Baseline High Sensitivity Cardiac Troponin I Level Below Limit of Quantitation Rules Out Acute Myocardial Infarction in the Emergency Department

The objective of our study was to determine the utility of a baseline high sensitivity cardiac troponin (hs-cTnI) value below the limit of quantitation to rule-out acute myocardial infarction (AMI) in patients presenting to the emergency department (ED) with any suspicious symptoms of a cardiac etiology. We enrolled subjects presenting to the ED with symptoms suspicious for AMI. Blood specimens were collected within 1 hour after a triage electrocardiogram. Cardiac troponin I was measured using the Beckman Coulter Access hs-cTnI assay. The diagnosis of AMI was adjudicated by 2 cardiologists using the Third Universal Definition of AMI and Roche Diagnostics Troponin T Generation 5 assay with all available clinical data at 30 days after presentation. A total of 567 subjects had all data required for data analyses. AMI was diagnosed in 46 (8.1%) patients. Two hundred thirty-two (40.9%) individuals had presentation hs-cTnI results <4.0 ng/L. None of the patients with baseline hs-cTnI <4.0 ng/L had an AMI, yielding a negative predictive value of 100.0% and a sensitivity of 100%, and a good prognosis (no AMIs or cardiac-related deaths at 30 days). In this single-center ED study, a baseline presenting novel hs-cTnI value of <4.0 ng/L effectively ruled out AMI in 40.9% of all patients presenting to the ED and having any symptoms suspicious for AMI. Importantly all patients, not only those with chest pain, and those having symptoms for any duration or those with end-stage renal disease requiring dialysis were included.