Precision performance at low levels and 99th percentile concentration of the Access AccuTnl assay on two different platforms

A New Risk Score for Patients With Acute Chest Pain and Normal High Sensitivity Troponin

Objective: To investigate a new risk score for patients who suffered from acute chest pain with normal high-sensitivity troponin I (hs-TnI) levels.

Methods: In this study, patients with acute chest pain who were admitted to the emergency department (ED) of our hospital had been recruited. Hs-TnI was measured in serum samples drawn on admission to the ED. The end point was the occurrence of major adverse cardiac events (MACE) within 3 months. Predictor variables were selected by logistic regression analysis, and external validity was assessed in this study. Furthermore, validation was performed in an independent cohort, i.e., 352 patients (validation cohort).

Results: A total of 724 patients were included in the derivation cohort. The results showed that four predictor variables were significant in the regression analysis—male, a history of chest pain, 60 years of age or older and with three or more coronary artery disease (CAD) risk factors. A total of 105 patients in the validation cohort had serious adverse cardiac events. The validation cohort showed a homogenous pattern with the derivation cohort when patients were stratified by score. The area under the curve (AUC) of the receiver operating characteristic (ROC) in the derivation cohort was 0.80 (95% CI: 0.76–0.83), while in the validation cohort, it was 0.79 (95% CI: 0.75–0.82).

Conclusion: A new risk score was developed for acute chest pain patients without known CAD and ST-segment deviation and with normal hs-TnI and may aid MACE risk assessment and patient triage in the ED.

Changes in cardiac and muscle biomarkers following an uphill-only marathon

The aim of the study was to evaluate changes in cardiac troponin I levels (cTnI) and the main biomarkers of skeletal muscle damage after an uphill-only marathon, along with its relationship with athletes' physiological parameters. Twenty-two runners participated in the "Supermaratona dell'Etna" (43 km, 0-2850 m AMSL). Before and immediately after the race, body mass and hydration status were measured together with blood sampling. At the end of the race, mean cTnI increased significantly in all athletes (mean +900%), and in 52% of them the cTnI values were over the normal range. Mean creatinine and cortisol increased significantly (by 30.5% and 291.4%), while C-reactive protein levels did not change significantly. Then, an uphill-only marathon showed a significant increase in cardiac and skeletal muscle blood biomarkers of injury, and cTnI levels were not significantly correlated with age, body mass index, V̇O₂max, training status, ultra-endurance training experience, race time and blood parameters.

Predictive significance of detectable cardiac troponin I measured with a contemporary-sensitive assay in a real life experience

BACKGROUND

Cardiac troponin (cTn) testing has reduced the likelihood of erroneous discharge of patients with acute coronary syndrome (ACS) from the emergency department (ED), but doubts remain about optimal clinical use. This study was planned for evaluating the predictive significance of cTn values between the limit of detection of the method and the 99th percentile in ED patients evaluated for suspected ACS.

METHODS

In this retrospective study all hospital records of patients admitted over a 6-month period to the ED and with at least one cTnI value comprised between the limit of detection (0.01 ng/mL) and the 99th percentile of the assay (0.05 ng/mL) were analyzed.

RESULTS

A total of 4,749 patients with cTnI value between 0.01-0.05 ng/mL were identified among 57,879 ED visits throughout the study period. Overall, 2,189 patients (46.1%) were discharged from the ED, 2,529 (53.25%) were admitted to the hospital and 31 (0.65%) died during ED stay. A total number of 289 patients out of 2,189 who were discharged (i.e., 13.2%) had additional ED visits within 30 days. Among these, 6 were diagnosed with ACS, representing 0.27% of patients discharged [negative predictive value (NPV) 0.997; 95% CI, 0.994-0.999] and 2.1% of those with second admission (NPV 0.979; 95% CI, 0.955-0.992). Only one of the 2,529 patients admitted to the hospital (i.e., 0.04%) developed an ACS during hospital stay.

CONCLUSIONS

The results of our retrospective study suggest that the suitability of using a contemporary-sensitive cTnI immunoassay assay in the context of an appropriate protocol represents a safe and effective strategy for ruling in and ruling out ACS in patients presenting to the ED.

A modified HEART risk score in chest pain patients with suspected non-ST-segment elevation acute coronary syndrome

Objective

To validate a modified HEART [History, Electrocardiograph (ECG), Age, Risk factors and Troponin] risk score in chest pain patients with suspected non-ST-segment elevation acute coronary syndrome (NSTE-ACS) in the emergency department (ED).

