Undetectable High-Sensitivity Cardiac Troponin T Level in the Emergency Department and Risk of Myocardial Infarction

Abstract

This study sought to evaluate if an undetectable (<5 ng/l) high-sensitivity cardiac troponin T (hs-cTnT) level and anelectrocardiogram (ECG) without signs of ischemia can rule out myocardial infarction (MI) in the emergency department (ED). Chest pain is a common symptom often associated with benign conditions, but may be a sign of MI. Because there is no rapid way to rule out MI, many patients are admitted to the hospital. All patients who sought medical attention for chest pain and had at least 1 hs-cTnT analyzed during 2 years at theKarolinska University Hospital, Stockholm, Sweden, were included. We calculated the negative predictive values of an undetectable hs-cTnT and ECG without ischemia for MI and death within 30 days. We included 14,636 patients, of whom 8,907 (61%) had an initial hs-cTnT of<5 ng/l; 21% had 5 to 14 ng/l, and18% had >14 ng/l. During 30-day follow-up, 39 (0.44%) patients with undetectable hs-cTnT had a MI, of whom 15 (0.17%) had no ischemic ECG changes. The negative predictive value for MI within 30 days in patients with undetectable hs-cTnT and no ischemic ECG changes was 99.8% (95% confidence interval [CI]: 99.7 to 99.9). The negative predictive value for death was 100% (95% CI: 99.9 to 100). All patients with chest pain who have an initial hs-cTnT level of<5 ng/l and no signs of ischemia on an ECG have aminimal risk of MI or death within 30 days, and can be safely discharged directly from the ED.