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

Elevated Myoglobin in Patients With Primary Aldosteronism: A Cross-Sectional Study

OBJECTIVES

Primary aldosteronism (PA) is characterized by the autonomous excessive production of aldosterone in the adrenal cortex. Aldosterone is associated with damages to heart muscle and skeletal muscle. The purpose of this study was to evaluate serum levels of muscle injury markers and their associated factors in patients with primary aldosteronism.

METHODS

We retrospectively enrolled subjects with PA and essential hypertension (EH) who had completed testing for serum high sensitivity troponin T (hs-TnT), creatine kinase isoenzyme MB (CK-MB) and myoglobin from the database of the Chongqing Primary Aldosteronism Study (CONPASS). Univariate and multivariate linear regression analyses were performed to analyze the influencing factors of myocardial injury markers.

RESULTS

In total, 278 patients with PA and 445 patients with EH were enrolled in this study. Compared with EH patients, serum concentrations of hs-TnT [7.0 (4.0-12.0) vs. 6.0 (3.0-11.0) ng/L; p=0.005] and myoglobin [24.2 (21.0-38.1) vs. 21.8 (21.0-31.9) μg/L; p=0.023] were significantly higher among PA patients, while no significant difference of CK-MB was found between two groups [1.4 (1.0-2.0) vs. 1.3 (0.9-1.9) μg/L; p=0.154]. Univariate linear regression analysis showed that myoglobin was negatively correlated with serum potassium (β=-0.31; p<0.01) and positively correlated with plasma aldosterone concentration (β=0.40; p<0.01) in the PA group, while no significant correlation was found between hs-TnT and biochemical parameters. After adjusting for multiple confounders, myoglobin was negatively correlated with serum potassium (β=-0.15; p<0.05) and positively correlated with plasma aldosterone concentration (β=0.34; p<0.01) in the PA group.

CONCLUSIONS

The serum level of myoglobin was significantly increased in PA patients, and myoglobin was independently correlated with plasma aldosterone concentration.

Is the true clinical value of high-sensitivity troponins as a biomarker of risk? The concept that detection of high-sensitivity troponin 'never means nothing'

INTRODUCTION

High-sensitivity troponin (hs-cTn) assays are central to the diagnosis of myocardial infarction (MI). Their increased sensitivity has facilitated rapid pathways for the exclusion of MI. However, hs-cTn is now more readily detectable in patients without symptoms typical of MI, in whom a degree of myocardial injury is assumed. Recently, the practice of using the 99^th centile of hs-cTn as a working 'upper reference limit' has been challenged. There is increasing evidence that hs-cTn may provide useful prognostic information, regardless of any suspicion of MI, and as such these assays may have potential as a general biomarker for mortality. This raises the concept that detection of hs-cTn 'never means nothing.'

AREAS COVERED

In this review, we will evaluate the evidence for the use of hs-cTn assays outside their common clinical indication to rule out or diagnose acute MI.

EXPERT OPINION

The data presented suggest that hs-cTn testing may in the future have a generalized role as a biomarker of mortality risk and may be used less as a test for ruling in acute MI, but will remain a frontline test to exclude that diagnosis in ED. Further, the data suggest that the detection of hs-cTn 'never means nothing.'

Cardiovascular Risk Assessment for Noncardiac Surgery: Are We Ready for Biomarkers?

Biomarkers aided perioperative cardiac assessment is a relatively new concept. Cardiac biomarkers with historical significance (aspartate transaminase, dehydrogenase, creatinine kinase and myoglobin) have paved the way for traditional biomarkers (cardiac troponin, C-reactive protein, lipoprotein). Contemporary biomarkers like natriuretic peptides (BNP and ProBNP) are validated risk markers in both acute and chronic cardiac diseases and are showing remarkable promise in predicting serious cardiovascular complications after non-cardiac surgery. This review is intended to provide a critical overview of traditional and contemporary biomarkers for perioperative cardiovascular assessment and management. This review also discusses the potential utility of newer biomarkers like galectin-3, sST-2, GDF-15, TNF-alpha, MiRNAs and many others that can predict inflammation, cardiac remodeling, injury and endogenous stress and need further investigations to establish their clinical utility. Though promising, biomarker led perioperative care is still in infancy and it has not been determined that it can improve clinical outcomes.

Comparison of prognostic values of high-sensitivity cardiac troponin T and N-terminal prohormone brain natriuretic peptide to assess mortality in elderly inpatients

BACKGROUND

Studies have shown that increases in low-level high-sensitivity cardiac troponin T (hs-cTnT) and N-terminal prohormone brain natriuretic peptide (NT-proBNP) in the elderly population lead to high risk of adverse clinical outcomes, such as mortality. In this study, associations between the two biomarkers and long-term mortality in elderly patients hospitalized for medical conditions other than acute cardiovascular events were investigated. A comparison of the predictive value of hs-cTnT and NT-proBNP for all-cause mortality was conducted.

METHODS

A cohort of 715 elderly inpatients free of acute cardiovascular events was initially recruited. Based on tertiles of baseline hs-cTnT and NT-proBNP levels, the elderly were arranged into low, middle, and high groups. The mortality of each group was observed and the predictive values of hs-cTnT and NT-proBNP compared. Additionally, all-cause mortality was analyzed for hs-cTnT and NT-proBNP combined.

RESULTS

There were 135 (18.9%) all-cause mortality cases identified during follow-up (median 47 months). The upper tertile of hs-cTnT was significantly associated with an increased risk of mortality (HR 3.29, 95% CI 1.85-5.85), even after adjustment for potential confounders. However, there were no significant differences observed in mortality rates among the three NT-proBNP groups after adjustment for potential confounders (HR 1.77, 95% CI 0.83-3.17). Compared to NT-proBNP, hs-cTnT was a better predictor of mortality, as area under curves for hs-cTnT and NT-proBNP at 60 months were 0.712 (95% CI 0.616-0.809) and 0.585 (95% CI 0.483-0.6871), respectively. Also, the combination of the two cardiac biomarkers did not render a better predictive value for mortality than hs-cTnT alone.

