Cardiac troponin I and troponin T: are enzymes still relevant as cardiac markers?

The Clinical Association between Carbon Monoxide Poisoning and Myocardial Injury as Measured by Elevated Troponin I Levels

Carbon monoxide (CO) poisoning accounts for over 50,000 estimated emergency room visits and approximately 1200 deaths per year in the US. Despite the high prevalence, there is a paucity of data looking at the association between laboratory biomarkers and clinical outcomes. Our study investigates the association between myocardial injury as assessed by increased troponin levels and its effect on in-hospital outcomes in CO poisoning. A total of 900 sequential charts of patients presenting with CO poisoning between 1 January 2012, and 31 August 2019, at our tertiary center with regional hyperbaric chamber and burn unit, were reviewed. Of the 900, a total of 488 patients had elevated carboxyhemoglobin levels. Of these 488 patients, 119 (24.4%) also had blood troponin levels measured. Patients were stratified based on the presence or absence of myocardial injury as evidenced by highly sensitive serum troponin I (TnI) level > 0.5 ng/mL to determine if a correlation exists relating to myocardial injury and risk of major adverse events. Mean age was 51.2 years, 58.8% were males, 35.3% were non-White, and 10.1% were intentional CO poisonings. Comorbidities included hypertension: 37%, diabetes: 21%, smoking: 21%, hyperlipidemia: 17.6%, coronary artery disease: 11.8%, asthma: 5.9%, heart failure: 5%, atrial fibrillation: 4.2%, and chronic obstructive pulmonary disease: 4.2%. Myocardial injury occurred in 22 patients (18.5%) and was associated with increased likelihood of requiring intensive care admission (54.5% vs. 20.6%, p = 0.002) and intubation (40.9% vs. 14.4%, p = 0.008). TnI elevation was associated with higher in-hospital mortality (p = 0.008, OR 21.3) compared to patients without TnI elevation. Older age was independently associated with increased in-hospital mortality (p = 0.03, OR 1.08). When controlling for age, in-hospital mortality remained statistically significant (p = 0.01, OR 21.37). No significant difference was found with respect to age, comorbidities, gender, race, ethnicity, or hospital length of stay in patients with and without myocardial injury. Myocardial injury induced by CO exposure occurs frequently and adversely affects clinical outcomes. Further research is needed to help guide physicians in the management of CO poisoning and associated myocardial injury to improve patient outcomes.

D-limonene (5 (one-methyl-four-[1-methylethenyl]) cyclohexane) diminishes CCl4-induced cardiac toxicity by alleviating oxidative stress, inflammatory and cardiac markers

Background: The cardiovascular crisis is advancing rapidly throughout the world. A large number of studies have shown that plant polyphenols affect major mechanisms involved in cardiovascular events through their action on the antioxidant system, signaling, and transcription pathways. D-limonene, a monocyclic monoterpene obtained from citrus fruits, is reported to possess many pharmacological activities.Methods: The experiment was designed to determine the protective effect of D-limonene against cardiac injury induced by CCl4 in Wistar rats. Rats were treated with two doses of D-limonene against cardiac injury induced by CCl4. Serum toxicity markers, cardiac toxicity biomarker enzymes, inflammatory mediators, anti-oxidant armory, lipid peroxidation, lipid profile, and histology were done.Results: CCl4 intoxication resulted in a substantial rise in FFA, TC, TG, PL, LDL, VLDL, and a reduction in HDL, restoring these changes with the administration of D-limonene at a dosage of 200 mg/kg. CCl4 administration also resulted in lipid oxidation and decreased antioxidant activity. At the same time, D-limonene at a dosage of 200 mg/kg body weight inhibited LPO and restored in vivo antioxidant components to normal. CCl4 intoxication also resulted in a significant increase in inflammatory markers like IL-6, TNF-α, high sensitivity Corticotropin Releasing Factor (Hs-CRF), and biomarkers of cardiac toxicity like alanine aminotransferase (ALT), lactate dehydrogenase (LDH), creatine kinase (CK), creatine kinase MB (CKMB), and Troponin I & troponin-t activities. D-limonene reversed all these changes to normal. Histology further confirmed our obtained results.Conclusion: These findings indicate that D-limonene can ameliorate cardiac injury at a 200 mg/kg body weight dosage. Henceforth, D-Limonene intervenes in mediating CCl4 induced toxicity by various signaling pathways.

Effect of thymoquinone on sepsis-induced cardiac damage via anti-inflammatory and anti-apoptotic mechanisms

Objective

Sepsis is a systemic and deleterious host reaction to severe infection. Cardiac dysfunction is an established serious outcome of multiorgan failure associated with this condition. Therefore, it is important to develop drugs targeting sepsis-induced cardiac damage and inflammation. Thymoquinone (TQ) has anti-inflammatory, anti-oxidant, anti-fibrotic, anti-tumor, and anti-apoptotic effects. This study examined the effects of thymoquinone on sepsis-induced cardiac damage.

Methods

Male BALB/c mice were randomly segregated into four groups: control, TQ, cecal ligation and puncture (CLP), and CLP + TQ groups. CLP was performed after gavaging the mice with TQ for 2 weeks. After 48 hours, we estimated the histopathological changes in the cardiac tissue and the serum levels of cardiac troponin-T. We evaluated the expression of factors associated with inflammation, apoptosis, oxidative stress, and the PI3K/AKT pathway.

Results

TQ significantly reduced intestinal histological alterations and inhibited the upregulation of interleukin-6, tumor necrosis factor-α, Bax, NOX4, p-PI3K, and p-AKT. TQ also increased Bcl-2, HO-1, and NRF2 expression.

Conclusion

These results suggest that TQ effectively modulates pro-inflammatory, apoptotic, oxidative stress, and PI3K/AKT pathways, making it indispensable in the treatment of sepsis-induced cardiac damage.

Graphene-Based Biosensors for Molecular Chronic Inflammatory Disease Biomarker Detection

Chronic inflammatory diseases, such as cancer, diabetes mellitus, stroke, ischemic heart diseases, neurodegenerative conditions, and COVID-19 have had a high number of deaths worldwide in recent years. The accurate detection of the biomarkers for chronic inflammatory diseases can significantly improve diagnosis, as well as therapy and clinical care in patients. Graphene derivative materials (GDMs), such as pristine graphene (G), graphene oxide (GO), and reduced graphene oxide (rGO), have shown tremendous benefits for biosensing and in the development of novel biosensor devices. GDMs exhibit excellent chemical, electrical and mechanical properties, good biocompatibility, and the facility of surface modification for biomolecular recognition, opening new opportunities for simple, accurate, and sensitive detection of biomarkers. This review shows the recent advances, properties, and potentialities of GDMs for developing robust biosensors. We show the main electrochemical and optical-sensing methods based on GDMs, as well as their design and manufacture in order to integrate them into robust, wearable, remote, and smart biosensors devices. We also describe the current application of such methods and technologies for the biosensing of chronic disease biomarkers. We also describe the current application of such methods and technologies for the biosensing of chronic disease biomarkers with improved sensitivity, reaching limits of detection from the nano to atto range concentration.

Cardiac monitoring in HER2-positive patients on trastuzumab treatment: A review and implications for clinical practice

Trastuzumab prolongs progression-free and overall survival in patients with human epidermal growth factor receptor 2 (HER2) positive breast cancer. However, trastuzumab treatment is hampered by cardiotoxicity, defined as a left ventricular ejection fraction (LVEF) decline with a reported incidence ranging from 3 to 27% depending on variable factors. Early identification of patients at increased risk of trastuzumab-induced myocardial damage is of great importance to prevent deterioration to irreversible cardiotoxicity. Although current cardiac monitoring with multi gated acquisition (MUGA) scanning and/or conventional 2D-echocardiography (2DE) have a high availability, their reproducibility are modest, and more sensitive and reliable techniques are needed such as 3D-echocardiography (3DE) and speckle tracking echocardiography (STE). But which other diagnostic imaging modalities are available for patients before and during trastuzumab treatment? In addition, what is the optimal frequency and duration of cardiac monitoring? At last, which biomarker monitoring strategies are currently available for the identification of cardiotoxicity in patients treated with trastuzumab?

•

Current MUGA is not sensitive and reliable enough to detect cardiotoxicity early.

