Unbound Free Fatty Acids and Heart-Type Fatty Acid–Binding Protein: Diagnostic Assays and Clinical Applications

Biochemical markers in acute coronary syndrome

Owing to their higher risk for cardiac death or ischemic complications, patients with acute coronary syndrome (ACS) must be identified from other causes of chest pain. Patients with acute coronary syndrome are divided into categories based on their electrocardiogram; those with new ST-segment elevation and those who present with ST-segment depression. The subgroups of patients with ST-segment elevation are candidates for immediate reperfusion, while fibrinolysis appears harmful for those with non-ST elevation myocardial infarction. There is increasing evidence to encourage appropriate risk stratification before deciding on a management strategy (invasive or conservative) for each patient. The TIMI, GRACE or PURSUIT risk models are recommended as useful for decisions regarding therapeutic options. Cardiac biomarkers are useful additions to these clinical tools to correctly risk stratify ACS patients. Cardiac troponin is the biomarker of choice to detect myocardial necrosis and is central to the universal definition of myocardial infarction. The introduction of troponin assays with a lower limit of detection will allow for earlier diagnosis of patients who present with chest pain. Analytical and clinical validations of these new assays are currently in progress. The question is whether the lower detection limit of the troponin assays will be able to indicate myocardial ischemia in the absence of myocardial necrosis. Previous to the development of ultrasensitive cardiac troponin assays free fatty acids unbound to albumin and ischemia modified albumin were proposed as biochemical markers of ischemia. Advances in our knowledge of the pathogenesis of acute coronary thrombosis have stimulated the development of new biomarkers. Markers of left ventricular performance (N-terminal pro-brain natriuretic peptide) and inflammation (e.g. C-reactive protein) are generally recognized as risk indicators. Studies suggest that using a number of biomarkers clinicians can risk stratify patients over a broad range of short and long term cardiac events. Nevertheless, it is still under debate as to which biomarker combination is best preferred for risk prediction. This review will focus on recent practice guidelines for the management of patients with ACS as well as current advances in cardiac biomarkers, their integration into clinical care and their diagnostic, prognostic and therapeutic utility.

The role of heart-type fatty acid-binding protein in predicting properties of coronary atherosclerosis in patients with acute coronary syndrome

INTRODUCTION

Fatty acid-binding protein (FABP) is an independent predictor of cardiac events. However, the relation between increasing FABP and coronary atherosclerosis is unknown. We have investigated the relation between FABP and angiographic properties of coronary atherosclerosis in patients with acute coronary syndrome (ACS).

METHODS

The study population consisted of 93 patients with ACS (mean age: 56±10 years). Patients presenting to the emergency department within 2 h after onset of anginal symptoms were enrolled in the study. FABP was measured at second, fourth and sixth hours of chest pain. Cut-off FABP was accepted as 1.9 ng/ml. Coronary atherosclerosis was assessed with diseased vessel number (≥50 and ≥70% luminal narrowing), Gensini and extent scores.

RESULTS

Median FABP-2 was 2.9 ng/ml (interquartile range: 1.6-10.4). Peak FABP was measured at fourth hour [median: 35.0 ng/ml (interquartile range: 2-77)]. There was a nonsignificant relation between angiographic findings and FABP-2. At fourth hour, Gensini, extent score and diseased vessel number were significantly higher above the cut-off level of FABP-4 (Gensini score: 3.7±3.4 vs. 6.2±3.4, P=0.005; extent score: 11.1±10 vs. 22.3±19.2, P=0.007; diseased vessel: 0.7±0.6 vs. 1.6±1.0, P=0.003, respectively). The sensitivity of FABP-2 for at least 50% lesion was 70%. The highest sensitivity was obtained at fourth hour (85% for ≥50% and 88% for ≥70% lesions). The sensitivity and positive predictive values for revascularization were 70 and 77% for FABP-2, 89 and 80% for FABP-4 and 89 and 81% for FABP-6.

CONCLUSION

FABP levels are closely related with angiographic properties of patients with ACS. FABP may be an early and important marker for predicting the coronary anatomy and decision of treatment.

