.7%). The specificity of a CCS of 5 (97.8%, 95% CI 96.5%-98.7%) was higher than when the overall 99th-percentile cut-off for the Ortho hs-cTnI assay (> 11 ng/L; 90.1%, 95% CI 87.9%-92.0%) was used. A similar pattern was observed in cohort 2 at 30 days and persisted at 90 days with the Abbott hs-cTnI assay.

INTERPRETATION

The CCS derived with 2 different hs-cTnI assays and ED populations yielded higher sensitivity and specificity estimates for MACE than hs-cTnI alone. An intervention study is needed to evaluate the impact of the CCS at both the patient and hospital levels.

TRIAL REGISTRATION

ClinicalTrials.gov, no. NCT01994577.

Performance of High-Sensitivity Cardiac Troponin Assays to Reflect Comorbidity Burden and Improve Mortality Risk Stratification in Older Adults With Diabetes

OBJECTIVE

Incorporation of comorbidity burden to inform diabetes management in older adults remains challenging. High-sensitivity cardiac troponins are objective, quantifiable biomarkers that may improve risk monitoring in older adults. We assessed the associations of elevations in high-sensitivity cardiac troponin I (hs-cTnI) and T (hs-cTnT) with comorbidities and improvements in mortality risk stratification.

RESEARCH DESIGN AND METHODS

We used logistic regression to examine associations of comorbidities with elevations in either troponin (≥85th percentile) among 1,835 participants in the Atherosclerosis Risk in Communities (ARIC) Study with diabetes (ages 67-89 years, 43% male, 31% black) at visit 5 (2011-2013). We used Cox models to compare associations of high cardiac troponins with mortality across comorbidity levels.

RESULTS

Elevations in either troponin (≥9.4 ng/L for hs-cTnI, ≥25 ng/L for hs-cTnT) were associated with prevalent coronary heart disease, heart failure, chronic kidney disease, pulmonary disease, hypoglycemia, hypertension, dementia, and frailty. Over a median follow-up of 6.2 years (418 deaths), both high hs-cTnI and high hs-cTnT further stratified mortality risk beyond comorbidity levels; those with a high hs-cTnI or hs-cTnT and high comorbidity were at highest mortality risk. Even among those with low comorbidity, a high hs-cTnI (hazard ratio 3.0 [95% CI 1.7, 5.4]) or hs-cTnT (hazard ratio 3.3 [95% CI 1.8, 6.2]) was associated with elevated mortality.

CONCLUSIONS

Many comorbidities were reflected by both hs-cTnI and hs-cTnT; elevations in either of the troponins were associated with higher mortality risk beyond comorbidity burden. High-sensitivity cardiac troponins may identify older adults at high mortality risk and be useful in guiding clinical care of older adults with diabetes.

Clinical outcomes for chest pain patients discharged home from emergency departments using high-sensitivity versus conventional cardiac troponin assays

BACKGROUND

High-sensitivity cardiac troponin (hs-cTn) assays enhance detection of lower circulating troponin concentrations, but the impact on outcomes in clinical practice is unclear. Our objective was to compare outcomes of chest pain patients discharged from emergency departments (EDs) using hs-cTn and conventional troponin (cTn) assays.

METHODS

We conducted an observational study of chest pain patients aged 40-105 years who presented to an ED from April 1, 2013, to March 31, 2017, and were discharged home. We compared 30-day and 1-year outcomes of EDs that used hs-cTn versus cTn assays. The primary outcome was a composite of all-cause death, myocardial infarction or unstable angina. Comparisons were conducted with (1) no adjustment; (2) adjustment for demographic, socioeconomic, and hospital characteristics; and (3) full clinical adjustment.

RESULTS

Among the 394,910 patients, 62,138 (15.7%) were evaluated at hs-cTn EDs and 332,772 (84.3%) were evaluated at cTn EDs. Patients discharged from hs-cTn EDs were less likely to have diabetes, hypertension, or prior heart disease. At 30 days, the unadjusted primary outcome rate was lower in hs-cTn EDs (0.9% vs 1.0%, P < .001). The 30-day hazard ratios for the primary outcome were 0.84 (95% CI 0.77-0.92) for no adjustment and 0.98 (95% CI 0.88-1.08) for full adjustment. Over 1 year, patients discharged from hs-cTn EDs had significantly fewer primary outcomes (3.7% vs 4.1%, P < .001) and lower hazard ratio (0.93; 95% CI 0.89-0.98) even after full adjustment.

CONCLUSIONS

Hs-cTn testing was associated with a significantly lower adjusted hazard of myocardial infarction, angina, and all-cause hospitalization at 1 year but not 30 days.

Effect of corticosteroids on myocardial injury among patients hospitalized for community-acquired pneumonia: rationale and study design. The colosseum trial

Community-acquired pneumonia (CAP) is often complicated by elevation of cardiac troponin, a marker of myocardial injury that can be isolated or associated with myocardial infarction (MI). A retrospective study showed that corticosteroid treatment lowers the incidence of MI during the hospital stay. No data exist so far on the effect of corticosteroids on myocardial injury in CAP patients. The primary objective of the study is to evaluate if methylprednisolone is able to reduce myocardial injury, as assessed by serum high-sensitivity cardiac T Troponin (hs-cTnT), in a cohort of patients hospitalized for CAP. Secondary aims are to evaluate the potential effect of methylprednisolone on cardiovascular events during hospitalization, at 30 days from hospital admission and during 2 years' follow-up. The trial will also examine whether the potential protective effects of methylprednisolone might be due to platelet activation down-regulation. Double-blind randomized placebo-controlled trial. One hundred twenty-two eligible patients will be randomized to a week treatment with iv methylprednisolone (20 mg b.i.d) or placebo from hospital admission. Serum hs-cTnT will be measured at admission and every day until up 3 days from admission. ECG will be monitored every day until discharge. After discharge, all patients will be followed-up 2 years. This is the first clinical trial aimed at examining whether methylprednisolone treatment may reduce myocardial injury. The results of this trial may constitute the basis for conducting a larger multicenter trial aimed to evaluate the effect of corticosteroid on cardiovascular events in this setting.

