EVALUATION OF A BEDSIDE WHOLE-BLOOD RAPID TROPONIN-T ASSAY IN THE EMERGENCY DEPARTMENT

Objective: To evaluate the performance of a new bedside whole-blood ra pid assay for cardiac troponin T (cTnT) in patients presenting to the ED with symptoms consistent with acute coronary ischemia, Methods: A p rospective, observational trial was performed in 8 participating medic al centers. Serial blood samples were obtained on presentation to the ED and 3 and 6 hours later. The cTnT whole-blood rapid assays were per formed immediately at the site. Treating physicians and patients were blinded to the results of the rapid assays. Serum samples were analyze d at the core laboratory for serum cTnT, creatine kinase (CK)-MB, and myoglobin. The sensitivity of the rapid assay for detecting acute myoc ardial infarction (AMI) was compared with the sensitivities of serum c TnT, CK-MB, and myoglobin assays. Results: Of 721 patients, 102 were d iagnosed as having AMI. The median elapsed time from symptom onset to ED arrival was 3 hours. The sensitivities of the rapid assay for detec ting AMI were 19.6%, 59.0%, and 69.7% at 0, 3, and 6 hours, respective ly. The sensitivities of the serum cTnT assay (p-values for comparison with the rapid assay for cTnT) were 25.0% (p = 0.18), 69.6% (p = 0.04 ), and 79.8% (p = 0.02) at 0, 3, anti 6 hours, respectively. The CK-MB and myoglobin sensitivities were 21.9%, 64.5%, and 81.0%; and 43.8%, 77.4%, and 71.4%, respectively. There were 7 patients with AMI who had negative rapid assay readings and positive serum cTnT levels; 4 of th ese patients were enrolled at the same site. Twenty patients not diagn osed as having AMI had at least one positive rapid assay. Fourteen of these 20 patients had a diagnosis of clinically relevant cardiac disea se. Conclusions: The sensitivity of this whole-blood rapid cTnT assay for detecting AMI is comparable to that of current serum assays and of fers the advantage of providing rapid bedside results. Discrepancies b etween serum and whole-blood assays for cTnT noted in this study may i ndicate the need for further education for the test reader prior to pa tient use.