Patients were not managed on the basis of test results and may have undergone additional investigations and management which could have influenced their outcomes. Finally, in keeping with the majority of studies in this area, the results are based on observational data. Blood samples were obtained at the bedside but were processed by research nurses not involved in patient care, so the impact on diagnostic efficiency is unmeasurable. Although this may reduce the generalisability of the findings, focusing on patients with a shorter duration of symptoms would be expected to reduce diagnostic accuracy, as troponin release is a time-dependent phenomenon. First, the majority of patients were male (74.3%), and only those with symptoms for less than 12 hours were included. While the findings of Body et al are encouraging, there are important limitations to consider. Point of care compared with central laboratory testing for cardiac troponin in patients with suspected acute coronary syndrome.
When T-MACS was applied with the 99th centile of the iSTAT assay at 0 and 3 hours, the authors report excellent diagnostic accuracy, with an Negative predictive value (NPV) of 99.5% (95% CI 96.5% to 99.9%) and sensitivity of 99.0% (95% CI 94.4% to 100%), for a primary outcome of myocardial infarction, coronary revascularisation or all-cause death at 30 days. 5 In this study, cardiac troponin I concentrations were measured on a central laboratory platform and on the point of care device in 716 patients across eight sites in England. The Abbott iSTAT point of care assay has a reported 99th centile of 80 ng/L and limit of detection of 20 ng/L, with a coefficient of variation of 16.5% at the 99th centile diagnostic threshold. Body et al report results from a prospective cohort study evaluating the diagnostic accuracy of the Troponin-only Manchester Acute Coronary Syndrome (T-MACS) decision aid when applied using a contemporary point of care cardiac troponin I assay.
Similar to blood glucose testing, the delivery of rapid and accurate measurements of cardiac troponin at the bedside could allow earlier diagnosis or rule out of myocardial infarction in practice see figure 1. One potential strategy to improve efficiency is through the use of point of care devices.
3 4 In practical terms, implementation of these approaches requires investment in infrastructure to deliver accurate and timely cardiac troponin results on a high-sensitivity platform which is not always available.
The higher precision and lower limits of detection afforded by these tests has facilitated the development of pathways which can rule out myocardial infarction at an earlier stage, the majority of which have demonstrated a magnitude of benefits in diagnostic accuracy compared with using the recommended diagnostic threshold (99th centile) alone. 2 While high-sensitivity assays were first introduced in Europe in 2010, they have only recently become available for use in clinical practice in the USA. Such strategies have the potential to improve patient experience and optimise resource allocation both in the emergency department and in hospital, at a time of ever-increasing demands.Ĭardiac troponin is the biomarker of choice for the detection of myocardial injury, and international guidelines recommend concentrations are measured using a high-sensitivity assay.
#Istat troponin procedure serial#
1 Therefore, for several years, there has been a drive to develop diagnostic strategies which allow accurate identification of patients without myocardial infarction at an earlier stage, who may not require admission to hospital for serial cardiac biomarker testing. However, only one in five patients are found to have had a myocardial infarction. Around one million patients present to hospital with chest pain every year, accounting for approximately 5% of all emergency department attendances in the UK.
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