Rapid rule-out of suspected acute coronary syndrome in the Emergency Department by high-sensitivity cardiac troponin T levels at presentation

The reliability of initial high-sensitivity cardiac troponin T (hs-cTnT) under limit-of-detection in ruling-out short- and long-term acute coronary events in subjects for suspected non-ST-segment elevation acute coronary syndrome (NSTE-ACS) is not definitely settled. In a retrospective chart review analysis, 1001 subjects with hs-cTnT ≤ 14 ng/L out of 4053 subjects with hs-cTnT measured at Emergency Department (ED) presentation were recruited. The main outcome measure is fatal or non-fatal myocardial infarction (MI) within 30 days; secondary outcomes are MI or major acute coronary events (MACE) as a combination of MI or re-hospitalization for unstable angina within 1 year. In subjects with hs-cTnT < 5 ng/L [32.6% of cases, mean age 63 years (interquartile range 23)], no cases (0%, NPV 100%) had MI within 30 days, 2 cases (0.6%, NPV 99.4%) MI at 1-year, and 11 cases (3.4%, NPV 96.6%) MACE at 1-year. Patients with hs-cTnT < 5 ng/L would have benefited from a shortened decision (9.30 h and 53% overnight ED stay saved). Hs-cTnT < 5 ng/L is confirmed as safe for patients and comfortable for physicians in ruling out MI or MACE both at short and long term, suggesting that a sizable number of patients can be rapidly discharged without unnecessary diagnostic tests and ED observation.

"Ultra-sensitive" cardiac troponins: Requirements for effective implementation in clinical practice

The measurement of cardiac troponins, either cardiac troponin I or T, has become the culprit of clinical decision making in patients with suspected acute coronary syndrome (ACS), especially in those with non-ST elevation myocardial infarction (NSTEMI). The leading analytical mainstays of cardiac troponin immunoassays include the limit of blank (LoB), limit of detection (LoD), functional sensitivity, the 99th percentile of a healthy reference population, along with the percentage of "ostensibly healthy" subjects displaying measurable values < 99th percentile. The latest generation of cardiac troponin immunoassays, conventionally defined as "high-sensitive" (HS), is characterized by a LoD over 100-fold lower compared to the first commercialized techniques and a percentage of measurable values consistently > 50% in the general healthy population. The very recent commercialization of methods with further improved analytical sensitivity (i.e., "ultra-sensitive" assays), which allow to measure cardiac troponin values in the vast majority of healthy subjects, is now challenging the diagnostic paradigm based on early rule-out of subjects with cardiac troponin values comprised between the 99th percentile and LoD. New diagnostic strategies, entailing assay-specific cut-offs, must hence be developed and validated in large multicenter studies. The aim of this article is to provide an update on commercially available HS and "ultra"-sensitive techniques for measuring cardiac troponins, along with possible implications of increasingly enhanced analytical sensitivity on diagnostic algorithms for evaluating patients with suspected ACS.

Label-Free Multiplexed Electrical Detection of Cancer Markers on a Microchip Featuring an Integrated Fluidic Diode Nanopore Array

We introduce an integrated array of glass nanopores on a silicon microchip fabricated in a batch process through low-resolution photolithography and standard semiconductor processing tools. By functionalizing each nanopore against a distinct target, we further demonstrate ultrasensitive, label-free, multiplexed electrical detection of cancer-marker proteins in real time through charge-dependent ionic current rectification. As nanofluidic diode biosensors, the nanopores return rapid results, with a limit of detection reaching concentrations as low as attomolars in assay buffer and femtomolars in undiluted untreated human serum, a rare achievement for this class of nanosensors. Multiplexed detection capability has been demonstrated on proteins carcinoembryonic antigen, α-fetoprotein antigen, and human epidermal growth factor receptor-2, with the assay further scalable to a size that is limited by the readout electronics. The nanopores are also found with a considerably advanced detection limit as well as dynamic range in relation to the nanoslit counterparts, validated by the measurements on cardiac protein troponin T. This highly robust assay platform draws from rich nanopore physics and could provide further enhanced detection through concentration polarization, subsequent target enrichment, and serum desalting, all potentially induced by the nanopores presently redundant in the array. This integration would be crucial for removing major obstacles for the practical use of nanopore-based assays.

Ultra-sensitive chemical and biological analysis via specialty fibers with built-in microstructured optofluidic channels

All-in-fiber optofluidics is an analytical tool that provides enhanced sensing performance with simplified analyzing system design. Currently, its advance is limited either by complicated liquid manipulation and light injection configuration or by low sensitivity resulting from inadequate light-matter interaction. In this work, we design and fabricate a side-channel photonic crystal fiber (SC-PCF) and exploit its versatile sensing capabilities in in-line optofluidic configurations. The built-in microfluidic channel of the SC-PCF enables strong light-matter interaction and easy lateral access of liquid samples in these analytical systems. In addition, the sensing performance of the SC-PCF is demonstrated with methylene blue for absorptive molecular detection and with human cardiac troponin T protein by utilizing a Sagnac interferometry configuration for ultra-sensitive and specific biomolecular specimen detection. Owing to the features of great flexibility and compactness, high-sensitivity to the analyte variation, and efficient liquid manipulation/replacement, the demonstrated SC-PCF offers a generic solution to be adapted to various fiber-waveguide sensors to detect a wide range of analytes in real time, especially for applications from environmental monitoring to biological diagnosis.

How Do We Balance the Long-Term Health of a Patient With the Short-Term Risk to the Physician?