Heart fatty acid-binding protein may not be an early biomarker for anthracycline-induced cardiotoxicity in rabbits

The objective of this study was to investigate the feasibility of using serum heart fatty acid-binding protein (H-FABP) concentrations as an early biomarker for doxorubicin-induced myocardial damage. Forty-four male rabbits were randomly divided into a control (8 rabbits) or one of four doxorubicin groups (8 rabbits in each group). Rabbits in the control group received saline, whereas rabbits in the doxorubicin group received 2 mg/kg doxorubicin weekly for 1-8 weeks. Rabbits in the doxorubicin groups received doxorubicin 2 mg/kg for one (Group 1, 8 rabbits), two (Group 2, 8 rabbits), four (Group 3, 9 rabbits), or eight (Group 4, 11 rabbits) weeks. Echocardiography was performed to measure left ventricular ejection fraction (LVEF), shortening fraction (FS), and E/A ratio. Cardiotoxicity scores were assessed by light microscopy using Billingham's method and also by electron microscopy. Serum H-FABP concentrations were quantified by a rabbit-specific enzyme-linked immunosorbent assay. Decreased LVEF, FS, and E/A ratio were detected in Group 4 (P < 0.05). Billingham cardiomyopathy scores of the rabbits in Group 3 were significantly higher (P < 0.05) than those of rabbits in the control group or Groups 1 or 2. Billingham cardiomyopathy scores in Group 4 were the highest of all groups (P < 0.05). Myocardial injury was demonstrable by electron microscopy in rabbits in Groups 2, 3, and 4. Compared with the control group, serum H-FABP concentrations increased only in Group 4 (P < 0.05). Serum H-FABP concentrations may not be a sensitive method for assessing early cardiotoxicity of doxorubicin.

Lysophosphatidylcholines activate G2A inducing G(αi)₋₁-/G(αq/)₁₁- Ca²(+) flux, G(βγ)-Hck activation and clathrin/β-arrestin-1/GRK6 recruitment in PMNs

Lyso-PCs (lysophosphatidylcholines) are a mixture of lipids that accumulate during storage of cellular blood components, have been implicated in TRALI (transfusion-related acute lung injury) and directly affect the physiology of neutrophils [PMNs (polymorphonuclear leucocytes)]. Because the G2A receptor, expressed on PMNs, has been reported to recognize lyso-PCs, we hypothesize that lyso-PC activation of G2A causes the increases in cytosolic Ca²(+) via release of G(α) and G(βγ) subunits, kinase activation, and the recruitment of clathrin, β-arrestin-1 and GRK6 (G-protein receptor kinase 6) to G2A for signal transduction. PMNs were isolated by standard techniques, primed with lyso-PCs for 5-180 s, and lysed for Western blot analysis, immunoprecipitation or subcellular fractionation, or fixed and smeared on to slides for digital microscopy. The results demonstrated that lyso-PCs cause rapid activation of the G2A receptor through S-phosphorylation and internalization resulting in G(αi)₋₁ and G(αq/)₁₁ release leading to increases in cytosolic Ca²(+), which was inhibited by an antibody to G2A or intracellular neutralization of these subunits. Lyso-PCs also caused the release of the G(βγ) subunit which demonstrated a physical interaction (FRET+) with activated Hck (haemopoietic cell kinase; Tyr⁴¹¹). Moreover, G2A recruited clathrin, β-arrestin-1 and GRK6: clathrin is important for signal transduction, GRK6 for receptor de-sensitization, and β-arrestin-1 both propagates and terminates signals. We conclude that lyso-PC activation of G2A caused release of G(αi)₋₁, G(αq/)₁₁ and G(βγ), resulting in cytosolic Ca²(+) flux, Hck activation, and recruitment of clathrin, β-arrestin-1 and GRK6.

Cardiac biomarkers - the old and the new: a review

Biomarkers are biological parameters that can be objectively measured and quantified as indicators of normal biologic processes, pathogenic processes, or responses to a therapeutic intervention. Typically thought of as disease process screening, diagnosing, or monitoring tools, biomarkers may also be used to determine disease susceptibility and eligibility for specific therapies. Cardiac biomarkers are protein components of cell structures that are released into circulation when myocardial injury occurs. They play a pivotal role in the diagnosis, risk stratification, and treatment of patients with chest pain and suspected acute coronary syndrome and those with acute exacerbations of heart failure. Cardiac markers are central to the new definition of acute myocardial infarction put forward by the American College of Cardiology and the European Society of Cardiology. Active investigation has brought forward an increasingly large number of novel candidate markers but few have withstood the test of time and become integrated into contemporary clinical care because of their readily apparent diagnostic, prognostic, or therapeutic utility.

Correlation of heart-type fatty acid-binding protein with mortality and echocardiographic data in patients with pulmonary embolism at intermediate risk

BACKGROUND

The management strategy in patients presenting with pulmonary embolism at intermediate risk still remains controversial. Our aim was to determine the role of heart-type fatty acid-binding protein (H-FABP) in this patient population.

METHODS

One hundred one consecutive patients with confirmed pulmonary embolism and echocardiographic signs of right ventricular overload but without evidence for hypotension or shock, referred to as pulmonary embolism at intermediate risk, were included in the study. Heart-type fatty acid-binding protein and other biomarkers were measured in all patients upon arrival in the emergency department.

