Cardiac troponin elevations in chronic renal failure: prevalence and clinical significance

Elevation of Highly Sensitive Cardiac Troponin T Among End-Stage Renal Disease Patients Without Acute Coronary Syndrome

Background

In end-stage renal disease (ESRD), troponin T concentrations can be elevated even without cardiac ischaemia, which hampers the diagnosis of acute myocardial infarction (AMI). The objectives of our study were to determine the proportion of dialysisdependent ESRD patients without acute coronary syndrome (ACS) but with highly sensitive cardiac troponin T (hs-cTnT) levels above the 99th percentile upper reference limit and to evaluate the range of hs-cTnT among this population.

Methods

A cross-sectional study was conducted at the haemodialysis (HD) unit of a tertiary hospital in Malaysia from January 2018 to February 2019. Dialysis-dependent ESRD patients were included and those with a recent history of ACS (within 30 days) were excluded. Pre-dialysed serum hs-cTnT levels were measured using Cobas e411. The upper limit of the 99th percentile value for troponin T was 14 ng/L.

Results

A total of 150 patients were recruited as study participants. The majority were female (62%) and of Malay ethnicity (94%), and the mean (SD) age was 45.19 (16.36) years old. The hs-cTnT range (min, max) was 11.39–738.30 ng/L and the median (interquartile range [IQR]) of hs-cTnT was 59.20 (83.41) ng/L. Elevated hs-cTnT levels were observed in 149/150 (99%) of the study participants (54/55 [98.2%] of the patients were on HD, and 95/95 [100.0%] of the patients were on continuous ambulatory peritoneal dialysis).

Conclusion

This study supports prior research showing that even without ACS, most ESRD patients have elevated concentrations of cardiac troponin. Furthermore, our study illustrates the need to revisit the use of absolute troponin values when making a diagnosis of ACS in ESRD patients.

Troponins in Renal Dysfunction

“I have yet to see any problem, however complicated, which, when you looked at it in the right way, did not become still more complicated.”

Poul (William) Anderson

Strategies to overcome misdiagnosis of type 1 myocardial infarction using high sensitive cardiac troponin assays

High sensitive cardiac troponin assays have become the gold standard in the diagnosis of an acute type 1 myocardial infarction (MI) in the absence of ST-segment elevation. Several acute or chronic conditions that impact cardiac troponin levels in the absence of a MI might lead to a misdiagnosis of MI. For example, patients with impaired renal function as well as elderly patients often present with chronically increased cardiac troponin levels. Therefore, the diagnosis of MI type 1 based on the 99th percentile upper limit of normal threshold is more difficult in these patients. Different diagnostic approaches might help to overcome this limitation of reduced MI specificity of sensitive troponin assays. First, serial troponin measurement helps to differentiate chronic from acute troponin elevations. Second, specific diagnostic cut-offs, optimized for a particular patient group, like elderly patients, are able to regain specificity. Such an individualized use and interpretation of sensitive cardiac troponin measurements improves diagnostic accuracy and reduces the amount of misdiagnosed MI type 1.

Neutrophil to lymphocyte ratio might help prediction of acute myocardial infarction in patients with elevated serum creatinine

Background and Objective:

Diagnostic performance of troponin assays is affected by renal insufficiency. Neutrophil to lymphocyte ratio(NLR) is an independent predictor of acute coronary syndrome. Our objective was to evaluate performance of NLR in diagnosing acute myocardial infarction (AMI) among patients with elevated serum creatinine.

Methods:

Patients with elevated creatinine levels evaluated for coronary artery disease were included (n=284). Patients were divided into two groups according to having AMI or non-specific chest pain. AMI diagnosis was made based on clinical and laboratory data, including serial EKG and cardiac enzymes, ECHO and coronary angiography.

Results:

Troponin, neutrophil, and NLR were found to be higher in patients with AMI, compared to patients without AMI (P= 0.001, P= 0.001 and P=0.028, respectively). ROC curve analysis for NLR in diagnosing AMI was significant (AUC: 0.607; P=0.003). Sensitivity, specificity, LR +, LR-, PPV and NPV for NLR>7.4 were found as 42.3%, 74.7%, 1.68%, 0.77%, 77% and 40%, respectively. Logistic regression analysis revealed that patients whose NLR>7.4 were 2.18 times as likely to have AMI.

Conclusions:

NLR can be used as an independent predictor of AMI in patients with renal insufficiency. This seems to get more important in the era of high sensitivity troponin assays. Our results might also help in early diagnosis of AMI in this high risk population while serial cardiac enzyme results are pending.

Factors underlying elevated troponin I levels following pacemaker primo-implantation

BACKGROUND

Cardiac troponins are routinely used as markers of myocardial damage. Originally, they were only intended for use in diagnosing acute coronary syndromes; however, we now know that raised serum troponin levels are not always caused by ischemia. There are many other clinical conditions that cause damage to cardiomyocytes, leading to raised levels of troponin. However, the specificity of cardiac troponins towards the myocardium is absolute. Our work focuses on mechanical damage to the myocardium and on monitoring the factors that raise the levels of cardiospecific markers after primo-implantation of a pacemaker with an actively fixed electrode.

AIMS

(i) To determine whether the use of a primo-implanted pacemaker with an electrode system with active fixation will raise troponin levels over baseline. (ii) To assess whether troponin I elevation is dependent on procedure complexity.

METHODS

We enrolled 219 consecutive patients indicated for pacemaker primo-implantation; cardiospecific marker values (troponin I, CKMB, myoglobin) were determined before the implantation procedure and again at 6- and 18-h intervals after the procedure. We monitored duration of cardiac skiascopy, number of attempts to place the electrode (active penetration into the tissue) and intervention range (single-chamber versus dual-chamber pacing), and we assessed the clinical data.

RESULTS

The average age of the enrolled patients was 78.2 ± 8.0 years (median age, 80 years); women constituted 45% of the group. We implanted 128 dual-chamber and 91 single-chamber devices with an average skiascopic time of 38.6 ± 22.0 s (median, 33.5 s). Troponin I serum levels increased from an initial 0.03 ± 0.07 μg/L (median, 0.01) to 0.18 ± 0.17 μg/L (median, 0.13) and 0.09 ± 0.18 μg/L (median, 0.04) at 6 and 18 h, respectively. The differences were statistically significant (P < 0.001 or P < 0.001). We confirmed a correlation between troponin increase and duration of skiascopy (P < 0.001). We also demonstrated a correlation between increased troponin I and number of attempts to place a pacemaker electrode (penetration into the tissue) at 6 h (P < 0.001) post-implantation.

CONCLUSION

We detected slightly elevated troponin I levels in patients with primo-implanted pacemakers using electrodes with active fixation. We demonstrated a direct correlation between myocardial damage (number of electrode penetrations into the myocardium) and troponin I elevation, as well as between complexity (severity) of the implantation procedure (indicated by prolonged skiascopy) and raised troponin I. The described phenomenon demonstrates the loss of the diagnostic role of troponin I early after pacemaker primo-implantation in patients with concomitant chest pain.