•

3DE (with STE) is most suitable for cardiac monitoring of patients on trastuzumab.

•

The optimal frequency and duration of cardiac monitoring is not yet established.

•

MPO and hs-troponin are promising biomarkers to detect cardiotoxicity.

H2S attenuates sepsis-induced cardiac dysfunction via a PI3K/Akt-dependent mechanism

The heart is the most vulnerable target organ in sepsis, and it has been previously reported that hydrogen sulfide (H₂S) has a protective role in heart dysfunction caused by sepsis. Additionally, studies have demonstrated that the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling pathway has a protective function during sepsis. However, the potential association between H₂S and PI3K/Akt in sepsis-induced cardiac dysfunction is unclear. Therefore, the PI3K inhibitor LY294002 was used to investigate the role of PI3K/Akt signaling in the protective effects of H₂S during sepsis-induced myocardial injury. A rat sepsis model was established using cecal ligation and puncture (CLP) surgery. Sodium hydrosulfide, a H₂S donor, was administered intraperitoneally (8.9 µmol/kg), and serum myocardial enzyme levels, inflammatory cytokine levels, cardiac histology and cardiomyocyte apoptosis were assessed to determine the extent of myocardial damage. The results demonstrated that exogenous H₂S reduced serum myocardial enzyme levels, decreased the levels of the inflammatory factors tumor necrosis factor (TNF)-α and interleukin (IL)-6, and increased the level of anti-inflammatory IL-10 following CLP. Staining of histological sections demonstrated that myocardial damage and cardiomyocyte apoptosis were alleviated by the administration of exogenous H₂S. Western blot analysis was used to detect phosphorylated and total PI3K and Akt levels, as well as NF-κB, B-cell lymphoma-2, Bcl-2-associated X protein (Bax) and caspase levels, and the results demonstrated that H₂S significantly increased PI3K and Akt phosphorylation. This indicated that the PI3K/Akt signaling pathway was activated by H₂S. Additionally, H₂S reduced Bax and caspase expression, indicating that apoptosis was inhibited, and decreased NF-κB levels, indicating that inflammation was reduced. Furthermore, the PI3K inhibitor LY294002 eliminated the protective effects of H₂S. In conclusion, the results of the current study suggest that exogenous H₂S activates PI3K/Akt signaling to attenuate myocardial damage in sepsis.

Relationship between Cardiac Troponin and Thrombo-Inflammatory Molecules in Prediction of Outcome after Acute Ischemic Stroke

BACKGROUND

In patients with acute ischemic stroke (AIS) without cardiovascular complications, we investigated the association of serum concentration of cardiac troponin (high-sensitivity cardiac troponin T [hs-cTnT]) with thrombo-inflammatory markers.

METHODS

Thirty-five patients with first-ever AIS were prospectively examined. Serum hs-cTnT was measured 6 and 24 hours after stroke, whereas S100B, high-sensitivity C-reactive protein (hsCRP), soluble CD40 ligand, tissue plasminogen activator (tPA), monocyte chemoattractant protein-1 (MCP-1), and P-selectin were measured 6 and 72 hours after stroke. Severity of stroke was assessed by the National Institutes of Health Stroke Scale (NIHSS) on admission, 24 hours later, and at discharge.

RESULTS

Concentration of MCP-1 at 6 hours was higher in the serum of patients with worsened NIHSS by 24 hours (P = .009). Concentration of hs-cTnT at both 6 and 24 hours was higher, if NIHSS worsened by discharge (P = .026 and P = .001). A cutoff value for hs-cTnT measured at T24 greater than or equal to  9.4 predicted worsened NIHSS on discharge with a sensitivity of 81% and a specificity of 74% (area: .808, P = .002). Concentration of hs-cTnT at both 6 and 24 hours was also higher in nonsurvivors compared with survivors (P = .03, respectively), and correlated with (1) tPA levels at 6 hours (P = .001 and P = .002, respectively); (2) MCP-1 concentration at 6 hours (P = .01 and P = .015, respectively); and increased hsCRP levels at 72 hours (P = .01, respectively). Concentration of hs-cTnT at 24 hours was an independent predictor of worsened NIHSS at discharge (odds ratio: 1.58, 95% confidence interval: 1.063-2.370, P = .024).

CONCLUSIONS

Elevated concentration of hs-cTnT measured 24 hours after AIS is an independent predictor of progressing neurologic deficit in patients without apparent myocardial damage, and also correlates with acute elevation of tPA and MCP-1.

Evaluation of a newly developed chemiluminescence immunoassay for detecting cardiac troponin T

BACKGROUND

To evaluate the performance of a chemiluminescence detection kit for cardiac troponin T (cTnT).

METHODS

According to the "Guiding principles on performance analysis of diagnostic reagents in vitro" and the Clinical and Laboratory Standards Institute (CLSI) Guidelines, we assessed the detection limit, linear range, reportable range, accuracy, precision, cross reactivity, interference factors, and matrix effect of the kit, and compared these parameters with that of the commercial electrochemiluminescence detection kit for cTnT (Roche).

RESULTS

The minimum detection limit of the kit was 0.01 ng/mL. The linear range was 0.01 ng/mL-25 ng/mL. The reportable range was from 0.01 ng/mL to 100 ng/mL. Precision within the batch was 2.9%-6.4%, and precision between batches was 6.0%; the accuracy was good and the recovery rate reached 96.2%. The cross-reaction test demonstrated that there was no reactivity between cTnT and a variety of troponins. Test results deviated by less than ±10% in the presence of hemoglobin ≤1000 μg/mL, bilirubin ≤250 μg/mL, triglycerides ≤11.25 mg/mL, and rheumatoid factor ≤206 U/mL, suggesting that kit results were not significantly interfered with these factors. Results from the matrix-effect assessment revealed absence of a matrix effect in the tested serum samples. Correlation study revealed that the performance of the kit was very consistent with that of the Roche electrochemiluminescence detection kit (Kappa = 0.900, P < .001) with a high correlation (r = .903, P < .001) and a total matching rate of 95.00%.

CONCLUSION

The performance of the evaluated chemiluminescence immunoquantitation kit for cTnT detection was acceptable in all tested parameters, fulfilling requirements for clinical applications.

Nuclear Magnetic Resonance-Based Metabolomics of Human Filtered Serum: A Great White Hope in Appraisal of Chronic Stable Angina and Myocardial Infarction

BACKGROUND

Biochemical detection of chronic stable angina (CSA) and myocardial infarction (MI) are challenging. To address the shortcomings of the conventional biochemical approach for detection of MI, we applied serum lacking proteins and lipoprotein-based metabolomics in an approach using proton nuclear magnetic resonance (1H NMR) spectroscopy for screening of coronary artery disease (CAD) and especially MI. Our aim was to discover differential biomarkers among subjects with normal coronary (NC), CSA, and MI.

METHODS

The study comprised serum samples from nondiabetic angiographically proven CAD [CSA (n = 88), MI (n = 90)] and NC (n = 55). 1H NMR spectroscopy was used to acquire metabolomics data. Clinical variables such as troponin I (TI), lactate dehydrogenase (LD), creatine kinase (CK, CK-MB, CK-MM), serum creatinine, and lipid profiles were also measured in all subjects. Metabolomic data and clinical measures were appraised separately using a chemometric approach and ROC analysis.

RESULTS

The screening outcomes revealed that the pattern of methylguanidine, lactate, creatinine, threonine, aspartate, and trimethylamine (TMA), and TI, LD, CK, and serum creatinine were changed in CAD compared to NC. Statistical analysis demonstrated high precision (93.6% by NMR and 67.4% by clinical measures) to distinguish CAD from NC. Further analysis indicated that methylguanidine, arginine, and threonine, and TI, LD, and serum creatinine were significantly changed in CSA compared to MI. Statistical analysis demonstrated high accuracy (88.2% by NMR and 92.1% by clinical measures) to discriminate CSA from MI.

CONCLUSIONS

In contrast to other laboratory methods, 1H NMR-based metabolomics of filtered sera appears to be a robust, rapid, and minimally invasive approach to probe CSA and MI.

The effect of elapsed time on cardiac troponin-T (cTnT) degradation and its dependency on the cause of death

PURPOSE

The aim of the present study is to evaluate the effect of elapsed time on cardiac troponin-T degradation and its dependency on the cause of death.

