Objective: The aim of this prospective study was to evaluate the diagnostic value of heart-type fatty acid binding protein (H-FABP) determined by qualitative immunoassay method for the detection of minor myocardial damage (MMD) in patients with non-ST elevation acute coronary syndrome (NSTE-ACS).
Methods: The study consisted of 62 patients with NSTE-ACS. Cardiac troponin I (cTnI) and creatine kinase MB isoenzyme (CK-MB) values were measured at arrival. Myoglobin and H-FABP were obtained if cTnI level was found to be elevated. A control group included 20 subjects with normal cTnI and CK-MB values. H-FABP was determined by a rapid qualitative immunochromatographic test. Patients were classified as MMD-ACS group if they had abnormal cTnI and normal CK-MB (n=24) and as NSTEMI-ACS group if they had elevated both cTnI and CK-MB (n=38). The diagnostic accuracy of H-FABP for minor myocardial damage was determined using ROC analysis.
Results: The sensitivity of the H-FABP was significantly higher for NSTEMI-ACS than for MMD-ACS (44.7% vs 0%, p<0.001) and its specificity was 95% for both groups. The diagnostic efficacy rates for myoglobin and H-FABP were 75% and 43% for MMD-ACS, 74% and 62% for NSTEMI-ACS. Positive predictive value for H-FABP and myoglobin were found to be 0% and 80.8% in MMD-ACS, 94% and 87% in NSTEMI-ACS and negative predictive value was 44% and 69.5% in MMD-ACS, 47.5% and 59% in NSTEMI-ACS, respectively. AUC for myoglobin was significantly greater than that for H-FABP in MMD-ACS group (0.754 vs 0.525, p=0.027). The sensitivity of the H-FABP was significantly higher in patients with >3-fold increase in cTnI than those with <3-fold increase in cTnI (46.8% vs. 6.7%, p<0.001). A positive correlation was found between the magnitude of cTnI rise and H-FABP results (r=0.45, p<0.001).
Conclusions: H-FABP determined by the rapid qualitative immunochromatographic test has almost similar diagnostic value to that of myoglobin for identifying NSTEMI-ACS, however, does not seem to represent diagnostic potential for the detection of MMD.