Heart fatty acid binding protein as a marker for postmortem detection of early myocardial damage

Depletion of heart fatty acid binding protein (H-FABP) from cardiomyocytes with varying post-ischemia intervals was studied in acute myocardial infarction (AMI) model of rat, and 22 human autopsy cases were studied with streptavidin-peroxidase conjugated method (S-P). It was observed that as early as 15 min after ischemia, the depletion of H-FABP could be detected in model rats. With the ischemic time prolonged, the depletion of H-FABP was more and more evident. In all human cases with myocardial infarction, absent H-FABP staining could be found in infarcted area. And in some suspected early myocardial infarction cases, depletion of H-FABP staining could be demonstrated in areas that showed normal hematoxylin-eosin (HE) staining. The blood samples from model rats before ligation, at varying post-ischemia intervals and various postmortem time were measured for plasma concentration of H-FABP with enzyme-linked immuno-sorbent assay (ELISA) method. At 15 min after myocardial ischemia, the concentration of H-FABP was 4 times higher (546.0 ± 85.3 μg/l) than that of the baseline level (103.7 ± 94.1 μg/l). With the continuation of ischemic time, the concentration of H-FABP increased and peaked at 4 h (1953.5 ± 405.3 μg/l), then decreased. The plasma concentration of H-FABP decreased slightly with postmortem time, but was still significant higher at any postmortem intervals than that of baseline level within 48 h after death. The results suggest that H-FABP staining can detect very early ischemic damages in human myocardium and the elevated plasma concentration of H-FABP in rat was an indicator of AMI, which was not affected by autolysis.