Elevated troponin I levels but not low grade chronic inflammation is associated with cardiac-specific mortality in stable hemodialysis patients

BACKGROUND

Elevated cardiac troponin I (TnI) levels are associated with all-cause mortality in stable hemodialysis patients. Their relationship to cardiac-specific death has been inconsistent, and the reason for their elevation is not well understood. We hypothesized that elevated TnI levels in chronic stable hemodialysis patients more specifically track with cardiac mortality, and this mechanism is independent of other contributors of cardiac mortality, such as inflammation.

METHODS

We conducted a single-centre, cohort study of prevalent hemodialysis patients at a tertiary care hospital. Plasma TnI levels were measured with routine monthly blood tests in clinically stable patients for two consecutive months. Plasma TnI was measured by immunoassay and a value above the laboratory reference range (0.06 μg/L) was considered elevated. The primary outcome of death was adjudicated separately for this study, and classified as cardiac, non-cardiac, or unknown. Cox proportional hazard models were used to examine the association of TnI with the all-cause and cardiac-specific mortality, adjusting for potential confounders, including C-reactive protein (CRP) as a marker of inflammation.

RESULTS

Of 133 patients followed for a median of 1.7 years, there were 38 deaths (58% non-cardiac, 39% cardiac, 3% unknown). Elevated TnI was associated with adjusted HR for all-cause mortality of 2.57 (95% CI 1.30-5.09) and an adjusted HR for cardiac death of 3.14 (95% CI 1.07-9.2), after accounting for age, time on dialysis, diabetes status, prior coronary artery disease history, and C-reactive protein. Although CRP was also independently associated with all-cause mortality, it did not add prognostic information to TnI for cardiac-specific death.

CONCLUSION

Elevated TnI levels are independently associated with cardiac and all-cause mortality in asymptomatic hemodialysis patients. The mechanism for this risk is likely independent of inflammation, but may reflect chronic subclinical myocardial injury or unmask those with subclinical atherosclerotic heart disease. Whether those with elevated TnI levels may benefit from additional investigations or more aggressive therapies to treat cardiovascular disease remains to be determined.

Diastolic dysfunction and high levels of new cardiac biomarkers as risk factors for cardiovascular events and mortality in hemodialysis patients

BACKGROUND/AIMS

Cardiovascular events (CVEs) are the most frequent cause of death in hemodialysis (HD). We aim to determine cardiovascular and mortality risk factors.

METHODS

A historical cohort study was made of 211 prevalent HD patients [73 (60-80) years, 58% males] between 2005 and 2012. Demographic, laboratory test and echocardiographic values were recorded. During follow-up, CVEs and mortality were documented and analyzed.

RESULTS

94 patients suffered a CVE. Age, history of cardiovascular disease (CVD), peripheral vascular disease, cardiac markers, systolic and diastolic dysfunction (DD) were associated to CVEs. Low albumin (RR 0.414, p = 0.002), DD (1.876, p = 0.038) and previous CVD (3.723, p < 0.001) were identified as independent predictors of CVEs. 98 patients died. Age, a history of CVD, peripheral vascular disease, cardiac markers, DD, dialysis vintage, and a vascular access different from autologous fistulae were associated to mortality. Low albumin (RR 0.499, p = 0.046), DD (RR 2.414, p = 0.017) and a vascular access different from autologous fistulae (RR 2.058, p = 0.034) were independent predictors of mortality.

CONCLUSIONS

DD is an emergent risk factor for death and CVEs in dialysis. Low albumin is also a predictor for CVE. Non-autologous fistulae and low albumin are predictors for death. Nt-proBNP and hsTnT offer good information for identifying high-risk patients, but they do not predict events independently as they are only cardiac damage markers.

Biomarkers in acute myocardial injury

Acute coronary syndrome (ACS) is a significant cause of morbidity and mortality worldwide. The proper diagnosis of ACS requires reliable and accurate biomarker assays to detect evidence of myocardial necrosis. Currently, troponin is the gold standard biomarker for myocardial injury and is used commonly in conjunction with creatine kinase-MB (CK-MB) and myoglobin to enable a more rapid diagnosis of ACS. A new generation of highly sensitive troponin assays with improved accuracy in the early detection of ACS is now available, but the correct interpretation of assay results will require a careful consideration of assay characteristics and the clinical setting prior to incorporation into routine practice. B-type natriuretic peptides, copeptin, ischemia-modified albumin, heart-type fatty-acid-binding protein, myeloperoxidase, C-reactive protein, choline, placental growth factor, and growth-differentiation factor-15 make up a promising group of other biomarkers that have shown the ability to improve prognosis and diagnosis of ACS compared with traditional markers.

Prognostic significance of elevated baseline troponin in patients with acute coronary syndromes and chronic kidney disease treated with different antithrombotic regimens: a substudy from the ACUITY trial

BACKGROUND

Elevation of baseline cardiac troponin in patients presenting with acute coronary syndromes (ACS) confers an adverse prognosis. The prognostic value of troponin elevation in patients with chronic kidney disease (CKD) and ACS is less certain.

METHODS AND RESULTS

In the ACUITY (Acute Catheterization and Urgent Intervention Triage strategy) trial, 13 819 patients with moderate and high-risk ACS were assigned randomly to receive heparin plus a glycoprotein IIb/IIIa inhibitor (GPI), bivalirudin plus a GPI, or bivalirudin monotherapy. Among 2179 patients with CKD (creatinine clearance <60 mL/min), baseline troponin elevation was present in 1291 patients (59.2%). Major bleeding and major adverse cardiac events (MACE), including death, myocardial infarction (MI), or unplanned revascularization, were examined according to baseline troponin status and randomization arm. Patients with CKD in whom the baseline troponin level was elevated had significantly higher rates of death, MI, and MACE at 30 days and 1 year compared with CKD patients without elevated baseline troponin. By multivariable analysis, baseline troponin elevation in patients with CKD was an independent predictor of composite death or MI at 30 days (hazard ratio [95% CI]=2.05 [1.48, 2.83], P<0.0001) and 1 year (1.72 [1.36, 2.17], P<0.0001). In CKD patients with baseline troponin elevation, bivalirudin monotherapy compared with heparin plus a GPI significantly reduced the 30-day rates of major bleeding with nonsignificantly different rates of MACE at 30 days and 1 year.

CONCLUSIONS

In patients with ACS and CKD, baseline troponin elevation is associated with significantly worse short- and long-term clinical outcomes. Bivalirudin monotherapy safely reduces major bleeding in ACS patients with CKD and baseline troponin elevation.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00093158.

[Interpretation of highly sensitive troponin assays: acute or chronic myocardial damage?]

Troponin is the first choice in the diagnosis of acute myocardial infarction. Correct interpretation is challenging, because high sensitive troponin tests used today detect even the smallest cardiac damage.

METHODS

High sensitive troponin T (Roche) and troponin I (Mitsubishi Pathfast) and creatine-kinase activity were measured in 20 patients, each having two samples with the time lapse 3-9 hours.

