Ischaemia modified albumin cannot be used for rapid exclusion of acute coronary syndrome

To evaluate ischaemia modified albumin (IMA) as an early negative predictor of acute coronary syndrome (ACS) in different time to presentation groups and different cardiac risk groups.

A prospective observational study was performed in the emergency department at Royal Perth Hospital. Consecutive patients with symptoms suggestive of ACS needing delayed troponin measurements were recruited. All enrolled patients had both IMA and troponin measurements performed on their initial blood samples. The time of the initial blood tests and thrombolysis in myocardial ischaemia (TIMI) risk scores were recorded. Initial IMA results were compared with 12 h troponin levels and a discharge diagnosis of ACS. More detailed analyses were made according to different times to presentation (0-4 h, 5-12 h) and cardiac risk (TIMI score 0-1, 2-7). Sensitivity, specificity, positive predictive value, negative predictive value and likelihood ratio were calculated. Receiver operating characteristic (ROC) curves were plotted to determine the best diagnostic cut-off for IMA.

248 patients were enrolled (151 (61%) men, mean age 65 years). All 248 patients had 'positive' IMA results using the 85 U/ml cut-off value recommended by the manufacturer. ROC curves failed to show improved cut-off points for diagnosing raised 12 h troponin levels or ACS; the area under the curve (AUC) was 0.52 and 0.53, respectively. ROC curves produced similar poor results in all subgroups. In the subgroup with time to presentation 0-4 h and TIMI score 0-1 for diagnosing ACS, the AUC was slightly better at 0.58.

This study does not support the use of IMA as a negative predictor for ACS.