Pericardial fluid level of heart-type cytoplasmic fatty acid-binding protein (H-FABP) is an indicator of severe myocardial ischemia

Pericardial fluid troponin in cardiac surgery

BACKGROUND AND OBJECTIVE

Pericardial Fluid (PF) is a rich reservoir of biologically active factors. Due to its proximity to the heart, the biochemical structure of PF may reflect the pathological changes in the cardiac interstitial environment. This manuscript aimed to determine whether the PF level of cardiac troponins changes in patients undergoing cardiac surgery.

METHODS

This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Medline, EMBASE, Cochrane, ClinicalTrials.gov, and Google Scholar databases were electronically searched for primary studies using the keywords "pericardial fluid," "troponin," and "cardiac surgery." The primary outcome of interest was changes in troponin levels within the PF preoperatively and postoperatively. Secondary outcomes of interest included comparisons between troponin level changes in the PF compared to plasma.

RESULTS

A total of 2901 manuscripts were screened through a title and abstract stage by two independent blinded reviewers. Of those, 2894 studies were excluded, and the remaining seven studies underwent a full-text review. Studies were excluded if they did not provide data or failed to meet inclusion criteria. Ultimately, six articles were included that discussed cardiac troponin levels within the PF in patients who had undergone cardiac surgery. Pericardial troponin concentration increased over time after surgery, and levels were significantly higher in PF compared to serum. All studies found that the type of operation did not affect these overall observations.

CONCLUSION

Our review of the literature suggest that the PF level of cardiac troponins increases in patients undergoing cardiac surgery, irrespective of the procedure type. However, these changes' exact pattern and clinical significance remain undefined.

Heart transplantation and biomarkers: a review about their usefulness in clinical practice

Advanced heart failure (AdvHF) can only be treated definitively by heart transplantation (HTx), yet problems such right ventricle dysfunction (RVD), rejection, cardiac allograft vasculopathy (CAV), and primary graft dysfunction (PGD) are linked to a poor prognosis. As a result, numerous biomarkers have been investigated in an effort to identify and prevent certain diseases sooner. We looked at both established biomarkers, such as NT-proBNP, hs-troponins, and pro-inflammatory cytokines, and newer ones, such as extracellular vesicles (EVs), donor specific antibodies (DSA), gene expression profile (GEP), donor-derived cell free DNA (dd-cfDNA), microRNA (miRNA), and soluble suppression of tumorigenicity 2 (sST2). These biomarkers are typically linked to complications from HTX. We also highlight the relationships between each biomarker and one or more problems, as well as their applicability in routine clinical practice.

Accumulation of Inflammatory Mediators in the Normal Pericardial Fluid

There is paucity of studies that focus on the composition of pericardial fluid under resting conditions. The purpose of this study is to determine the levels of inflammatory mediators in pericardial fluid and their correlation with plasma levels in patients undergoing elective cardiac surgery. We conducted a prospective cohort study on candidates for elective aortic valve replacement surgery. Pericardial fluid and peripheral venous blood samples were collected after opening the pericardium. Levels of interleukin 1α (IL-1α); interleukin 1β (IL-1β); interleukin 2 (IL-2) interleukin 4 (IL-4); interleukin 6 (IL-6); interleukin 8 (IL8); interleukin 10 (IL10); tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), vascular endothelial growth factor (VEGF), monocyte chemotactic protein-1 (MCP-1) epidermal growth factor (EGF), soluble E-selectin, L-selectin, P-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) were determined in both pericardial fluid and serum samples. A total of 45 patients with a mean age of 74 years were included of which 66% were males. Serum levels of all study mediators were within normal limits. Serum and pericardial levels of IL-1 α, IL-1 β, IL-2, IL-4, and IL-10 were similar. Levels of VEGF, EGF, VCAM-2, ICAM 1, E-selectin, P-selectin, and L-selectin were significantly lower in pericardial fluid than in serum. However, levels of IL-6, IL-8, TNF-α, IFN-γ, MCP-1, and MCP-1 were significantly higher in the pericardial fluid than in serum. Under normal conditions, the pattern of distribution of different inflammatory mediators in the pericardial fluid does not reflect serum levels. This may either reflect the condition of the underlying myocardium and epicardial fat or the activity of the mesothelial and mononuclear cells present in pericardial fluid.

