Comparison of heart-type fatty acid binding protein and cardiac troponin I for early detection of myocardial infarction after coronary bypass surgery

Abstract

Objectives: Heart-type fatty acid binding protein (hFABP) is as a novel marker to detect myocardial injury shortly after onset of ischemia. We therefore compared cardiac troponin I (cTnI), which is most sensitive and specific for myocardial infarction, with hFABP in respect of fast and reliable response following coronary artery bypass grafting (CABG). Methods: One-hundred-eight consecutive patients undergoing isolated CABG with cardiopulmonary bypass were enrolled in this prospective, observational study. Serial blood samples were taken preoperatively, at 1, 6, 12, and 24h after surgery; electrocardiograms, clinical data and adverse events were recorded. hFABP and cTnI were analyzed using a combined quantitative bedside assay (CardioDetect® combi, Rennessens GmbH, Berlin, Germany). Postoperative myocardial infarction (PMI) was defined as a cTnI-elevation (>10ng/ml) within the first 24h after surgery. Results: Fourteen out of 108 patients (group1) were identified with PMI following the PMI criteria mentioned above, whereas 94 patients had no PMI and thus, were used as controls (group2). As a result, both hFABP and cTnI were significantly increased in group 1 compared to group 2 (P<0.001; ANOVA), hFABP however separated much earlier within 1h after CABG between group 1 and 2, whereas cTnI differed not until 12h after surgery between groups. A hFABP level of 20µg/mL at 1h after CABG best detected the presence of PMI with an area under the receiver operating characteristic (ROC) curve of 78.3% (sensitivity:93%, specificity:68%). Conclusion: hFABP is a highly sensitive biomarker, which detects PMI reliably as soon as 1h after CABG surgery and thus much earlier than standard cTnI measurement.