The Use in the United States of a Baseline High-Sensitivity Cardiac Troponin T Value Below the Level of Detection to Rule out Acute Myocardial Infarction
Nowak RM, Gandolfo C, Jacobsen G, Christenson R, Moyer M, Hudson M, and McCord J. The use in the United States of a baseline high-sensitivity cardiac troponin t value below the level of detection to rule out acute myocardial infarction. Acad Emerg Med 2018; 25:S147.
Acad Emerg Med
Background: The use of a single baseline high sensitivity cardiac troponin T (hs-cTnT) measurement < level of detection (LoD) to rule-out acute myocardial infarction (AMI) is recommended in the 2015 European Society of Cardiology guidelines. However, this suggestion is mostly based on trials including European populations and using a LoD for hs-cTnT of 5 ng/L. The purpose of this study was to determine if a single baseline hs-cTnT level < 6 ng/L (the FDA approved LoD) could rule-out AMI in a United States (US) Emergency Department (ED) population.
Methods: Patients presenting to the ED with any symptoms suspicious for ACS at a single US tertiary care urban center were enrolled. Baseline blood samples were obtained within 60 minutes of a triage ECG. AMI diagnosis was independently adjudicated by a cardiologist and emergency physician using the 3rd Universal Definition and serial troponin I (TnI) levels (Siemens TnI-Ultra) over 3 hours and all clinical data available 30 days post discharge.
Results: Of the 569 studied subjects 44 (7.7%) had AMI and all enrolled patients had a baseline blood sample drawn. There were 164 (28.8%) subjects that had a baseline hs-cTnT value < the LoD of 6 ng/L and all were without adjudicated AMI (negative predictive value 100% [95%CI 97.8-100.0], sensitivity 100% [95%CI 92.0-100.0]), irrespective of any ECG abnormalities. There were 30 hemodialysis patients enrolled and all had hs-cTn â%o¥ 6 ng/L at presentation. At 30 days there was 1 non-cardiac death, no cardiac deaths, 1 AMI (0.6%), and no revascularization procedures in those patients with a baseline hs-cTnT < 6 ng/ L. The past medical histories of subjects with a hs-cTnT < 6 ng/L included hypertension 98 (59.8%), diabetes mellitus 26 (15.9%), hypercholesterolemia 48 (29.3%), coronary artery disease 31 (18.9%), prior revascularization procedure 21 (12.8%), myocardial infarction 26 (15.9%), and congestive heart failure 11 (6.7%).
Conclusion: A single baseline hs-cTnT level < the US LoD of 6 ng/L can be used to rule-out AMI and identifies a low risk population which may be considered, after appropriate work up for non ACS etiologies as cause for presenting symptoms, for early discharge without further observation and/or cardiac testing. These findings are required to be validated prospectively in further multi-center US trials.