METHODS

The cases included in this study were divided into six groups depending upon the cause of death without any prior history of disease that died in the hospital and their exact time of death was known. The analysis involves extraction of the protein, separation by denaturing gel electrophoresis and visualization by Western blot.

RESULTS

Western blot data shows the rate of degradation of cTnT into lower molecular weight fragments with respect to time. In cases of control group the greatest amount of protein breakdown was observed within the first 64 h while in MI cases within first 6 h, the original band of cTnT (42 kDa) decreased markedly into seven major fragments, with 25 kDa & 20 kDa fragments being the most prominent. In burn group, at 41.40 h blot shows maximum fragmentation. In electrocution group the greatest amount of protein breakdown was observed within the first 50 Hrs. Within asphyxia cases, the original band of cTnT (42 kDa) decreased markedly into many major and minor fragments which continues up to 210 Hrs while the original band of cTnT (42 kDa) in poisoning cases decreased markedly into many major & minor fragments up to 140 h but after it blot shows only intact protein of very less intensity with few minor fragments.

CONCLUSION

It can be observed that in case of death due to MI, the intact cTnI fragmented at a much faster rate than in burn, electrocution, control, poisoning and asphyxia group. Thus, the rate of fragmentation of intact cTnT into lower molecular weight fragments depends upon the cause of death.

Unstable coronary plaque characteristics are associated with high-sensitivity cardiac troponin T and N-terminal Pro-Brain Natriuretic Peptide

BACKGROUND

Unstable plaque characteristics on coronary CT angiography (CTA), serum high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal Pro-Brain Natriuretic Peptide (NT-proBNP) concentrations are associated with cardiovascular events.

OBJECTIVE

To investigate the association between coronary CTA defined quantifiable plaque characteristics, hs-cTnT and NT-proBNP.

METHODS

81 consecutive stable chest pain patients with an intermediate-to-high risk were analyzed. Coronary CTA was performed using a 64-slice multidetector-row CT-scanner. Total coronary plaque volume, calcified volume, non-calcified volume, plaque burden, remodeling index (RI) and number of plaques were measured using dedicated software. A total plaque score ("Sum plaque score") incorporating total plaque volume, RI, plaque burden and number of plaques was defined. Hs-cTnT and NT-proBNP concentrations were measured in serum samples before coronary CTA.

RESULTS

Univariate regression analysis demonstrated significant associations of hs-cTnT and NT-proBNP with total plaque volume (r hs-cTnT = .256; r NT-proBNP = .270), calcified volume (r hs-cTnT = .344; r NT-proBNP = .344), RI (r hs-cTnT = .335; r NT-proBNP = .342) and number of plaques (r hs-cTnT = .355; r NT-proBNP = .301) (all P values ≤ .021). Non-calcified plaque volume showed no association with hs-cTnT and NT-proBNP (r hs-cTnT = .050; r NT-proBNP = .087; P value = .660 and P value = .442). The "Sum plaque score" showed the highest correlation compared to other plaque parameters (r hs-cTnT = .362; r NT-proBNP = .409; P value = .001 and P value ≤ .001).

CONCLUSION

Our data suggest that coronary plaque morphology parameters, derived by dedicated software, are associated with serum hs-cTnT and NT-proBNP concentrations.

Time-dependent Degradation Pattern of Cardiac Troponin T in Cases of Death by Burn

OBJECTIVE

Death due to burn occurs frequently. This study investigated time-dependent alterations in cardiac troponin T (cTnT) associated with fatal burns.

METHODS

Cardiac tissue samples were collected from 10 medico-legal autopsies after informed consent from the relatives and post-mortem degradation by incubation of the cardiac tissue was studied at room temperature for different time periods. The cases included in this study were the subjects of burns without any prior history of disease who died in the hospital and their exact time of death was known. An efficient extraction protocol to analyse the banding pattern of cTnT in post-mortem tissue was developed.

RESULTS

The data show a distinct time-dependent profile corresponding to the degradation of cTnT by proteases found in cardiac muscle. Both post-mortem interval and cardiac tissue of burned corpses had a statistically significant effect where the greatest amount of protein breakdown was observed within the first 41.20 hours, after which intact protein slowly disappears. The average molecular weight of all fragments showed intact cTnT to be rapidly degraded into smaller fragments.

CONCLUSION

In cases of burns, such knowledge will assist in knowing if there were previous scars that might have mimicked a burn and also help to properly evaluate the real cause of death.

The effect of elapsed time on cardiac troponin-T (cTnT) degradation and its relation to postmortem interval in cases of electrocution

BACKGROUND

The estimation of postmortem interval (PMI) is of paramount importance for the police in their investigation when arriving at the scene of a questionable death. The aim of present study is to evaluate the effect of elapsed time on cardiac Troponin-T degradation and its association with PMI in cases of death due to electrocution.

METHODS

Cardiac tissue samples were collected from medico-legal autopsies, after informed consent from the relatives. The cases included were the subjects of electrocution without any prior history of disease who died in the hospital and their exact time of death was known. The analysis involves extraction of the protein at room temperature for different time periods (∼5, 26, 50, 84, 132, 157, 180, 205 and 230 Hrs), separation by SDS-PAGE and visualization by Western blot using cTnT specific monoclonal antibodies.

RESULTS

The results specify a characteristic banding pattern amongst human cadavers (n = 5), a pseudo-linear relationship between percent cTnT degraded and the time since death (R(2) = 0.87, p = 0.0001) was observed. The area of the bands within a lane was quantified by scanning and digitizing the image using Gel Doc (Universal Hood II).

CONCLUSIONS

The post-mortem Troponin-T fragmentation observed in this study reveals a sequential, time-dependent process with the potential for use as a predictor of PMI in cases of electrocution.

Butanolic fraction of Moringa oleifera Lam. (Moringaceae) attenuates isoprotrenol-induced cardiac necrosis and oxidative stress in rats: an EPR study

The preventive effect of Moringa oleifera polyphenolic fraction (MOPF) on cardiac damage was evaluated in isoproterenol (ISO) induced cardiotoxicity model of Wistar rats. Male rats in different groups were treated with MOPF orally at the dose of 50, 100 and 150 mg/kg/day for 28 days and were subsequently administered (s.c.) with ISO (85 mg/kg body weight) for the last two days. At the end of the experiment levels of serum troponin-T, creatine kinase-MB, lactate dehydrogenase, content of malondialdehyde (MDA), activities/levels of different cellular antioxidants were estimated in control and experimental groups. Additionally, scavenging potential to the hydroxyl radical of the fraction was measured by electron paramagnetic resonance (EPR). ISO administered rats showed significant increase in the levels of serum troponin-I, creatine kinase, lactate dehydrogenase, and heart tissue MDA content. Furthermore, marked reduction in the activities of antioxidants such as superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione levels were observed. EPR study showed an increase in signal intensity in ISO-induced rats. Triphenyl tetrazolium chloride (TTC) staining of heart section revealed a marked increase in infarcted area in ISO-induced rats. Histological features of the heart also indicated a disruption in the structure of cardiac myofibrils in these animals. MOPF (100 mg/kg body weight) pretreatment prevented all these adverse effects of ISO. Present results show that the rich polyphenolic content of Moringa oleifera significantly reduced the myocardial damage and decreased the oxidative stress, possibly through hydroxyl radical scavenging activity as evidenced from the EPR spectra.

Cardioprotective role of leaves extracts of Carissa opaca against CCl4 induced toxicity in rats

BACKGROUND

Carissa opaca are used traditionally in Pakistan for the treatment of various human ailments. Therefore, the study is arranged out to assess the cardio protective potential of different fractions of Carissa opaca leaves on CCl4-induced oxidative trauma in kidney.

METHODS

The parameters studied in this respect were the cardiac function test (CK (U/l), CKMB (U/l), genotoxicity (% DNA fragmentation), characteristic morphological findings and antioxidant enzymatic level of cardiac tissue homogenate.