Methods

This retrospective cohort study used a prospectively acquired database and chest pain patients admitted to the emergency department with suspected NSTE-ACS were enrolled. Data recorded on arrival at the ED were used. The serum sample of high-sensitivity cardiac Troponin I other than conventional cardiac Troponin I used in the HEART risk score was tested. The modified HEART risk score was calculated. The end point was the occurrence of major adverse cardiac events (MACE) defined as a composite of acute myocardial infarction (AMI), percutaneous intervention (PCI), coronary artery bypass graft (CABG), or all-cause death, within three months after initial presentation.

Results

A total of 1,300 patients were enrolled. A total of 606 patients (46.6%) had a MACE within three months: 205 patients (15.8%) were diagnosed with AMI, 465 patients (35.8%) underwent PCI, and 119 patients (9.2%) underwent CABG. There were 10 (0.8%) deaths. A progressive, significant pattern of increasing event rate was observed as the score increased (P < 0.001 by χ² for trend). The area under the receiver operating characteristic curve was 0.84. All patients were classified into three groups: low risk (score 0–2), intermediate risk (score 3–4), and high risk (score 5–10). Event rates were 1.1%, 18.5%, and 67.0%, respectively (P < 0.001).

Conclusions

The modified HEART risk score was validated in chest pain patients with suspected NSTE-ACS and may complement MACE risk assessment and patients triage in the ED. A prospective study of the score is warranted.

Cardiac troponin I for prediction of clinical outcomes and cardiac function through 3-month follow-up after primary percutaneous coronary intervention for ST-segment elevation myocardial infarction

BACKGROUND

Circulating levels of cardiac troponin I (cTnI) after ST-segment elevation myocardial infarction (STEMI) are associated with infarct size and chronic left ventricular dysfunction, but the relation to clinical end points and biochemical measures of global cardiac function remains less well defined.

METHODS

One thousand sixty-six patients receiving primary percutaneous coronary intervention (PCI) in the PROTECTION AMI trial were studied in a post hoc analysis. Cardiac troponin I was measured at several time points during the index hospitalization, and patients were followed up for 3 months before reassessment including N-terminal pro-B-type natriuretic peptide (NT-proBNP) and left ventricular ejection fraction (LVEF) measurements.

RESULTS

The median (quartile 1-3) cTnI levels were 0.4 (0.1-0.4) μg/L at admission, 33.1 (12.8-72.1) μg/L after 16 to 24 hours, and 9.1 (3.9-17.5) μg/L after 70 to 80 hours. In adjusted models, all post-PCI single points, peak, and area under curve were found to be independently associated with clinical events, NT-proBNP >118 pmol/L, or LVEF <40% (P for all <.001). When cTnI was added to a baseline risk model for prediction of clinical events, the C statistic improved from 0.779 to 0.846 (16-24 hours) and 0.859 (70-80 hours). Quantified by integrated discrimination improvement, the addition of cTnI significantly augmented prediction ability (relative integrated discrimination improvement 44%-154%; P for all ≤.001). Consistent improvements in discrimination of NT-proBNP >118 pmol/L and LVEF <40% were observed.

CONCLUSIONS

Cardiac troponin I measured after primary PCI for STEMI is independently associated with clinical outcomes and cardiac function through 3-month follow-up. These results suggest that cTnI levels are a useful risk stratification tool in STEMI patients.

Decision limits and the reporting of cardiac troponin: Meeting the needs of both the cardiologist and the ED physician

Cardiac troponin is the preferred biomarker for defining the acute coronary syndrome and acute myocardial infarction. Currently, the only decision limit formally endorsed with regard to the cardiac troponins is the 99th percentile. This is a "rule-in" criterion, intended to ensure that only persons with the acute coronary syndrome are reviewed. The 99th percentile is an arbitrary cut point and there are many problems associated with its application, including defining a truly healthy population, the difficulty of standardisation of cardiac troponin assays, especially but not only cardiac troponin I, and the effects of age and sex on this parameter. The Emergency Department (ED) screens many more persons for possible acute coronary syndromes than actually have the condition and their needs are best met by a "rule-out" test that enables them to clear their busy departments of the many persons who do not actually have the condition. The needs of the ED are not optimally met using the 99th percentile. The index of individuality for the cardiac troponins is small and significant changes consistent with an acute coronary syndrome can occur without the 99th percentile being exceeded. It appears that the ED may be better served by use of delta troponin changes rather than the 99th percentile, but there are problems with this approach, particularly in persons who present late when troponin release has plateaued. In addition, there are many non-acute coronary syndrome causes for cardiac troponin release. The needs of the cardiologist and the ED physician are so different that it may be inappropriate for both groups to use the same diagnostic criteria for cardiac troponin, and it is of great importance that cardiac troponin measurement be used as only one part of the assessment of the person presenting with possible acute coronary syndrome.