CONCLUSION

Unlike hs-cTnT, baseline NT-proBNP levels failed to show an independent association with all-cause mortality in hospitalized elderly without acute cardiovascular events. hs-cTnT provided significant prognostic value for mortality in the study cohort.

Cardiovascular Risk Markers in Hemodialysis Patients

Cardiovascular events are the main cause of death in hemodialysis patients. Nevertheless, acute myocardial infarction may be misdiagnosed in uremic patients, because typical markers have a high rate of false positivity. A recent two-year prospective study showed that predialytic high serum concentrations of troponin T and CK-MB mass were associated with high mortality, cardiac mortality, myocardial infarction and unstable angina (MACEs). We studied 16 uremic patients (13 M; 3 W) on standard HD and 6 patients (4 M; 2 W) on on-line HDF, who had been taking folic acid for at least three months. Patients who suffered from acute or chronic cardiac ischemic disease were excluded. Anthropometric parameters, pre and post-dialytic pH, HCO3 and electrolytes did not differ between the two groups. Kt/V and URR % were lower in conventional HD vs on-line HDF (p<0.04; p<0.04). ORR % was strongly elevated in on-line HDF compared with HD (p<0.005). In conventional HD, ORR % was directly correlated with Kt/V and URR% (r = 0.49, p<0.04; r = 0.48, p<0.04, respectively). Even in on-line HDF ORR % was directly correlated with Kt/V and URR % (r = 0.79, p<0.04; r = 0.76, p<0.05, respectively). Troponin I and CK-MB mass were not significantly different in pre vs post-dialysis, both in standard HD and on-line HDF. Nevertheless, in standard HD postdialytic troponin I correlated with serum sodium concentration (r = 0.93, p < 0.000), potassium (r = 0.67, p < 0.004) and serum chlorine (r = 0.92, p < 0.92, p < 0.000). CK-MB mass showed a correlation with serum chlorine (r = 0.49, p < 0.05). Postdialytic CK-MB mass correlated with serum potassium in on-line HDF (r = 0.83, p < 0.03). Our data suggest that hemodialytic treatments, both standard HD and on-line HDF, do not modify serum troponin I and CK-MB mass. Consequently, we can use these parameters for the diagnostic approach in acute or chronic ischemic heart disease in hemodialysis patients.

Effect Modification of Chronic Kidney Disease on the Association of Circulating and Imaging Cardiac Biomarkers With Outcomes

Background

Cardiac troponin T and brain natriuretic peptide (BNP) are elevated in >50% of dialysis patients and are associated with poor outcomes. Few data investigated these associations in earlier chronic kidney disease (CKD).

Methods and Results

We studied whether CKD modified associations of elevated BNP, N‐terminal‐pro‐BNP, high‐sensitivity cardiac troponin T, coronary artery calcification, and left ventricular hypertrophy with all‐cause death and cardiovascular death/events in 3218 multiethnic individuals followed for 12.5 years, and whether biomarkers added prognostic information to traditional cardiovascular risk factors in CKD. Of the cohort, 279 (9%) had CKD. There were 296 deaths and 218 cardiovascular deaths/events. Of non‐CKD individuals, 7% died and 6% had cardiovascular death/event versus 32% and 30% of CKD participants, P<0.001 for both. The interaction between BNP and CKD on death was significant (P=0.01): the adjusted hazard ratio in CKD was 2.05, 95% CI (1.34, 3.14), but not significant in non‐CKD, 1.04 (0.76, 1.41). CKD modified the association of high‐sensitivity cardiac troponin T with cardiovascular death/event, adjusted hazard ratio 3.34 (1.56, 7.18) in CKD versus 1.65 (1.16, 2.35) in non‐CKD, interaction P=0.09. There was an interaction between N‐terminal‐pro‐BNP and CKD for death in those without prior cardiovascular disease. Addition of each biomarker to traditional risk factors improved risk prediction, except coronary artery calcification was not discriminatory for cardiovascular death/event in CKD.

Conclusions

Cardiac biomarkers, with the exception of coronary artery calcification, prognosticated outcomes in early‐stage CKD as well as, if not better than, in non‐CKD individuals, even after controlling for estimated glomerular filtration rate, and added to information obtained from traditional cardiovascular risk factors alone.

Short-term prognostic value of perioperative coronary sinus-derived-serum cardiac troponin-I, creatine kinase-MB, lactate, pyruvate, and lactate-pyruvate ratio in adult patients undergoing open heart surgery

OBJECTIVES

To investigate the release pattern of different cardiac metabolites and biomarkers directly from the coronary sinus (CS) and to establish the diagnostic discrimination limits of each marker protein and metabolites to evaluate perioperative myocardial injury in patients undergoing cardiac surgery under cardiopulmonary bypass (CPB).

PATIENTS AND METHODS

Sixty-eight patients undergoing first mitral and/or aortic valve replacements with/without coronary artery bypass grafting and Bentall procedure under CPB and blood cardioplegic arrest were studied. All cardiac metabolites and biomarkers were measured in serial CS-derived blood samples at pre-CPB, immediate post aortic declamping, 10 minutes post-CPB and 12 hrs post-CPB.

RESULTS

Receiver operating characteristic curve analysis of cardiac biomarkers indicated lactate-pyruvate ratio as the superior diagnostic discriminator of myocardial injury with an optimal "cut-off" value >10.8 immediately after aortic declamping (AUC, 0.92; 95% CI: 0.85-0.98). Lactate was the second best diagnostic discriminator of myocardial injury with an optimal "cut-off" value >2mmol/l at immediately after aortic declamping (AUC, 0.89; 95% CI: 0.80-0.96). Cardiac troponin-I was the third best diagnostic discriminator of myocardial injury with an optimal "cut-off" value >2.1ng/ml at immediately after aortic declamping (AUC, 0.88; 95% CI: 0.80-0.95). Creatine kinase-MB was the fourth best diagnostic discriminator of myocardial injury with an optimal "cut-off" value >58 log units/ml prior to decanulation (AUC, 0.85; 95% CI: 0.78-0.94).