RESULT

The protective effects of various fractions of Carissa opaca (C. opaca) leaves extract against CCl4 administration was reviewed by rat cardiac functions alterations. Chronic toxicity caused by eight week treatment of CCl4 to the rats significantly changed the cardiac function test, decreased the activities of antioxidant enzymes and glutathione contents whereas significant increase was found in lipid peroxidation comparative to control group. Administration of various fractions of C. opaca leaves extract with CCl4 showed protective ability against CCl4 intoxication by restoring the cardiac functions alterations, activities of antioxidant enzymes and lipid peroxidation in rat. CCl4 induction in rats also caused DNA fragmentation and histopathalogical abnormalities which were restored by co-admistration of various fraction of C. opaca leaves extract.

CONCLUSION

Results revealed that various fraction of C. opaca are helpful in cardiac dysfunctions.

The influence of age on serum concentrations of cardiac troponin I: results in rats, monkeys, and commercial sera

Cardiac troponins serve as serum biomarkers of myocardial injury. The current study examined the influence of age on serum concentrations of cardiac troponin I (cTnI). An ultrasensitive immunoassay was used to monitor cTnI concentrations in Sprague-Dawley (SD) rats and Erythrocebus patas monkeys of different ages. The mean cTnI concentrations were highest in 10-day-old rats compared to 25-, 40-, and 80-day-old SD rats. Cardiomyocyte remodeling was apparent in hearts from 10-day-old SD rats as evident by hypercellularity, irregularly shaped nuclei, and moderate numbers of myocytes undergoing mitosis and apoptosis. The mean concentration of cTnI in 5 newborn monkeys was considerably higher than that of three 1-year-old monkeys. Evidence of cardiomyocyte remodeling was also observed in these newborn hearts (loss of myofibrils and cytoplasmic vacuolation). Commercial animal serum samples were also analyzed. The concentrations of cTnI detected in fetal equine and porcine serum were considerably higher than that found in adult equine and porcine serum samples Likewise, fetal bovine serum had higher cTnI concentrations (>2,400 pg/ml) than did adult caprine and laprine samples (2.5-2.7 pg/ml). The present study found age-related differences in cTnI concentrations, with higher levels occurring at younger ages. This effect was consistent across several animal species.

Elevated troponin level with negative outcome was found in ischemic stroke

Background. Troponin increment is a highly sensitive and specific marker of myocardial necrosis. The reason of high troponin levels in acute stroke is not clear. The aim of this study was to identify the relationships between cardiac troponin-I (cTnI) level and stroke. Methods. This study recruited 868 patients who were admitted to Istanbul Medeniyet University due to acute ischemic stroke, and the diagnosis was confirmed by diffusion magnetic resonance imaging. The patients with the causes increasing troponin level were excluded from the study. A total of 239 patients were finally included in the study. Clinics were evaluated by the modified Rankin Scale (mRS) and the National Institutes of Health Stroke Scale (NIHSS). Results. Serum level of troponin was higher in ischemic stroke patients with anterior circulation involvement in comparison to posterior involvement or hemorrhagic stroke (P < 0.05). Higher troponin levels related to increased stroke scale scores at discharge in ischemic stroke (P < 0.05). The level of cTnI was correlated with stroke scale scores at both admission and discharge in posterior stroke patients (P < 0.01). Conclusion. cTnI is a highly specific and sensitive marker of myocardial damage, and its elevation was associated with more severe neurological deficits in acute ischemic stroke.

Acceptable cardiac safety profile of neoadjuvant 5-fluorouracil, epirubicin, cyclophosphamide and celecoxib (FEC-C) for breast cancer: a subanalysis of biomarkers for cardiac injury

PURPOSES

This substudy aimed to examine the changes in biomarkers for cardiac injury in patients who received neoadjuvant 5-fluorouracil, epirubicin, cyclophosphamide with concurrent celecoxib (FEC-C).

METHODS

Thirty-four female patients with histologically confirmed locally advanced breast cancer preoperatively received 3 cycles of FEC-C (500 mg/m², 75 mg/m², 500 mg/m²) with concurrent celecoxib (400 mg bid). Blood samples were drawn from patients on day (D) 0, D3, D21, D42, and D63 (end of therapy), and the serum levels of lactate dehydrogenase (LDH) and plasma levels of cardiac troponin I (cTnI) and N-terminal prohormone brain-type natriuretic peptide (NT-proBNP) were measured with commercially available test kits.

RESULTS

All patients tolerated this regimen well. Neither life-threatening toxicity nor clinical symptoms of cardiac damage were observed. Serum LDH increased significantly from baseline after 3 cycles of FEC-C (p<0.0001), but the change was possibly brought about by chemotherapy-induced liver derangement. However, NT-proBNP decreased significantly (p=0.009), while cTnI increased nonsignificantly (p=0.078) after 3 cycles of FEC-C compared to baseline, although this increase was still regarded as normal.

CONCLUSIONS

Short-term use of the FEC-C regimen has proven to be effective in locally advanced breast cancer, with an acceptable cardiac safety profile.

Effect of ursolic acid treatment on apoptosis and DNA damage in isoproterenol-induced myocardial infarction

The present study was designed to evaluate the protective effect of ursolic acid (UA) against isoproterenol-induced myocardial infarction. Myocardial infarction was induced by subcutaneous injection of isoproterenol hydrochloride (ISO) (85 mg/kg BW), for two consecutive days. ISO-induced rats showed elevated levels of cardiac troponins T (cTn T) and I (cTn I) and increased activity of creatine kinase-MB (CK-MB) in serum. Lipid peroxidative markers (thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and lipid hydroperoxides (HP)) elevated in the plasma and heart tissue whereas decreased activities of enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR)) in erythrocytes and heart tissue of ISO-induced rats. Non-enzymatic antioxidants (vitamin C, vitamin E and reduced glutathione (GSH)) levels were decreased significantly in the plasma and heart tissue of ISO-induced rats. Furthermore, ISO-induced rats showed increased DNA fragmentation, upregulations of myocardial pro-apoptotic B-cell lymphoma-2 associated-x (Bax), caspase-3, -8 and -9, cytochrome c, tumor necrosis factor-α (TNF-α), Fas and down-regulated expressions of anti-apoptotic B-cell lymphoma-2 (Bcl-2) and B-cell lymphoma-extra large (Bcl-xL). UA-administered rats showed decreased levels/activity of cardiac markers, DNA fragmentation and the levels of lipid peroxidative markers in the plasma and heart tissue. Activities of enzymatic antioxidants were increased significantly in the erythrocytes and heart tissue and also non-enzymatic antioxidants levels were increased significantly in the plasma and heart tissue in UA-administered rats. UA influenced decreased DNA fragmentation and an apoptosis by upregulation of anti-apoptotic proteins such as Bcl-2, Bcl-xL and down-regulation of Bax, caspase-3, -8 and -9, cytochrome c, TNF-α, Fas through mitochondrial pathway. Histopathological observations were also found in line with biochemical parameters. Thus, results of the present study demonstrated that the UA has anti-apoptotic properties in ISO-induced rats.

Myocardial infarction in thrombotic thrombocytopenic purpura: a single-center experience and literature review

BACKGROUND

Several case reports and series have described myocardial infarctions (MIs) in patients hospitalized for thrombotic thrombocytopenic purpura (TTP). The exact magnitude and outcome of this complication are unknown.

METHODS

Electronic medical records for patients admitted to Wake Forest University Baptist Medical Center were examined from 1996 to 2005. Those patients having a diagnosis of TTP during the hospitalization period were included in the analysis. Only patients' initial episodes of TTP were analyzed. Baseline cardiac and TTP risk factors were documented. Outcomes analyzed included MIs, arrhythmias, development of congestive heart failure and death.

RESULTS

Eighty-five patients diagnosed with TTP were identified with 13 (15.3%) having MIs, as defined by an elevation of cardiac enzymes. Median troponin I value was 5.9 ng/mL (range 3.7-8.8 ng/mL). Twelve patients had non-ST segment elevation MIs and one had ST segment elevation. Two of 13 patients who had echocardiographic analysis had documented wall motion abnormalities. There was no difference between non-MI and MI patients in cardiac risk factors, prior cardiac events, history of thromboembolic disease or heart failure. There was no in-hospital mortality difference.

CONCLUSION

MI is an important complication of TTP, identified in 15.3% of patients in our study. Routine cardiovascular evaluation with cardiac enzymes, electrocardiography, and telemetry is warranted in acute TTP patients. Appropriate intervention is yet to be determined.