BACKGROUND

There is a wide variation in practice patterns among emergency medicine physicians; many factors weigh into the medical decision-making process including the health of the patient as well as short-term risk to the physician.

OBJECTIVE

The objective of our discussion is to illustrate specific scenarios where medical decisions are focused on the physician's short-term risk, then to propose an approach to shifting the balance to the patient's long-term health.

METHODS

Using recent data on the evaluation, disposition, and outcomes of patients with low-risk chest pain in the emergency department, we calculate the risk of outpatient evaluation compared to the common practice of admission or observation.

RESULTS

Patients with low-risk chest pain and negative initial evaluation in the emergency department with 2 normal cardiac biomarkers, normal vital signs, and non-ischemic, interpretable ECGs, have an extremely low-risk of a short term clinically relevant adverse cardiac event. There is a suggestion of a higher patient risk from admission, prompting consideration that continued evaluation of the chest pain as an outpatient may be safer than admission or observation.

CONCLUSION

A test/intervention should be done if the risk of a missed diagnosis or adverse outcome is greater that the risk of the test/intervention. Involving the patient in the decision-making process may help to shift the management balance from the physician's short-term concern of their own risk, to the patient's long-term health.

Troponins, intrinsic disorder, and cardiomyopathy

Cardiac troponin is a dynamic complex of troponin C, troponin I, and troponin T (TnC, TnI, and TnT, respectively) found in the myocyte thin filament where it plays an essential role in cardiac muscle contraction. Mutations in troponin subunits are found in inherited cardiomyopathies, such as hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). The highly dynamic nature of human cardiac troponin and presence of numerous flexible linkers in its subunits suggest that understanding of structural and functional properties of this important complex can benefit from the consideration of the protein intrinsic disorder phenomenon. We show here that mutations causing decrease in the disorder score in TnI and TnT are significantly more abundant in HCM and DCM than mutations leading to the increase in the disorder score. Identification and annotation of intrinsically disordered regions in each of the troponin subunits conducted in this study can help in better understanding of the roles of intrinsic disorder in regulation of interactomes and posttranslational modifications of these proteins. These observations suggest that disease-causing mutations leading to a decrease in the local flexibility of troponins can trigger a whole plethora of functional changes in the heart.

Analytical and Clinical Validation of a Point-of-Care Cardiac Troponin T Test with an Improved Detection Limit

BACKGROUND

The point-of-care test Roche CARDIAC POC Troponin T (PoC TnT) is an improved assay which has been developed for the Roche cobas h 232 system.

METHODS

We performed a multicentre evaluation (four sites) to assess the analytical performance of the PoC TnT assay and to compare it with the central laboratory Elecsys® troponin T high sensitive (lab cTnT-hs) assay.

RESULTS

The relative mean differences found in method comparisons of PoC TnT vs. lab cTnT-hs ranged from -4.1% to +6.8%. Additionally, there was good concordance between PoC TnT and lab cTnT-hs for the number of samples with troponin T values below the measuring range of 40 ng/L. Lot-to-lot differences of PoC TnT ranged from -8.6% to +4.6%. Within-series coefficients of variation (CV) resulting from 81 ten-fold measurements with patient samples were 9.3%, 11.8%, and 12.9% in the low (40 to < 200 ng/L), medium (200 to < 600 ng/L), and high (600 to 2000 ng/L) measuring range, respectively. Using the system quality control, the mean CV for between-day imprecision was 11.3%. No interference was observed by triglycerides (up to 11.4 mmol/L), bilirubin (up to 376 µmol/L), hemoglobin (up to 0.12 mmol/L), biotin (up to 30 µg/L), rheumatoid factor (up to 200 IU/mL), or with 52 standard or cardiovascular drugs at therapeutic concentrations. There was no influence on the results by varying hematocrit values in a range from 25% to 53%. However, interferences with human anti-mouse antibodies were found. No significant influence on the results was found with PoC TnT by using sample volumes between 135 to 165 µL. High troponin T concentrations up to 500 µg/L did not lead to false low results, indicating no high-concentration hook effect. No cross-reactivity was found between the PoC TnT assay and human skeletal troponin T up to 1000 µg/L (< 0.05%). Diagnostic sensitivity and specificity data of a subpopulation (23 patients) of this study are in agreement with results of another large pre-hospital study.

CONCLUSIONS

The PoC TnT assay showed good analytical performance with excellent concordance with the calibration and reference laboratory method. It should therefore be suitable for its intended use in point-of-care settings.

The HEART score with high-sensitive troponin T at presentation: ruling out patients with chest pain in the emergency room

The HEART score is a simple scoring system, ranging from 0 to 10, specifically developed for risk stratification of patients with undifferentiated chest pain. It has been validated for the conventional troponin, but not for high-sensitive troponin. We assess a modified version of the HEART score using a single high-sensitivity troponin T dosage at presentation, regardless of symptom duration, and with different ECG criteria to evaluate if the patients with a low HEART score could be safely discharged early. The secondary aim was to confirm a statistically significant difference in each HEART score group (low 0-3, intermediate 4-6, high 7-10) in the occurrence of major adverse cardiac events at 30 and 180 days. We retrospectively analyzed the HEART score of 1597 consecutive patients admitted to the Emergency Department of our Hospital for chest pain between January 1 and June 30, 2014. Of these, 190 did not meet the inclusion criteria and 29 were lost to follow-up. None of the 512 (37.2 %) patients with a low HEART score had an event within 180 days. The difference between the cumulative incidences of events in the three HEART score groups was statistically significant (P < 0.0001). We demonstrate that it might be possible to safely discharge Emergency Department chest pain patients with a low modified HEART score after an initial determination of high-sensitive troponin T, without a prolonged observation period or an additional cardiac testing.