High-sensitivity cardiac troponins in everyday clinical practice

High-sensitivity cardiac troponin (hs-cTn) assays are increasingly being used in many countries worldwide, however, a generally accepted definition of high-sensitivity is still pending. These assays enable cTn measurement with a high degree of analytical sensitivity with a low analytical imprecision at the low measuring range of cTn assays (coefficient of variation of < 10% at the 99^th percentile upper reference limit). One of the most important advantages of these new assays is that they allow novel, more rapid approaches to rule in or rule out acute coronary syndromes (ACSs) than with previous cTn assay generations which are still more commonly used in practice worldwide. hs-cTn is also more sensitive for the detection of myocardial damage unrelated to acute myocardial ischemia. Therefore, the increase in early diagnostic sensitivity of hs-cTn assays for ACS comes at the cost of a reduced ACS specificity, because more patients with other causes of acute or chronic myocardial injury without overt myocardial ischemia are detected than with previous cTn assays. As hs-cTn assays are increasingly being adopted in clinical practice and more hs-cTn assays are being developed, this review attempts to synthesize the available clinical data to make recommendations for their everyday clinical routine use.

Analytical performance and clinical decision limit of a new release for cardiac troponin I assay

Background

Cardiac troponins (cTns) are the ‘gold standard’ biomarker for the diagnosis and prognosis of acute coronary syndrome. Analytical performance is critical at low concentrations of cTn, and many of the current assays do not meet the guideline requirement of a 10% coefficient of variation (CV) at the 99th percentile concentrations. The aim of the study was to establish if the newly released Access® AccuTnI®+3 (AccuTnI+3) cardiac troponin I assay (Beckman Coulter Inc., Brea, CA, USA) reached this objective.

Methods

All AccuTnI+3 assays were performed on UniCel® DxI800 analyzer (Beckman Coulter Inc). Limit of Blank (LoB), Limit of Detection (LoD) and Limit of Quantitation (LoQ) were determined according to Clinical Laboratory Standard Institute EP17-A and EP5-A2 protocols. The 99th percentile upper reference limit (URL) was determined by analysing serum samples from 330 apparently healthy blood donors (260 men, 70 women, age range 18–70 years, median age 36 years).

Results

LoB and LoD values were 2.6 and 12 ng/L, respectively. The 10% CV was at 18 ng/L (95% confidence interval [CI] 8–25). The 99th percentile URL was 22 ng/L (95% CI 11–34).

Conclusions

The newly released assay has improved low-end analytical performance and reaches the goal of having a total imprecision ≤10% at 99th percentile of a healthy reference population (guideline acceptable). With this assay, it is now possible to utilize the 99th percentile as decision level for myocardial injury detection.

Perspectives on the value of biomarkers in acute cardiac care and implications for strategic management

Biomarkers in acute cardiac care are gaining increasing interest given their clinical benefits. This study is a review of the major conditions in acute cardiac care, with a focus on biomarkers for diagnostic and prognostic assessment. Through a PubMed search, 110 relevant articles were selected. The most commonly used cardiac biomarkers (cardiac troponin, natriuretic peptides, and C-reactive protein) are presented first, followed by a description of variable acute cardiac conditions with their relevant biomarkers. In addition to the conventional use of natriuretic peptides, cardiac troponin, and C-reactive protein, other biomarkers are outlined in variable critical conditions that may be related to acute cardiac illness. These include ST2 and chromogranin A in acute dyspnea and acute heart failure, matrix metalloproteinase in acute chest pain, heart-type fatty acid binding protein in acute coronary syndrome, CD40 ligand and interleukin-6 in acute myocardial infarction, blood ammonia and lactate in cardiac arrest, as well as tumor necrosis factor-alpha in atrial fibrillation. Endothelial dysfunction, oxidative stress and inflammation are involved in the physiopathology of most cardiac diseases, whether acute or chronic. In summary, natriuretic peptides, cardiac troponin, C-reactive protein are currently the most relevant biomarkers in acute cardiac care. Point-of-care testing and multi-markers use are essential for prompt diagnostic approach and tailored strategic management.

