Elevated Troponin Values in the Emergency Department: Most Often Not Associated with Acute Myocardial Infarction
Nowak R, Jain T, Hrabec D, Moyer M, Hudson M, Jacobsen G, and McCord J. Elevated troponin values in the emergency department: Most often not associated with acute myocardial infarction. Acad Emerg Med 2017; 24:S253.
Acad Emerg Med
Background: Cardiac troponin I (cTnI) is widely measured in Emergency Department (ED) patients of having suspicion of possible Acute Myocardial Infarction (AMI). The objective of this study was to determine how often elevated cTnI, at various levels, is associated with a final diagnosis of AMI.
Methods: Adult ED patients being evaluated for possible AMI were prospectively enrolled (from May, 2013 through April 2015) in a single urban center study. Those requiring immediate reperfusion were excluded. Serial cTnI (Siemens Ultra cTnI) measurements were obtained with values > 0.04 ng/ml (99th %) considered to be elevated. The diagnosis of AMI was adjudicated by a cardiologist and an emergency medicine physician (with a 3rd cardiologist available if there was diagnosis disagreement) in accordance with the 3rd universal definition of AMI using all available clinical information over the 30 days after the ED visit. The highest individual patient cTnI was utilized for the analysis and the cTnI values were divided into interquartile ranges.
Results: Of the 569 patients enrolled 116 (20.4 %) had at least one cTnI > 0.04 ng/ml and of these individual 45 (38.8 %) had a final AMI diagnosis. Patients with lower cTnI levels were unlikely to have AMI and the incidence of AMI increased with higher cTnI values (p< 0.001). The highest individual patient cTnI values were divided into interquartile ranges. The number of individuals in each quartile with AMI were: 0.05-0.06; 1 AMI, 28 non-AMI (3.6 %): 0.07-0.10; 7 AMI, 21 non-AMI (25.0 %): 0.11-0.67; 13 AMI, 17 non-AMI (43.3 %): 0.68-100; 24 AMI, 5 non-AMI (82.8 %).
Conclusions: The majority of ED patients being evaluated for possible AMI and having at least one elevated cTnI (> 99th %) value did not have a final AMI diagnosis. However the incidence of AMI increased with higher cTnI interquartile ranges. This trend will likely increase in the United States with the introduction of high sensitivity cardiac troponin assays.