CONCLUSIONS

Measurable cardiac damage exists in all patients undergoing cardiac surgery under cardioplegic arrest. The degree of myocardial injury is more in patients with poor ventricular function and those requiring longer aortic clamp time. CS-derived lactate-pyruvate ratio, lactate, cTn-I served as superior diagnostic discriminators of peri-operative myocardial damage.

Incidence of sudden cardiac death in adults with end-stage renal disease: a systematic review and meta-analysis

BACKGROUND

Although sudden cardiac death (SCD) is recognized as a distinct cause of death in patients with end stage renal disease (ESRD), its incidence has not been well summarized.

METHODS

We performed a systematic review and meta-analysis of the literature based on a protocol developed a priori. We searched MEDLINE and EMBASE (inception to March 2015) for randomized controlled trials and cohort studies reporting the incidence of SCD in adult patients with ESRD on hemodialysis or peritoneal dialysis. We collected data on number of SCD as well as the definition of SCD for each individual study. A random-effects model was used to summarize the incidence of SCD. We conducted subgroup analyses to explore sources of heterogeneity.

RESULTS

Forty two studies (n = 80,382 patients) were included in the meta-analysis. The incidence of SCD among adults with ESRD ranged from 0.4 to 10.04 deaths per 100 person-years. The definitions and assessment of SCD varied across the included studies. There was evidence of significant heterogeneity (I(2) = 98; p < 0.001), which was not explained by subgroup analyses stratified by mean age, proportion of hypertensive or diabetic patients, follow-up time, study size, or type of cohort studied.

CONCLUSION

Current estimates of the incidence of SCD among adults with ESRD vary widely. There is a need for further studies to more accurately estimate the incidence of SCD in patients with ESRD.

Cardiac troponin T elevation at dialysis initiation is associated with all-cause and cardiovascular mortality on dialysis in patients without diabetic nephropathy

BACKGROUND

It is not known whether asymptomatic cardiac troponin T (cTnT) elevation is associated with all-cause or cardiovascular mortality in non-diabetic and advanced chronic kidney disease (CKD) patients.

METHODS

We measured cTnT in 248 consecutive patients at 1-2 weeks before dialysis initiation between March 2005 and August 2010 and followed them prospectively. A Cox proportional hazard model was used to investigate the relationship between cTnT and all-cause and cardiovascular mortality on dialysis.

RESULTS

The median age of the patients was 67 years (male 59.3 %), and the prevalence of diabetic nephropathy (DN) was 38.3 %. Asymptomatic cTnT elevation (>0.01 ng/mL) was observed in 196 (79 %) and 111 (73 %) patients among the overall patients and among patients without DN, respectively. A total of 51 patients died during a median follow-up period of 31.6 months. The cTnT level was associated with all-cause [hazard ratio (HR) 1.453; 95 % confidence interval (CI) 1.093-1.931; P = 0.010] and cardiovascular mortality [HR 1.973; 95 % CI 1.127-3.454; P = 0.017] on dialysis after extensive adjustment in the overall patient population. Patients without DN showed similar associations as those for the overall patient population (all-cause mortality: HR 1.566; 95 % CI 1.048-2.339; P = 0.029 and cardiovascular mortality: HR 2.657; 95 % CI 1.115-6.328; P = 0.027).

CONCLUSION

Asymptomatic cTnT elevation might be strongly associated with all-cause and cardiovascular mortality in patients without DN, as well as in the overall advanced CKD patients. We suggest that cardiovascular risk in patients with pre-dialysis CKD should be stratified according to cTnT levels.

Creatine-kinase and dialysis patients, a helpful tool for stratifying cardiovascular risk?

BACKGROUND AND AIMS

Hemodialysis patients have an enhanced risk for cardiovascular events. Cardiac biomarkers provide useful information for stratifying their risk. However the prognosis value of creatine kinase MB isoenzyme (CKMB) has not yet been validated in this population. The aim of the present study is to determine the predictable value of CK-MB in hemodialysis.

METHODS

A cohort of 211 hemodialysis patients (58.3% male, median age 73 (60-80) years) were followed for 39 (19-56) months. Cardiac biomarkers including CKMB were recorded at baseline. Factors associated to CKMB and prognosis value of this biomarker was studied.

RESULTS

The median value of CKMB was 1 (1-2) ng/mL with no patient exceeding normal laboratory values. Previous heart disease, diabetes mellitus, peripheral vascular disease and systolic and diastolic dysfunction were associated with higher levels of CKMB. Ninety-four patients (44.5%) cardiovascular events were recorded. CKMB levels ≥2ng/mL was independently associated to cardiovascular events during the follow up after adjusting. Adding CKMB to a model including several variables for predicting cardiovascular events, resulted in 17% improvement in risk discrimination (IDI) with a relative IDI of 9.9% (p=0.04).

CONCLUSIONS

CKMB is a good marker for stratifying cardiovascular risk in hemodialysis patients and adds prognosis information to other well known independent predictors for cardiovascular events.

NT-proBNP: is it a more significant risk factor for mortality than troponin T in incident hemodialysis patients?

Numerous studies have demonstrated that cardiac biomarkers are significant predictors of cardiovascular (CV) and all-cause mortality in ESRD patients, but most of the studies were retrospective or included small numbers of patients, only prevalent dialysis patients, or measured 1 or 2 biomarkers. This study was to analyze the association between 3 cardiac biomarkers and mortality in incident HD patients. A prospective cohort of 864 incident HD patients was followed for 30 months. Based on the median values of baseline NT-proBNP, cTnT, and hsCRP, the patients were divided into "high" and "low" groups, and CV and all-cause mortality were compared between each group. Additionally, time-dependent ROC curves were constructed, and the NRI and IDI of the models with various biomarkers were calculated. The CV survival rates were significantly lower in the "high" NT-proBNP and cTnT groups compared to the corresponding "low" groups, while there was no significant difference in CV survival rate between the 2 hsCRP groups. However, all-cause mortality rates were significantly higher in all 3 "high" groups compared to each lower group. In multivariate analyses, only Ln NT-proBNP was found to be an independent predictor of mortality. Moreover, NT-proBNP was a more prognostic marker for mortality compared to cTnT. In conclusion, NT-proBNP is the biomarker that results in the most added prognostic value on top of traditional risk factors for CV and all-cause mortality in incident HD patients.