Feasibility study of intraoperative pericardial fluid biomarkers and length of stay after cardiac surgery

Objective

Pericardial fluid biomarkers reflect the physiologic state of the myocardium. Previously, we showed a sustained increase in pericardial fluid biomarkers compared with blood in the 48 hours after cardiac surgery. We assess the feasibility of analyzing 9 common cardiac biomarkers from pericardial fluid collected during cardiac surgery and test a preliminary hypothesis of association between the most common biomarkers, troponin and brain natriuretic peptide, and length of stay after surgery.

Methods

We prospectively enrolled 30 patients aged 18 years or more undergoing coronary artery or valvular surgery. Patients with ventricular assist devices, atrial fibrillation surgery, thoracic aorta surgery, redo surgery, concomitant noncardiac surgery, and preoperative inotropic support were excluded. Before pericardial excision during surgery, a 1-cm pericardial incision was made to insert an 18-gauge catheter and collect 10 mL of pericardial fluid. Concentrations of 9 established biomarkers of cardiac injury or inflammation including brain natriuretic peptide and troponin were measured. Zero truncated Poisson regression adjusted for Society of Thoracic Surgery Preoperative Risk of Mortality tested for a preliminary association between pericardial fluid biomarkers and length of stay.

Results

Pericardial fluid was collected and pericardial fluid biomarkers resulted for all patients. Adjusted for Society of Thoracic Surgery risk, brain natriuretic peptide, and troponin were associated with increased intensive care unit and overall hospital length of stay.

Conclusions

In 30 patients, pericardial fluid was obtained and analyzed for cardiac biomarkers. Adjusting for Society of Thoracic Surgery risk, pericardial fluid troponin and brain natriuretic peptide were preliminarily associated with increased length of stay. Further investigation is needed to validate this finding and to investigate the potential clinical utility of pericardial fluid biomarkers.

Electrochemical immunosensor development based on core-shell high-crystalline graphitic carbon nitride@carbon dots and Cd0.5Zn0.5S/d-Ti3C2Tx MXene composite for heart-type fatty acid-binding protein detection

Acute myocardial infarction (AMI) is a significant health problem owing to its high mortality rate. Heart-type fatty acid-binding protein (h-FABP) is an important biomarker in the diagnosis of AMI. In this work, an electrochemical h-FABP immunosensor was developed based on Cd_0.5Zn_0.5S/d-Ti₃C₂T_x MXene (MXene: Transition metal carbide or nitride) composite as signal amplificator and core-shell high-crystalline graphitic carbon nitride@carbon dots (hc-g-C₃N₄@CDs) as electrochemical sensor platform. Firstly, a facile calcination technique was applied to the preparation of hc-g-C₃N₄@CDs and immobilization of primary antibody was performed on hc-g-C₃N₄@CDs surface. Then, the conjugation of the second antibody to Cd_0.5Zn_0.5S/d-Ti₃C₂T_x MXene was carried out by strong π-π and electrostatic interactions. The prepared electrochemical h-FABP immunosensor was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD) method, Fourier-transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The prepared electrochemical h-FABP immunosensor indicated a good sensitivity with detection limit (LOD) of 3.30 fg mL^-1 in the potential range +0.1 to +0.5 V. Lastly, low-cost, satisfactory stable, and environmentally friendly immunosensor was presented for the diagnosis of acute myocardial infarction.

Evaluation of the cardioprotective effects of crystalloid del Nido cardioplegia solution via a rapid and accurate cardiac marker: heart-type fatty acid-binding protein

Background/aim

Our aim in this study was to compare the efficacy and safety of crystalloid del Nido solution and cold blood cardioplegia solution on clinical and laboratory parameters.

Materials and methods

Sixty patients who underwent elective coronary bypass operation between July 2019 and January 2020 were included in our study. Patients were divided into 2 groups of 30 patients using del Nido solution (DNS) and cold blood cardioplegia solution (CBCS), which were given for cardiac arrest. Demographic data, preoperative, postoperative 0th h, 6th h and 4th day creatine kinase myocardial band (CK-MB) and troponin I values were compared with a specific cardiac enzyme heart-type fatty acid-binding protein (H-FABP).