Heart-type fatty acid-binding protein is more sensitive than troponin T to detect the ongoing myocardial damage in chronic heart failure patients

BACKGROUND

Heart-type fatty acid-binding protein (H-FABP) is a small cytosolic protein and released into the circulation when the myocardium is injured. Previous studies have demonstrated that both H-FABP and troponin T (TnT) are detectable in venous blood samples in chronic heart failure (CHF) patients, suggesting the presence of ongoing myocardial damage (OMD). We hypothesized that a cytosolic marker (H-FABP) is more sensitive than a myofibrillar component (TnT) in the detection of OMD in CHF.

METHODS AND RESULTS

We measured serum H-FABP and TnT levels in 126 consecutive CHF patients at admission, and patients were followed-up with a mean period of 474 +/- 328 days. Cutoff values for H-FABP (4.3 ng/mL) and TnT (0.01 ng/mL) were determined from previous studies. Positive rate of H-FABP was higher than that of TnT in all CHF patients (46% [58/126] versus 26% [33/126], P < .0001), and in severe CHF (New York Heart Association III/IV) patients (69% [34/49] versus 47% [23/49], P = .0121). There were 27 cardiac events during a follow-up period. In patients with cardiac events, H-FABP was more frequently detected than TnT (88% [24/27] versus 44% [12/27], P = .0103). There were 33 patients with positive H-FABP among 93 patients with negative TnT. Those patients had more severe New York Heart Association class, higher levels of brain natriuretic peptide, and higher rates of cardiac events (36% versus 5%, P < .0001) compared with those both H-FABP and TnT were negative. Kaplan-Meier analysis demonstrated that in patients with negative TnT, positive H-FABP group had higher risk for cardiac events than negative H-FABP group (P < .0001). A multivariate analysis with Cox proportional hazard model showed that H-FABP was the only independent predictor of cardiac events (hazard ratio 15.677, P = .0001). The area under the receiver operating characteristic curve was larger for H-FABP than for TnT (0.779 versus 0.581; P = .009), suggesting that H-FABP had greater predictive capacity for cardiac events than TnT.

CONCLUSIONS

H-FABP was more sensitive to detect OMD and could identify patients at high risk more effectively than TnT.

Early prediction of anthracycline induced cardiotoxicity

AIM

The purpose of this study is to evaluate echocardiographically determined cardiac functions with serum levels of brain natriuretic peptide (BNP), cardiac troponin I (cTnI) and total antioxidant status (TAOS) in childhood leukemia treated with chemotherapeutics containing anthracyclines.

METHODS

A study group of 29 patients who have been followed for acute lymphoblastic leukemia (ALL) and administered a treatment protocol containing chemotherapy of anthracyclines were included in the analysis. Levels of BNP, cTnI and TAOS were studied in serum samples of the patients.

RESULTS

We demonstrated that as the drug dosage increased, systolic ejection fraction (EF) and shortening fraction (FS) values decreased (EF r2=0.2327, FS r2=0.251). On the other hand, increased dosage of anthracycline therapy was associated with significant raise in plasma BNP levels (r2=0.246) and significant decrease in serum TAOS levels (r2=0.317) without any change in serum cTnI levels.

CONCLUSION

Our study suggest that serum TAOS and BNP levels may be useful as an early and sensitive indicator of anthracycline induced cardiotoxicity.

Positive troponin-T in noncompaction is associated with neuromuscular disorders and poor outcome

OBJECTIVES

Though cardiac troponin-T may be positive in hypertrophic and dilated cardiomyopathy, it is not known how often troponin-T is positive in left ventricular hypertrabeculation/ noncompaction (LVHT), an unclassified cardiomyopathy. This retrospective study aimed to assess how often troponin-T is positive in LVHT, is associated with elevated CK, is attributable to cardiac or extra-cardiac causes, in particular neuromuscular disorders (NMDs), or if it is a predictor of poor survival.

RESULTS

Among 100 patients, detected over a period of 11 years, troponin-T was determined at least once in 71 (71%) of them. Troponin-T was determined once in 36 patients, twice in 8 cases, three times in 11 patients, and more than three times in 16 cases. Troponin- T was positive at least once in 12 patients (17%). Forty-five of the 71 patients suffered from a NMD (63%). Troponin-T positivity was associated with elevated CK in 6 cases. Troponin-T-positivity was attributable to acute myocardial ischemia in a single case, to chronic renal failure in 5 cases, to dilated cardiomyopathy in 4 cases, to atrial fibrillation in 3 cases, to heart failure in 4 cases, and to NMD in 10 cases. Troponin-T positivity in LVHT patients with NMD was assumed to be due to cardiac involvement in the disease. Among the 22 patients who died during the observational period troponin was determined in 16 and was positive in 4 (25%).

CONCLUSIONS

Troponin-T is positive in 17% of the patients with LVHT. Most of these patients suffer from a NMD. Troponin-T positivity in LVHT predicts the presence of NMD and poor survival.

Clinical Evaluation of Point‐of‐Care‐Testing of Heart‐Type Fatty Acid‐Binding Protein (H‐FABP) for the Diagnosis of Acute Myocardial Infarction

The present study was carried out for clinical evaluation of point-of-care-testing (POCT) of heart-type fatty acid-binding protein (H-FABP), Rapicheck H-FABP, for the diagnosis of acute myocardial infarction (AMI), in comparison with conventional cardiac biochemical markers such as myoglobin, creatine kinase isoenzyme MB (CK-MB), and cardiac troponin T. Whole blood samples from patients with confirmed AMI (n = 53), patients with non-AMI cardiac diseases (n = 24), and patients with non-cardiac diseases with chest pain (n = 6) were used. When a test line appeared within 15 min after the addition of 150 microL of whole blood, it was designated to be positive for H-FABP. A control line indicates a proper use of the test. On the other hand, when no test line appeared, it was negative. In the superacute phase of AMI within 3 hours, the diagnostic sensitivity of H-FABP was 93.1%, which was the highest of the four markers compared here. The diagnostic specificity in the phase for H-FABP was 64.3%, while it was 100% with cardiac troponin T. The POCT of H-FABP is thought to be practical for the detection of cardiac damage and effective for the diagnosis of AMI in superacute phase within 3 hours and/or 6 hours.

Protective effect of labedipinedilol-A, a novel dihydropyridine-type calcium channel blocker, on myocardial apoptosis in ischemia-reperfusion injury

The effects of labedipinedilol-A, a novel dihydropyridine-type calcium channel blocker with alpha-/beta-adrenoceptor blocking activities, on myocardial infarct size, apoptosis and necrosis in the rat after myocardial ischemia/reperfusion (45 min/120 min) were investigated. Ten minutes prior to left coronary artery occlusion, rats were treated with vehicle or labedipinedilol-A (0.25 or 0.5 mg/kg, i.v.). In the vehicle group, myocardial ischemia-reperfusion induced creatine kinase (CK) release and caused cardiomyocyte apoptosis, as evidenced by DNA ladder formation and terminal dUTP deoxynucleotidyltransferase nick end-labeling (TUNEL) staining. Treatment with labedipinedilol-A (0.25 or 0.5 mg/kg) reduced infarct size significantly compared to vehicle group (18.75+/-0.65% and 8.27+/-0.29% vs. 41.72+/-0.73%, P<0.01). Labedipinedilol-A also reduced the CK, CK-MB, lactate dehydrogenase (LDH) and troponin T levels in blood. In addition, labedipinedilol-A (0.5 mg/kg) significantly decreased TUNEL positive cells from 19.21+/-0.52% to 9.73+/-0.81% (P<0.01), which is consistent with absence of DNA ladders in the labedipinedilol-A group. Moreover, labedipinedilol-A pretreatment also decreased calcium content in ischemic-reperfused myocardial tissue. In conclusion, these results demonstrate that labedipindielol-A, through reduction of calcium overload and apoptosis, exerts anti-infarct effect during myocardial ischemia-reperfusion and would be useful clinically in the prevention of acute myocardial infarction.