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.

What Is the Meaning of Increased Myocardial Injury Enzymes during Hemodialysis? A Tissue Doppler Imaging Study

BACKGROUND

Cardiovascular death is decreasing in the general population; however, it appears in still higher rates and even increases gradually in hemodialysis (HD) patients. This situation has led to a debate about cardiovascular adverse effects of HD which lead to significant changes in cardiac and hemodynamic events. It is known that troponins are often elevated in HD patients, and high levels of troponin are associated with increased mortality. Therefore, it is difficult to interpret the value of elevations in chronic kidney disease patients.

METHODS

Echocardiographic and biochemical parameters of 41 patients treated with HD were evaluated before and after a HD session.

RESULTS

HD led to an increased heart rate, and tissue Doppler imaging parameters such as early diastolic mitral peak velocity (E)/early diastolic myocardial peak velocity (é) and septal é decreased significantly after HD. HD caused an increase in troponin I, myoglobin and cardiac creatine kinase (CK MB) levels (p = 0.019, p < 0.001 and p = 0.018, respectively). A decrease in the left ventricular peak systolic myocardial (LV S') velocity (p = 0.011) was detected in patients with increased levels of cardiac damage markers (group 2) compared to those without increased levels of cardiac damage markers (group 1) in HD.

CONCLUSION

A decrease in LV S' velocity was found to be an independent predictor of an increase of myocardial injury enzymes in HD (odds ratio = 1.099; p = 0.039). We concluded that HD may lead to significant acute stress upon the myocardium.

Echocardiography to predict adverse cardiac and vascular events in patients with severe chronic kidney disease (stage 4): a prospective study

BACKGROUND

Cardiovascular disease is the primary cause of mortality and morbidity among patients with chronic kidney disease.

AIMS

To investigate whether echocardiography can predict the occurrence of major cardiovascular events in patients with severe chronic kidney disease.

PATIENTS

Patients with stable stage 4 chronic kidney disease (estimated glomerular filtration rate 15-29 mL/min/1.73 m(2)) and followed in the nephrology department were included. Clinical, biological, electrocardiographic and echocardiographic data were recorded. Endpoint was defined as fatal or non-fatal cardiovascular event (acute coronary syndrome, acute heart failure, stroke, sustained ventricular arrhythmias, arterial thrombotic events and death).

RESULTS

We included 71 patients (46 men); mean age 72±14 years. Mean glomerular filtration rate was 21.9±4.8 mL/min/1.73 m(2). Over a mean follow-up of 258±30 days, 18 (25%) patients reached endpoint (death in 7/18). Male sex, blood urea, atrial fibrillation, Sokolow index, left atrial size, pulmonary arterial pressure, indexed left ventricular mass and protodiastolic peak velocity of transmitral Doppler flow were significantly higher whereas left ventricular ejection fraction was significantly lower in these patients. By multivariable analysis, blood urea and left ventricular ejection fraction remained predictive of major cardiovascular event with odds ratios of 1.10 (95% confidence interval 1.02-1.18) and 0.93 (95% confidence interval 0.89-0.97), respectively. The negative predictive value was 95% when left ventricular ejection fraction was>50% with blood urea<15 mmol/L.

CONCLUSION

Patients with stage 4 chronic kidney disease are at high risk of major cardiovascular events and death. Echocardiographic evaluation is effective in identifying patients at highest risk of adverse cardiac events.

Troponin I as a prognostic marker of cardiac events in asymptomatic hemodialysis patients using a sensitive troponin I assay

Elevated troponin T is known to be a prognostic marker for long-term cardiac events and mortality in asymptomatic end-stage renal disease patients. There are conflicting data in this regard with respect to troponin I (TnI). We recently showed a high incidence of elevated TnI levels in asymptomatic hemodialysis (HD) patients using a new generation sensitive TnI assay. The aim of this pilot study was to explore the prognostic value of TnI, as measured with this new assay, as a marker for outcomes in HD patients over a 2-year follow-up period. Fifty-one asymptomatic HD patients were enrolled, and pre-dialysis TnI levels were checked once monthly over 3 consecutive months. Patients were considered to be in the TnI positive group if TnI level on any of the three draws was ≥0.035 ng/ml. All patients were followed for a period of 2 years. The primary end points were acute coronary syndrome, coronary revascularization, sudden death, or cardiac arrest. The secondary end point was all-cause mortality. Elevated TnI levels were found in 51% (26/51) of patients in our cohort. One TnI positive patient was subsequently lost to follow up. There were 6 cardiac events over 2 years, all of which were in the troponin positive group (6/25 or 24%). The presence of a positive TnI at baseline was significantly associated with future cardiac events (p=0.022). A prior history of coronary artery disease (CAD) was also significantly related to future cardiac events (p=0.010). No patient with negative TnI at baseline developed a cardiac event, while 45.5% of those with both a positive TnI and a history of CAD had an event. Fourteen deaths occurred over 2 years, 8 in TnI positive and 6 in the negative group. All-cause mortality was not associated with elevated TnI levels at baseline. We found a significant association between positive TnI and subsequent cardiac events in asymptomatic HD patients followed for 2 years. TnI levels, as measured with a sensitive assay, may be useful in assessing cardiac risk in asymptomatic HD patients. This needs further confirmation in a larger cohort.