RESULTS

Of the included 101 patients, 14 had positive H-FABP tests. Ten patients with positive H-FABP (71%) had clinical deterioration during the hospital course and required inotropic support and 8 of these patients died. None of the 87 patients with a negative test worsened or needed inotropic support or died during hospital stay (P < .005). In the H-FABP-positive group, right ventricular function on echocardiography was more impaired (tricuspid annular plane systolic excursion 13 +/- 4 vs 18 +/- 4 mm, RV/LV ratio 1.1 +/- 0.2 vs 0.9 +/- 0.2, presence of paradoxical septal movement 79% vs 46%, presence of McConnell sign 100% vs 60%, respectively, all P < .05) compared to the H-FABP-negative group. After adjusting for potential confounding parameters, in multivariate analysis, H-FABP was the only independent predictor of mortality.

CONCLUSIONS

Heart-type fatty acid-binding protein significantly predicts mortality in patients with pulmonary embolism at intermediate risk. Furthermore, it is significantly associated with impaired right ventricular function and shows better correlation with mortality than troponin I. It may be a novel prognostic parameter enabling the optimization of management strategy in the very difficult population of pulmonary embolism at intermediate risk.

Heart fatty acid binding protein (H-FABP) as a diagnostic biomarker in patients with acute coronary syndrome

AIMS AND OBJECTIVES

Diagnosis of myocardial ischaemia at an early stage in the emergency department is often difficult. A recently proposed biomarker, heart fatty acid binding protein (H-FABP) has been found to appear in the circulation superior to that of cardiac troponins in the early hours of acute coronary syndrome. We proposed to evaluate the levels of H-FABP and ascertain its utility as an early biomarker for acute coronary syndrome (ACS).

METHODS AND RESULTS

The present study was carried out in 485 subjects, of whom 297 were diagnosed as patients with ACS, 89 were diagnosed as non-cardiac chest pain (NCCP) and 99 people served as healthy controls. H-FABP levels were measured in comparison with standard markers such as troponin I and CK-MB in all subjects enrolled in the study. The levels of H-FABP were significantly raised in patients when compared to controls and NCCP (P<0.001). Receiver Operator Characteristic Curve (ROC) analysis showed H-FABP to be a good discriminator between patients with ischaemic heart disease and patients without ischaemic heart disease. The area under the curve was found to be 0.965 with 95% CI (0.945-0.979). The cut-off value above which H-FABP can be considered positive was found to be 17.7ng/ml.

CONCLUSION

H-FABP is a promising biomarker for the early detection of patients with acute coronary syndrome.

Biomarkers of vulnerable plaque: the missing link with ischemia

The initial evaluation of chest pain in the emergency department is based on the patient’s clinical history, changes in the ECG and necrosis biomarkers. Although management of patients with ST-elevation myocardial infarction or non-ST-elevation myocardial infarction with positive markers of myocardial damage is well defined, exclusion of coronary artery disease or myocardial ischemia in the remaining patients is more challenging. This group represents the majority of patients admitted for chest pain syndromes and that have a substantial risk of an adverse outcome. Given that troponin, as a marker of myocardial damage, detects terminal events in the cascade of acute coronary syndrome, there is a need to search for biomarkers that are able to identify patients at high risk, allowing rapid, bedside stratification. Data suggest that clinical events are prone to occur more frequently in patients with coronary artery stenosis associated with myocardial ischemia. Accordingly, identification of systemic biomarkers of ischemia could facilitate identification of high-risk patients with a high burden of coronary atherosclerosis and plaque rupture. We describe six biomarkers that have been linked to myocardial ischemia. Until now, these biomarkers of ischemia are relevant in order to exclude ischemic heart disease (high negative predictive value) but still lack specificity. Future prospective studies should be performed in larger and more diverse sets of patients presenting with ischemia, and in a complementary fashion in order to provide valuable tools for clinical decision making.

Heart-type fatty acid binding protein is an independent predictor of death and ventricular dysfunction after coronary artery bypass graft surgery

BACKGROUND

Heart-type fatty acid binding protein (hFABP) functions as a myocardial fatty acid transporter and is released into the circulation early after myocardial injury. We hypothesized that hFABP is superior to conventional cardiac biomarkers for predicting early perioperative myocardial injury after coronary artery bypass graft (CABG) surgery.

METHODS

A prospective cohort study of 1298 patients undergoing primary CABG with cardiopulmonary bypass (CPB) was performed at 2 institutions. Four plasma myocardial injury biomarkers (hFABP; cardiac troponin I [cTnI]; creatine kinase, MB [CK-MB] fraction; and myoglobin) were measured at 7 perioperative time points. The association among perioperative cardiac biomarkers and ventricular dysfunction, hospital length of stay (HLOS), and up to 5-year postoperative mortality (median 3.3 years) was assessed using Cox proportional hazard models. We defined in-hospital ventricular dysfunction as a new requirement for 2 or more inotropes, or new placement of an intraaortic balloon pump, or ventricular assist device either during the intraoperative period after the patient separated from CPB or postoperatively in the intensive care unit.

