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Abstract
Aims, Objectives and Background Recent guidelines for Acute Coronary Syndrome have recommended rapid diagnosis based on repeat sampling at 2 hours from admission. We investigated the feasibility and diagnostic equivalence of repeat measurement at 2 hours by comparing the diagnostic classification achieved by measurement at 0 and 2 hours with a delta value of <=3 between samples to measurement at 0 and 3 hours and a delta of <=7ng/L between samples.
Method and Design From August to November 2021 all patients with chest pain where a diagnosis of acute coronary syndrome (ACS) was considered had a diagnostic protocol of measurement of cardiac troponin T (cTnT) on admission and at 2 and 3 hours from admission. Requests and results were extracted from the laboratory information system including date and time of result. Data was transferred to a relational database (Access, Microsoft corp) for analysis. Non-parametric statistics were used throughout using the Analyse It.(www.analyse-it.com) add in for Excel.Cardiac troponin T (cTnT) was measured by the Roche high sensitivity cardiac troponin T assay hs-cTnT (Roche diagnostics), range 3 – 10,000ng/L, 10% CV 13ng/L, 99th percentile 14 ng/L.
Results and Conclusion 728 sets of serial samples where obtained on 711 patients, 40.1% female median age 61.8 years,(interquartile range 50.6–75). Comparison of classification is shown in table 1. Overall agreement was good but there were 6 cases where a positive 3 hour delta occurred with a 2 hour delta of 3 or less. 4 had values exceeding the 99th percentile on the admission sample so would have been retained for further investigation. The remaining 4 patients had co-existing clinical conditions that required further investigation.
Conclusion The routine use of serial sampling at admission and 2 hours was clinically safe and resulted in the same clinical decisions in the context of the busy ED environment for the population served by the hospital.