Baseline Cardiovascular Characteristics of Adult Patients with Chronic Kidney Disease from the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD)

Cardiovascular disease (CVD) is the most common cause of death in patients with chronic kidney disease (CKD). We report the baseline cardiovascular characteristics of 2,238 participants by using the data of the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD) study. The cohort comprises 5 subcohorts according to the cause of CKD: glomerulonephritis (GN), diabetic nephropathy (DN), hypertensive nephropathy (HTN), polycystic kidney disease (PKD), and unclassified. The average estimated glomerular filtration rate (eGFR) was 50.5 ± 30.3 mL/min⁻¹/1.73 m⁻² and lowest in the DN subcohort. The overall prevalence of previous CVD was 14.4% in all patients, and was highest in the DN followed by that in the HTN subcohort. The DN subcohort had more adverse cardiovascular risk profiles (higher systolic blood pressure [SBP], and higher levels of cardiac troponin T, left ventricular mass index [LVMI], coronary calcium score, and brachial-ankle pulse wave velocity [baPWV]) than the other subcohorts. The HTN subcohort exhibited less severe cardiovascular risk profiles than the DN subcohort, but had more severe cardiovascular risk features than the GN and PKD subcohorts. All these cardiovascular risk profiles were inversely correlated with eGFR. In conclusion, this study shows that the KNOW-CKD cohort exhibits high cardiovascular burden, as other CKD cohorts in previous studies. Among the subcohorts, the DN subcohort had the highest risk for CVD. The ongoing long-term follow-up study up to 10 years will further delineate cardiovascular characteristics and outcomes of each subcohort exposed to different risk profiles.

Antigen-Dissociation from Antibody-Modified Nanotransistor Sensor Arrays as a Direct Biomarker Detection Method in Unprocessed Biosamples

The detection of biomolecules is critical for a wide spectrum of applications in life sciences and medical diagnosis. Nonetheless, biosamples are highly complex solutions, which contain an enormous variety of biomolecules, cells, and chemical species. Consequently, the intrinsic chemical complexity of biosamples results in a significant analytical background noise and poses an immense challenge to any analytical measurement, especially when applied without prior efficient separation and purification steps. Here, we demonstrate the application of antigen-dissociation regime, from antibody-modified Si-nanowire sensors, as a simple and effective direct sensing mechanism of biomarkers of interest in complex biosamples, such as serum and untreated blood, which does not require ex situ time-consuming biosample manipulation steps, such as centrifugation, filtering, preconcentration, and desalting, thus overcoming the detrimental Debye screening limitation of nanowire-based biosensors. We found that two key parameters control the capability to perform quantitative biomarkers analysis in biosamples: (i) the affinity strength (k_off rate) of the antibody-antigen recognition pair, which dictates the time length of the high-affinity slow dissociation subregime, and (ii) the "flow rate" applied during the solution exchange dissociation step, which controls the time width of the low-affinity fast-dissociation subregime. Undoubtedly, this is the simplest and most convenient approach for the SiNW FET-based detection of antigens in complex untreated biosamples. The lack of ex situ biosample manipulation time-consuming processes enhances the portability of the sensing platform and reduces to minimum the required volume of tested sample, as it allows the direct detection of untreated biosamples (5-10 μL blood or serum), while readily reducing the detection cycle duration to less than 5 min, factors of great importance in near-future point-of-care medical applications. We believe this is the first ever reported demonstration on the real-time, direct label-free sensing of biomarkers from untreated blood samples, using SiNW-based FET devices, while not compromising the ultrasensitive sensing capabilities inherent to these devices.

Time from symptom onset influences high-sensitivity troponin T diagnostic accuracy for the diagnosis of acute myocardial infarction

BACKGROUND

The time required for patients with acute chest pain to reach a hospital emergency department varies, possibly lowering the diagnostic performance of a general cut-off value for high-sensitivity cardiac troponin T (hs-cTnT) in diagnosing acute myocardial infarction (AMI). The aim of this study was to determine the cut-off values as calculated by receiver operating characteristic (ROC) of hs-cTnT at different times from onset of symptoms to admission, and to evaluate their diagnostic performance.

METHODS

Our study included 3096 patients with symptoms suggestive of AMI. These patients were classified according to time from onset of symptoms to admission. The diagnostic accuracy was quantified by the area under the ROC curve (AUC).

RESULTS

Of the patients, 1082 (49.3%) were diagnosed as having AMI (317 were non-ST segment elevation myocardial infarction [NSTEMI]). The AUC for hs-cTnT to diagnose AMI was 0.881 at <3 h after symptom onset, 0.940 at 3-6 h after symptom onset, 0.966 at 6-12 h after symptom onset, and 0.974 at >12 h after symptom onset. The threshold as determined by ROC of hs-cTnT was 13.5 ng/L to diagnose AMI at ≤3 h after symptom onset with a sensitivity of 81.8% and a specificity of 80.1%, 17.8 ng/L at 3-6 h after symptom onset with a sensitivity of 94.6% and a specificity of 84.3%, 30.0 ng/L at 6-12 h after symptom onset with a sensitivity of 95.9% and a specificity of 85.5%, and 58.0 ng/L at >12 h after symptom onset with a sensitivity of 92.7% and a specificity of 93.3%. The same observations were performed for the diagnosis of NSTEMI.

CONCLUSIONS

The ROC-determined cut-off value of hs-cTnT for AMI or NSTEMI diagnosis gradually increased with time from onset of symptoms to presentation. Using a higher cut-off value by ROC for hs-cTnT will improve its accuracy in diagnosing AMI or NSTEMI patients in late presenters. The higher value will enable physicians to more quickly rule in patients compared to the 99th percentile cut-off, and can rule out patients safely.

Clinical presentation and in-hospital death in acute pulmonary embolism: does cancer matter?

