Evaluation of a novel high sensitivity cardiac troponin I assay with whole blood.

BACKGROUND: High-sensitivity cardiac troponin (hs-cTn) assays provide high sensitivity detection of myocardial injury. Although an assay using whole blood can reduce turn-around-time and labour, hs-cTn assays using whole blood samples are novel requiring characterization of their analytical performance. METHODS: The imprecision of Pylon hs-cTnI assay was evaluated with whole blood, plasma and commercial quality control samples. The limit of quantitation (LOQ) of whole blood samples and plasma were determined for the Pylon hs-cTnI assay. The correlation between the Pylon hs-cTnI assay and the Abbott Architect hs-cTnI assay was evaluated using whole blood samples and plasma. RESULTS: The average concentrations of pooled patient plasma were 8.3, 15.0 and 396.9 ng/l, while the corresponding CVs of repeatability and within-laboratory CVs were calculated respectively as 7.6% and 9.9%, 4.3% and 4.5%, and 3.3% and 4.5%. LOQ (20% CV) was 1.2 ng/l in plasma and 2.0 ng/l in whole blood. The lowest concentrations to reach 10% CV were 4.8 ng/l with plasma and 9.4 ng/l with whole blood. Quantification of whole blood and corresponding plasma samples correlated with no effect by hematocrits ranging from 25 to 44%. CONCLUSION: The analytical performance of the Pylon hs-cTnI assay with whole blood is comparable to that of a clinical lab instrument.

How to choose a point-of-care testing for troponin.

BACKGROUND: Point-of-care (POC) cTn assays are needed when the central laboratory is unable to provide timely results to the emergency department. Many POC devices are available. The prospect of choosing them is daunting. In order to provide a quick decision-making reference for POC cTn device selection comparing them to the central laboratory, seven POC devices commonly employed by emergency department were evaluated. METHODS: Firstly, we reviewed all devices package inserts. Secondly, we evaluated several POC cTn assays for imprecision, linearity, and correlation with central laboratory assays according to CLSI EP protocols. The linear regression analyses were performed only for the detectable concentrations. Five cTnI devices (Alere Triage, BioMerieux Vidas, Mitsubishi Pathfast, ReLIA TZ-301, and Radiometer AQT90) were evaluated against a contemporary cTnI assay (Beckman Access II Accu TnI). Two cTnT assays (Radiometer AQT90 and Roche Cobas h232) were compared to a high-sensitivity (hs) cTnT method (Roche Cobas e601). RESULTS: For cTn levels around the 99th percentile upper reference limits (URLs) of the comparator assays, imprecision could not be assessed for the Alere, BioMerieux, and Cobas h232 as they gave undetectable readings due to a lack of assay sensitivity. Imprecision (CV) was unacceptably high for the ReLIA (33.3%). On account of this precision metric, these four assays were deemed unsuitable. Regression analyses showed acceptable linearity for all the POC devices. The correlation coefficients for ReLIA, BioMerieux, Cobas h232, and Radiometer cTnT were >0.95. Unlike the cTnT devices, the cTnI assays employ different capture and detection antibodies leading to non-commutable results. The POC cTn results were concordant with their comparator-Radiometer cTnT 90%, Pathfast cTnI 85%, and Radiometer cTnI 75%. CONCLUSION: Our study provides the procedure and essential data to guide selection of a POC cTn device. Of the point-of-care devices, methods evaluated Radiometer AQT90 (cTnI and cTnT) and Pathfast might be considered.

Distribution and clinical association of plasma soluble ST2 during the development of type 2 diabetes.

AIM: ST2 plays important roles in diabetes and cardiovascular diseases. However, the distribution and changes in plasma soluble ST2 during the development of type 2 diabetes remain unclear. METHODS: In the present study, 525 subjects were recruited and divided into three groups: normal, prediabetic and diabetic subjects. The sST2 levels of all subjects were measured using a high-sensitivity assay. RESULTS: sST2 levels were modestly but significantly elevated in patients with diabetes (26.1ng/ml) compared with normal subjects (19.3ng/ml, P<0.001) and persons with prediabetes (20.3ng/ml, P<0.001). The third and fourth quartiles (21.3 and 29.1ng/ml, respectively) of the sST2 levels were associated with a 2.31- and 4.00-fold increased risk of having diabetes. With the prediabetic group as a reference population, patients with sST2 levels in the fourth quartiles had a higher increased risk of having diabetes mellitus (odds ratios=2.19, P<0.05). Furthermore, each SD log sST2 was associated with a 1.57-fold increased risk of atherosclerosis when all relevant variables was added to the multivariable logistic regression models. After adjustment for age and sex, all markers of liver and renal function, HDL-cholesterol, total cholesterol and smoking status showed a significant association with sST2 levels. CONCLUSION: Elevated sST2 levels were not only associated with metabolic characteristics of diabetes but also with a significantly increased risk of having diabetes.

Differences in the predictive value of red cell distribution width for the mortality of patients with heart failure due to various heart diseases.

BACKGROUND: Increased red blood cell distribution width (RDW) is associated with adverse outcomes in patients with heart failure (HF). The objective of this study was to compare the differences in the predictive value of RDW in patients with HF due to different causes. METHODS: We retrospectively investigated 1,021 HF patients from October 2009 to December 2011 at Fuwai Hospital (Beijing, China). HF in these patients was caused by three diseases; coronary heart disease (CHD), dilated cardiomyopathy (DCM) and valvular heart disease (VHD). Patients were followed-up for 21 ± 9 months. RESULTS: The RDW, mortality and survival duration were significantly different among the three groups. Kaplan-Meier analysis showed that the cumulative survival decreased significantly with increased RDW in patients with HF caused by CHD and DCM, but not in those with HF patients caused by VHD. In a multivariable model, RDW was identified as an independent predictor for the mortality of HF patients with CHD (P < 0.001, HR 1.315, 95% CI 1.122-1.543). The group with higher N-terminal pro-brain natriuretic peptide (NT-proBNP) and higher RDW than median had the lowest cumulative survival in patients with HF due to CHD, but not in patients with HF due to DCM. CONCLUSIONS: RDW is a prognostic indicator for patients with HF caused by CHD and DCM; thus, RDW adds important information to NT-proBNP in CHD caused HF patients.