RESULTS

The positive and negative predictive values of mortality for hFABP are 13% (95% confidence interval [CI], 9%-19%) and 95% (95% CI, 94%-96%), respectively, which is higher than for cTnI and CK-MB. After adjusting for clinical predictors, both postoperative day (POD) 1 and peak hFABP levels were independent predictors of ventricular dysfunction (P < 0.0001), HLOS (P < 0.05), and 5-year mortality (P < 0.0001) after CABG surgery. Furthermore, POD1 and peak hFABP levels were significantly superior to other evaluated biomarkers for predicting mortality. In a repeated-measures analysis, hFABP outperformed all other models of fit for HLOS. Patients with POD2 hFABP levels higher than post-CPB hFABP levels had an increased mortality compared with those patients whose POD2 hFABP levels decreased from their post-CPB level (hazard ratio, 10.9; 95% CI, 5.0-23.7; P = 7.2 × 10(-10)). Mortality in the 120 patients (10%) with a later hFABP peak was 18.3%, compared with 4.7% in those who did not peak later. Alternatively, for cTnI or CK-MB, no difference in mortality was detected.

CONCLUSION

Compared with traditional markers of myocardial injury after CABG surgery, hFABP peaks earlier and is a superior independent predictor of postoperative mortality and ventricular dysfunction.

Point-of-care test of heart-type fatty acid-binding protein for the diagnosis of early acute myocardial infarction

AIM

To investigate the efficacies of point-of-care test of heart-type fatty-acid binding protein (H-FABP) and its combinations with the conventional biomarkers in the diagnosis of early acute myocardial infarction (AMI).

METHODS

227 patients suspected of AMI were consecutively recruited in two centers. Biomarkers including H-FABP, myoglobin (MYO), creatine kinase-myocardial band (CK-MB) and cardiac troponin T (cTnT) were determined simultaneously at admission. AMI was defined according to the universal definition of myocardial infarction. Chi-Square test was adopted for the analysis.

RESULTS

In patients presenting within 12 h of symptom onset, the sensitivity of H-FABP[93.0% (95% CI: 86.6%-96.9%)] was significantly higher than that of initial CK-MB [67.5% (95% CI: 58.1%-76.0%), P<0.0001], cTnT [69.3% (95%CI: 60.0%-77.6%), P<0.0001] and MYO [68.6% (95% CI: 54.1%-80.9%), P<0.05]. The negative predictive value of H-FABP [92.8% (95%CI: 86.3%-96.8%)] was significantly higher than that of initial CK-MB [74.7% (95% CI: 66.8%-81.5%), P<0.001] and cTnT [75.9% (95% CI: 68.1%-82.6%), P<0.001]. The sensitivity of H-FABP+cTnT combination [94.7% (95% CI: 88.9%-98.0%)] was significantly higher than that of admission cTnT [69.3% (95% CI: 60.0%-77.6%), P<0.0001], CK-MB+cTnT [75.4% (95% CI: 66.5%-83.0%), P<0.0001] and MYO+CK-MB+cTnT [74.5% (95% CI: 60.4%-85.7%), P<0.05]. The negative predictive value of H-FABP+cTnT [94.5% (95% CI: 88.4%-98.0%] was significantly higher than that of initial cTnT [75.9% (95% CI: 68.1%-82.6%), P<0.001] and CK-MB+cTnT [79.1% (95% CI: 71.2%-85.6%), P<0.001]. Subgroup analysis showed that the superiorities of both the sensitivities and the negative predictive values of H-FABP and H-FABP+cTnT combination occurred only in patients who presented within 6 h of the symptom onset.

CONCLUSION

Point-of-care test of H-FABP can be used as a valuable biomarker to detect or exclude an early-stage AMI. Combining H-FABP and cTnT provides the best performance for early AMI diagnosis.

Is there a fatty acid taste?

Taste is a chemical sense that aids in the detection of nutrients and guides food choice. A limited number of primary qualities comprise taste. Accumulating evidence has raised a question about whether fat should be among them. Most evidence indicates triacylglycerol is not an effective taste stimulus, though it clearly contributes sensory properties to foods by carrying flavor compounds and altering texture. However, there is increasing anatomical, electrophysiological, animal behavior, imaging, metabolic, and psychophysical evidence that free fatty acids are detectable when non-taste cues are minimized. Free fatty acids varying in saturation and chain length are detectable, suggesting the presence of multiple transduction mechanisms and/or a nonspecific mechanism in the oral cavity. However, confirmation of "fatty" as a taste primary will require additional studies that verify these observations are taste specific. Oral exposure to free fatty acids likely serves as a warning signal to discourage intake and influences lipid metabolism.

