Single high-sensitivity cardiac troponin T reading can safely exclude MI in ED

USA: A single high-sensitivity cardiac troponin T (hs-cTnT) below the cutoff of 6 ng/L is a rapid and safe strategy for identifying a substantial number of patients at very low risk for acute myocardial injury and infarction, claims a recent study in Circulation. 

The use of a single hs-cTnT below the limit of detection (LoD) of 5 ng/L to exclude acute myocardial infarction has a backing of good data. As per the United States Food and Drug Administration (US FDA), hs-cTnT can only report to the limit of quantitation (LoQ) of 6 ng/L -- a threshold for which the data is limited. 

Yader Sandoval, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, and colleagues conducted the study with the goal to determine whether a single hs-cTnT below the LoQ of 6 ng/L is a safe strategy to identify patients at low risk for acute myocardial injury and infarction.

For this purpose, the researchers examined the efficacy (proportion identified as low-risk based on baseline hs-cTnT<6 ng/L) of identifying low-risk patients in a multicenter (n=22 sites) US cohort study of emergency department patients undergoing at least one hs-cTnT (CV Data Mart Biomarker cohort). They then determined the performance of a single hs-cTnT<6 ng/L (biomarker alone) to exclude acute myocardial injury (subsequent hs-cTnT >99th percentile in those with an initial hs-cTnT<6 ng/L). 

Subsequently, they tested the clinically intended rule-out strategy combining a nonischemic electrocardiogram with a baseline hs-cTnT<6 ng/L in an adjudicated cohort in which the diagnostic performance for ruling-out acute myocardial infarction and safety (myocardial infarction or death at 30-days) were evaluated.