RESULTS

In the group without acute myocardial infarction (n = 10) no significant increase in creatine-kinase and creatine-kinase-MB levels were seen, and the mild raise of troponins was due to other cardiovascular problems (atrial fibrillation, paroxysmal supraventricular tachycardia). With acute myocardial infarction (n = 10) a dramatic increase of troponin levels was found in the second samples, and also an increase of creatine-kinase and creatine-kinase-MB activity. According to Fischer-probe a twofold or higher increase of troponin implies 19-times higher risk of acute myocardial infarction in the case of troponin T and 8-times odds ratio at troponin I.

CONCLUSIONS

The patient's accompanying diseases should always be considered. If the troponin level is elevated, the measurement should be repeated within 3-6 hours. When troponin shows at least a twofold increase and the patient has chest pain or positive ECG, AMI is likely, and the patient needs special medical care. Although the first troponin level might be elevated if accompanying diseases cause chronic cardiac damage, it can be differentiated by a second troponin measurement.

Cardiorenal syndromes and sepsis

The cardiorenal syndrome is a clinical and pathophysiological entity defined as the concomitant presence of renal and cardiovascular dysfunction. In patients with severe sepsis and septic shock, acute cardiovascular, and renal derangements are common, that is, the septic cardiorenal syndrome. The aim of this paper is to describe the pathophysiology and clinical features of septic cardiorenal syndrome in light of the actual clinical and experimental evidence. In particular, the importance of systemic and intrarenal endothelial dysfunction, alterations of kidney perfusion, and myocardial function, organ “crosstalk” and ubiquitous inflammatory injury have been extensively reviewed in light of their role in cardiorenal syndrome etiology. Treatment includes early and targeted optimization of hemodynamics to reverse systemic hypotension and restore urinary output. In case of persistent renal impairment, renal replacement therapy may be used to remove cytokines and restore renal function.

Effects of acetate-free haemodiafiltration (HDF) with endogenous reinfusion (HFR) on cardiac troponin levels

BACKGROUND

Haemofiltrate reinfusion (HFR) is a form of haemodiafiltration (HDF) in which replacement fluid is constituted by ultrafiltrate from the patient 'regenerated' through a cartridge containing hydrophobic styrene resin. Bicarbonate-based dialysis solutions (DS) used in routine haemodialysis and HDF contain small quantities of acetate (3-5 mMol/L) as stabilizing agent, one of the major causes of intradialytic hypotension. Acetate-free (AF) DS have recently been made available, substituting acetate with hydrochloric acid. Cardiac troponin (cTnT) constitutes an appreciable marker of myocardial damage and cardiac hypertrophy, and correlates with left ventricular mass.

METHODS

The aim of this study was to assess the impact of the presence or lack of acetate in DS on cTnT levels in patients treated with HFR and to evaluate outcome of intra-session cardiovascular stability. Twenty-five patients devoid of major cardiovascular comorbidity were randomized and treated with AF HFR for 3 months. The same patients were subsequently treated by means of HFR with DS containing 3 mMol/L acetate for 3 months and finally with AF HFR for a further 3 months. Prior and subsequent to each treatment period, samples were collected for cTnT measurement.

RESULTS

A significant decrease was observed in cTnT levels throughout the first session of AF HFR (1.32 ± 0.35-1.12 ± 0.31 ng/mL, P < 0.05) with a subsequent rise being registered during HFR with acetate-containing DS (1.12 ± 0.31-1.28 ± 0.37 ng/mL, P < 0.05) and a further drop from 1.28 ± 0.37 to 1.21 ± 0.35 ng/mL in the last AF HFR period. During HFR with acetate-containing DS, a significant drop in systolic and diastolic arterial pressure was observed in conjunction with a higher heart rate at the end of the session.

CONCLUSION

We observed an increase in cTnT during HFR with acetate and drops manifested during HFR without acetate; it may therefore be concluded that the drop in cTnT level, significantly correlated with lack of acetate, is indicative of improvement of cardiac microvascular function.

Cardiac troponin-I and its prognostic significance in a dialysis population

BACKGROUND

The objective was to study the prevalence and specificity of elevated levels of cardiac troponin-I (cT-I) in patients on maintenance hemodialysis in relation to creatine kinase (CK), the CK-MB fraction, and the ratio CK-MB of total CK and to assess its significance for the long-term prognosis in these patients, compared to other parameters known to influence the outcome.

METHODS

Predialysis blood samples were taken from 93 asymptomatic hemodialysis patients for cT-I, total CK, the CK-MB fraction, and the ratio of CK-MB to total CK. cT-I was measured by a microparticle enzyme immunoassay. The patients were followed for 1 year, after which baseline levels of cT-I and age, duration of dialysis, and the presence of diabetes mellitus and ischemic heart disease were correlated by linear regression analysis with the outcome parameter all-cause mortality.

RESULTS

None of the patients had a cT-I level higher than the manufacturer's indicated cutoff point of 2.0 ng/mL for myocardial infarction, indicating a specificity of 100%. Nine of the 93 patients (9.7%) had detectable cT-I levels (>0.0 ng/mL). Twelve patients died within 1 year, among which 4 had baseline cT-I levels above 0 ng/mL. From the study variables, an elevated baseline cT-I was found to be the only factor that significantly correlated with the outcome all-cause mortality (p = 0.029).

CONCLUSIONS

cT-I has a high specificity for the diagnosis of myocardial infarction in dialysis patients. Despite the relatively low number of positive test results, cT-I was found to be significantly correlated with the outcome all-cause mortality at 1 year.

Evaluation of ischaemia-modified albumin as a marker of myocardial ischaemia in end-stage renal disease

The early diagnosis of myocardial ischaemia is problematic in patients with ESRD (end-stage renal disease). The aim of the present study was to determine whether IMA (ischaemia-modified albumin) increases during dobutamine stress and detects myocardial ischaemia in patients with ESRD. A total of 114 renal transplant candidates were studied prospectively, and all received DSE (dobutamine stress echocardiography). IMA levels were taken at baseline and 1 h after cessation of DSE. A total of 35 patients (31%) had a positive DSE result. Baseline IMA levels were not significantly different in the DSE-positive and -negative groups. The increase in IMA was significantly higher in the DSE-positive group compared with those with no ischaemic response (26.5±19.1 compared with 8.2±9.6 kU/l respectively; P=0.007; where kU is kilo-units). From ROC (receiver operator charactertistic) curve analysis, the optimal IMA increase to predict an ischaemic response was 20 kU/l, with a sensitivity of 81% and a specificity of 72% [area under the curve, 0.80 (95% confidence interval, 0.44–0.94); P=0.03]. There were 18 deaths, ten of which were cardiac in nature over a follow up period of 2.25±0.71 years. An increase in IMA ≥20 kU/l was associated with significantly worse survival (P=0.02). In conclusion, IMA is a moderately accurate marker of myocardial ischaemia in ESRD. Patients with an increase in IMA ≥20 kU/l during DSE had significantly worse survival.

The incidence of myocardial injury following post-operative Goal Directed Therapy

BACKGROUND

Studies suggest that Goal Directed Therapy (GDT) results in improved outcome following major surgery. However, there is concern that pre-emptive use of inotropic therapy may lead to an increased incidence of myocardial ischaemia and infarction.