Results

We found that aortic cross clamp duration and cardiopulmonary bypass (CPB) time were shorter in patients using del Nido solution than cold blood cardioplegia solution (57.30 ± 23.57 min, 76.07 ± 27.18 min, P = 0.006) (95.07 ± 23.06 min, 114.13 ± 33.93, P = 0.014). Total cardioplegia solution volume was higher in the cold blood cardioplegia solution group (1426.67 ± 416.00 vs. 1200 ± 310.73 P = 0.02). Preoperative and postoperative levels of cardiac enzymes including CK-MB, troponin I and H-FABP were comparable in del Nido solution and cold blood cardioplegia solution groups.

Conclusion

According to these results, when we compare both demographic data and CK-MB, troponin I and H-FABP levels, both cardioplegia solutions were comparable regarding safety and efficacy in terms of myocardial protection.

Technologies for intrapericardial delivery of therapeutics and cells

The pericardium, which surrounds the heart, provides a unique enclosed volume and a site for the delivery of agents to the heart and coronary arteries. While strategies for targeting the delivery of therapeutics to the heart are lacking, various technologies and nanodelivery approaches are emerging as promising methods for site specific delivery to increase therapeutic myocardial retention, efficacy, and bioactivity, while decreasing undesired systemic effects. Here, we provide a literature review of various approaches for intrapericardial delivery of agents. Emphasis is given to sustained delivery approaches (pumps and catheters) and localized release (patches, drug eluting stents, and support devices and meshes). Further, minimally invasive access techniques, pericardial access devices, pericardial washout and fluid analysis, as well as therapeutic and cell delivery vehicles are presented. Finally, several promising new therapeutic targets to treat heart diseases are highlighted.

Comparison between creatine kinase MB, heart-type fatty acid-binding protein, and cardiac troponin T for detecting myocardial ischemic injury after cardiac surgery

BACKGROUND

Heart-type fatty acid-binding protein (H-FABP) is a cytoplasmic protein and is released form necrotic cardiac myocytes, as well as ischemic cardiac myocytes. In this study, we compared creatine kinase MB (CK-MB), H-FABP, and cardiac troponin T (cTnT) after coronary artery bypass grafting (CABG), heart valve surgery, or septal defect surgery to evaluate the difference in detecting myocardial injury between three markers.

METHODS

A total of 69 patients (CABG, 32; valve surgery, 27; and septal defect surgery, 10) were prospectively enrolled. Blood samples were taken at specific intervals.

RESULTS

Mean amount (AUC_0-72h) of CK-MB and cTnT released for 72 h in the patients with valve surgery were 2446 h·ng/ml and 93.2 h·ng/ml, which were significantly larger than those in the patients with CABG or septal defect surgery (p < .05). Mean amount (AUC_0-72h) of H-FABP released for 72 h in the patients with CABG was 1939 h·ng/ml, which was significantly larger than that in the patients with septal defect surgery (700.1 h·ng/ml) (p < .05).

CONCLUSION

H-FABP would be a more useful marker for detecting myocardial ischemic injury than CK-MB and cTnT. CK-MB and cTnT would be more sensitive to myocardial injury with surgical trauma than with ischemic injury in the patients with cardiac surgery.

Proteomic and Bioinformatic Characterization of Extracellular Vesicles Released from Human Macrophages upon Influenza A Virus Infection

Influenza A viruses (IAVs) are aggressive pathogens that cause acute respiratory diseases and annual epidemics in humans. Host defense against IAV infection is initiated by macrophages, which are the principal effector cells of the innate immune system. We have previously shown that IAV infection of human macrophages is associated with robust secretion of proteins via conventional and unconventional protein release pathways. Here we have characterized unconventional, extracellular vesicle (EV)-mediated protein secretion in human macrophages during IAV infection using proteomics, bioinformatics, and functional studies. We demonstrate that at 9 h postinfection a robust EV-mediated protein secretion takes place. We identified 2359 human proteins from EVs of IAV-infected macrophages compared with 1448 proteins identified from EVs of control cells. Bioinformatic analysis shows that many proteins involved in translation, like components of spliceosome machinery and the ribosome, are secreted in EVs in response to IAV infection. Our data also shows that EVs derived from IAV-infected macrophages contain fatty acid-binding proteins, antiviral cytokines, copper metabolism Murr-1 domain proteins, and autophagy-related proteins. In addition, our data suggest that secretory autophagy plays a role in activating EV-mediated protein secretion during IAV infection.

