Ischemia-Modified Albumin Improves the Usefulness of Standard Cardiac Biomarkers for the Diagnosis of Myocardial Ischemia in the Emergency Department Setting

Abstract

We studied the role of ischemia-modified albumin (IMA) with standard biomarkers (myoglobin, creatine kinase-MB [CK-MB], troponin I [TnI]) in assessment of 200 patients with suspected myocardial ischemia admitted to the emergency department. Every case was reviewed by a cardiologist. A clinical diagnosis of ischemia was assigned and correlated with biomarker test results. Of the patients, 25 (13.0%) had myocardial ischemia. Receiver operating characteristic curves demonstrated IMA as highly sensitive but somewhat poorly specific for the presence of ischemia (area under curve, 0.63; P = .01). With a cut point of 90 U/mL, the Albumin Cobalt Binding Test had 80% sensitivity and 31% specificity for diagnosing ischemia and a negative predictive value of 92%. IMA was positive in 4 of 5 patients with electrocardiographic (ECG) evidence of ischemia and 16 of 20 patients with coronary ischemia but negative ECG. Among the same patients, the myoglobin-CK-MB-TnI triad had a sensitivity of 57%. The combination of IMA-myoglobin-CK-MB-TnI increased the sensitivity for detecting ischemia to 97%, with a negative predictive value of 92%. IMA is highly sensitive and has a high negative predictive value, which might improve the usefulness of standard biomarkers of myocardial ischemia.