Diagnostic efficacy of biochemical markers in diagnosis post-mortem of ischaemic heart disease

In forensic medicine, there is a need for more sensitive biochemical markers for the post-mortem diagnosis of acute myocardial infarction. A study of the distribution of biochemical markers in different fluids is of great significance in post-mortem diagnosis, because their distribution depends on the location of tissue damage and release kinetics. The aim of this study is to compare the sensitivities and specificities of creatine kinase-MB (CK-MB), myoglobin and cTnI in serum and pericardial fluid for the post-mortem diagnosis of acute myocardial infarction (AMI). We studied 188 cadavers selected during 1 year from medicolegal autopsies. The groups were as follows: (1) myocardial infarction (n = 52); (2) asphyxia (n = 59); (3) multiple trauma (n = 41); (4) natural deaths excluding myocardial infarction (n = 36). We obtained statistically significant differences in pericardial fluid for all the biochemical markers, the highest levels being obtained in the group of cadavers who had died from myocardial infarction. A common factor is the high negative predictive value found in biochemical markers, which is contrary to the findings obtained in clinical practice, when the percentages of sensitivity are very high.

Leucocyte depletion in cardiopulmonary bypass: a comparison of four strategies

Leucocytes have been shown to play a fundamental role in the pathophysiology of inflammation. This prospective, randomized, controlled study was designed to identify the most advantageous leucocyte depletion technique in terms of reduction in systemic inflammatory response syndrome and myocardial ischaemia reperfusion injury associated with cardiopulmonary bypass (CPB). Forty consecutive patients undergoing elective coronary artery bypass graft (CABG) surgery were randomly allocated to one of four groups. The four groups consisted of a control group, a systemic leucocyte depletion (SLD) group, a cardioplegic leucocyte depletion (CLD) group and a total leucocyte depletion (TLD) group. There were 10 patients in each group. Lactoferrin (marker of neutrophil activation) and troponin-I (marker of myocardial ischaemia reperfusion injury) were measured at six time points: post induction, 5 min on CPB, 5 min before releasing the aortic crossclamp, 15 min after releasing the clamp and 1 and 24 hours after the discontinuation of CPB. Plasma lactoferrin levels increased rapidly in every group after the commencement of CPB, subsequently reached a peak after releasing the aortic crossclamp and gradually declined after the discontinuation of CPB. The lowest lactoferrin concentration was observed in the TLD (range 2.15-141.9 ng/mL) and CLD groups (7.469-114.6 ng/mL). Regarding myocardial injury, plasma cardiac troponin-I levels did not differ significantly between groups; but troponin-I concentrations rose dramatically after releasing the aortic crossclamp in all groups. Nevertheless, the CLD group had the lowest troponin-I level (1.37-5.55 ng/mL). In conclusion, it is believed that myocardial ischaemia is probably a major contributor to the inflammatory response. Although there is no clear statistical significance shown in this pilot study, the data tend to support the cardioplegic leucocyte depletion strategy as the optimal method for attenuating neutrophil activation and myocardial ischaemia reperfusion injury.

Use of cytosolic and myofibril markers in the detection of ongoing myocardial damage in patients with chronic heart failure

PURPOSE

Measurement of serum levels of cytosolic and myofibril components of cardiac tissue could indicate ongoing myocardial damage in patients with chronic heart failure.

METHODS

We correlated serum levels of a cytosolic marker (heart-type fatty acid-binding protein) and a myofibril marker (troponin T) with the severity of symptoms (based on the New York Heart Association [NYHA] class), neurohumoral derangement, and subsequent cardiac events in 56 patients with chronic heart failure.

RESULTS

Mean (+/- SD) levels of heart-type fatty acid-binding protein were greater in patients with NYHA class III or IV heart failure (9.9 +/- 5.2 ng/mL) than in those with NYHA class II (4.9 +/- 1.9 ng/mL, P <0.0001). Detection of troponin T (> or =0.02 ng/mL) was also more common in patients with worse heart failure (81% [13/16] in class III or IV vs. 43% [17/40] in class II, P = 0.02). Significant correlations were found between heart-type fatty acid-binding protein levels and plasma levels of A-type natriuretic peptide (r = 0.45, P = 0.0004), B-type natriuretic peptide (r = 0.66, P <0.0001), and norepinephrine (r = 0.36, P = 0.006). Male sex (hazard ratio [HR] = 5.0; 95% confidence interval [CI]: 1.3 to 19), detectable troponin T levels (HR = 7.0; 95% CI: 1.1 to 44), heart-type fatty acid-binding protein (HR = 2.6 per 3.9-ng/mL increase; 95% CI: 1.1 to 6.5), and left ventricular ejection fraction (HR = 3.6 per 15% decrease; 95% CI: 1.2 to 11) were independently associated with subsequent cardiac events (8 deaths or 10 readmissions because of worsening heart failure).

CONCLUSION

Heart-type fatty acid-binding protein and troponin T are markers of ongoing myocardial damage, and are associated with subsequent cardiac events in patients with chronic heart failure.

Cardiac troponins

Cardiac troponins I and T are proteins integral to the function of cardiac muscle. They are very sensitive markers for the detection of myocardial damage, and the ability to assay their serum levels accurately and quickly have revolutionized the concepts of minor myocardial injury and infarction. They are also powerful prognostic indicators of future adverse cardiac events. Limitations, more of troponin T than I, include decreased specificity in renal failure and skeletal muscle disease. Rapid, whole blood assays are now available that can be done at the patient's bedside. This review discusses the cardiac troponins, their biochemistry, the assays for them currently available, and their roles in the evaluation of cardiac disease in the Emergency Department (ED).

Cardiac troponin I release after severe scorpion envenoming by Tityus serrulatus

Eight children aged 2-9 years, with signs and symptoms of severe scorpion envenoming by Tityus serrulatus were studied. All patients showed clinical manifestations of cardiac dysfunction, with ECG and echocardiographic alteration and five developed pulmonary edema. Troponin I levels were normal in all patients on admission, except for two who arrived later, and increased thereafter, with maximum values being observed 24-36 h after the sting. The detection of TnI in patients with severe scorpion envenoming, and the observed temporal pattern and serum levels meet the criteria established for the diagnosis of acute myocardial infarction. The rapid reversibility of cardiac dysfunction, together with the normalization of the enzymatic, ECG and echocardiographic data, indicates the occurrence of an acute myocardial lesion without underlying or associated coronary disease.

Troponin T concentrations 72 hours after myocardial infarction as a serological estimate of infarct size

BACKGROUND

After acute myocardial infarction, the structural protein T is released considerably longer than cytosolic creatine kinase (CK), CK MB isoenzyme (CK-MB), or lactate dehydrogenase (LDH) and late troponin T release (> 48 hours after onset of chest pain) appears to be less affected by early coronary reperfusion.

OBJECTIVE

To investigate the precision of a single measurement of circulating troponin T concentrations 72 hours after onset of chest pain compared with standard scintigraphic and enzymatic estimates of myocardial infarct size.

METHODS

Quantitative single photon emission computed tomography thallium-201 scintigraphy at rest was performed in 37 patients 2-3 weeks after myocardial infarction (group 1: 14 patients without early coronary reperfusion; group 2: 23 patients with early reperfusion achieved by thrombolytic therapy, by percutaneous transluminal coronary angioplasty, or by both).

RESULTS

In both groups, the number of myocardial segments with abnormal thallium-201 uptake indicating the individual extent of irreversible myocardial damage correlated significantly with the troponin T concentrations 72 hours after infarction as well as with peak concentrations of CK, CK-MB, and LDH.

CONCLUSION

The data show that a single measurement of circulating troponin T 72 hours after onset of chest pain--independent of reperfusion--is superior for the estimation of myocardial infarct size to measurement of peak CK, CK-MB, or LDH, which require serial determinations and depend on coronary reperfusion.

Cardiac troponins: utility in renal insufficiency and end-stage renal disease

Currently available serum markers of cardiac injury in patients with renal insufficiency suffer from impaired sensitivity and specificity. Cardiac troponins (cTnI, cTnT) are relatively new diagnostic markers of myocardial injury and have gained widespread application in the non-renal-failure population to diagnose myocardial infarction. Over the past few years the specificity and sensitivity of cardiac troponins for diagnosing acute myocardial infarction in patients with renal dysfunction have been examined. Most data indicate that cardiac troponin I has an excellent specificity, but until more studies are available this marker should be considered a useful but imperfect serum marker of an acute coronary syndrome in patients with underlying renal dysfunction.