Asymmetric dimethylarginine and heart-type fatty acid-binding protein 3 are risk markers of cardiotoxicity in carbon monoxide poisoning cases in Zagazig university hospitals

Carbon monoxide (CO) poisoning is a leading cause of toxicity-related mortality and morbidity worldwide. Recent studies focused on CO-induced cardiovascular toxicity. Oxidative stress plays an important role in the pathophysiology of CO toxicity. The aim of this study was to elucidate the relationship between cardiac damage biomarkers and oxidative stress biomarkers in patients with CO-induced cardiotoxicity. This study was carried out on 36 CO-poisoned patients admitted to Zagazig University Hospitals. Forty healthy individuals (age- and sex-matched) were selected as a control group. Clinical examination and electrocardiography (ECG) were performed for CO-poisoned patients. These patients have been investigated for carboxyhaemoglobin percent (COHB%) and cardiac damage biomarkers; cardiac troponin I (cTn-I), heart-type fatty acid-binding protein 3 (H-FABP3). Oxidative stress biomarkers comprising malondialdehyde (MDA), asymmetric dimethylarginine (ADMA), and total antioxidant capacity (TAC) have been also assessed. All biomarkers have been assessed on admission (0 h) and 6 h after treatment of CO-poisoned patients with high-flow oxygen and compared with those of the control groups. ECG findings were abnormal in 31 patients (86.11%), where sinus tachycardia was the commonest finding (58.33%). There was a statistically significant increase of COHB%, MDA, ADMA, and H-FABP3 levels, and a significant decrease of TAC level in CO-poisoned patients compared to controls with no significant changes in cTn-I. Six hours following treatment, all measured parameters were significantly improved except for cTn-I, which was significantly increased when compared with admission status (0 h). Furthermore, H-FABP3 showed a significant positive correlation with COHB%, MDA, ADMA, and a negative correlation with TAC, while cTn-I was significantly correlated with COHB% only. ADMA and MDA seem to be the strongest determinants for the prediction of H-FABP3 changes and hence cardiovascular toxicity. Thus, cardiac damage in patients with CO poisoning could be partially mediated by CO-induced oxidative stress, where H-FABP3 level was directly and strongly associated with MDA and ADMA levels.

The utility of serum biomarkers to detect myocardial alterations induced by Imatinib in rats

BACKGROUND

Imatinib (Imb) is a tyrosine kinase inhibitor with cardiotoxic activity (decreases in left ventricular function and congestive heart failure) in patients. Currently, clinical diagnosis of Imb cardiotoxicity relies primarily on evaluation of left ventricular function, Imb also induces cardiac lesions in rats.

AIMS

This study, in rats, sought to determine whether monitoring biochemical markers would be a sensitive means to detect Imb-induced changes in cardiomyocyte morphology.

MATERIALS AND METHODS

Groups of male Sprague-Dawley rats were dosed orally with 50, 100, 200 mg kg(-1) Imb or water daily for 28 days. Tissues and blood samples were collected 24 h after the last dosing. Cardiac biomarkers such as cardiac troponin I (cTnI), cardiac troponin T (cTnT), and fatty acid binding protein 3 (FABP3) were monitored by the Erenna, Elecsys, and Meso Scale immunoassay systems.

RESULTS

Imb caused microscopic myocardial lesions (myofibrillar loss, cytoplasmic vacuolization, and necrosis) at all doses as determined by unbiased histopathology analysis. The severity of the alterations was dose-related with mean lesion scores (based on a scale of 0-3) of 1.2 (50 mg kg(-1)), 2.1 (100 mg kg(-1)) and 2.9 (200 mg kg(-1)). However, the increases in cTnI, cTnT, and FABP3 levels were noted primarily in high-dose Imb treated animals.

DISCUSSION AND CONCLUSION

The occurrence of myocardial alterations in animals without consistent changes in cardiac troponin and FABP3 concentrations raises questions regarding the utility of these biomarkers as early indicators of Imb-induced cardiotoxicity. Due to limited numbers of animals the reasons for this discrepancy could not be determined.