Increases in serum concentration of human heart-type fatty acid-binding protein following elective coronary intervention

BACKGROUND

Heart-type fatty acid-binding protein (H-FABP) is considered a marker of myocardial necrosis but whether or not it is modified by myocardial ischemia is not clear. We sought to investigate if H-FABP serum levels increase following non-urgent coronary angioplasty.

METHODS

We studied 31 patients undergoing coronary angioplasty. Peripheral venous samples were drawn immediately before angioplasty, 1 h after the first balloon inflation and 24 h after the procedure and assayed for H-FABP.

RESULTS

Serum levels of H-FABP increased significantly at 1 h vs baseline from 2554 +/- 1268 to 3322 +/- 245 pg ml(-1) (p = 0.024). However, no differences were observed between 1 h and 24 h after angioplasty (3268 +/- 1861 vs 3322 +/- 2459 pg ml(-1), p = 0.87). Moreover, no significant difference was observed when we compared 24 h after angioplasty with the baseline (3268 +/- 1861 vs 2554 +/- 1268 pg ml(-1), p = 0.112).

CONCLUSIONS

We conclude that H-FABP significantly increases after elective coronary angioplasty at 1 h compared with baseline values; whether or not this has any prognostic significance for future events, as it occurs with troponins, needs to be studied further.

Relationships between single nucleotide polymorphisms of the H-FABP gene and slaughter and meat quality traits in chicken

Using PCR-SSCP with five primer pairs, we detected six single nucleotide polymorphisms of the H-FABP gene: 332G --> A, 534G --> A, 783C --> T, 835C --> T, 1198T --> C, and 2329C --> T. Chi-square results showed significant differences (P < 0.05) in genotype frequency among breeds in Fragment 1 and extremely significant differences (P < 0.01) in Fragments 2-4. We found a significant association between Fragment 2 genotype and muscle fiber number, Arg and Thr (P < 0.05); between Fragment 3 genotype and living weight, carcass weight, breast muscle weight, abdominal fat weight, and abdominal fat percentage (P < 0.05); between Fragment 4 genotype and Thr, Phe, and inosinic acid (P < 0.05). It was concluded that H-FABP was the major gene influencing slaughter performance and meat quality or was linked with the major gene in these strains and that the C783T mutation could be used as a candidate molecular genetic marker for breeding selection. The combination M1C2-B2B2-D1D1 is an ideal model for breeding in these strains because it can improve slaughter and meat quality traits.

Oral thresholds and suprathreshold intensity ratings for free fatty acids on 3 tongue sites in humans: implications for transduction mechanisms

Multiple putative free fatty acid (FFA) transduction mechanisms have been identified in the oral cavity. They reportedly differ in their distribution on the tongue and each has a unique range of ligand specificities. This suggests that there should be regional differences in sensory responses to varying FFAs. This was assessed through spatial testing with caproic (C), lauric (L), and stearic (S) FFAs among 35 healthy adults. Stimuli were applied to the fungiform (FU), foliate (FO), and circumvallate (CV) papillae with a cotton-tipped applicator. Oral detection thresholds were measured by an ascending, 3-alternative, forced-choice, sip and spit procedure. Intensity ratings were obtained on the general labeled magnitude scale. Nongustatory cues were minimized by testing with the nares blocked, eyes covered, and by masking tactile cues with the addition of gum acacia and mineral oil to the stimuli vehicle. Thresholds were obtained from nearly all individuals at each site, and the concentration was similar across the 3 FFAs. Absolute intensity ratings differed significantly with C > L > S overall and at the CV and FO papillae. At the FU papillae, the L and S ratings were comparable. Ratings were highest at the FU followed by the CV and then the FO papillae. Slopes of the concentration-intensity rating functions were higher for L compared with C and S at the CV papillae as well as both L and C compared with S at the FO papillae. However, overall, slopes were comparable across sites. These findings strengthen evidence for oral FFA perception in humans by replicating threshold sensitivity findings and documenting monotonic scaling ability for these stimuli. Further, they challenge current views on transduction as sensory responsiveness was observed at tongue sites not predicted to support FFA detection.

Cardiac markers: a clear cause for point-of-care testing

Point-of-care testing (POCT) in patients with ischemic heart disease is driven by the time-critical need for fast, specific, and accurate results to initiate therapy instantly. According to current guidelines, the results of the cardiac marker testing should be available to the physician within 30 min ("vein-to-brain" time) to initiate therapy within 60-90 min ("door-to-needle" time) after the patient has arrived at the emergency room or intensive care unit. This article reviews the current efforts to meet this goal (1) by implementing POCT of established biochemical markers such as cardiac troponins, creatine kinase MB, and myoglobin, in accelerated diagnosis and management workflow schemes, (2) by improving current POCT methods to obtain more accurate, more specific, and even faster tests through the integration of optical and electrochemical sensor technology, and (3) by identifying new markers for the very early and sensitive detection of myocardial ischemia and necrosis. Furthermore, the specific requirements for cardiac POCT in regard to analytical performance, comparability, and diagnostic sensitivity/specificity are discussed. For the future, the integration of new immunooptical and electrochemical chip technology might speed up diagnosis even further. However, every new development will have to meet the stringent method validation criteria set for corresponding central laboratory testing.

