Application of Albumin-adjusted Ischemia Modified Albumin Index as an Early Screening Marker for Acute Coronary Syndrome / 임상검사와정도관리

ABSTRACT

BACKGROUND: It is often difficult to make a diagnosis of cardiac ischemia in patients attending emergency department (ED) with symptoms of acute coronary syndromes (ACS) because existing cardiac markers are not sensitive for reversible myocardial ischemia. Ischemia modified albumin (IMA) has recently been shown to be an early and sensitive marker of myocardial ischemia. We investigated the usefulness of ischemia modified albumin (IMA) as an early triage marker for ACS and tried to establish a newly standardized albumin-adjusted IMA index which has been expected to be more sensitive and accurate than conventional IMA value. METHODS: We enrolled 209 consecutive patients (men 95, women 114) who presented to the ED with symptoms suggestive of ACS from June to July, 2005. All patients were classified to ACS group (n=42) and others (n=167) based on diagnosis of cardiologists. The ideal cutoff value of IMA was calculated by the receiver operating characteristic (ROC) curve analysis and diagnostic utilities of combination tests (myoglobin, CK-MB, troponin T and EKG) were compared with those of IMA. The albumin-adjusted IMA index was calculated and applicated from the results of correlation assay between serum albumin concentration and IMA value. RESULTS: Mean IMA level (U/mL) of ACS group was significantly higher than that of non-ACS group (P<0.05) and sensitivity and specificity was 92.9% and 35.9% at a cutoff value of 85.1 U/mL, respectably. In combination with conventional cardiac markers, the sensitivity increased to 96.3%. IMA value had a negative lnear relationship with serum albumin concentration (YIMA= -23.1Xalbumin+200, R=0.99) and albumin-adjusted IMA index was calculated as [IMA index = serum albumin conc. (g/dL) x 23 + IMA (U/mL) -100]. The sensitivity and specificity was 97.6% and 34.1% at a cutoff value of 83.3 IMA index, respectively. CONCLUSIONS: IMA is a useful sensitive marker for the identification of ACS in patients with normal cardiac markers and EKG finding and follow-up combination testing may be required to rule out other diseases. The calculated albumin-adjusted IMA index is recommended to make a diagnosis of ACS more sensitively.