Biomarker Differentiation of Type 1 from Type 2 Acute Myocardial Infarction in the Emergency Department: N-Terminal Pro B-Type Natriuretic Peptide/High-Sensitivity Cardiac Troponin T

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Conference Proceeding

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Acad Emerg Med


Background: Type 1 acute myocardial infarction (AMI) is caused by coronary artery thrombus leading to decreased myocardial blood flow with myocyte necrosis while type 2 is related to non-coronary artery disease causing imbalance between myocardial oxygen supply/demand resulting in myocardial injury with necrosis. Accurate differentiation can be clinically difficult but is necessary as specific therapies for each AMI type differ. The purpose of this study was to determine whether the N-terminal pro B-type natriuretic peptide (NT-proBNP)/high sensitivity cardiac troponin T (hs-cTnT) ratio could aid in this AMI type differentiation in Emergency Department (ED) diagnosed patients.

Methods: Patients presenting with any symptoms suspicious of ACS at a single United States tertiary care urban center were enrolled. Baseline (within 1 hour of triage ECG) and 30, 60 and 180 minute blood samples were obtained for blinded independent NT-proBNP (Roche) and hs-cTnT (Roche) measurements. AMI diagnosis (type 1 or 2) was independently adjudicated by 2 physicians after reviewing all available 30 day clinical data and serial cardiac troponin I (Siemens Ultra) levels over 3 hours in accordance with the 3rd Universal Definition of AMI.

Results: Of the 569 enrolled (2013-2015) patients 44 (7.7%) had AMI. Twenty-six (59%) had type 1 while 18 (41%) had type 2. The mean (median) NT-proBNP/hscTnT ratio at all 4 time points was significantly higher in type 2 AMI as shown: Type 1 Type 2 P-value Baseline 34.8 ± 74.9 (7.3) 70.1 ± 72.9 (53.0) 0.003 30 minutes 34.5 ± 76.0 (5.8) 68.9 ± 76.3 (49.5) 0.002 60 minutes 35.0 ± 79.2 (6.3) 65.3 ± 69.4 (47.5) 0.003 180 minutes 34.4 ± 79.8 (4.3) 48.6 ± 41.9 (33.7) 0.016 Additionally the NT-proBNP/hs-cTnT ratio changes from baseline-30 minutes, 30-60 minutes and 60-180 minutes were not significantly different.

Conclusion: The NT-proBNP/hs-cTnT ratio may help to consistently differentiate type 1 from type 2 AMI in the ED from baseline to 3 hour measurements. This may be the case as type 2 AMI results from cardiac supply/demand mismatch caused by non ACS disease which may result in increased cardiac wall stress with release of earlier and larger amounts of NT-proBNP. Further studies are needed to determine the validity of these results and how to use them to direct correct ED care in patients diagnosed with AMI.



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