Cardiac troponin T as a marker for myocardial ischemia in patients seen atthe emergency department for acute chest pain

Background Identification of patients with acute chest pain at high risk fo r cardiovascular complications is a common and difficult challenge for clin icians and must be based initially on data from the history, physical exami nation, electrocardiogram, and chest radiograph. Some data suggest that ele vations in cardiac troponin T (cTnT) may be useful for detection of less se vere degrees of myocardial injury that may occur in some patients with unst able angina. Therefore we designed a prospective follow-up study to assess the diagnostic performance and prognostic value of cTnT in a population of patients presenting to the emergency department with acute chest pain. Methods The patient population included all 1477 admitted patients aged 30 years or more who presented to the emergency department of an urban teachin g hospital from October 1992, through February 1994, with a chief symptom o f acute chest pain not explained by trauma or chest radiograph abnormalitie s. The 1303 patients (88%) who had 2 or more measurements of cTnT during th e first 24 hours after presentation comprised the final study population, S ensitivity specificity, positive predictive value, negative predictive valu e, and receiver operator characteristics curve (ROC) were determined for cT nT and creatine kinase-MB (CK-MB) (measured using activity and mass assays) data from the first 24 hours after admission for the outcomes of acute myo cardial infarction (AMI) and major cardiac events during the first 72 hours of hospitalization. Results The sensitivity and specificity of cTnT (threshold of 0.1 ng/mL) Fo r detecting AMI during the first 24 hours after presentation were 99% and 8 6%, respectively. The CK-MB activity and mass assays had diagnostic perform ance for detecting AMI similar to cTnT. Among patients who did not meet stu dy criteria for AMI, cTnT was elevated during the first 24 hours in 31% of patients who had major complications, compared with a 17% rate for the CK-M B activity assay and a 3% rate for the CK-MB mass assay. In these patients, the cTnT assay had superior diagnostic performance compared with the CK-MB mass assay as a marker for cardiac complications as assessed with ROC anal ysis (P<.0004). Conclusions In a heterogeneous population of patients seen in the emergency department with acute chest pain, cTnT was similar to CK-MB (activity and mass assays) for detection of AMI and superior to the CK-MB mass assay as a marker For major cardiac events early in the hospital course among those w ho were ruled out for an AMI. Further study is required to determine how th is assay con be used to provide more appropriate, cost-effective care.