Predictors of sudden cardiac death: a competing risk approach in the hemodialysis study

BACKGROUND AND OBJECTIVES

There are few data on risk factors for sudden cardiac death (SCD) in patients undergoing hemodialysis (HD). The study objective was to identify predictors associated with various causes of death in the Hemodialysis (HEMO) Study and to develop a prediction model for SCD using a competing risk approach.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this analysis of 1745 HEMO participants, all-cause mortality was classified as SCD, non-SCD, and noncardiac death. Predictors for each cause of death were evaluated using cause-specific Cox proportional hazards models, and a competing risk approach was used to calculate absolute risk predictions for SCD.

RESULTS

During a median follow-up of 2.5 years, 808 patients died. Rates of SCD, non-SCD, and noncardiac death were 22%, 17%, and 61%, respectively. Predictors of various causes of death differ somewhat in HD patients. Age, diabetes, peripheral vascular disease, ischemic heart disease, serum creatinine, and alkaline phosphatase were independent predictors of SCD. The 3-year C-statistic for SCD was 0.75 (95% confidence interval, 0.70-0.79), and calibration was good (χ(2)=1.1; P=0.89). At years 3 and 5 of follow-up, the standard Cox model overestimated the risk for SCD as compared with the competing risk approach on the relative scale by 25% and 46%, respectively, and on the absolute scale by 2% and 6%, respectively.

CONCLUSIONS

Predictors of various causes of death differ in HD patients. The proposed prediction model for SCD accounts for competing causes of death. External validation of this model is required.

Cardiac troponins: outcome predictors in hemodialysis patients

Cardiovascular diseases represent the main cause of death in hemodialysis (HD) patients. Cardiac troponins (cTnT and cTnI) are indicators of myocardial damage. The aims of this study were to assess the prevalence of increased serum cTn in the absence of acute coronary syndrome, to determine overall and cardiovascular mortality rates, and to investigate the possible predictive values of cTnT and cTnI on the outcome in HD patients over a 2-year follow-up period. The study included 115 patients (71 men and 44 women) with an average age of 53.30 +/- 12.17 years who had undergone regular HD for 4.51 +/- 4.01 years and had a mean HD adequacy (Kt/Vsp) of 1.17 +/- 0.23. Increased serum cTnT concentration was found in 37.39% of patients and elevated serum cTnI concentration was present in 11.30% of HD patients without symptoms or signs of acute coronary syndrome. The average 2-year mortality rate was 13.74% and the average 2-year cardiovascular mortality rate was 8.51%. Patients with serum cTnT levels greater than 0.10 ng/ml had significantly lower overall and cardiovascular survival rates than patients with serum cTnT levels of less than 0.10 ng/ml. Patients with serum cTnI levels greater than 0.15 ng/ml had significantly lower overall and cardiovascular survival rates than patients with serum cTnI of less than 0.15 ng/ml. In patients on regular HD, cTn levels are significant outcome predictors.

Elevation of Pro-Inflammatory Cytokines, C-Reactive Protein and Cardiac Troponin T in Chronic Renal Failure Patients on Dialysis

Chronic renal failure (CRF) patients suffer from a chronic inflammation. They are at increased risk of cardiovascular disease. In order to investigate this inflammatory process and cardiovascular risk factors associated with haemodialysis (HD) and peritoneal dialysis (PD), we compared serum/plasma pro-inflammatory cytokines, C-reactive protein (CRP), and cardiac troponin T (cTnT) of 146 CRF patients treated or not treated with PD or HD. Serum cytokines and CRP as well as plasma cTnT were measured by enzyme-linked immunosorbent assay, chemiluminescence immunoassay, and electrochemiluminescence immunoassay, respectively. Results indicated that serum interleukin (IL)-18 concentrations were significantly higher in PD and low creatinine clearance pre-dialysis CRF (LCC) patients than HD patients (both p < 0.05). IL-6 and tumour necrosis factor (TNF)-alpha concentrations were significantly higher in PD patients than LCC patients (both p < 0.01). Serum hsCRP and plasma cTnT in HD were significantly higher than LCC (both p < 0.01). The elevation of pro-inflammatory cytokines should play an important role in the chronic inflammation and increased cardiovascular risk of CRF patients on dialysis. We are evaluating further the diagnostic and prognostic applications of pro-inflammatory cytokines and biochemical inflammatory markers for these patients.

Vitamin D levels and their relationship with cardiac biomarkers in chronic hemodialysis patients

Vitamin D insufficiency may be associated with cardiovascular (CV) mortality in HD patients. To test this hypothesis, we cross-sectionally measured 25-hydroxyvitamin D (25D), 1,25-dihydroxyvitamin D (1,25D), cardiac troponin T (cTnT), and N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) in chronic HD patients. Sixty-five patients (M:F=31:34, age 52.2+/-13.2 yr, DM 41.5%) were selected. Along with the expected low levels of 1,25D, 59 (90.8%) patients had 25D insufficiency (<30 ng/mL) among whom 15 (23.1%) were 25D deficient (<10 ng/mL). The 25D levels showed a negative correlation with cTnT levels (Spearman's rho=-0.44, p<0.01) but not with NT-pro-BNP levels (Spearman's rho=-0.17, p=0.17). The 1,25D levels, however, did not show any relationship with either cTnT or NT-pro-BNP. In multivariate analysis, being male and having low levels of 25D were independent risk factors associated with cTnT elevation (beta=0.44, p<0.01 and beta=-0.48, p<0.01, respectively). In conclusion, not only 1,25D but also 25D are commonly decreased in HD patients. Lower 25D levels appear to be associated with cTnT elevation, predicting worse CV outcome, and are possible to involve cardiac hypertrophy or coronary artery disease.