METHODS

Post hoc analysis of data collected prospectively during a randomised controlled trial of the effects of post-operative GDT in high-risk general surgical patients. Serum troponin T concentrations were measured at baseline and on day 1 and day 2 following surgery. Continuous ECG monitoring was performed during the eight hour intervention period. Patients were followed up for predefined cardiac complications. A univariate analysis was performed to identify any associations between potential risk factors for myocardial injury and elevated troponin T concentrations.

RESULTS

GDT was associated with fewer complications, and a reduced duration of hospital stay. Troponin T concentrations above 0.01 microg l-1 were identified in eight patients in the GDT group and six in the control group. Values increased above 0.05 microg l-1 in four patients in the GDT group and two patients in the control group. There were no overall differences in the incidence of elevated troponin T concentrations. The incidence of cardiovascular complications was also similar. None of the patients, in whom troponin T concentrations were elevated, developed ECG changes indicating myocardial ischaemia during the intervention period. The only factor to be associated with elevated troponin T concentrations following surgery was end-stage renal failure.

CONCLUSION

The use of post-operative GDT does not result in an increased incidence of myocardial injury.

Predictive Risk Factors for Upper Gastrointestinal Bleeding with Simultaneous Myocardial Injury

The aims of this study were to: (1) evaluate the epidemiology of simultaneous upper gastrointestinal bleeding (UGIB) and myocardial injury using parameters including troponin I (TnI); and (2) investigate the predictive risk factors of this syndrome. One hundred and fifty-five patients (101 men, 54 women; mean age, 64.7+/-10.4 years; range, 38-94 years) at the emergency department (ED) with the major diagnosis of UGIB were included. They underwent serial electrocardiography (ECG) and cardiac enzyme follow-up. Emergent gastroendoscopy was performed within 24 hours in most patients except for those who refused or were contraindicated. Mild myocardial injury was defined as the presence of any of the following: typical ST-T change on ECG, elevated creatine kinase-MB (CK-MB)>12 U/L, or TnI>0.2 ng/dL. Moderate myocardial injury was defined as the presence of any two of the previously mentioned conditions. In total, 51 (32.9%) and 12 (7.74%) patients developed mild and moderate myocardial injuries, respectively. Myocardial injury was more common among patients with variceal bleeding (20/25=80.0%) than those with ulcer bleeding (23/112=20.5%). It could partially be attributed to a higher baseline TnI level in cirrhotic patients. After adjusting for significant risk factors revealed by the univariate analysis, UGIB patients with a history of liver cirrhosis and more than three cardiac risk factors comprised a high-risk group for simultaneously developing myocardial injury. Other factors including age, gender, the color of nasogastric tube irrigation fluid, history of nonsteroidal anti-inflammatory drug use, vasopressin or terlipressin administration, vital signs, and creatinine recorded at the ED were not significant predictors. Those who developed myocardial injury had a longer hospital stay (mean duration, 8.73+/-6.94 vs. 6.34+/-2.66 days; p=0.03) and required transfusion of more units of packed erythrocytes.

Time course of degradation of cardiac troponin I in patients with acute ST-elevation myocardial infarction: the ASSENT-2 troponin substudy

Although measurement of troponin is widely used for diagnosing acute myocardial infarction (AMI), its diagnostic potential may be increased by a more complete characterization of its molecular appearance and degradation in the blood. The aim of this study was to define the time course of cardiac troponin I (cTnI) degradation in patients with acute ST-elevation myocardial infarction (STEMI). In the ASSENT-2 substudy, 26 males hospitalized with STEMI were randomized to 2 different thrombolytic drugs within 6 hours after onset of symptoms. Blood samples were obtained just before initiation of thrombolysis and at 30 minutes intervals (7 samples per patient). Western blot analysis was performed using anti-cTnI antibodies and compared with serum concentrations of cTnI. All patients exceeded the cTnI cutoff for AMI during the sampling period; at initiation of therapy, 23 had elevated cTnI values. All patients demonstrated 2 bands on immunoblot: intact cTnI and a single degradation product as early as 90 minutes after onset of symptoms. On subsequent samples, 15 of 26 patients showed multiple degradation products with up to 7 degradation bands. The appearance of fragments was correlated with higher levels of cTnI (P<0.001) and time to initiation of treatment (P=0.058). This study defines for the first time the initial time course of cTnI degradation in STEMI. Intact cTnI and a single degradation product were detectable on immunoblot as early as 90 minutes after onset of symptoms with further degradation after 165 minutes. Infarct size and time to initiation of treatment was the major determinant for degradation.

Cardiac troponin levels in asymptomatic patients on the renal transplant waiting list

AIMS

Cardiac troponin levels predict mortality and cardiovascular events in asymptomatic patients receiving dialysis and may be a useful clinical tool to stratify high-risk asymptomatic individuals.

METHODS

The present study examined levels of troponins I (cTnI) and T (cTnT) in patients with chronic renal impairment, patients receiving dialysis and renal transplant recipients. Patients receiving dialysis on the renal transplant waiting list were compared with those excluded from the list based on medical criteria. Median levels were compared using the Kruskal-Wallis test and proportions compared by chi-squared.

RESULTS

Median troponin levels were higher in patients on dialysis than transplant recipients. Comparing patients receiving dialysis not listed compared with those listed for renal transplant, median cTnI levels were significantly higher (0.03 versus 0.02 microg/L, P < 0.01) whereas median cTnT levels were not. Patients listed for transplantation were younger, had less clinical cardiovascular disease and lower C-reactive protein than those awaiting renal transplantation. The proportion of patients with elevated cTnT was not substantially different between patients awaiting renal transplantation (38%) and those excluded (52%). Levels of cTnI and cTnT were inversely related to renal function in predialysis and transplant patients, but were not related to time on dialysis for those receiving dialysis therapy.

CONCLUSION

As patients awaiting renal transplantation are clinically screened for cardiovascular disease but have frequently elevated cardiac troponin levels, troponin may be a useful clinical tool to identify high-risk asymptomatic patients on dialysis prior to renal transplantation. The influence of renal function on the interpretation of cardiac troponin and risk prediction requires further evaluation.

Cardiovascular Biomarkers in CKD: Pathophysiology and Implications for Clinical Management of Cardiac Disease

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in patients with all forms of chronic kidney disease (CKD). The underlying pathological state is caused by a complex interplay of traditional and nontraditional risk factors that results in atherosclerosis, arteriosclerosis, and altered cardiac morphological characteristics. This multifactorial disease introduces new challenges in predicting and treating patients with CVD sufficiently early in the course of CKD to positively alter patient outcome. Asymptomatic individuals with progressive CVD are a group of patients that deserve focused attention because early detection and intervention may provide the best opportunity for improved outcome. However, identifying CVD in asymptomatic patients with CKD or end-stage renal disease remains a significant hurdle in the management of these patients. Recently, a number of cardiovascular biomarkers were identified as predictors of patient outcome in individuals with CVD and, with additional research, may be used to guide the early diagnosis of and therapy for CVD in patients with CKD. This review examines the pathophysiological characteristics and potential clinical role of these novel cardiovascular biomarkers in risk stratification, risk monitoring, and selection of preventive therapies for patients with CKD.