Cancer is one of the most common risk factors for acute pulmonary embolism (PE), but only few studies report on the short-term outcome of patients with PE and a history of cancer. The aim of the study was to assess whether a cancer diagnosis affects the clinical presentation and short-term outcome in patients hospitalized for PE who were included in the Italian Pulmonary Embolism Registry. All-cause and PE-related in-hospital deaths were also analyzed. Out of 1702 patients, 451 (26.5 %) of patients had a diagnosis of cancer: cancer was known at presentation in 365, or diagnosed during the hospital stay for PE in 86 (19 % of cancer patients). Patients with and without cancer were similar concerning clinical status at presentation. Patients with cancer less commonly received thrombolytic therapy, and more often had an inferior vena cava filter inserted. Major or intracranial bleeding was not different between groups. In-hospital all-cause death occurred in 8.4 and 5.9 % of patients with and without cancer, respectively. At multivariate analysis, cancer (OR 2.24, 95 % CI 1.27-3.98; P = 0.006) was an independent predictor of in-hospital death. Clinical instability, PE recurrence, age ≥75 years, recent bed rest ≥3 days, but not cancer, were independent predictors of in-hospital death due to PE. Cancer seems a weaker predictor of all-cause in-hospital death compared to other factors; the mere presence of cancer, without other risk factors, leads to a probability of early death of 2 %. In patients with acute PE, cancer increases the probability of in-hospital all-cause death, but does not seem to affect the clinical presentation or the risk of in-hospital PE-related death.

A novel method for monitoring troponin T fragment from rabbit skeletal muscle during aging using quartz crystal microbalance

BACKGROUND

Troponin T (TnT) is degraded during aging of meat. The proteolytic fragment of TnT, especially the 30 kDa fragment, is used as one of indices for estimating aging of meat. We have tried to use quartz crystal microbalance (QCM), which is widely used to analyze interaction among macromolecules, to detect proteolytic fragments of TnT during aging of meat.

RESULT

The frequency of the QCM sensor with immobilized anti-TnT antibody in high-salt solution extracts of both myofibrils and whole meat decreased with time of aging. The staining intensity of the bands, including a 30 kDa fragment bound to anti-TnT antibody, also increased with time of aging in western blotting. These results confirm that TnT is degraded during aging and released from thin filaments, and QCM analysis is sufficiently sensitive to detect the TnT fragments.

CONCLUSION

The QCM analysis of muscle and myofibrillar extracts using anti-TnT antibody-immobilized sensor can be used as a convenient tool for monitoring the extent of aging of meat. © 2015 Society of Chemical Industry.

Bovine Cardiac Troponin T is Not Accurately Quantified with a Common Human Clinical Immunoassay

The detection of myocardial injury in cattle caused by the ingestion of cardiotoxic compounds or cardiac diseases would be facilitated by the availability of a rapid and specific quantitative serum assay for cardiac troponins. Therefore, the accuracy of the only cardiac troponin T (cTnT) immunoassay to receive approval by the US Food and Drug Administration for the measurement of cTnT in human serum was evaluated to quantify the protein in bovine serum. Recovery experiments were performed by the addition of purified bovine cTnT to normal bovine serum. Cardiac troponin T was quantified using an immunoassay commonly used for the measurement of cTnT in human serum. The immunoassay demonstrated a well correlated ( r = 0.99) and linear dose-dependent response to bovine cTnT but with poor accuracy (slope = 0.024; 95% CI = 0.018 to 0.030). The mean recovery of bovine cTnT was 2.4% across a concentration range of 10 ng/ml to 1,000 ng/ml. These studies demonstrate that a commonly used immunoassay for the measurement of cTnT in human serum demonstrates poor accuracy for the quantification of bovine cTnT.

Abnormal Expression of Genes Associated with Development and Inflammation in the Heart of Mouse Maternal Phenylketonuria Offspring

This study descibes gene expression in the fetus hearts obtained from mouse model for Phenylketonuria. These hearts have cardiovascular disease (CVD). Therefore genes involved in CVD were examined. Several genes associated with heart development and inflammation were found to be altered. In order to investigate whether the abnormal gene expression alters transcription and translation, the levels of troponin mRNA and protein were determined. One step real time RT-PCR showed a reduction in cardiac troponin I, troponin T2 and ryanodine receptor 2. Determination of troponin I and T protein levels showed reduced levels of these proteins. Our results suggest that altered gene expression affects protein production. These changes are likely involved in the cardiovascular defects seen in the mouse.

Analytical validation and establishment of reference intervals for a 'high-sensitivity' cardiac troponin-T assay in horses

BACKGROUND

Cardiac troponin-I assays have been validated in horses.'High-sensitivity' cardiac troponin assays are now the standard in human cardiology.

OBJECTIVE

Appropriately validate the'high-sensitivity' cardiac Troponin-T (hscTnT) assay for clinical use in horses, establish reference intervals, determine the biological variation, and demonstrate assay utility in selected clinical cases.

METHODS

Analytical validation of the Roche hscTnT assay included within- and between-run precision, linear dose response, limit of quantitation (LoQ), stability, and comparison with cTn-I (iSTAT). Reference intervals and biological variation were determined using adult, healthy, Non-Competition Horses (N = 125) and Racing-Thoroughbreds (N = 178). HscTnT levels were measured in two horses with cardiac pathology.

RESULTS

The hscTnT demonstrates acceptable within-run (L1 = 6.5 ng/L, CV 14.9 %, L2 = 10.1 ng/L, CV 8.7 %, L3 = 15.3 ng/L, CV 5.4 %) and between-run precision (L1 = 12.2 ng/L, CV 8.4 %, L2 = 57.0 ng/L, CV 8.4 %, L3 = 256.0 ng/L, CV 9.0 %). The assay was linear from 3 to 391 ng/L. The LoQ was validated at 3 ng/L. Samples demonstrated insignificant decay over freeze-thaw cycle. Comparison with cTnI assay showed excellent correlation (range: 8.0-3535.0 ng/L, R(2) = 0.9996). Reference intervals: The upper 95(th) and 99(th) percentile of the hscTnT population distribution were 6.8 and 16.2 ng/L in Non-Competition Horses, and 14.0 and 23.2 ng/L in Racing-Thoroughbreds. Between-breed, diurnal effect, and between-day variation was below LoQ. Two clinical cases with presumed cardiac pathology had hscTnT levels of 220.9 ng/L and 5723.0 ng/L.