The association of sudden cardiac death with inflammation and other traditional risk factors

Despite the frequency of cardiovascular death in dialysis patients, few studies have prospectively measured sudden cardiac death in these individuals. Here, we sought to determine the frequency of sudden cardiac death and its association with inflammation and other risk factors among the CHOICE (Choices for Healthy Outcomes In Caring for ESRD) cohort of 1,041 incident dialysis patients. Sudden cardiac death was defined as that occurring outside of the hospital with an underlying cardiac cause from death certificate data. Over a median 2.5 years of follow-up, 22% of all mortality in this cohort was due to sudden cardiac death. Using Cox proportional hazards, we found that the highest tertiles of high-sensitivity C-reactive protein and of IL-6 were each associated with twice the risk of sudden cardiac death compared to their lowest tertiles when adjusted for demographics, comorbidities and laboratory factors. A decrement in serum albumin was associated with a 1.35 times increased risk for sudden cardiac death in the highest compared to the lowest tertile. These findings were robust and consistent when accounting for competing risks of death from other causes. Hence, we found that sudden cardiac death is common among patients with end stage renal disease and that inflammation and malnutrition significantly increased its occurrence independent of traditional cardiovascular risk factors.

Influence of sampling time and ultrafiltration coefficient of the dialysis membrane on cardiac troponin I and T

CONTEXT

The measurement of cardiac troponin I (TnI) and T (TnT) is essential to diagnose, guide therapy, and predict outcomes of the acute coronary syndrome. Increased levels of troponins, especially TnT, are frequently observed in patients on chronic hemodialysis (HD), reflecting ongoing and subclinical myocardial damage.

OBJECTIVE

Because these markers are increasingly used for stratification of cardiac risk in these patients, their behavior during HD should be acknowledged to optimize their clinical usefulness.

DESIGN

TnI and TnT were measured in 34 patients pre-HD and post-HD by either high- or low-flux membranes. The post-HD concentrations were corrected for hemoconcentration.

RESULTS

Pre-HD levels above the 99th percentile reference limits of the general population of TnI (>0.06 ng/ mL) and TnT (>0.01 ng/mL) were observed in 9% (13% high-flux, 6% low-flux membranes) and 88% (94% high-flux; 83% low-flux membranes) of the patients, respectively. No significant difference was observed in mean pre-HD values between patients dialyzed by low- and high-flux membranes. The overall decrease post-HD of both troponins (-21% and -17% for TnI and TnT, respectively) only reached statistical significance in patients dialyzed by low-flux membranes (-27% and -37% for TnI and TnT, respectively). A significant correlation was observed between absolute variations of TnI and TnT pre-HD to post-HD.

CONCLUSIONS

Results of our investigation attest that high-flux membranes clear both troponins more efficiently from circulation than low-flux membranes. Therefore, sampling time and ultrafiltration coefficient of the HD membrane should be regarded as potential sources of variability in the clinical interpretation of troponin measurement in HD patients.

Presentation and outcome of patients with systemic amyloidosis undergoing dialysis

BACKGROUND AND OBJECTIVES

Light chain (AL) and secondary (AA) amyloidosis usually present as a systemic disease frequently involving the kidney and leading to ESRD. Data regarding patients with AA or AL amyloidosis undergoing dialysis remain scarce.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We retrospectively studied patients with AA or AL amyloidosis who started dialysis in five French centers between January 1, 1995 and December 31, 2005.

RESULTS

We identified 19 patients with AL and 20 patients with AA amyloidosis undergoing dialysis. Patients with AL amyloidosis had shorter time from diagnosis to dialysis (25.2 versus 69.3 mo, P < 0.05) and more extrarenal amyloidosis, especially cardiac (63.2 versus 5%, P < 0.0001). Mean duration of follow-up was 37.4 and 31.8 mo for patients with AL and AA amyloidosis, respectively. Fifteen patients (78.9%) with AL and three patients (15%) with AA amyloidosis died on dialysis. Median survival was shorter in patients with AL (26 mo) than AA amyloidosis [not definable (ND)] (P < 0.02). Sepsis and cardiac deaths were the main causes of mortality. Prognosis factors for death at 1 yr were AL type (P < 0.01), cardiac amyloidosis [odds ratio (OR) = 18, P < 0.01], heart failure (OR = 8, P < 0.04), and shorter time from diagnosis to dialysis (6.1 versus 56 mo, P < 0.03). Multivariate analysis indicated that AL type (P = 0.02), but not cardiac amyloidosis was independently associated with global mortality.

CONCLUSIONS

Survival of patients with amyloidosis undergoing dialysis, especially AL type, is probably better than previously reported. However, mortality is higher in AL than AA type, especially in the setting of cardiac involvement.

Relationships of N-terminal pro-B-natriuretic peptide and cardiac troponin T to left ventricular mass and function and mortality in asymptomatic hemodialysis patients

BACKGROUND

Although the cardiac biomarker troponin T (cTnT) is related strongly to mortality in patients with end-stage renal disease, the independent association of N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) and cTnT levels in predicting outcomes is unknown. The objective of this study is to determine factors associated with NT-pro-BNP and cTnT and determine whether these levels are associated with mortality.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

Asymptomatic hemodialysis patients (n = 150) in 4 university-affiliated hemodialysis units. EXPOSURE & OUTCOMES: For cross-sectional analysis, echocardiographic variables as exposures and NT-pro-BNP and cTnT levels as outcomes; for longitudinal analysis, association of NT-pro-BNP and cTnT levels as exposures to all-cause and cardiovascular disease mortality as outcomes.

RESULTS

In a multivariate regression analysis, low midwall fractional shortening, a measure of poor systolic function, was an independent correlate of log NT-pro-BNP level (P < 0.01), whereas left ventricular mass index was an independent correlate of cTnT level (P < 0.01). During a median follow-up of 24 months, 46 patients died, 26 of cardiovascular causes. NT-pro-BNP levels had a strong graded relationship with all-cause (hazard ratios [HRs], 1.54, 4.78, and 4.03 for increasing quartiles; P < 0.001) and cardiovascular mortality (HRs, 2.99, 10.95, and 8.54; P < 0.01), whereas cTnT level had a weaker relationship with all-cause (HRs, 1.57, 2.32, and 3.39; P < 0.01) and cardiovascular mortality (HRs, 0.81, 2.12, and 2.14; P = 0.1). The combination of the 2 biomarker levels did not improve the association with all-cause or cardiovascular mortality compared with NT-pro-BNP level alone. NT-pro-BNP level was a marker of mortality even after adjusting for left ventricular mass index and midwall fractional shortening.