Using postoperative cardiac Troponin-I (cTi) levels to detect myocardial ischaemia in patients undergoing vascular surgery

BACKGROUND

Cardiac complications occur commonly in vascular surgery patients. Diagnosis of cardiac complications is difficult because of the inaccuracies associated with traditional cardiac enzyme measurements. CTi, a highly sensitive and specific marker of myocardial injury, may be able to detect cardiac complications with greater ease and accuracy.

METHODS

The study prospectively examined 100 consecutive patients who underwent major vascular surgery between 6/7/98 and 31/12/98 at the Royal Brisbane Hospital. Daily measurements of cTi, creatine kinase (CK), creatine kinase MB (CKMB), CKMB index, renal function and haemoglobin were taken for three postoperative days. One postoperative electrocardiograph (ECG) was taken. An extensive cardiac history was taken. Intraoperative and postoperative events were recorded.

FINDINGS

There were 100 patients. 18 patients (18%) had a cTi elevation. On the basis of classical diagnostic criteria, 15 patients (15%) suffered one or more cardiac complication (either myocardial infarction, congestive cardiac failure, unstable angina or atrial fibrillation). One patient (1%) who had a cTi elevation died. CTi elevation occurred in five patients (5%) who were not diagnosed with cardiac complications based on traditional criteria. Despite not meeting specific diagnostic criteria for cardiac complications, all patients showed signs and symptoms that could be attributed to myocardial ischaemia. Every patient who developed congestive cardiac failure or atrial fibrillation had a cTi elevation. A Chi-square analysis revealed a significant association between cTi elevation and postoperative cardiac complications. Four variables contributed small but significant amounts of unique variance to the prediction of peak cTi on linear regression analysis. These were peak CKMB index, postoperative congestive cardiac failure, postoperative chest pain and postoperative cardiac complications.

CONCLUSIONS

Routine cTi monitoring of postoperative vascular patients would be an effective and inexpensive way to detect patients with cardiac complications. The relationship between postoperative cTi elevation and significant coronary artery disease remains to be shown.

Cardiac troponin and beta-type myosin heavy chain concentrations in patients with polymyositis or dermatomyositis

Cardiac troponin T (cTnT), cardiac troponin I (cTnI), myosin heavy chains (MHC), myoglobin, creatine kinase (CK), and creatine kinase isoenzyme MB (CKMB), were measured in blood samples from 39 polymyositis (PM) or dermatomyositis (DM) patients without clinical evidence for cardiac involvement to evaluate their clinical usefulness in this patient population. MHC, myoglobin, and CKMB were frequently elevated and correlated with each other and with disease severity. Undetectable cTnI in all but one patient indicated that MHC was released from skeletal muscle, thereby providing the first laboratory evidence of frequent slow-twitch muscle fibre-necrosis in patients with PM or DM. CKMB was elevated in 51%, cTnT in 41%, and cTnI in only 2.5% of patients. cTnI did not correlate with other markers or with disease severity scores. The close correlations found between cTnT and skeletal muscle damage markers and the relationship between cTnT with disease severity without clinical evidence for myocardial damage suggest a release of cTnT from skeletal muscle. The relationship of cTnT with disease severity indicates a possible role of the marker for risk stratification. However, the prognostic values of cardiac troponins and other muscle damage markers in PM/DM patients remain to be compared in prospective outcome trials.

Leukocyte filtration in the early reperfusion phase on cardiopulmonary bypass reduces myocardial injury

Improved myocardial protection and cardiopulmonary bypass (CPB) have limited, but not abolished, intraoperative myocardial damage due to surgical reperfusion injury after release of the aortic crossclamp. In this double-blind, randomized study, we evaluated whether short-term leukocyte filtration during reperfusion may further reduce myocardial damage. Thirty-eight patients with coronary artery disease were randomly assigned to CPB with (group I; n = 19) or without leukocyte filtration (group II; n = 19). There was no difference in bypass time or crossclamp time between the groups. No patient in group I required catecholamines, whereas three patients in group II were supported with adrenaline or dobutamine on the first and second postoperative day. In addition, troponin T plasma levels were lower in group I (p < 0.05), whereas other markers for tissue injury (CK, CK-MB, LDH, S-GOT and S100B) did not differ. In conclusion, leukocyte filtration during reperfusion may further improve CPB by reducing myocardial damage.

Heterogeneity in human cardiac troponin I standards

The LC-MS analysis of recombinant cardiac troponin I (cTnI) and cTnI extracted from human hearts showed a high degree of structural heterogeneity among all samples. The examined recombinant cTnI samples indicated posttranslational modifications, presumably due to their purification (i.e., 2-mercaptoethanol adducts and carbamylation) and related to their expression (i.e., an N-terminal expression tag). The extracted cTnI samples, while having a higher degree of structural heterogeneity, showed less structural variance between samples than the recombinant proteins. The LC-MS analysis of the extracted cTnI samples provided evidence of posttranslational modification by phosphorylation, acetylation, proteolytic cleavage, and intrachain disulfide bond formation.

Specificity of cardiac troponin I and creatine kinase-MB isoenzyme in asymptomatic long-term hemodialysis patients and effect of hemodialysis on these cardiac markers

OBJECTIVES

The objectives of this study were: (1) to evaluate the specificity of cardiac troponin I and creatine kinase-MB isoenzyme in ambulatory asymptomatic chronic renal failure patients on long-term hemodialysis, and (2) to evaluate the effect of hemodialysis on the serum levels of cardiac troponin I and creatine kinase-MB isoenzyme.

METHODS

One hundred and forty-four consecutive ambulatory asymptomatic chronic renal failure patients on hemodialysis for a minimum of 1 year were evaluated clinically. Serum cardiac troponin I and creatine kinase-MB isoenzyme levels were measured with specific monoclonal antibodies before and after dialysis using ACCESS Troponin I and ACCESS CK-MB assays.

RESULTS

The specificity of serum cardiac troponin I was 83% with a cutoff level of 0.03 ng/ml, which is an expected level for healthy population, but it rose to 100% with a cutoff level of 0.15 ng/ml, which is a reference level for patients with acute myocardial infarction. Twenty-four (17%) patients had borderline elevation in cardiac troponin I (>0.03 to <0.15 ng/ml). A history of angina pectoris was more common in the borderline-elevated cardiac troponin I subgroup. In 28% of the patients, serum creatine kinase-MB isoenzyme levels were increased with a specificity of 72% at a cutoff level of 4 ng/ml, which is the upper limit of normal, but the specificity rose to 98% by increasing the cutoff level value to 10 ng/ml. There were no statistically significant differences in serum levels of cardiac troponin I and creatine kinase-MB isoenzyme before and after dialysis.

CONCLUSIONS

Cardiac troponin I is highly specific in ambulatory asymptomatic chronic renal failure patients on long-term hemodialysis; borderline elevations in cardiac troponin I may represent microinjury to the myocardium. A serum level of creatine kinase-MB isoenzyme >2.5 times of the normal upper limit may be highly specific in this patient population. Hemodialysis per se does not significantly change the serum levels of cardiac troponin I and creatine kinase-MB isoenzyme.