Significance of urinary liver-fatty acid-binding protein in cardiac catheterization in patients with coronary artery disease

OBJECTIVES

We investigated the significance of urinary liver fatty acid-binding protein (U-L-FABP) monitoring during cardiac catheterization in patients with cardiovascular disease (CVD). Methods The subjects included 27 consecutive patients with stable angina (SAP group) or acute coronary syndrome (ACS group) who had undergone successful percutaneous coronary intervention (PCI), and 12 patients were also enrolled as controls (C group). Urinary and serum parameters were measured immediately before and after and 1 day after PCI.

RESULTS

The ratio of U-L-FABP to U-creatinine (U-Cr) (U-L-FABP/U-Cr) in the ACS group was significantly higher than those in both the SAP and C groups before PCI. In addition, none of the patients in the SAP group showed contrast-induced nephropathy (CIN) based on the levels of serum (S)-Cr and U-L-FABP/U-Cr after PCI. Although none of the patients in the ACS group showed CIN according to S-Cr, the level of U-L-FABP/U-Cr was continuously high throughout the study period. Moreover, since there were significant differences in U-L-FABP/U-Cr, U-N-acetyl-beta-D-glucosaminidase, S-uric acid and % medication with calcium channel blockers before PCI between the ACS and SAP groups, a multiple regression analysis was performed using these parameters. It showed that U-L-FABP/U-Cr was most closely associated with the classification of SAP and ACS (p<0.0001). The cut-off level for the greatest sensitivity and specificity for U-L-FABP for the diagnosis of ACS was 13.4 microg/g. Cr in all subjects (sensitivity 0.800, specificity 0.963).

CONCLUSIONS

To the best of our knowledge, this is the first report indicating that the measurement of U-L-FABP can be beneficial for in the diagnosis of ACS.

Relationship between arterial stiffness and myocardial damage in patients with newly diagnosed essential hypertension

BACKGROUND

Arterial stiffness increases in hypertensive individuals. Arterial stiffness is associated with impairment of systolic and diastolic myocardial function in hypertension (HT). However, the relationship between arterial stiffness and serum heart-type fatty acid-binding protein (H-FABP) levels, a sensitive marker of myocardial damage, has not been previously examined in patients with HT. We investigate the relationship between serum H-FABP levels and arterial stiffness in patients with newly diagnosed HT.

METHODS

We studied 46 (48.5 +/- 10.6, years) never-treated patients with HT and age-matched control group of 40 (47 +/- 8.6, years) normotensive individuals. H-FABP levels were determined in all subjects. We evaluated arterial stiffness and wave reflections of study population, using applanation tonometry (Sphygmocor). Carotid-femoral pulse wave velocity (PWV) was measured as indices of elastic-type, aortic stiffness. The heart rate-corrected augmentation index (AIx@75) was estimated as a marker of wave reflections.

RESULTS

Carotid-femoral PWV (10.5 +/- 2.2 vs. 8.7 +/- 1.6, m/s, P = 0.0001) and AIx@75 (22.7 +/- 9.5 vs. 15 +/- 11, %, P = 0.001) were significantly higher in patients with HT than control group. H-FABP levels were increased in hypertensive patients compared with control group (21.1 +/- 14.8 vs. 12.9 +/- 8.5, ng/ml, P = 0.002). In multiple linear regression analysis, we found that the body mass index (beta = 0.42, P = 0.0001) and carotid-femoral PWV (beta = 0.23, P = 0.03) were significant determinants of H-FABP levels.

CONCLUSION

Arterial stiffness is associated with serum H-FABP levels, a sensitive marker of myocardial damage, in patients with newly diagnosed HT.