LIMITATIONS

Our cohort was predominantly black and of limited sample size.

CONCLUSION

NT-pro-BNP level strongly correlates with left ventricular systolic dysfunction and is associated more strongly with mortality than cTnT level in asymptomatic hemodialysis patients.

Cardiac troponins I and T in hemodialysis patients without acute coronary syndrome

BACKGROUND

There is a reluctance to use cardiac troponins (cTn) for the monitoring of acute coronary syndrome (ACS) in hemodialysis (HD) patients because renal failure per se is thought to lead to increased cTn levels. The aim of this study was to analyse the proportion of patients with increased cTn levels in HD patients without ACS.

METHODS

cTnI was measured with the AccuTnI(trade mark) from Beckman (cTnI-B) and Troponin I Stat(trade mark) from Dade Behring (cTnI-DB) assays; cTnT was measured with the third generation assay from Roche. The study included 105 HD patients. The clinical outcomes were determined after 2.5 years.

RESULTS

Considering the receiver operator characteristic (ROC) cutoff, the proportion of patients with elevated cTnI-B, cTnI-DB and cTnT levels was respectively 2%, 3% and 27%. The proportion of patients with abnormal cTn values increased when a lower cutoff value was considered, based on the 99th percentile of a reference population with a coefficient of variation of less than 10% (99th percentile-10% CV cutoff). The proportion of patients with elevated values did not differ before and after the HD session. The 2.5 years mortality was associated with increased levels of cTnT but not with increased levels of cTnI.

CONCLUSIONS

When the ROC cutoff is applied, cTnI assays are suitable for the monitoring of ACS in HD patients. cTnT could lead to false positive diagnosis of myocardial infarction, however it is predictive of long-term mortality. The 99th percentile-10% CV cutoff does not seem appropriate in HD patients.

The Acute Cardiac Effects of Dialysis

It is well recognized that the procedure of hemodialysis is associated with significant changes in blood pressure and systemic hemodynamics; 20-30% of treatments are complicated by intradialytic hypotension (IDH). There are now an increasing number of studies using electrocardiographic, isotopic and echocardiographic techniques that show that subclinical myocardial ischemia occurs during dialysis. This concept is supported by some studies showing that dialysis can induce acute rises in troponins and creatinine kinase MB, although this has not been found by all authors. Some of this controversy may at least in part be due to the collection of blood samples immediately postdialysis, which is likely to be too early to reliably detect dialysis-induced elevations of cardiac enzymes. Cardiovascular death is the biggest single cause of mortality in dialysis patients and of this sudden death comprises the largest proportion. As such, there is a large body of evidence examining whether dialysis is pro-arrhythmogenic. It is clear that dialysis can increase QTc interval and QT dispersion and is capable of inducing arrhythmias on Holter monitoring, likely due to the interaction of multiple factors, some of which prime for the development of arrhythmias (particularly the presence of preexisting cardiac disease), and some of which act as triggers. However, the link between these electrocardiographic alterations and sudden death is relatively poorly studied. This review summarizes the available literature regarding the acute cardiac effects of dialysis in relation to the above, and discusses how these acute changes may contribute to the genesis of uremic cardiomyopathy and longer term cardiac outcomes.

Usefulness of clinical evaluation, troponins, and C-reactive protein in predicting mortality among stable hemodialysis patients

This study prospectively examined the hypothesis that dividing stable dialysis patients into different clinical subsets by presence or absence of coronary disease equivalent will lead to clearer risk stratification by abnormal troponins and highly sensitive C-reactive protein (hs-CRP). Patients with end-stage renal disease have an annual mortality of 18%. Previous studies have shown that elevated cardiac troponins T and I and hs-CRP predict increased mortality, although these studies have not taken clinical parameters into account. Stable patients with end-stage renal disease (n = 173) were divided into 2 groups: 115 patients with coronary disease equivalent (known coronary or peripheral vascular disease or diabetes mellitus) and 58 patients without it. The 2 groups were then stratified by biomarkers (cardiac troponins T and I and hs-CRP) and followed for 27 months. The primary outcome was all-cause mortality. Patients with coronary disease equivalent had twofold greater annual mortality than those without (20.4% vs 9.8%, p = 0.003). Among patients with coronary disease equivalent, those with elevated troponins had a further increase in the risk for death relative to patients with normal troponins (25% vs 9% with cardiac troponin I elevation, p <0.001; 24% vs 12% with cardiac troponin T elevation, p = 0.04). hs-CRP did not add to the risk stratification of patients with coronary disease equivalent. Conversely, in patients without coronary disease equivalent, neither troponin further predicted the risk for death. In the small subset of patients without coronary disease equivalent who had hs-CRP >or=3 mg/L, mortality was significantly increased (p = 0.01). In conclusion, initial clinical assessment, followed by the addition of biomarkers, can be used to risk-stratify stable patients with end-stage renal disease.

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.

Serum troponin T concentration as a predictor of mortality in hemodialysis and peritoneal dialysis patients

BACKGROUND

Troponin T is a good predictor of all-cause and cardiovascular mortality in cardiac patients. Although it is known that troponin T is an independent risk factor in dialysis patients as well, its prognostic value when measured routinely in clinical practice, particularly in addition to other risk indicators, is unclear.

METHODS

A cohort of 847 patients who started dialysis therapy between 1997 and 2001 and participated in a multicenter follow-up study was examined. Clinical data were determined 3 months after the start of dialysis therapy. Patients were followed up until date of death or censoring in November 2003.

RESULTS

For patients with troponin T values of 0.05 to 0.10 microg/L, hazard ratio for all-cause mortality was 2.2 (95% confidence interval [CI], 1.7 to 2.8) compared with patients with values less than 0.05 microg/L. For patients with values greater than 0.10 microg/L (11%), hazard ratio was 3.3 (95% CI, 2.5 to 4.5). A survival model with clinical and laboratory risk indicators yielded an area under the curve of 0.81, which did not increase when troponin T level was added to the model. The area under the curve for troponin T level alone was 0.67. No important differences were found between patients on hemodialysis or peritoneal dialysis therapy and between patients with high and low residual renal function.

