Heart-type fatty acid binding protein--a reliable marker of myocardial necrosis in a heterogeneous group of patients with acute coronary syndrome without persistent ST elevation.

BACKGROUND Myocardial infarction (MI) is one of the most serious challenges of contemporary cardiology. Among biochemical markers, heart-type specific fatty acid binding protein (h-FABP) has a high potential as a marker for the early diagnosis of acute MI. The h-FABP is released early to the bloodstream and may be useful for both rapid confirmation and exclusion of infarction. As opposed to patients with ST segment elevation MI (STEMI), patients with unstable angina (UA)/non-ST segment elevation MI (NSTEMI) present a heterogeneous group in which the confirmation of MI often meets diagnostic difficulties. A rapid, qualitative immunoenzymatic 'point of care' type test, revealing h-FABP in blood, has recently been made available (CardioDetect med). AIM To evaluate diagnostic value of early measurements of h-FABP and other markers of necrosis (cTnT, CK-MB, CK-MB mass) in a group of 100 patients with an acute coronary syndrome (ACS) without persistent ST segment elevation (NSTE ACS). METHODS We studied 100 consecutive patients (34 women, 66 men; mean age 61.6 years) with strong suspicion of NSTE ACS and chest pain lasting <24 h before admission. During admission and after 3 and 6 hours patients had measured a panel of conventional biomarkers as well as quantitative measurements of h-FABP (on admission and 3 hours later) using CardioDetect med. The ultimate diagnosis of infarction (NSTEMI) was confirmed in case of a second (6 h after admission) positive quantitative result of cardiac troponin. Non-ST segment elevation MI was finally diagnosed in 56 patients. RESULTS The comparison of diagnostic utility of all analysed biomarkers of necrosis revealed that h-FABP was superior to other parameters, when measured on admission, and was characterised by 94.7% sensitivity, 100% specificity, 100% positive predictive value, 93.4% negative predictive value and 97% accuracy. Other biomarkers had on admission lower sensitivity - 70.1% for CK-MB mass, 66.7% for CK-MB, 64.9% for cTnT, whereas their specificity was 97.6% for CK-MB mass, 93% for CK-MB and 100% for cTnT. CONCLUSIONS Qualitative h-FABP test (CardioDetect med) showed excellent sensitivity, higher than measurements of CK-MB mass, CK-MB, and cTnT on hospital admission, and high specificity in the patient group with NSTE ACS. The h-FABP seems to be an excellent biochemical cardiac marker for diagnosing NSTEMI, especially in its early phase, allowing exclusion of myocardial necrosis.