Implications of the new definition of myocardial infarction

The new definition of acute myocardial infarction is based primarily on raised troponin levels because of the sensitivity and specificity of these markers and their correlation with the pathophysiology of acute coronary syndromes with plaque fissuring or rupture and embolisation of platelets causing myocyte necrosis. Raised troponin levels are associated with increased risks of death and recurrent myocardial infarction. Greater treatment benefit with low molecular weight heparin, IIb/IIIa antagonists and revascularisation is seen when troponin levels are raised. There are many implications for patients and society of the new definition including changes in insurability and ability to continue certain occupations. Many more patients, who would previously been diagnosed as having unstable angina, will now be diagnosed as having had an acute myocardial infarction. In addition case fatality rates will fall and comparison with previous epidemiological studies using the old definition will be problematic. However, the new definition may result in greater use of evidence based therapies with improved patient outcomes and decreased community death rates.

[Differences in cardiac troponin I and T levels measured in asymptomatic hemodialysis patients with last generation immunoassays]

Previous studies reported cardiac troponin I (cTnI) and T (cTnT) levels to be higher than normal in a significant proportion of asymptomatic chronic hemodialysis (HD) patients without evidence of acute myocardial injury. We have therefore evaluated in such patients the accuracy of cTnI and cTnT determinations measured with last generation assays. Fifty chronic HD patients (34 males) without symptoms of acute myocardial ischemia were studied. Their mean age (+/-SD) was 64.4+/-12.7 years, 22 patients (44%) had an history of cardiac ischemic disease and 19 (38%) were diabetics. Serum cardiac markers were measured with last generation assays before and after a single HD session and in a control group including 30 hospitalized patients without renal failure. The cTnI were determined with Dimension RxL "Improved method" assay (Dade Behring), the cTnT with Elecys "Third generation" assay (Roche Diagnostics) and the creatine kinase (CK) with Integra (Roche Diagnostics). The cTnI were also simultaneously determined with the assay previously used at our institution (Dimension RxL, Dade Behring), indicated as old-method-cTnI. With the last generation assay only 1 patient (2%) had elevated cTnI (>0.1 microg/l) in the study group compared to none in the control group (P=NS). Instead, with the old-method-cTnI assay 11 patients (22%) had elevated (>0.3 microg/l) predialysis cTnI levels (P<0.01 compared to the "Improved method" assay). The predialysis cTnT levels were higher than normal (>0.1 microg/l) in 23 patients (46%), compared to none in the control group (P<0.01). The CK levels were elevated (>170 IU/L) in 4 dialysis patients (8%) compared to one (3,3%) in the control group (P=NS). The cTnT levels slightly but non-significantly diminished during dialysis (from 0.102+/-0.070 to 0.085+/-0.067 mug/l, P=NS), while in the same time no changes were observed for cTnI and CK levels. In conclusion, the specificity of cTnI determinations in HD patients is greatly improved by the last generation assay (from 78 to 98%), and is actually similar to that observed in a population with normal renal function. Therefore cTnI, determined with the last generation assay used in the present study, can be reliably used for the diagnosis of acute coronary syndromes in HD patients. Instead, cTnT levels remain higher than normal in a significant proportion of asymptomatic HD patients (46%) and the reasons for this fact need further investigations.

Prognostic Value of Troponin T and I Among Asymptomatic Patients With End-Stage Renal Disease

Background— The prognostic usefulness of troponin enzymes in end-stage renal disease (ESRD) patients is controversial. To resolve this uncertainty of troponin as a prognostic tool, we conducted a systematic review to quantify the association between elevated troponin I or T and long-term total mortality among ESRD patients not suspected of having acute coronary syndrome.

Methods and Results— We conducted an unrestricted search from the MEDLINE, EMBASE, and DARE bibliographic databases to December 2004 using the terms troponin.mp. or exp troponin and exp kidney, exp renal, exp kidney disease exp renal replacement therapy . We also manually searched review articles and bibliographies to supplement the search. Studies were included if they were prospective observational studies, used cardiac-specific troponin assays, and evaluated long-term risk of death or cardiac events for asymptomatic ESRD patients. Two authors independently abstracted data on study and patient characteristics. Studies findings were stratified according to troponin T or I levels. We used a random-effects model to pool study results and tested for heterogeneity using χ 2 testing and used funnel-plot inspection to evaluate the presence of publication bias. Data from 28 studies (3931 patients) published between 1999 and December 2004 were included in this review. Patients received dialysis for a median duration of 4 years, with a mean follow-up of 23 months. From the pooled analysis, elevated troponin T (>0.1 ng/mL) was significantly associated with increased all-cause mortality (relative risk, 2.64; 95% CI, 2.17 to 3.20). Although the prognostic effect sizes were all consistent with a positive relationship between troponin T and mortality, there was significant heterogeneity in the magnitude of these effect sizes ( P =0.015). The funnel plot showed evidence of publication bias. Elevated troponin T was also strongly associated with increased cardiac death. Studies evaluating troponin I included a wide variety of assays and differing cut points, rendering synthesis of the study findings difficult.

Conclusions— Elevated troponin T (>0.1 ng/mL) identifies a subgroup of ESRD patients who have poor survival and a high risk of cardiac death despite being asymptomatic. These findings suggest that troponin T is a promising risk stratification tool and may help frame therapeutic decisions. The clinical interpretation of elevated troponin I levels, however, remain unclear, largely because of the lack of standardization of assays.

Cardiac troponins in renal failure - time for an optimistic consensus?

Elevated cardiac troponin concentrations are now accepted as the gold standard biochemical markers for the diagnosis of myocardial damage in patients with unstable coronary syndromes, having also a demonstrated value in early risk stratification and in adopting different therapeutic strategies. The specificity and sensitivity of cardiac troponins for diagnosis of acute coronary diseases in renal failure have been a point of confusion over the past decade, mainly because of moderate elevations of these cardiac biomarkers, commonly observed in patients with chronic renal dysfunction and without any significant myocardial damage. This review discusses the cardiac troponins, their biochemistry, their currently accepted cut-off values and their real significance in chronic renal failure (CRF), concluding that troponins maintain their diagnostic and prognostic values in patients with CRF, being predictive not only of cardiovascular mortality but also of general mortality in this patient group.

Serum levels of cardiac enzymes before and after renal transplantation

BACKGROUND

Cardiac troponins are very sensitive and specific indicators of myocardial damage; however, they are sometimes found to be increased in patients with end-stage renal disease (ESRD).

HYPOTHESIS

The aim of this study was to determine cardiac troponin I (cTpI) and creatine kinase myocardial isoform (CK-MB) levels and to assess their diagnostic and prognostic importance before and after renal transplantation.