CONCLUSION

Although troponin T level is an independent risk factor for mortality in dialysis patients, it has limited added predictive power as a routine screening test over other clinical risk factors in dialysis patients.

Cardiac enzymes, renal failure and renal transplantation

Diagnostic accuracy of the currently available serum markers of cardiac injury, such as myoglobin, creatine kinase and its myocardial isoform, are altered in patients with renal failure. It is shown that cardiac troponins have decreased diagnostic sensitivity and specificity in patients receiving renal replacement therapy. Data regarding serum levels of these cardiac biomarkers, especially those of the cardiac troponins, in patients with a transplanted kidney are limited. Current data show that levels of cardiac troponin I are unaltered in patients who have undergone renal transplantation, while levels of cardiac troponin T may be elevated.We believe that cardiac troponin I should be the biomarker of choice for diagnosis of myocardial injury in these patients. However, further trials are required for conclusive results.

[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.

Assessment of coronary artery disease in hemodialysis patients with delayed systolic blood pressure response after exercise testing

BACKGROUND

We evaluated usefulness of the postexercise systolic blood pressure (SBP) response for detecting coronary artery disease (CAD) in hemodialysis patients.

METHODS

A treadmill exercise testing was done, and the SBP response was measured in 44 hemodialysis patients (30 men, 14 women; age 41 to 81 years). The postexercise SBP response was defined as the ratio of SBP after 3 minutes of recovery to SBP at peak exercise.

RESULTS

The SBP ratio of the 25 subjects with coronary artery stenosis (1.01+/- 0.13) was significantly greater (p<0.01) than 19 subjects without coronary artery stenosis (0.83+/- 0.10). An SBP ratio greater than 0.92 identified CAD with higher sensitivity, specificity, and accuracy than did the conventional ST-segment depression criterion (76 vs. 56%, 90 vs. 53%, and 82 vs. 55%, respectively).

CONCLUSION

Determination of the SBP ratio is a clinically useful, noninvasive method for accurately detecting CAD in hemodialysis patients.

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.

Use of cardiac troponin T in diagnosis and prognosis of cardiac events in patients on chronic haemodialysis

BACKGROUND

Patients undergoing chronic haemodialysis frequently have elevated serum cardiac troponin T (cTnT) levels resulting in difficulty in diagnosing acute coronary syndromes (ACS) in these patients. We sought to determine whether: (i) cTnT concentrations were consistent over time; (ii) intradialytic changes in cTnT levels were due to haemoconcentration; (iii) baseline cTnT levels predicted subsequent mortality or ACS.

METHODS

We measured serial pre- and post-dialysis cTnT concentrations in 75 asymptomatic patients undergoing chronic haemodialysis at baseline, and at 48 h, 8 months and 15 months. At 15 months, we also measured pre- and post-dialysis haematocrit levels in order to adjust the post-dialysis cTnT concentration for the effect of ultrafiltration. Kaplan-Meier survival curves, log-rank tests and Cox models were employed to determine whether baseline cTnT levels predicted death or ACS within 18 months.

RESULTS

Thirty-five (47%) patients had a baseline pre-dialysis cTnT concentration in the diagnostic range for an ACS (cTnT > or = 0.03 microg/l). There was a strong correlation between serial cTnT concentrations in individual patients (P<0.0001 for each time point). The median cTnT concentration was significantly greater post- than pre-dialysis (P<0.01 for each serial analysis); however, there was no significant difference following correction of post-dialysis cTnT levels for the effect of haemoconcentration (P = 0.48). Elevated baseline cTnT levels were associated with an increased risk of mortality or ACS at 18 months (P = 0.0015).

CONCLUSION

In asymptomatic patients on haemodialysis, serum cTnT concentrations are frequently elevated, and they rise during dialysis due to haemoconcentration. cTnT levels fluctuate minimally in individual patients in the medium term, therefore annual measurements may be useful reference points in the diagnosis of chest pain and in the prediction of ACS and mortality.

Chronic Kidney Disease: A Risk Factor for Cardiovascular Disease

The goal of risk stratification of CVD inpatients with CKD is to lead to effective and early intervention and to prevent the adverse outcomes associated with this complex multisystem disease that is characteristic of growing number of patients with CKD in the general population and of patients receiving dialysis therapy or kidney transplantation. By 2030, there will be 2.24 million patients with ESRD in the United States, and approximately 1.3 million of these cases of ESRD will be caused by diabetes mellitus. Thus, CVD in this high-risk population presents a challenge for the nephrology and the cardiology community.

Prognostication of survival using cardiac troponins and N-terminal pro-brain natriuretic peptide in patients with primary systemic amyloidosis undergoing peripheral blood stem cell transplantation

Primary systemic amyloidosis (AL) is a fatal plasma cell disorder. Pilot data suggest survival is better in patients undergoing peripheral blood stem cell transplantation (PBSCT), but the selection process makes the apparent benefit suspect. We have reported that circulating cardiac biomarkers are the best predictors of survival outside of the transplantation setting. We now test whether cardiac troponins (cTnT and cTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) are prognostic in transplant recipients. In 98 patients with AL undergoing PBSCT, serum cardiac biomarkers were measured (cTnT, 98 patients; cTnI, 65 patients; and NT-proBNP, 63 patients). Elevated levels of cTnT, cTnI, and NT-proBNP were present in 14%, 43%, and 48% of patients, respectively. At 20 months median follow-up, median survival has not been reached for patients with values below the thresholds; in patients with values above the thresholds, median survival is 26.1 months, 66.1 months, and 66.1 months, respectively. Our previously reported risk systems incorporating these markers were also prognostic, notably the cTnT/NT-proBNP staging. Using this system, 49%, 38%, and 13% of patients were in stage I, stage II, and stage III, respectively. Determining levels of circulating biomarkers may be the most powerful tool for staging patients with AL undergoing PBSCT.