Ischemia-modified albumin: We are ready for use in the emergency room?

Abstract

We read the article by Shen et al.[1] about the assessment of ischemia-modified albumin (IMA) for emergency room diagnosis of acute coronary syndrome (ACS). We would like to point out some important aspect of the potential usefulness of serum IMA measurement in patients presenting to the emergency room with acute chest pain are suffering ACS. Most patients brought to the hospital with chest pain and suspected of ACS are eventually ruled out for acute myocardial infarction and active unstable coronary disease. The ideal role of an ischemia marker would thus be as a rule out test. The most logical place to use such a test is in the emergency department [2]. Not all investigators consider the diagnostic performance of IMA either alone or in combination with cardiac troponin, or other biomarkers of necrosis, to be adequate [3]. Recently, a large study prospectively on 248 patients presenting emergency department with symptoms suggestive of ACS did not support the use of IMA as a negative predictor for ACS. All patients had positive IMA results using the 85 U/ml cut-off value recommended by the manufacturer. Receiver operating characteristic curves failed to show improved cut-off points for diagnosis raised 12 h troponin levels or ACS, and the area under the curve was 0.52 and 0.53, respectively [4]. Likewise, Hjortshoj et al.[5] enrolled 107 subjects admitted with suspected ACS, where the sensitivity of admission IMA for a final diagnosis of ACS was 86%, a specificity of 49% and a negative predictive value of 88%. For efficient provision of care in the emergency department, a high negative predictive value may be most critical, for while false negatives are undesirable, true negatives are greater importance, because the correct exclusion of myocardial infarction preserves limited and expensive resources [3]. Although the main limitation of IMA at present is its low specificity, it may be a useful test to rule out ACS from low to moderate pre-test probability conditions with negative cardiac troponins and a negative electrocardiogram. As with any new marker, there are several issues and limitations that require caution: its cardiospecificity, its kinetics during the first hours after ACS, and the optimal cutpoint for clinical validation [6]. Further studies are required to investigate the role of IMA in cardiac ischemic diseases in the emergency department setting. An example is the large multicenter randomised controlled trial evaluating the utility of IMA for risk stratification in 1250 patients presenting with chest discomfort and possible ischemic heart disease, and to evaluate the diagnosis and prognostic implication for IMA for major adverse cardiac events (the IMAgine trial NCT00355992). This probably will provide a definitive answer. Therefore, a test like IMA may be enormously valuable to the emergency physician assessing chest pain patients but we require a better understanding on this marker before it is ready for use. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology (Shewan and Coats 2010;144:1–2).