Delta troponin for the early diagnosis of AMI in emergency patients with chest pain

Objectives: In patients presenting to the Emergency Department (ED) with potential acute myocardial infarction (AMI), elevated cardiac troponin (cTn) levels are indicative of myocardial necrosis. We assessed the accuracy of ` delta cTn' at 2 h or 6 h compared to the cTn concentration above the 99th percentile reference value for AMI in a prospective study of adult patients presenting to ED with symptoms suggestive of possible acute coronary syndrome. Methods: Blood was sampled for cardiac troponin I (cTnI) on presentation, and at 2 h and 6 h following presentation using a sensitive assay (Beckman AccuTnI). All clinical endpoints were adjudicated by a cardiologist who was blinded to the 2 h cTn assay result. Results: Of the 874 patients, 70 (8%) were diagnosed with an AMI during their index presentation. The area under the ROC curve for diagnosing AMI at 2 h was 0.89 [95%CI, 0.84-0.95] for absolute delta cTn versus 0.79 [95%CI 0.73-0.85] for the relative change. Specificity and PPV at 2 h were optimized using a delta cTnI >= 0.03 mu g/L (95.8% [95%CI 94.1-97.0] and 61.4% [95%CI 50.9-70.9] respectively). Sensitivity and NPV for AMI were optimized using the 99th percentile with the addition of a delta of < 0.03 mu g/L (97.1% [95%CI 90.2-99.2] and 99.7% [95%CI 99-99.9] respectively). Conclusions: An algorithm incorporating cTnI concentration and delta cTn values with a sensitive troponin assay allows accurate diagnosis of AMI within 2 h from presentation and earlier rule-out of AMI in the majority of patients. Crown Copyright (C) 2013 Published by Elsevier Ireland Ltd. All rights reserved.