Evaluation of the relationship between heart type fatty acid binding protein levels and the risk of cardiac damage in patients with obstructive sleep apnea syndrome

The aim of this study was to establish cardiac damage related to nocturnal ischemia using heart type fatty acid binding protein (h-fabp), which reaches detectable levels in plasma after being released from myocytes in case of ischemia in obstructive sleep apnea syndrome (OSAS) patients without coronary artery disease (CAD). Fifty patients diagnosed with OSAS in our sleep laboratory with polysomnographic analysis (PSG), who did not have any previous history of cardiac disease and in whom CAD was ruled out with myocardium perfusion scintigraphy, were included in the study. Control group comprised 19 volunteers without history of cardiac disease and risk factors in whom OSAS was excluded with PSG analysis. Blood samples were drawn from the patients to examine h-fabp, creatine kinase (CK), creatine kinase-MB (CK-MB), aspartate aminotransferase (AST), troponin I levels before and after sleep. No significant difference was found in CK, CK-MB, AST, Troponin I, and h-fabp levels before and after sleep in patient and control groups (p > 0.05). No significant difference was found between groups in terms of CK, CK-MB, AST, and Troponin I levels before and after sleep, while a significant difference was found between them with regard to h-fabp levels before (p = 0.006) and after sleep (p = 0.022). When arithmetical mean of the fabp levels before and after sleep was taken in the patient group, it was found that mean value of h-fabp was associated with the desaturated period in sleep which was under 80% (p = 0.04). H-fabp seems to be a marker that will enable the detection of cardiac injury in the early asymptomatic period in OSAS patients before development of disease that can be detected by imaging methods. Further studies are required to investigate the relation between the value of h-fabp and the development of cardiac dysfunction in the long term.

Analytical and clinical performance of a fully automated cardiac multi-markers strategy based on protein biochip microarray technology

OBJECTIVES

The analytical and clinical performance of the Evidence Cardiac Panel were evaluated.

DESIGN AND METHODS

The Evidence Cardiac Panel, an automated protein biochip microarray system, allows the simultaneous determination of creatine kinase MB (CK-MB), myoglobin (MYO), glycogen phosphorylase BB (GPBB), heart-type fatty acid-binding protein (H-FABP), carbonic anhydrase III (CA III), cardiac troponin I (cTnI). Precision: 3 levels of quality control (QC) and 2 in house pools (P) were assayed. Method comparison: MYO and cTnI concentrations measured on Evidence (E) and on Dimension RxL (D) analyzers were compared. Clinical study: 132 non-consecutive patients admitted to the Emergency Department for chest pain were enrolled.

RESULTS AND CONCLUSIONS

The between-day imprecision was CK-MB=6.80-10.08%; MYO=5.36-16.50%; GPBB=6.51-12.12%; H-FABP=6.26-12.63%; CA III=6.98-13.61%; cTnI=6.02-9.80%. Method comparison: E-MYO vs. D-MYO, Bias=-29.22, 95% CI from -40.25 to -18.18; E-cTnI vs. D-cTnI, Bias=-2.75, 95% CI from -4.04 to -1.46. In patients studied (at discharge: AMI, acute myocardial infarction n=42; non-AMI, n=90) H-FABP showed the highest accuracy (ROC analysis, AUC=0.92) and "cTnI+H-FABP" the greatest diagnostic efficacy (89.4%) in AMI diagnosis.

Human heart-type fatty-acid-binding protein as a point-of-care test in the early diagnosis of acute myocardial infarction

BACKGROUND

At very early stages of acute myocardial infarction (AMI), highly sensitive biomarkers are still lacking.

AIM

To evaluate the utility of human heart-type fatty acid-binding protein (h-FABP) for early diagnosis of AMI.

DESIGN

Prospective diagnostic study.

METHODS

Consecutive patients presenting to the emergency department with chest pain or dyspnoea within 24 h of symptom onset were included. At presentation, the h-FABP test result was compared to the standard diagnostic work-up, including repeated ECG and troponin T measurements. Sensitivity analysis was performed for inconclusive tests.

RESULTS

We enrolled 280 patients presenting to hospital with a median symptom onset of 3 h (IQR 2-6 h): 109 (39%) had AMI. At presentation, h-FABP had a sensitivity of 69% (95%CI 59-77) and specificity of 74% (95%CI 66-80); 45 tests were false-positive and 34 were false-negative. Omitting inconclusive tests increased sensitivity and specificity only slightly. AMI was identified significantly earlier by h-FABP than by troponin T (24 vs. 8 patients, p=0.005).

DISCUSSION

Although h-FABP can help to detect myocardial damage at an early stage in patients with chest pain or dyspnoea, it appears unsuitable as a stand-alone test for ruling out AMI.