CONCLUSIONS

This benchmark study is the first to comply with CLSI guidelines, thus further establishing the performance characteristics of the hscTnT assay, and reference intervals in healthy horses. Two clinical cases demonstrated further the clinical utility of the assay.

Monolithic integration of a silicon nanowire field-effect transistors array on a complementary metal-oxide semiconductor chip for biochemical sensor applications

We present a monolithic complementary metal-oxide semiconductor (CMOS)-based sensor system comprising an array of silicon nanowire field-effect transistors (FETs) and the signal-conditioning circuitry on the same chip. The silicon nanowires were fabricated by chemical vapor deposition methods and then transferred to the CMOS chip, where Ti/Pd/Ti contacts had been patterned via e-beam lithography. The on-chip circuitry measures the current flowing through each nanowire FET upon applying a constant source-drain voltage. The analog signal is digitized on chip and then transmitted to a receiving unit. The system has been successfully fabricated and tested by acquiring I-V curves of the bare nanowire-based FETs. Furthermore, the sensing capabilities of the complete system have been demonstrated by recording current changes upon nanowire exposure to solutions of different pHs, as well as by detecting different concentrations of Troponin T biomarkers (cTnT) through antibody-functionalized nanowire FETs.

Prediction of functional recovery by cardiac magnetic resonance feature tracking imaging in first time ST-elevation myocardial infarction. Comparison to infarct size and transmurality by late gadolinium enhancement

PURPOSE

To investigate whether myocardial deformation imaging, assessed by feature tracking cardiac magnetic resonance (FTI-CMR), would allow objective quantification of myocardial strain and estimation of functional recovery in patients with first time ST-elevation myocardial infarction (STEMI).

METHODS

Cardiac magnetic resonance (CMR) imaging was performed in 74 consecutive patients 2-4 days after successfully reperfused STEMI, using a 1.5T CMR scanner (Philips Achieva). Peak systolic circumferential and longitudinal strains were measured using the FTI applied to SSFP cine sequences and were compared to infarct size, determined by late gadolinium enhancement (LGE). Follow-up CMR at 6 months was performed in order to assess residual ejection fraction, which deemed as the reference standard for the estimation of functional recovery.

RESULTS

During the follow-up period 53 of 74 (72%) patients exhibited preserved residual ejection fraction ≥50%. A cut-off value of -19.3% for global circumferential strain identified patients with preserved ejection fraction ≥50% at follow-up with sensitivity of 76% and specificity of 85% (AUC=0.86, 95% CI=0.75-0.93, p<0.001), which was superior to that provided by longitudinal strain (ΔAUC=0.13, SE=0.05, z-statistic=2.5, p=0.01), and non-inferior to that provided by LGE (ΔAUC=0.07, p=NS). Multivariate analysis showed that global circumferential strain and LGE exhibited independent value for the prediction of preserved LV-function, surpassing that provided by age, diabetes and baseline ejection fraction (HR=1.4, 95% CI=1.0-1.9 and HR=1.4, 95% CI=1.1-1.7, respectively, p<0.05 for both).

CONCLUSIONS

Estimation of circumferential strain by FTI provides objective assessment of infarct size without the need for contrast agent administration and estimation of functional recovery with non-inferior accuracy compared to that provided by LGE.

Label-free specific detection of femtomolar cardiac troponin using an integrated nanoslit array fluidic diode

We demonstrate here for the first time the utility of an integrated nanofluidic diode for detecting and quantifying physiologically relevant macromolecules. Troponin T, a key human cardiac protein biomarker, was selectively and rapidly detected free of labels for concentrations down to 10 fg/mL (∼ 0.3 fM) in buffer as well as 10 pg/mL (∼ 300 fM) in untreated human serum. This ultrasensitive detection arises from monolithic integration of a unique nanofluidic diode structure that is highly robust and amenable to site-specific surface modification. The structure features a planar nanoslit array where each nanoslit is defined at a nominal width of 70 nm over a micrometer-scale silicon trench without the use of high-resolution patterning techniques. Through vapor deposition, a glass layer is placed at a nonuniform thickness, tapering the trench profile upward and contributing to the triangular nanoslit structure. This asymmetric profile is essential for ionic current rectification noted here at various pH values, ionic strengths, and captured target species, which modulate the surface-charge density within the sensitive region of the nanoslit. The nanoslit, unlike nanopores, offers only 1D confinement, which appears to be adequate for reasonable rectification. The measurements are found in quantitative agreement with the diode simulations for the first time based on a pH- and salt-dependent surface-charge model.

Cost consequences of point-of-care troponin T testing in a Swedish primary health care setting

OBJECTIVE

To evaluate the safety and cost-effectiveness of point-of-care troponin T testing (POCT-TnT) for the management of patients with chest pain in primary care.

DESIGN

Prospective observational study with follow-up.

SETTING

Three primary health care (PHC) centres using POCT-TnT and four PHC centres not using POCT-TnT in south-east Sweden.

PATIENTS

All patients ≥ 35 years of age, contacting one of the PHC centres for chest pain, dyspnoea on exertion, unexplained weakness and/or fatigue, with no other probable cause than cardiac, were included. Symptoms must have commenced or worsened during the previous seven days.

MAIN OUTCOME MEASURES

Emergency referral rates, diagnoses of acute myocardial infarction (AMI) or unstable angina (UA), and costs were collected for 30 days after the patient sought care at the PHC centre.

