Decreasing Ischemic Electrocardiocraphic Changes in Patients Diagnosed with Acute Myocardial Infarction in the Era of High Sensitivity Troponin Assays
Nowak R, Al-Darzi W, Noll S, Hudson M, Moyer M, Jacobsen G, and McCord J. Decreasing ischemic electrocardiocraphic changes in patients diagnosed with acute myocardial infarction in the era of high sensitivity troponin assays. Acad Emerg Med 2017; 24:S18.
Acad Emerg Med
Background: Previous reports show ST-segment ischemic changes on the electrocardiogram (ECG) in 40-60 % of patients diagnosed with acute myocardial infarction (AMI). Also 1-6 % of these patients were reported to have a normal ECG. The objective of this study were to determine if these ECG findings in those with AMI diagnosis have changed in the era of high sensitivity troponin assays.
Methods: Patients presenting to the Emergency Department (ED) with symptoms suspicious for AMI were prospectively enrolled (May 2013 through April 2015) in this single urban center study. Patients requiring immediate reperfusion therapy were excluded. The cardiac troponin I (cTnI) assay used for patient AMI assessment was the Siemens Ultra (99th % > 0.04 ng/ml). The final AMI diagnosis was adjudicated by a cardiologist and an emergency physician (with a third cardiologist consulted if there was AMI disagreement) according to the 3rduniversal definition of AMI, utilizing all available data in the 30 days post ED visit.
Results: Of the 569 patients enrolled 45 (7.9 %) had a final adjudicated AMI diagnosis. The ECG findings in these patients were: T wave inversion 13 (28.9%), normal 13 (28.9%), left ventricular hypertrophy 10 (22.2%), ST segment depression of ≥ 1 mm 6 (13.3%), ST segment ≥ 1 mm 2 (4.4%) and left bundle branch block 1 (2.2%). In comparing patients with versus without ST-segment elevation or depression there was a non-significant increase in the cTnI levels (13.2 ± 28.3 v 5.9 ± 15.6 ng/ml; p = 0.355).
Conclusions: ST-segment ECG changes are becoming less common and the number of patients with a normal ECG increasing in ED patients diagnosed with AMI. This might be explained by an increased number of patients having a smaller AMI identified using higher sensitivity cardiac troponin assays. These are important trends for ED physicians to be aware of given the increasing numbers of ED triage ECGs being performed. Larger clinical trials are needed to verify these ECG findings in ED patients with a final diagnosis of AMI.