METHODS

Thirty-four patients with ESRD (mean age 31.8 +/- 8.6 years, 11 women) were enrolled. Serum levels of cTpI and CK-MB were measured pre- and postoperatively on Days 1, 7, and 30. Patients were followed up for cardiac events, and possible myocardial damage was investigated by exercise thallium-201-labeled myocardial perfusion scintigraphy. Mean cTpI levels were 0.24 +/- 0.11 ng/ml (preoperative), and 0.34 +/- 0.27 ng/ml (Day 1), 0.26 +/- 0.11 ng/ml (Day 7), and 0.28 +/- 0.30 ng/ml (Day 30).

RESULTS

Compared with preoperative levels, cTpI was increased in 16 (47%), decreased in 6 (17.6%), and did not change in 12 (35.4%) patients. However, the increase did not exceed the myocardial infarction reference level of 2.3 ng/ml in any patient. Mean CK-MB levels were 12.6 (8.7U/l (preoperative), and 16.8 +/- 9.2U/l (Day 1), 16.3 +/- 8.1U/l (Day 7), and 13.3 +/- 6.6U/l (Day 30). Creatine kinase-MB was increased to above normal levels of 24 U/l in 13 (38.2%) patients on postoperative Days 1 or 7, and decreased to normal at the end of Month 1. No cardiac events occurred, and there was no abnormality in any patient on thallium scintigraphy.

CONCLUSION

There was no significant difference in the levels of cTpI in patients with ESRD without cardiac events before and after renal transplantation (p > 0.05). Our findings show that cTpI has very high sensitivity and specificity for detecting cardiac damage in patients with ESRD after renal transplantation.

The significance of elevated troponin T in patients with nondialysis-dependent renal insufficiency: a validation with coronary angiography

BACKGROUND

Patients with elevated troponin are at high risk of adverse outcomes, future cardiac events, and are more likely to have hemodynamically significant coronary artery stenoses. Elevated troponin T (cTnT) in patients with poor renal function portends a poor prognosis; however, findings of significant coronary artery disease (CAD) by coronary angiography have not been demonstrated in patients with poor renal function and elevated cTnT.

HYPOTHESIS

The purpose of this study was to correlate the angiographic findings of patients with elevated cTnT with respect to renal function in patients with nondialysis-dependent renal insufficiency.

METHODS

We retrospectively identified 342 patients with elevated cTnT who underwent coronary angiography in the setting of acute coronary syndrome. Patients were divided into poor (< 40 ml/min) and normal (> 40 ml/min) renal function by measuring their glomerular filtration rate. Our primary outcome was CAD stenosis, defined as epicardial stenosis > or = 70%. Secondary outcomes were rates of contrast nephropathy, initiation of hemodialysis, revascularization, length of stay (LOS), and in-hospital mortality.

RESULTS

There was no significant difference in the prevalence of CAD between patients who had positive cTnT with poor renal function versus patients with positive cTnT and normal renal function (87.1 vs. 89.7%, p = 0.54). This finding persisted after stratifying by age. Patients with impaired renal function had a higher mortality, longer LOS, and a higher rate contrast nephropathy requiring hemodialysis.

CONCLUSION

The association between elevated cTnT and significant CAD stenosis does not vary with renal function.

Comparison of serum cardiac troponin T and creatine kinase MB isoenzyme mass concentrations in asphyxiated term infants during the first 48 h of life

OBJECTIVE

This prospective study aimed to compare serum creatine kinase MB isoenzyme (CK-MB) mass concentrations and cardiac troponin T (cTnT) concentrations during the first 48 h of life in asphyxiated term infants.

METHODS

Serum cTnT and CK-MB mass concentrations of 50 term infants with clinical features of perinatal asphyxia were measured at birth and at 12, 24 and 48 h of age by chemiluminescence immunoassay. These infants were followed up until discharge or death. Cord blood CK-MB and cTnT concentrations of 50 healthy term infants were also assayed.

RESULTS

At birth, asphyxiated infants had significantly higher concentrations of cTnT and CK-MB than controls (P < 0.0001). Serum cTnT of asphyxiated infants with low ejection fraction <60% was significantly higher at 12 and 24 h than those with normal ejection fraction (P < 0.05). Asphyxiated infants with congestive cardiac failure had significantly higher serum cTnT concentration during the first 48 h of life than those without congestive cardiac failure (P <or= 0.04). Serum cTnT concentrations during the first 48 h of life were significantly higher in asphyxiated infants who died than those who survived (P < 0.0001). There was no significant difference in serum CK-MB mass concentrations between asphyxiated infants with and without these complications (P >or= 0.1).

CONCLUSION

Unlike CK-MB, serum cTnT concentrations are significantly higher in asphyxiated infants who die or develop cardiac dysfunction.

Elevated cardiac troponin T in hemodialysis patients receiving more intravenous iron sucrose

Elevated cardiac troponin T (cTnT) has been associated with shorter survival in hemodialysis patients. Moreover, intravenous (IV) iron treatment has been held responsible for oxidative stress and accelerated atherosclerosis in these patients. In the present study, we investigated the relationship between cTnT concentration, IV iron treatment, and parameters of iron status. In addition, parameters of oxidative stress, inflammation, and atherosclerosis were evaluated. Predialysis blood samples of 78 chronic hemodialysis patients were analyzed for cTnT, malondialdehyde, creatine kinase (CK), and CK-isoenzyme MB (CK-MB). In addition, the mean value of predialysis serum samples collected during the last year, were considered for homocysteine, ferritin, iron, iron binding capacity, blood cell counts, blood urea nitrogen, creatinine, albumin, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), calcium, phosphate, iPTH, cholesterol, and triglyceride. The quantity of IV iron sucrose administered during the last two years was counted from the patients' files. Echocardiography, all events related to ischemic heart disease, and urine volume were also recorded. Elevated cTnT levels (> or =0.10 ng/mL) were found in 18 patients (23.1%). The amount of iron administered was 2264+/-1871 mg with a range 0-7000 mg. Patients with elevated cTnT levels received more IV iron than those with normal cTnT (3692+/-1771 vs. 1761+/-1595 mg, p<0.001). The serum ferritin level was higher in patients with elevated cTnT (median levels; 477 vs. 288 ng/mL; P<0.05). Patients with elevated cTnT were longer on dialysis compared to those with normal levels (median times; 35.5 vs. 15 months, P<0.01) and regression analysis identified the amount of administered iron as an independent factor for elevated cTnT (P<0.01). Intravenous iron treatment and high ferritin concentration are related to high cTnT level, which has previously been incriminated as a survival marker in hemodialysis patients.

Cardiac troponins in renal insufficiency and other non-ischemic cardiac conditions

The emergence of cardiac troponins has been an interesting step in the diagnosis of ACS. It has clearly helped us to better triage patients toward a more aggressive posture in performing early cardiac catheterization, and in some cases, early use of adjunctive Gp IIb/IIIa antagonists and percutaneous or surgical myocardial revascularization. However, with this step forward has come uncertainty and many cardiology consults regarding positive cardiac troponins in patients without ACS or myocardial infarction. In general, increased cardiac troponins imply a worse prognosis. This is clearly true of patients with ESRD and advanced heart failure. It is also true of patients with severe, noncardiac illnesses. In other situations, such as acute pericarditis and cardiac surgery, slightly elevated cardiac troponins do not seem to predict a worse prognosis, and can probably be disregarded. The elevation of cardiac troponins after successful percutaneous coronary interventions is not unexpected, and the level of cardiac troponin release seems to predict problems, but lively controversy persists. Last, monitoring cardiac troponins in cardiac transplant recipients and those receiving certain cardiotoxic chemotherapies may be of some diagnostic value, but clearly more experience and clinical research are needed.