RESULTS

A total of 196 patients with chest pain were included: 128 in PHC centres with POCT-TnT and 68 in PHC centres without POCT-TnT. Fewer patients from the PHC centres with POCT-TnT (n = 32, 25%) were emergently referred to hospital than from centres without POCT-TnT (n = 29, 43%; p = 0.011). Eight patients (6.2%) from PHC centres with POCT-TnT were diagnosed with AMI or UA compared with six patients (8.8%) from centres without POCT-TnT (p = 0.565). Two patients with AMI or UA were classified as missed cases from PHC centres with POCT-TnT and there were no missed cases from PHC centres without POCT-TnT. SKr290 000 was saved per missed case of AMI or UA.

CONCLUSION

The use of POCT-TnT in primary care may be cost saving but at the expense of missed cases.

Troponin T in acute heart failure: clinical implications and prognosis in the Spanish National Registry on Heart Failure

BACKGROUND

Elevated troponin in heart failure has been associated with worse prognosis, but there are differences in the design and results of published studies. Our objective was to determine the association of troponin T with mortality and readmissions in patients with acute heart failure in clinical practice conditions.

METHODS

We included patients from the RICA registry who were hospitalized for acute heart failure. They were classified into 3 groups according to troponin T levels: normal, intermediate and high (<0.02, 0.02-0.049 and ≥ 0.05 ng/mL, respectively). Survival was studied by Kaplan-Meier curves and the association of variables was tested by Cox regression analysis.

RESULTS

A total of 406 patients was included. Average age was 76.9 (76.0-77.7) years. Hypertensive heart disease was the most common etiology. Left ventricular ejection fraction was <45% in 22.1% of the patients. The group with elevated troponin T had higher proportions of women, systolic dysfunction, renal failure and anemia, a lower body mass index and longer hospital stay. At one year, patients with elevated troponin T had higher mortality than patients with normal troponin (35.5 vs. 13.9%, p<0.001). The composite event (mortality and readmissions) was also more frequent (51.6 vs. 30.9%, p<0.001), but there were no differences in readmissions alone. Troponin T ≥ 0.02 ng/mL was independently associated with mortality.

CONCLUSIONS

Elevated troponin T levels are common in patients with heart failure in clinical practice and are associated with increased mortality and events after one year of follow-up.

Bioelectrode applied to diagnosis of cardiac disease

This paper describes the assembly of a bioelectrode based on poly(3-aminophenol) and anti-troponin T antibody for recognition of troponin T, which is a specific biomarker for diagnosis of acute myocardial infarction. This disease causes loss of cellular components, allowing the output of molecules such as troponin T. This proteic component acts as biomarker for diagnosis of acute myocardial infarction due to their high sensitivity and specificity. Poly(3-aminophenol) was electrodeposited onto fluorine doped tin oxide (FTO) coated glass and characterized by spectroscopic methods (UV-Visible, fluorescence, infrared), electrochemical methods (cyclic voltammetry and electrochemical impedance spectroscopy) and morphological methods (laser interferometry, field emission scanning electronic microscopy, and atomic force microscopy). UV/Vis analysis indicated that poly(3-aminophenol) presents extension of conjugation, in according with fluorescence studies. Electrochemical studies indicated that poly(3-aminophenol) electrodeposited in FTO is a material with passivating characteristics for anions and capacity of retaining cationic compounds. Laser interferometry showed that poly(3-aminophenol) covers the FTO surface with a thickness off 375 ± 75 nm. Surface images by FE-SEM and AFM have shown a full coverage on the FTO by the polymer film. The incorporation of anti-troponin T antibody on FTO electrode modified with poly(3-aminophenol) allowed effective and selective detection of cardiac biomarker troponin T, by electrochemical impedance spectroscopy (label free) and by photoluminescence, based on CdSe/ZnS quantum dots. This research shows the step by step assembly of the bioelectrode, used for detection of troponin T by impedimetric and fluorescence methods, opening the opportunity for its use in the diagnosis of others diseases.

Cardiac troponins I and T: molecular markers for early diagnosis, prognosis, and accurate triaging of patients with acute myocardial infarction

Acute myocardial infarction (AMI) is the leading cause of death worldwide, with early diagnosis still being difficult. Promising new cardiac biomarkers such as troponins and creatine kinase (CK) isoforms are being studied and integrated into clinical practice for early diagnosis of AMI. The cardiac-specific troponins I and T (cTnI and cTnT) have good sensitivity and specificity as indicators of myocardial necrosis and are superior to CK and its MB isoenzyme (CK-MB) in this regard. Besides being potential biologic markers, cardiac troponins also provide significant prognostic information. The introduction of novel high-sensitivity troponin assays has enabled more sensitive and timely diagnosis or exclusion of acute coronary syndromes. This review summarizes the available information on the potential of troponins and other cardiac markers in early diagnosis and prognosis of AMI, and provides perspectives on future diagnostic approaches to AMI.

[Diagnostic value of small concentrations of troponin in patients with myocardial infarction]

We have reviewed here studies of measurement of small concentrations of troponin in patients with myocardial infarction conducted in 2010-2011 which were most significant for the clinic. Troponin is a most specific and sensitive cardiomarker appearance of which in blood serum evidence for a necrotic process in cardiac muscle. We discuss the problem of interpretation of small troponin concentrations by clinicians as well as the states in which appearance of the cardiomarker in blood serum has noncardiac origin. We also discuss novel possibilities of application of troponin as a prognostic marker in patients with stable or unstable angina after revascularization procedures.

