To the Editor We have with great interest read the study by Carlton et al1 on rapid rule-out of acute myocardial infarction (AMI) using high-sensitivity cardiac troponin I (hs-cTnI) level at presentation to the emergency department. This study included a pooled population of 3155 patients with symptoms suggestive of cardiac ischemia but with an electrocardiogram without evidence of ischemia. The study contributes important new knowledge on ruling out AMI. In total, 594 patients (18.8%) were ruled out for AMI at presentation to the emergency department using the limit of detection at 1.2 ng/L as a cutoff. Rule out was performed with a negative predictive value of 99.5%, allowing early discharge. The study used the hs-cTnI analysis (Architect Stat; Abbott Diagnostics), and the authors reported an impressive coefficient of variation of 10% at 4.7 ng/L. However, the assay performance in the study by Carlton et al1 raises a pivotal question: is assay performance in studies comparable with assay performance in daily clinical practice?
Lauridsen KG, Revsholm J, Løfgren B. Appropriate Use of High-Sensitivity Cardiac Troponin Levels in Patients With Suspected Acute Myocardial Infarction. JAMA Cardiol. 2017;2(2):228-229. doi:10.1001/jamacardio.2016.4249