Serum heart-type fatty acid binding protein levels in acromegaly patients

BACKGROUND

Heart-type fatty acid-binding protein (H-FABP) is a major cytoplasmic low molecular weight protein and released into the circulation when the myocardium is injured. Previous studies have demonstrated that H-FABP is closely associated with acute coronary syndrome, hypertrophic and dilated cardiomyopathy, heart failure, stroke, obstructive sleep apnea syndrome, and pulmonary embolism. The aim of this study was to investigate serum H-FABP value in patients with acromegaly.

METHODS AND RESULTS

We measured serum H-FABP levels in 30 consecutive patients with acromegaly, and 55 age-matched control subjects by using a sandwich enzymelinked immunosorbent assay. Serum H-FABP levels were significantly higher in patients with acromegaly than in control subjects (17.40 ± 10.70, and 8.30 ± 7.20, respectively) (p<0.001). A significant positive correlation was found by Spearman's correlation test between serum H-FABP levels and left ventricular end-systolic diameter (r=0.483, p=0.004).

CONCLUSION

Patients with acromegaly have increased levels of H-FABP. Serum H-FABP levels might be a marker of myocardial performance in patients with acromegaly.

Potential influence of the pericardial space on myocardial function: Cardiac interactions of adenosine and endothelin-1

Adenosine (ADO) and endothelin-1 (ET-1) play an important role in the regulation of myocardial functions. The pericardial fluid accumulates these regulatory agents and reflects well their levels in the myocardial interstitium. The aim was to investigate the interaction and cardiovascular effects of ADO and ET-1 evoked from the pericardial space, determine the pericardial elimination of intrapericardially applied adenosine and its first metabolite, inosine (INO) and observe their effects on the cardiovascular function compared to their intravenous administration. The present studies were performed on in situ dog heart using the closed pericardium model. Significant increase of the pericardial concentrations of adenine nucleosides (adenosine and inosine) after intrapericardial administration of ET-1 has been found. Regarding the adenine nucleosides-ET-1 interaction, we have demonstrated ET-1 liberation after intrapericardial administration of adenine nucleosides. The present study confirmed significantly slower elimination of adenine nucleosides in the pericardial space than in the systemic circulation. In conclusion, characteristic cardiovascular effect and bidirectional interaction of adenine nucleosides and ET-1 could be provoked by and detected in the pericardial space, reflecting parallel changes in the myocardial interstitium. The low pericardial turnover rate of adenine nucleosides may offer the opportunity of utilizing their multiple beneficial effects for local pharmaco-therapeutic interventions.

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.

Clinical assessment of ischemia-modified albumin and heart fatty acid-binding protein in the early diagnosis of non-ST-elevation acute coronary syndrome in the emergency department

OBJECTIVES

Heart fatty acid-binding protein (h-FABP) and ischemia-modified albumin (IMA) have recently been evaluated, but to the best of our knowledge, no study has reported an analysis of these two markers for the detection of early myocardial infarction and myocardial ischemia in a large cohort of consecutive patients presenting to an emergency department (ED). This study evaluates the diagnostic accuracy and the clinical utility of h-FABP and IMA for non-ST-segment elevation acute coronary syndrome (ACS) diagnosis in the first hour of management in an ED.

METHODS

In a prospective 11-month study, 677 patients admitted to the ED with chest pain and suspected non-ST-segment elevation ACS were enrolled. On presentation, blood samples were obtained for the measurement of the biomarkers h-FABP (immunodetection with CardioDetect) and IMA (albumin cobalt-binding test). Two physicians, blinded to the results of the markers, independently categorized patients as having or not having non-ST-segment elevation ACS.

RESULTS

Of the 677 patients who were prospectively recruited, non-ST-segment elevation ACS was diagnosed in 185 (27.3%). While IMA was not predictive of the ACS diagnosis (odds ratio [OR] = 1.23; 95% CI = 0.87 to 1.81), h-FABP was predictive of ACS diagnosis (OR = 4.65; 95% CI = 2.39 to 9.04) with specificity at 96.8% (95% CI = 95.4% to 98.1%) and sensitivity at 13.5% (95% CI = 10.9% to 16.1%). However, h-FABP did not add significant additional information to a predictive model that included the usual diagnostic tools for non-ST-elevation ACS management (p = 0.40).