Effect of population selection on 99th percentile values for a high sensitivity cardiac troponin I and T assays

OBJECTIVE

Using objective laboratory and clinical criteria to more accurately determine the 99th percentile values for cardiac troponin I and T.

DESIGN AND METHODS

We measured cardiac troponin T and cardiac troponin I with high-sensitivity assays in a large cohort of apparently healthy community subjects and calculated 99th percentiles for different sexes and ages. Subjects with possible subclinical disease were eliminated based on objective laboratory criteria, eGFR and NT-proBNP, and clinical criteria, history and examination and echocardiogram.

RESULTS

For men and women of all ages, separately, more than 50% of subjects were excluded using these criteria, with a lesser proportion of younger subjects being excluded. In men aged <75 years, the 99th percentile for cTnI decreased by more than 50% from 22.9 ng/L to 10.3 ng/L. In other age groups and for cTnT the decrease was smaller (%) but still considerable.

CONCLUSIONS

For establishing cardiac troponin 99th percentiles, simply using self-reporting of health is insufficient. Objective laboratory measures and clinical and echocardiographic assessments are essential to define a healthy population, especially in older persons.

Highly-sensitive troponin I is increased in patients with gynecological cancers

OBJECTIVES

To investigate troponin I (TnI) in patients with gynecological cancers.

METHODS

Highly-sensitive (HS) and conventional TnI were measured in 25 patients with untreated ovarian cancer, 25 with endometriosis and 25 with benign masses.

RESULTS

Both HS and conventional TnI were increase in cancer patients. Values above the cut-off were found in 44% and 16% cancer patients using HS and conventional TnI methods, respectively.

CONCLUSIONS

Cardiac involvement is frequent in patients with gynecological cancers and should be preferably assessed using HS troponin immunoassays.

Recurrent low-level troponin I elevation is a worse prognostic indicator than occasional injury pattern in patients hospitalized with heart failure

BACKGROUND

Elevated troponin at baseline is associated with higher mortality in heart failure (HF) patients, but the prognostic role of recurrently elevated troponin is not well described.

METHODS AND RESULTS

We performed chart reviews of 196 HF patients without acute coronary syndrome, with at least three Troponin I (TnI) measurements on different admissions. For the analyses, three sets of TnI values closest to baseline, one year and two years were selected for each patient. Based on the three sets of TnI, the lowest value of TnI (minimum), the highest value of TnI (maximum), median value of TnI and delta TnI (3rd TnI-baseline TnI) were derived for each patient. The study population of 196 patients had 632 person-year follow-up, consisted predominantly of elderly (68 ± 10 years) male patients (99%) with mean ejection fraction of 26 ± 13%. Using multivariate Cox proportional hazards model only minimum TnI, but not the maximum, median or delta of TnI values, was significantly associated with mortality (HR: 13.7, 95% CI: 3.7 to 50.8, p<0.001). As a categorical variable, minimum TnI value of >0.04ng/ml was also independently associated with mortality (p=0.01, HR=1.6, 95% CI: 1.1 to 2.3).

CONCLUSIONS

In HF patients without acute coronary syndrome, the persistence of TnI elevation, even at low levels, is associated with a worse survival than sporadic TnI elevations of higher magnitude or any single elevation in TnI; and a recurrent elevation of TnI >0.04ng/ml portends a poor prognosis.

Influence of hemolysis on troponin testing: studies on Beckman Coulter UniCel Dxl 800 Accu-TnI and overview of the literature

Hemolyzed specimens are the leading pre-analytical problem in the laboratory practice, and exert a negative impact on test results. We assessed the reliability of Beckman Coulter UniCel Dxl 800 Accu-TnI testing on hemolyzed specimens.

Twelve non-hemolyzed K

As compared with aliquot #A (HI: 0), a progressive increase of hemolysis occurred in aliquots #B (HI: 25) and #C (HI: 45). The concentration of Accu-TnI gradually decreased from aliquots #A (0.89 μg/L, 0.20–20.16 μg/L), to aliquots #B (0.81 μg/L, 95% CI 0.17–18.37 μg/L; p=0.041) and #C (0.78 μg/L, 95% CI 0.15–17.48 μg/L; p=0.026). In 0/12 (aliquots #B) and 3/12 cases (aliquots #C) the percent decrease exceeded 20% variation. The values remained unchanged in nine samples with Accu-TnI <0.04 μg/L.

Accu-TnI values decrease in hemolyzed samples, but the bias might not be clinically significant in samples with hemoglobin <14.5 g/L.