Analytical and clinical evaluation of a new heart-type fatty acid-binding protein automated assay

Background: The accurate and rapid recognition of myocardial injury in patients presenting in the emergency department (ED) with chest pain continues to be a clinical challenge. Heart-type fatty acid-binding protein (H-FABP) appears to be one of the best candidates among the new early cardiac markers studied. Methods: We evaluated the analytical characteristics of a new quantitative and fully automated H-FABP assay (Randox Laboratories Ltd., Crumlin, UK) and compared its clinical performance with respect to the myoglobin (Myo) assay (Dade Behring, Milan, Italy). A precision study was carried out by testing three levels of quality control (QC) material and two in-house pool (P) samples. To test the accuracy of H-FABP determinations in plasma (lithium-heparin) samples, H-FABP concentrations measured in a set of matched sera and plasma samples were compared. A total of 77 non-consecutive patients (51 males and 26 females; 62 +/- 16 years) who presented to the ED with chest pain suggesting myocardial ischernia were enrolled. The patients were classified into two groups (acute myocardial infarction, n=22; non-acute myocardial infarction, n=55) on the basis of the discharge diagnosis. Results: The between-day imprecision for three levels of control material and serum pool samples was 6.26%-8.04% (range 2.32-44.03 mu g/L) and 9.03%-12.63% (range 11.85-65.13 mu g/L), respectively. In the serum vs. plasma study, bias was +0.178 (95% Cl -0.033 to +0.389). The best cut-off and the associated diagnostic efficacy were 95 mu g/L and 89.47% for Myo and 5.09 mu g/L and 98.70% for H-FABP, respectively. Conclusions: H-FABP determination in patients with ischemic symptoms may be a more reliable early indication of cardiac damage than myoglobin.