Ultrarapid Rule-out for Acute Myocardial Infarction Using the Generation 5 Cardiac Troponin T Assay: Results From the REACTION-US Study.

STUDY OBJECTIVE: We determine how well a new Food and Drug Administration-approved single cardiac troponin T (cTnT) Generation 5 baseline measurement below the level of quantification (6 ng/L) and a novel study-derived baseline and 30-minute cTnT Generation 5 algorithm might adequately exclude acute myocardial infarction in patients with suspected acute coronary syndrome in a US emergency department (ED). METHODS: Patients presenting with any symptoms suspicious for acute coronary syndrome were enrolled at a single US ED. Baseline and 30-minute blood samples were obtained and cTnT Generation 5 levels were later batch analyzed in an independent core laboratory. Acute myocardial infarction diagnosis was adjudicated by a cardiologist and an emergency physician. RESULTS: Of the 569 study patients, 44 (7.7%) had an acute myocardial infarction diagnosis. One hundred sixty-four patients (28.8%) had a presentation cTnT Generation 5 level less than 6 ng/L, and none of these individuals had an acute myocardial infarction (negative predictive value of 100% [95% confidence interval 97.8% to 100.0%] and sensitivity of 100% [95% confidence interval 92.0% to 100.0%]). A baseline cTnT Generation 5 value of less than 8 ng/L and a 30-minute Δ of less than 3 ng/L were present in 221 patients (41.0%), and none had acute myocardial infarction (negative predictive value of 100% [95% confidence interval 98.3% to 100.0%] and sensitivity of 100% [95% confidence interval 92.0% to 100.0%]). CONCLUSION: In a single US ED, a single baseline cTnT Generation 5 measurement less than 6 mg/L and values at baseline less than 8 ng/L and a 30-minute Δ of less than 3 ng/L ruled out acute myocardial infarction in 28.8% and 41.0% of patients, respectively. Additional multicenter US studies evaluating these ultrarapid acute myocardial infarction rule-out guidelines are needed, especially to narrow the confidence intervals.