Author(s): C Geraldine McMahon, John V Lamont
Objective The aim of this study was to evaluate the diagnostic efficacy of multiple tests—heart-type fatty acid–binding protein (H-FABP), cardiac troponin I (cTnI), creatine kinase-MB, and myoglobin—for the early detection of acute myocardial infarction among patients who present to the emergency department with chest pain. Methods A total of 1128 patients provided a total of 2924 venous blood samples. Patients with chest pain were nonselected and treated according to hospital guidelines. Additional cardiac biomarkers were assayed simultaneously at serial time points using the Cardiac Array (Randox Laboratories Ltd, Crumlin, United Kingdom). Results Heart-type fatty acid–binding protein had the greatest sensitivity at 0 to 3 hours (64.3%) and 3 to 6 hours (85.3%) after chest pain onset. The combination of cTnI measurement with H-FABP increased sensitivity to 71.4% at 3 to 6 hours and 88.2% at 3 to 6 hours. Receiver operating characteristic curves demonstrated that H-FABP had the greatest diagnostic ability with area under the curve at 0 to 3 hours of 0.841 and 3 to 6 hours of 0.894. The specificity was also high for the combination of H-FABP with cTnI at these time points. Heart-type fatty acid–binding protein had the highest negative predictive values of all the individual markers: 0 to 3 hours (93%) and 3 to 6 hours (97%). Again, the combined measurement of cTnI with H-FABP increased the negative predictive values to 94% at 0 to 3 hours, 98% at 3 to 6 hours, and 99% at 6 to 12 hours. Conclusion Testing both H-FABP and cTnI using the Cardiac Array proved to be both a reliable diagnostic tool for the early diagnosis of myocardial infarction/acute coronary syndrome and also a valuable rule-out test for patients presenting at 3 to 6 hours after chest pain onset.