CONCLUSIONS

In this study on a large cohort of patients admitted to an ED for chest pain, IMA and h-FABP did not provide valuable information for ACS diagnosis.

Serum heart type fatty acid binding protein levels in metabolic syndrome

Heart type fatty acid binding protein (H-FABP) is a major cytoplasmic low-molecular weight protein and released into the circulation when the myocardium is injured. Previous studies have demonstrated that H-FABP is closely associated with acute coronary syndrome, hypertrophic and dilated cardiomyopathy, heart failure, stroke, obstructive sleep apnea syndrome, pulmonary embolism. The aim of this study was to investigate serum H-FABP value in the patients with metabolic syndrome (MetS). We measured serum H-FABP levels in 55 consecutive patients with MetS, and 73 age-matched control subjects by using a sandwich enzyme-linked immunosorbent assay. Serum H-FABP levels were significantly higher in patients with MetS than in control subjects 18.37 ± 13.0 and 7.9 ± 6.5 ng/ml, respectively, (P < 0.001). Serum H-FABP levels were significantly higher in patients with diabetic MetS than in without diabetic MetS, 24.0 ± 10.2 and 13.9 ± 12.6 ng/ml, respectively, (P: 0,003). There were statistically significant differences between patients without diabetic MetS and control subjects, 13.8 ± 12.6 and 7.9 ± 6.5 ng/ml, respectively, (P = 0.023). Patients with MetS have an increased risk of death from cardiovascular diseases. H-FABP seems to be a marker that will enable the detection of cardiac injury in the early asymptomatic period in patients with MetS.

Biomarkers in Acute Coronary Syndrome

BACKGROUND: Evaluation of patients who present to the hospital with acute undifferentiated chest pain or other symptoms and signs suggestive of Acute Coronary Syndrome (ACS) is often a clinical challenge. The initial assessment, requiring a focused history (including risk factors analysis), a physical examination, an electrocardiogram (EKG) and serum cardiac marker determination, is time-consuming and troublesome. Recent investigations have indicated that increases in biomarkers of necrosis, inflammation, ischemia and myocardial stretch may provide earlier assessment of overall patient risk, help in identifying the adequate diagnostic and therapeutic management for each patient and allow for prevention of substantial numbers of new events. APPROACH AND CONTENT: The purpose of this review is to provide an overview of the characteristics of several biomarkers that may have potential clinical utility to identify ACS patients. Patho-physiology, analytical and clinical characteristics have been evaluated for each marker, underlying the properties for potential routine clinical use. SUMMARY: The biomarkers discussed in this review are promising and might lead to improved diagnosis and risk stratification of patients with ACS, however their clinical application requires further studies. It is important to define their clinical role as diagnostic markers, their predictive value and the specificity, standardization and detection limits of the assays.

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.

Is there progress in the autopsy diagnosis of sudden unexpected death in adults?

Sudden death is now currently described as natural unexpected death occurring within 1h of new symptoms. Most studies on the subject focused on cardiac causes of death because most of the cases are related to cardiovascular disease, especially coronary artery disease. The incidence of sudden death varies largely as a function of coronary heart disease prevalence and is underestimated. Although cardiac causes are the leading cause of sudden death, the exact incidence of the other causes is not well established because in some countries, many sudden deaths are not autopsied. Many risk factors of sudden cardiac death are identified: age, gender, heredity factors such as malignant mutations, left ventricular hypertrophy and left ventricle function impairment. The role of the police surgeon in the investigation of sudden death is very important. This investigation requires the interrogation of witnesses and of the family members of the deceased. The interrogation of physicians of the rescue team who attempted resuscitation is also useful. Recent symptoms before death and past medical history must be searched. Other sudden deaths in the family must be noted. The distinction between sudden death at rest and during effort is very important because some lethal arrhythmia are triggered by catecholamines during stressful activity. The type of drugs taken by the deceased may indicate a particular disease linked with sudden death. Sudden death in the young always requires systematic forensic autopsy performed by at least one forensic pathologist. According to recent autopsy studies, coronary artery disease is still the major cause of death in people aged more than 35 years. Cardiomyopathies are more frequently encountered in people aged less than 35 years. The most frequent cardiomyopathy revealed by sudden death is now arrhythmogenic right ventricular cardiomyopathy also known simply as right ventricular cardiomyopathy (RVC). The postmortem diagnosis of cardiomyopathies is very important because the family of the deceased will need counseling and the first-degree relatives may undergo a possible screening to prevent other sudden deaths. In each case of sudden death, one important duty of the forensic pathologist is to inform the family of all autopsy results within 1 month after the autopsy. Most of the recent progress in autopsy diagnosis of sudden unexpected death in the adults comes from molecular biology, especially in case of sudden death without significant morphological anomalies. Searching mutations linked with functional cardiac pathology such as long-QT syndrome, Brugada syndrome or idiopathic ventricular fibrillation is now the best way in order to explain such sudden death. Moreover, new syndromes have been described by cardiologists, such as short-QT syndrome and revealed in some cases by a sudden death. Molecular biology is now needed when limits of morphological diagnosis have been reached.

