Abstract 21588: Utilization of a High Sensitive Troponin T Assay Optimizes Serial Sampling in the Diagnosis of Acute Myocardial Infarction Compared to Multiple Contemporary Troponin Assays
Background: Cardiac troponin (cTn) is the preferred biomarker for detection of cardiac injury and acute myocardial infarction (AMI). Optimal diagnosis is inhibited due to the relative insensitivity of current cTn assays at the time of initial presentation. Accordingly, we evaluated the diagnostic accuracy of serial sampling using a high sensitive troponin T assay for early diagnosis of AMI. Contemporary cTn assays were used as comparators.
Methods: The study population consisted of 288 patients presenting to the Emergency Department with symptoms suggestive of AMI. Specimens were drawn at presentation (baseline), 3 hours, and 6 hours. cTn concentrations were quantitated with two troponin I assays (Beckman Coulter Accu-TnI, Siemens TnI Ultra) and two troponin T assays (Roche 4th generation TnT and high sensitive TnT). The 99th percentile defined abnormality for each assay: 0.04 ng/mL, 0.03 ng/mL, 0.01 ng/mL, and 14 pg/mL, respectively. Sensitivity, specificity, PPV, NPV, and optimal cTn changes over defined time intervals (deltas) were calculated.
Results: Diagnosis of AMI (43% STEMI, 57% NSTEMI) was made in 98 patients, 92 patients ruled out AMI but were admitted for further evaluation, and 98 patients ruled out AMI and were discharged. Baseline cTn sensitivity was greatest with the hsTnT (93.9%) and Ultra TnI (98.0%) assays but with significant loss of specificity (79.9% and 89.3%, respectively). After 3 hours, sensitivity and specificity of all cTn assays was statistically significant to 6 hour cTn concentrations (p <0.001), utilizing the optimal delta for each assay (Table 1). At 3 hours, hsTnT had the greatest sensitivity with an absolute change of 8 pg/mL yielding the highest NPV (98.9%).
Conclusions: Utilizing the optimal delta for cTn affords accurate diagnosis of AMI in a majority of patients 3 hours after presentation. Furthermore, the hsTnT assay demonstrates the greatest sensitivity in serial sampling, potentially resulting in improved patient triage.
- © 2010 by American Heart Association, Inc.