[Value of troponins in acute coronary syndrome in patients with renal failure]

Patients with renal insufficiency can have elevations of serum troponin without suspected clinical coronary ischemia. Although cardiovascular disease is the main cause of death in patients with renal failure, the process of elevation of serum troponin is not well known. Troponin T is more frequently elevated than troponin I in these patients which leads to uncertainty in the clinical interpretation of results. There are studies suggesting that troponin elevations are associated with a higher risk and increased mortality. To explain the process leading to troponin increases in this kind of pathology and to confirm its usefulness in the diagnosis, evolution and prognosis it would be necessary to carry out more clinical studies monitoring troponin and studying the stratification of risk.

Clinical Association between Renal Insufficiency and Positive Troponin I in Patients with Acute Coronary Syndrome

BACKGROUND

Whether renal insufficiency (RI) influences troponin levels in patients with acute coronary syndromes (ACS) is controversial. We attempted to determine whether there is an association between RI and troponin I (TnI) elevation in patients presenting with ACS.

METHODS

We studied 764 consecutive patients with ACS admitted to our institution from January 1999 to June 2000. Patients were identified prospectively and data were collected through chart review of all cases with an admission diagnosis of ACS. In order to assess the relationship of TnI and RI, we calculated the creatinine clearance (Cr-Cl) for all patients. We conducted an analysis of variance comparing TnI in quintiles of patients with lowest to highest Cr-Cl.

RESULTS

Among 764 patients, 173 patients had a discharge diagnosis of ST elevation myocardial infarction and 591 had non-ST elevation myocardial infarction. There was no correlation between peak TnI levels and renal function as measured by Cr-Cl in the entire cohort with ACS and in the subgroups with ST elevation myocardial infarction and non ST elevation myocardial infarction.

CONCLUSIONS

This large cohort study demonstrates that there appears to be no association between RI and positive TnI in patients with ACS.

Review Article. Cardiac troponins and renal disease

Cardiovascular disease is the most common cause of death in patients with renal failure. Patients with renal failure are at greater risk of atypical presentations of myocardial ischaemia. Traditional markers of myocardial damage are often increased in renal failure in the absence of clinically suspect myocardial ischaemia. The cardiac troponins are specific markers of myocardial injury. Large-scale trials, excluding patients with renal disease, have shown the importance of the cardiac troponins in predicting adverse outcome and in guiding both therapy and intervention in acute coronary syndromes. Cardiac Troponin T and cardiac Troponin I are increased in patients with renal failure and this is likely to represent multifactorial pathology including cardiac dysfunction, left ventricular hypertrophy and cardiac microinfarctions. Increases in serum troponin from baseline, in patients with renal disease with acute coronary syndromes, may represent a poor prognosis. Small studies of patients with renal failure have suggested that elevation of the cardiac troponins is associated with an increased risk of cardiac death.

Prognostic usefulness of marginal troponin T elevation

Marginal elevations of troponin T among patients with chest pain are often considered to be insignificant. We sought to define the prognostic value of marginal troponin T elevations in patients presenting to the emergency department with suspected myocardial ischemia. Four hundred twenty-eight consecutive patients presenting to the emergency department with ongoing chest pain were evaluated, followed through their hospital course, and contacted for follow-up 4 months after discharge. Two hundred ninety-nine patients had undetectable troponin T levels (<0.01 microg/L), 76 had marginal troponin T elevations (0.01 to 0.09 microg/L), and 53 had frank troponin T elevations (> or =0.1 microg/L). Patients with either marginally or frank elevated troponin levels were older and more likely to be men, but did not differ from patients with undetectable troponin levels with regard to the prevalence of coronary artery disease risk factors, history of coronary disease, or race. While in the hospital, the undetectable and marginal troponin groups were referred for cardiac testing in equal proportions (58% and 59%, respectively), whereas 87% of the elevated group underwent further testing. After adjustment for possible confounders, a significantly increased rate of death/myocardial infarction/revascularization was observed in the marginal troponin group compared with the undetectable troponin group (p = 0.004). Marginal elevations of troponin T identified a currently underevaluated high-risk subgroup of patients with suspected myocardial ischemia who are more likely to have adverse clinical outcomes than those with undetectable troponin levels.

Impaired Renal Clearance Explains Elevated Troponin T Fragments in Hemodialysis Patients

Background— Patients with severe renal dysfunction often have unexplained elevated serum concentrations of cardiac troponin T (cTnT). We investigated whether in vivo fragmentation of cTnT could explain these increases.

Methods and Results— cTnT, creatine kinase isoenzyme MB, and myoglobin serum concentrations were measured in all 63 dialysis patients of our in-hospital dialysis department. A highly sensitive immunoprecipitation assay, followed by electrophoresis and Western blotting, was used to extract and concentrate cTnT and its possible fragments from serum of these 63 hemodialysis patients. Although creatine kinase isoenzyme MB values excluded recent ischemic myocardial events in 55 of the 63 cases, cTnT fragments ranging in size from 8 to 25 kDa were present in the serum samples of all dialysis patients.

Conclusions— cTnT is fragmented into molecules small enough to be cleared by the kidneys of healthy subjects. Impaired renal function causes accumulation of these cTnT fragments and is very likely the cause of the unexplained elevations of serum cTnT found in patients with severe renal failure.

Cardiac troponin T and I and creatine kinase-MB as markers of myocardial injury and predictors of outcome following percutaneous coronary intervention

AIMS

This study was performed to determine the most sensitive biochemical marker for the detection of cardiac myocyte damage potentially sustained during percutaneous coronary intervention (PCI) and to assess whether such a marker can be used to identify patients at increased risk of poor subsequent clinical outcome.

METHODS AND RESULTS

We studied 109 consecutive patients presenting with clinical stable and unstable angina and undergoing PCI at our institution. Blood was sampled for creatine kinase-MB (CK-MB), cardiac Troponin T (cTnT) and I (cTnI) immediately before and at 6, 14 and 24 h post-PCI. Five patients with raised cardiac markers pre-PCI were excluded from further analysis. The occurrence of major adverse cardiac events (MACE) was documented in-hospital, at 30 days and at long-term clinical follow up of up to 20 months. MACE occurred in 26/109 (24%) patients: death=1, QWMI=4, NQWMI=5, repeat PCI=16 (nine target vessel revascularisations and seven de-novo lesions), CABG=5. cTnI had the highest detection rate for myocardial damage, with 58 cTnI-positive patients, 38 cTnT-positive patients and 28 CK-MB-positive patients in the 24 h following PCI (Pearson's Chi square test, P<0.01). The type of interventional strategy per se was not significantly associated with post-procedural cardiac marker concentrations (Kruskal-Wallis ANOVA, P>0.05). There was a significant association between post-procedural cardiac marker concentrations of CK-MB, cTnT and cTnI and the occurrence of procedural angiographic complications (P=0.0003, 0.0002, 0.001, respectively). All three markers, at each sampling time point between 6 and 24 h post-PCI, showed a significant predictive relationship with MACE in-hospital and at long-term follow up (ROC curve AUC analysis, P<0.05). All three markers provided equally predictive information at each of the three post-procedural sampling time points between 6 and 24 h following PCI. All levels of cardiac marker elevation above the clinically discriminant cut-off values were significantly predictive of outcome at long-term follow up.