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

Background: A biomarker that reliably detects myocardial ischemia in the absence of necrosis would be useful for initial identification of unstable angina patients and for differentiating patients with chest pain of an etiology other than coronary ischemia, and could provide clinical utility complementary to that of cardiac troponins, the established markers of necrosis. Unbound free fatty acids (FFAu) and their intracellular binding protein, heart-type fatty acid–binding protein (H-FABP), have been suggested to have clinical utility as indicators of cardiac ischemia and necrosis, respectively.

Methods: We examined results of clinical assessments of FFAu and H-FABP as biomarkers of cardiac ischemia and necrosis. Data published on FFAu and H-FABP over the past 30 years were used as the basis for this review.

Results: Although little clinical work has been done on FFAu since the initial reports, recent studies documented an association between increased serum FFAs and ventricular dysrhythmias and death in patients with acute myocardial infarction (AMI). Recent data suggest that serum FFAu concentrations increase well before markers of cardiac necrosis and are sensitive indicators of ischemia in AMI. H-FABP is abundant in cardiac muscle and is presumed to be involved in myocardial lipid homeostasis. Similar to myoglobin, plasma H-FABP increases within 3 h after AMI and returns to reference values within 12–24 h.

Conclusions: FFAu may have a potential role in identifying patients with cardiac ischemia. H-FABP is useful for detecting cardiac injury in acute coronary syndromes and predicting recurrent cardiac events in acute coronary syndromes and in congestive heart failure patients. Assays are available for both markers that could facilitate further clinical investigations to assess their possible roles as markers of cardiac ischemia and/or necrosis.

Fatty acid-binding proteins as plasma markers of tissue injury

BACKGROUND

One of the novel and promising plasma markers for detection of tissue injury is the family of 15 kDa cytoplasmic fatty acid-binding proteins of which various tissue-specific types occur.

AIMS AND OBJECTIVES

The present status of heart-type fatty acid-binding protein (H-FABP) as a diagnostic and prognostic marker for acute and chronic cardiac injury, as well as the preliminary diagnostic use of other types of FABP for detecting injury in other organs, is reviewed.

METHODS

This review is based on an overview of the literature on clinical diagnostics of various forms of organ injury, and uses additional literature on physiological aspects relevant for the interpretation of plasma marker concentrations.

RESULTS

H-FABP not only proves to be an excellent early marker for cardiac injury in acute coronary syndromes, but also allows detection of minor myocardial injury in heart failure and unstable angina. Preliminary results indicate that sensitivity, rule-out power and prognostic value of H-FABP in cardiac injury surpass the performance of the standard early marker myoglobin. The liver only contains liver-type FABP (L-FABP), but co-expression of H-FABP and L-FABP occurs in the kidney. Similarly, intestinal-type FABP (I-FABP) and L-FABP are found in intestines, and brain-type FABP (B-FABP) and H-FABP occur in the brain. Preliminary but promising applications of these proteins have been demonstrated for liver rejection, viability selection of kidneys from non-heart-beating donors (NHBD), inflammatory and ischemic bowel disease, traumatic brain injury and in the prevention of muscle injury in trained athletes.

CONCLUSIONS

Further study of the diagnostic and prognostic use of various FABP types is warranted, but their clinical application will require further commercialization of automated and rapid assays.