Comparison of the diagnostic value of cardiac troponin I and T determinations for detecting early myocardial damage and the relationship with histological findings after isoprenaline-induced cardiac injury in rats

Cardiac troponins I (cTnI) and T (cTnT) have been shown to be highly sensitive and specific markers of myocardial cell injury. The purpose of this study was to investigate the diagnostic value of cTnI and cTnT with regard to creatine kinase (CK) and lactate dehydrogenase (LD) and to determine whether they can be used for early diagnosis of myocardial damage in rats, and to examine the relationship between cTnl and cTnT release with histological examinations, using isoprenaline-induced cardiac muscle damage as an experimental model in the rat. Eighteen Wistar rats per group were treated with a single dose of either isoprenaline (iso) or with normal saline as a control group. The anti-cTnI and cTnT monoclonal antibodies (mAbs) employed in the cTnI (Access) and cTnT (Elecsys) assays cross-react with cTnI and cTnT of the rat. A highly significant rise of cTnl or cTnT was found already 2 h after iso. The time-courses of cTnI and cTnT were monophasic in form. The highest cTnI (mean+/-S.D., 1.1+/-2.3 ng/ml) and cTnT (mean+/-S.D. 3.6+/-30 ng/ml) were found 4 h after iso. cTnI and cTnT significantly increased in iso-treated rats in comparison with controls whether the differences between 2-, 4- and 6-h levels and basal levels were considered or not. The areas under cTnl and cTnT curves (AUC) (0-6 h) and the maximal cTnI and cTnT (0-6 h) after iso were significantly different from the controls. For CK and LD, no elevation in comparison with controls could be detected (except a trend for LD whether or not the difference between 6-h levels and basal levels were considered (P=0.08) and for LD AUC (0-6 h) (P=0. 059)). Correlations between maximal cTnI and cTnT and AUC were 0.69 (P=0.0001) and 0.60 (P=0.0066), respectively. Histological examinations of iso-treated rats revealed acute focal or multifocal myofibrillar degeneration of the myocardial tissue in ten out of 14 rats and showed the earliest alterations 4 h after iso in one treated rat. Only four of the controls exhibited evidence of mild changes and slight mononuclear cell infiltration. cTnl and cTnT peak values to at least 0.35 and 1.3 ng/ml, respectively, were necessary to detect histological myocardial cell injury after iso. cTnI and cTnT were found to be early markers for diagnosing iso-induced myocardial damage in comparison with CK and LD. Elevations of cTnI and cTnT appeared to relate to the severity of histologic changes after myocardial injury. Although there was a difference in the absolute concentration of results between cTnI and cTnT assays, due to a lack of standardization and heterogeneity in the cross-reactivities of mAbs to various troponin I and T forms, cTnI and cTnT can be used as easily measurable target parameters for detection of cardiotoxic and/or cardiodegenerative effects in rats.

Minor cardiac troponin T release in patients undergoing coronary artery bypass graft surgery on a beating heart

OBJECTIVES

To determine whether and to what extent coronary artery bypass graft (CABG) surgery without extracorporeal circulation is associated with cardiac troponin T (TnT) release.

DESIGN

Prospective study.

SETTING

A single university hospital.

PARTICIPANTS

Twenty-three patients scheduled for minimally invasive CABG surgery. Sixteen patients received one coronary anastomosis, and seven received two.

INTERVENTIONS

TnT and creatine kinase-MB (CK-MB) levels were determined immediately before induction of anesthesia (baseline) and at 0, 12, and 24 hours after surgery. Hemodynamic measurements were made, and 5-lead electrocardiograms with continuous automated ST-segment trends were analyzed.

MEASUREMENTS AND MAIN RESULTS

All patients had a good cardiac outcome. Median cumulative coronary artery occlusion time was 27 minutes (range, 10 to 49 minutes). TnT levels were undetectable in 91.3% of patients at baseline when a detection limit of 0.01 ng/mL was employed. TnT and CK-MB showed significant elevations at 12 and 24 hours versus baseline. Postoperatively, TnT was detectable in 91.3% of patients, and 17.4% suffered minor myocardial damage, as evidenced by an abnormal increase in TnT greater than 0.2 ng/mL, excluding those exhibiting myocardial infarction. ST segment changes developed in seven patients, persisting for 13.0 minutes (range, 9.5 to 15.8 minutes) and disappearing immediately after coronary artery clamp release. There were no significant correlations between cumulative coronary occlusion time and peak TnT or CK-MB levels.

CONCLUSIONS

TnT was detected after surgery in most patients, and significant TnT levels indicative of myocardial injury (>0.2 ng/mL) were detected in only 17% of patients, probably as a result of brief periods of coronary artery occlusion.

Laboratory diagnosis of patients with acute chest pain

The enzyme activities of creatine kinase (CK), its isoenzyme MB (CK-MB) and of lactate dehydrogenase isoenzyme 1 (LD-1) have been used for years in diagnosing patients with chest pain in order to differentiate patients with acute myocardial infarction (AMI) from non-AMI patients. These methods are easy to perform as automated analyses, but they are not specific for cardiac muscle damage. During the early 90's the situation changed. First creatine kinase MB mass (CK-MB mass) replaced the measurement of CK-MB activity. Subsequently cardiac-specific proteins troponin T (cTnT) and troponin I (cTnI) appeared on the scene, displacing LD-1 analysis. However, troponin concentrations in blood increase only from four to six hours after onset of chest pain. Therefore a rapid marker such as myoglobin, fatty acid binding protein or glycogen phosphorylase BB could be used in early diagnosis of AMI. On the other hand, CK-MB isoforms alone may also be useful in rapid diagnosis of cardiac muscle damage. Myoglobin, CK-MB mass, cTnT and cTnI are nowadays widely used in diagnosing patients with acute chest pain. Myoglobin is not cardiac-specific and therefore requires supplementation with some other analyses such as troponins to support the myoglobin value. Troponins are very highly cardiac-specific. Only the sera of some patients with severe renal failure, which requires hemodialysis, have elevated cTnT and/or cTnI without there being any evidence of cardiac damage. On the other hand, the latest studies have shown that elevated troponin levels in sera of hemodialysis patients point to an increased risk of future cardiac events in a similar manner to the elevated troponin values in sera of patients with unstable angina pectoris. In addition, the bedside tests for cTnT and cTnI alone or together with myoglobin and CK-MB mass can be used instead of quantitative analyses in the diagnosis of patients with chest pain. These rapid tests are easy to perform and they do not require expensive instrumentation. For routine clinical laboratory practice we suggest that in diagnosis of patients with chest pain, myoglobin and CK-MB mass measurements should be performed whenever they are requested (24 h/day) and cTnT or cTnI on admission to the hospital and then 4-6 and 12 hours later.

Acute coronary ischemia: troponin I and T

Despite advances in diagnosis and management, ischemic heart disease remains the leading cause of death in the USA. Serum cardiac enzymes, one of the three fundamental criteria for establishing the diagnosis of myocardial infarction, are not specific for cardiac muscle and have a narrow time-window. The recent development of monoclonal antibodies to cardiac troponin I and troponin T has resulted in cardiac-specific assays. Several published studies have documented the utility of troponin proteins in the evaluation of myocardial necrosis. A brief overview of the characteristics and clinical utility of troponin T and I is presented here.

Emergency department triage strategies for acute chest pain using creatine kinase-MB and troponin I assays: a cost-effectiveness analysis

BACKGROUND

Evaluation of acute chest pain is highly variable.

OBJECTIVE

To evaluate the cost-effectiveness of strategies using cardiac markers and noninvasive tests for myocardial ischemia.

DESIGN

Cost-effectiveness analysis.

DATA SOURCES

Prospective data from 1066 patients with chest pain and from the published literature.

TARGET POPULATION

Patients admitted with acute chest pain.

TIME HORIZON

Lifetime.

PERSPECTIVE

Societal.

INTERVENTIONS

Creatine kinase (CK)-MB mass assay alone; CK-MB mass assay followed by cardiac troponin I assay if the CK-MB value is normal; CK-MB mass assay followed by troponin I assay if the CK-MB value is normal and electrocardiography shows ischemic changes; both CK-MB mass and troponin I assays; and troponin I assay alone. These strategies were evaluated alone or in combination with early exercise testing.

OUTCOME MEASURES

Lifetime cost, life expectancy (in years), and incremental cost-effectiveness.

RESULTS OF BASE-CASE ANALYSIS

For patients 55 to 64 years of age, measurement of CK-MB mass followed by exercise testing in appropriate patients was the most competitive strategy ($43000 per year of life saved). Measurement of CK-MB mass followed by troponin I measurement had an incremental cost-effectiveness ratio of $47400 per year of life saved for patients 65 to 74 years of age; it was also the most cost-effective strategy when early exercise testing could not be performed, CK-MB values were normal, and ischemic changes were seen on electrocardiography.

RESULTS OF SENSITIVITY ANALYSIS

Results were influenced by age, probability of myocardial infarction, and medical costs.

CONCLUSIONS

Measurement of CK-MB mass plus early exercise testing is a cost-effective initial strategy for younger patients and those with a low to moderate probability of myocardial infarction. Troponin I measurement can be a cost-effective second test in higher-risk subsets of patients if the CK-MB level is normal and early exercise testing is not an option.