CONCLUSIONS

cTnI proved to be the most sensitive marker in detecting myocardial necrosis following PCI. CK-MB, cTnT and cTnI all provided similarly reliable prognostic information, with cTnT and cTnI being marginally superior in predicting MACE at follow up.

Prognostic value of cardiac markers in ESRD: Chronic Hemodialysis and New Cardiac Markers Evaluation (CHANCE) study

BACKGROUND

Cardiac disease is the main cause of mortality in long-term hemodialysis patients. Cardiac troponins (cTn) have been proposed to be markers of cardiac damage, but their value is still debated in hemodialysis patients. The aim of this prospective study is to assess the prognostic value of biochemical cardiac markers in long-term hemodialysis patients.

METHODS

We measured serum levels of cTn I (cTnI), cTn T (cTnT), and creatine kinase-MB (CK-MB) in 258 asymptomatic patients (mean age, 60 +/- 15 years; 150 men) before the dialysis treatment. All causes of death and major adverse cardiac events (MACEs: cardiac death, myocardial infarction, or unstable angina) were recorded at 1 and 2 years of follow-up. A Cox proportional hazard regression model was used to identify factors predictive of mortality.

RESULTS

On inclusion, 48 patients (18.6%) had cTnT levels greater than 0.1 ng/mL, 46 patients (17.8%) had cTnI levels greater than 0.15 ng/mL, and 18 patients (7.0%) had CK-MB levels greater than 3 ng/mL. Of 246 patients followed up at 2 years, 64 patients (26%) had died, including 29 patients (11.8%) of cardiac disease, and 49 patients (19.9%) experienced at least 1 MACE. MACEs were significantly greater for patients with elevated predialysis serum cTnT and CK-MB levels (>0.1 ng/mL and 3 ng/mL, respectively) than for patients with normal levels of these cardiac markers (31.9% versus 17.1%; P = 0.01; 38.9% versus 18.4%; P = 0.02, respectively). No differences were found for cTnI levels. In multivariate analysis, age (relative risk [RR], 1.04; P = 0.002), previous ischemic heart disease (RR, 2.5; P = 0.0001), and serum cTnT levels greater than 0.1 ng/mL (RR, 1.9; P = 0.04) were independent significant factors for MACEs.

CONCLUSION

Increased predialysis serum levels of cTnT and CK-MB, but not cTnI, were predictive of a high risk for overall mortality and MACEs at 2 years in asymptomatic hemodialysis patients.

Cardiac troponin I (2nd generation assay) in chronic haemodialysis patients: prevalence and prognostic value

BACKGROUND

Elevated serum cardiac troponin T (cTnT) levels are frequently observed in chronic dialysis patients and have been shown to be associated with increased morbidity and mortality. The aim of this study was to determine whether cardiac troponin I (cTnI), which is less frequently elevated, has similar clinical significance.

METHODS

We studied 101 asymptomatic patients with no clinical evidence of coronary artery disease who were undergoing chronic dialytic treatment. We measured their serum cTnI levels immediately before the start of their dialysis sessions by a second-generation assay (OPUS-DADE). Our study included a year-long follow-up with trimestrial cTnI assays as well as clinical, X-ray and echocardiographic surveillance. We considered patients with serum cTnI > or =0.15 ng/ml as positive and those with levels <0.15 ng/ml as negative.

RESULTS

Among the 14 patients with high serum cTnI levels, nine (64%) suffered acute cardiac events during the 12-month follow-up. In contrast, among the 72 patients with low cTnI levels only seven (9.7%) had acute events. In another group of 15 patients with variable cTnI levels, three patients (20%) had cardiac events.

CONCLUSION

Based on these results, serum cTnI appears to be a valuable predictive marker of cardiovascular events in asymptomatic dialysis patients. For those patients who might benefit from thorough cardiac investigation and treatment, information on cTnI could be useful in preventing cardiac events.

Cardiac troponins in renal insufficiency: review and clinical implications

Patients with renal insufficiency may have increased serum troponins even in the absence of clinically suspected acute myocardial ischemia. While cardiovascular disease is the most common cause of death in patients with renal failure, we are just beginning to understand the clinical meaning of serum troponin elevations. Serum troponin T is increased more frequently than troponin I in patients with renal failure, leading clinicians to question its specificity for the diagnosis of myocardial infarction. Many large-scale trials demonstrating the utility of serum troponins in predicting adverse events and in guiding therapy and intervention in acute coronary syndromes have excluded patients with renal failure. Despite persistent uncertainty about the mechanism of elevated serum troponins in patients with reduced renal function, data from smaller groups of renal failure patients have suggested that troponin elevations are associated with added risk, including an increase in mortality. It is possible that increases in serum troponin from baseline in patients with renal insufficiency admitted to hospital with acute coronary syndrome may signify myocardial necrosis. Further studies are needed to clarify this hypothesis.

Diagnostic value of troponin T for alterations in left ventricular mass and function in dialysis patients

BACKGROUND

Cardiac troponin T (cTnT) is related to left ventricular (LV) mass in patients with end-stage renal disease (ESRD). Furthermore, cTnT reflects the severity of systolic dysfunction in patients with heart diseases. We tested the diagnostic value of cTnT for left ventricular hypertrophy (LVH) and LV systolic dysfunction in a large group of clinically stable hemodialysis patients without heart failure.

RESULTS

CTnT was significantly (P < 0.001) higher in patients with LVH than in those with normal LV mass. In a multiple logistic regression model, adjusting for potential confounders (including cardiac ischemia), systolic pressure and cTnT (both P = 0.003) were the strongest correlates of LVH. Similarly, cTnT was significantly higher (P = 0.005) in patients with systolic dysfunction than in those with normal LV function and in a multiple logistic regression model cTnT ranked as the second independent correlate of this alteration after male sex. Serum cTnT had a high positive prediction value for the diagnosis of LVH (87%) but its negative prediction value was relatively low (44%). The positive predictive value of cTnT for LV dysfunction was low (25%) while its negative predictive value was high (93%). A combined analysis including systolic pressure (for the diagnosis of LVH) and sex (for the diagnosis of LV systolic dysfunction) augmented the diagnostic estimates to an important extent (95% positive prediction value for LVH and 98% negative prediction value for LV systolic dysfunction).

CONCLUSIONS

CTnT has a fairly good diagnostic potential for the identification of LVH and for the exclusion of LV systolic dysfunction in patients with ESRD without heart failure. This marker may be useful for the screening of alterations in LV mass and function in clinically stable hemodialysis patients.