Predictive value of heart-type fatty acid-binding protein for left ventricular remodelling and clinical outcome of hypertensive patients with mild-to-moderate aortic valve diseases

Heart-type fatty acid-binding protein (H-FABP), a marker of acute myocardial infarction and a soluble cytosolic protein, may be released following left ventricular remodelling in cardiac overloaded hearts caused by hypertension, aortic regurgitation (AR) or aortic stenosis (AS). Our aim was to investigate if H-FABP levels are associated with left ventricular remodelling and clinical outcome in hypertensive patients with AR or AS. H-FABP and brain natriuretic peptide (BNP) were measured, glomerular filtration rate (GFR) was estimated using the modification of diet in renal disease (MDRD) equation, and left ventricular dimension at systole corrected for body surface area (LVDs/BSA) and relative wall thickness (RWT) were determined by echocardiography in hypertensive patients with mild-to-moderate AR (n=78), those with mild-to-moderate AS (n=73) and those without valvular heart diseases (HT) (n=50). H-FABP levels were significantly higher in AR (4.9+/-3 ng/ml) and in AS (4.5+/-3) than in HT (3.4+/-1) and BNP (65+/-73 pg/ml, 76+/-75, 35+/-22). H-FABP correlated with LVDs/BSA in AR (beta=0.23, P<0.05), and RWT in AS (beta=0.18, P<0.05) after adjustment for age, gender and all the other variables. AS and AR patients were prospectively followed up for cardiac events during 34+/-19 months. A multivariate Cox hazard analysis indicated H-FABP was an independent predictor of outcome both in AR (relative risk (RR)=7.61, 95% CI=2.39-25.3) and AS (RR=13.6, 95% CI=3.27-66.9). H-FABP, associated with left ventricular remodelling, is useful in predicting clinical outcome in hypertensive patients with mild-to-moderate aortic valve diseases.

Free fatty acids are independently associated with all-cause and cardiovascular mortality in subjects with coronary artery disease

CONTEXT

Free fatty acids (FFAs) are associated with several cardiovascular risk factors and exert harmful effects on the myocardium.

OBJECTIVE

The aim of our study was to elucidate the relationship between FFAs and mortality in subjects who underwent coronary angiography.

DESIGN, SETTING, AND PARTICIPANTS

Ludwigshafen Risk and Cardiovascular Health is a prospective cohort study of Caucasians who had undergone coronary angiography at baseline (1997-2000). During a median time of follow-up of 5.38 yr, 513 deaths had occurred among 3315 study participants with measured FFAs.

MAIN OUTCOME MEASURE

Hazard ratios for mortality according to FFA levels were measured.

RESULTS

At the fourth quartile of FFAs, fully adjusted hazard ratios for death from any cause and cardiovascular causes were 1.58 (P = 0.002) and 1.83 (P = 0.001), respectively. In persons with angiographic coronary artery disease (CAD), stable CAD, and unstable CAD, the predictive value of FFAs was similar to that in the entire cohort, but the association did not attain statistical significance in persons without CAD analyzed separately. FFA levels were not related to the presence of angiographic CAD but were elevated in subjects with unstable CAD, compared with probands with stable CAD. Furthermore, FFAs increased with the severity of heart failure and were positively correlated with N-terminal pro-B-type natriuretic peptide (P < 0.001).

CONCLUSIONS

FFA levels independently predict all-cause and cardiovascular mortality in subjects with angiographic CAD. A possible diagnostic use of FFAs warrants further studies, but our results may underline the importance of therapeutic approaches to influence FFA metabolism.

Urinary fatty acid binding protein in renal disease

The number of patients with end stage renal failure has been increasing throughout the world. The importance of measuring clinical parameters in renal injury has been emphasized for administering appropriate treatment and preventing a worsening of the disease. However, there are no clinically useful markers in predicting and monitoring the progression of renal disease. Liver type fatty acid binding protein (L-FABP) of 14.4 kDa is expressed in human proximal tubules. In order to evaluate the clinical significance of urinary L-FABP as a biomarker in renal disease, a monoclonal antibody against human L-FABP was developed and a two step sandwich enzyme linked immunosorbent assay (ELISA) method was established for determining human L-FABP in urine. In some clinical studies, urinary excretion of L-FABP was shown to be an excellent clinical marker that can help predict and monitor the progression of renal disease. The dynamics of renal L-FABP in pathophysiological settings has been revealed in experimental studies using transgenic mice with the human L-FABP gene. This review presents recent findings on the function and pathophysiological role of L-FABP, and summarizes the clinical importance of measuring urinary L-FABP in renal disease.

Time-dependent effects of fatty acids on skeletal muscle metabolism

Increased plasma levels of free fatty acids (FFA) occur in states of insulin resistance such as type 2 diabetes mellitus, obesity, and metabolic syndrome. These high levels of plasma FFA seem to play an important role for the development of insulin resistance but the mechanisms involved are not known. We demonstrated that acute exposure to FFA (1 h) in rat incubated skeletal muscle leads to an increase in the insulin-stimulated glycogen synthesis and glucose oxidation. In conditions of prolonged exposure to FFA, however, the insulin-stimulated glucose uptake and metabolism is impaired in skeletal muscle. In this review, we discuss the differences between the effects of acute and prolonged exposure to FFA on skeletal muscle glucose metabolism and the possible mechanisms involved in the FFA-induced insulin resistance.