A nanostructured piezoelectric immunosensor for detection of human cardiac troponin T

A piezoelectric immunosensor based on gold nanoparticles (AuNPs) co-immobilized on a dithiol-modified surface is proposed for detection of human cardiac troponin T (TnT). Anti-human troponin T (anti-TnT) antibodies were covalently immobilized on the nanostructured electrode surface by thiol-aldehyde linkages. In a homogeneous bulk solution, TnT was captured by anti-TnT immobilized on the QCM electrode. Cyclic voltammetry studies were used to characterize the AuNPs layer on the electrode surface and the anti-TnT immobilization steps. The QCM-flow immunosensor exhibited good reliability, measuring concentrations of TnT from 0.003 to 0.5 ng mL(-1) in human serum with high linearity (r = 0.989; p < 0.01). The immunosensor exhibited a 7% coefficient of variation and 0.0015 ng mL(-1) limit of detection, indicating a high reproducibility and sensitivity. The proposed QCM nanostructured immunosensor is easy to use and has promising potential in the diagnosis of acute myocardial infarction due to its speed and high sensitivity.

Recent improvements in survival in primary systemic amyloidosis and the importance of an early mortality risk score

OBJECTIVE

To examine whether the outcome of patients with primary systemic amyloidosis (AL) has improved over time and to identify predictors of early mortality in patients with AL.

PATIENTS AND METHODS

We studied 2 separate cohorts of patients. The first cohort, consisting of 1998 patients with AL seen at Mayo Clinic between January 1977 and August 2006, was used to examine the trends in overall survival (OS) from diagnosis during this 30-year period. The second cohort, consisting of 313 patients seen between September 2006 and August 2009, was used to validate a model for predicting early mortality.

RESULTS

The 4-year OS from diagnosis improved during each decade of follow-up: 21%, 24%, and 33%, respectively, for the periods 1977-1986, 1987-1996, and 1997-2006 (P<.001). Within the last group (1997-2006), 4-year OS during 1997-1999, 2000-2002, and 2003-2006 was 28%, 30%, and 42%, respectively (P=.02). However, the 1-year mortality remained high during the 30-year period. A risk stratification score using cardiac troponin T, N-terminal probrain natriuretic peptide, and uric acid identified patients at risk of early mortality. The 1-year mortality with 0, 1, 2, or 3 risk factors was 19%, 37%, 61%, and 80%, respectively, in this training cohort of 459 patients. This was confirmed in a validation cohort of 313 patients.

CONCLUSION

Survival in AL has improved over time, with maximum improvement occurring in the past decade. However, early mortality remains high, and prospective identification of patients at risk of early mortality may allow development of risk-adapted strategies.

Prospective validation of a modified thrombolysis in myocardial infarction risk score in emergency department patients with chest pain and possible acute coronary syndrome

OBJECTIVES

This study attempted to prospectively validate a modified Thrombolysis In Myocardial Infarction (TIMI) risk score that classifies patients with either ST-segment deviation or cardiac troponin elevation as high risk. The objectives were to determine the ability of the modified score to risk-stratify emergency department (ED) patients with chest pain and to identify patients safe for early discharge.

METHODS

This was a prospective cohort study in an urban academic ED over a 9-month period. Patients over 24 years of age with a primary complaint of chest pain were enrolled. On-duty physicians completed standardized data collection forms prior to diagnostic testing. Cardiac troponin T-values of >99th percentile (> or =0.01 ng/mL) were considered elevated. The primary outcome was acute myocardial infarction (AMI), revascularization, or death within 30 days. The overall diagnostic accuracy of the risk scores was compared by generating receiver operating characteristic (ROC) curves and comparing the area under the curve. The performance of the risk scores at potential decision thresholds was assessed by calculating the sensitivity and specificity at each potential cut-point.

RESULTS

The study enrolled 1,017 patients with the following characteristics: mean (+/-SD) age 59.3 (+/-13.8) years, 60.6% male, 17.9% with a history of diabetes, and 22.4% with a history of myocardial infarction. A total of 117 (11.5%) experienced a cardiac event within 30 days (6.6% AMI, 8.9% revascularization, 0.2% death of cardiac or unknown cause). The modified TIMI risk score outperformed the original with regard to overall diagnostic accuracy (area under the ROC curve = 0.83 vs. 0.79; p = 0.030; absolute difference 0.037; 95% confidence interval [CI] = 0.004 to 0.071). The specificity of the modified score was lower at all cut-points of >0. Sensitivity and specificity at potential decision thresholds were: >0 = sensitivity 96.6%, specificity 23.7%; >1 = sensitivity 91.5%, specificity 54.2%; and >2 = sensitivity 80.3%, specificity 73.4%. The lowest cut-point (TIMI/modified TIMI >0) was the only cut-point to predict cardiac events with sufficient sensitivity to consider early discharge. The sensitivity and specificity of the modified and original TIMI risk scores at this cut-point were identical.

CONCLUSIONS

The modified TIMI risk score outperformed the original with regard to overall diagnostic accuracy. However, it had lower specificity at all cut-points of >0, suggesting suboptimal risk stratification in high-risk patients. It also lacked sufficient sensitivity and specificity to safely guide patient disposition. Both scores are insufficiently sensitive and specific to recommend as the sole means of determining disposition in ED chest pain patients.

Long-range fluorescence quenching by gold nanoparticles in a sandwich immunoassay for cardiac troponin T

We report the first homogeneous sandwich immunoassay with gold nanoparticles (AuNPs) as fluorescence quenchers. The sandwich assay is designed for the detection of the protein cardiac troponin T (cTnT) by its simultaneous interaction with two different antibodies, one attached to AuNPs and the other labeled with fluorescent dyes. We demonstrate the working principle of the assay and using time-resolved fluorescence spectroscopy, we determine the quenching efficiency of the gold nanoparticles. In spite of the relatively large separation distance between dye molecules and AuNPs, ranging from 3 to 22 nm, the AuNPs quench the fluorescence with efficiencies as high as 95%. A limit of detection of 0.02 nM (0.7 ng/mL) was obtained for cTnT, which is the lowest value reported for a homogeneous sandwich assay for cTnT. These results illustrate the use of metallic nanoparticles as fluorescence quenchers in immunoassays where the large biomolecules involved impose distances for which energy transfer between fluorophores would be inefficient.