A superior early myocardial infarction marker: Human heart -type fatty acid -binding protein

Various biochemical markers are available to detect cardiac tissue injury after an acute myocardial infarction (AMI) and to estimate the extent of this injury. One of the markers used to detect AMI early after onset of symptoms is heart-type fatty acid-binding protein (H-FABP). To make it clinically applicable it is important to develop rapid diagnostic tests to assess its concentration in whole blood. For this purpose, a one-step quantitative lateral-flow assay for rapid detection of H-FABP has been developed.;To have sufficient amount of H-FABP for in vitro studies, a high-level expression of human H-FABP in Escherichia coli was achieved with a yield of the recombinant protein of 112 mg/L culture. This was the first time in Asia to produce recombinant H-FABP. Moreover, time-consuming procedures for purifying the recombinant protein were eliminated by the one-step purification method.;Among 218 patients presenting with chest pain and suspected myocardial infarction at the Prince of Wales Hospital in Hong Kong, increased H-FABP was found in those with confirmed MI. The area under the receiver operating characteristic (ROC) curve indicating diagnostic performance for H-FABP was 0.995 one hour after admission (1.00 corresponding to 100% sensitivity and 100% specificity). Similar values were reached for CK (0.998) and the "gold-standard" in cardiology, cTnI (0.995), only 8 hours after admission. Therefore, H-FABP reveals the same information 7 hours earlier compared to cTnI and CK. Sensitivity and negative predictive value for H-FABP reached 100% 1 hour after admission. Thus, H-FABP is a promising marker for AMI as it can reliably confirm or exclude myocardial infarction with two tests only, one at admission and one 1 hour post admission.;A rapid and quantitative lateral-flow assay for the detection of H-FABP in serum samples has been successfully developed with a performance time of 5 minutes. 51 serum samples from patients were evaluated using a conventional ELISA and the newly developed lateral-flow assay. A good agreement between the two methods was found according to the Bland and Altman plot. The correlation found was y = 0.9685x - 0.6270 (r2 = 0.9585). With the successful development of the H-FABP lateral-flow assay, we have been the first to develop a novel FABP test designed for quantitative detection of H-FABP in whole blood samples. It requires no sample pretreatment and gives result within 15 minutes. With this rapid and sensitive immunoassay, H-FABP will be soon introduced in clinical practice.;Furthermore, H-FABP also presents in skeletal muscle but with much lower content than in cardiac muscle. This feature makes it possible to use H-FABP in monitoring skeletal muscle injury induced by exercise and physical training. The timely feedback based on the monitoring system will allow coaches to modify the training program as appropriate and thus will prevent athletes from excessive muscle damage and overtraining.