Circulating cardiac troponin-T in patients before and after renal transplantation

Diagnostic value of high sensitivity cardiac troponin T (hs-cTnT) in dialysis patients with myocardial infarction

Background

As a sensitive diagnostic marker for myocardial infarction (MI) in people with normal renal function, elevated high sensitivity cardiac troponin T (hs-cTnT) was often found in chronic kidney disease (CKD) patients requiring dialysis. However, the accuracy of baseline hs-cTnT in the diagnosis of MI (including Type 1 MI (T1MI) and Type 2 MI (T2MI)) in dialysis patients is still controversial. The aim of this study was to retrospectively explore whether there were any clinical indices that could increase the predictive value of hs-cTnT on admission for MI occurrence in dialysis patients.

Methods

Here, 136 patients with uremia who underwent regular dialysis with coronary angiography in the First Affiliated Hospital of Nanjing Medical University from August 2017 to October 2021 were enrolled. According to the coronary angiography results and the presence of clinical symptoms, the patients were divided into: (1). AMI group (n = 69; angiography positive) and Control group (n = 67; angiography negative); (2). T1MI group (n = 69; angiography positive), T2MI group (n = 7; angiography negative & symptomatic), and Control group (n = 60; angiography negative & asymptomatic).

Results

Here, we found the mean hs-cTnT on admission in the Control group was much lower than that in the AMI group. Hs-cTnT alone had a mediocre predictive performance, with an AUROC of 0.7958 (95% CI: 0.7220, 0.8696). Moreover, the ROC curve of hs-cTnT combined with the Triglyceride (TG), Time of dialysis, and Albumin (Alb) showed a higher sensitivity area [0.9343 (95% CI: 0.8901, 0.9786)] than that of single hs-cTnT. Next, hs-cTnT combined with the TG, Time of dialysis, and Alb also presented a better performance in predicting T1MI [0.9150 (95% CI: 0.8678, 0.9621)] or T2MI (0.9167 [0.9167 (95% CI: 0.8427, 0.9906)] occurrences. Last, these combined variables could better distinguish patient between T1MI and T2MI group than hs-cTnT alone.

Conclusions

On admission, a combination of hs-cTnT, TG, Time of dialysis, and Alb presented a higher sensitivity than hs-cTnT alone in predicting MI occurrence in dialysis patients, suggesting a better diagnostic approach for future clinical applications.

Cardiac biomarkers in pediatric CKD-a prospective follow-up study

BACKGROUND

The N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitive cardiac-specific troponin T (hs-cTnT) are associated with abnormal cardiac structure and function and an increased risk of cardiovascular death in chronic kidney disease (CKD) patients. There is limited knowledge about these cardiac markers in pediatric CKD patients.

METHODS

Longitudinal levels of NT-proBNP and hs-cTnT were analyzed in 48 pediatric patients, 22 with CKD (GFR range 8.8-68 mL/min/1.73 m²) and 26 transplanted patients (CKD-T; GFR range 30-99 mL/min/1.73 m²). Follow-up was scheduled after 1 and 3 years. Longitudinal patterns and associations to kidney function, cardiovascular risk markers, and echocardiographic parameters were assessed.

RESULTS

High NT-proBNP was present in 27% of CKD and 11% of CKD-T patients. Similarly 32% of CKD and 8% of CKD-T patients had elevated hs-cTnT levels. In longitudinal multivariate analyses, high log NT-proBNP was associated with low GFR (β =  - 0.01, p = 0.01) and elevated left ventricular mass index (LVMI; β = 0.02, p = 0.05). The strong association to LVMI remained when using GFR-adjusted NT-proBNP in similar analysis. Patients with left ventricular hypertrophy (LVH) also had higher NT-proBNP (235 [146-301] ng/L) than patients without LVH (86 [11-477] ng/L), p = 0.02. High hs-cTnT over-time was also associated with low GFR (β =  - 0.007, p = 0.01) and a low cc-TDI e´/a´, indicating a worse LV diastolic function (β =  - 0.09, p = 0.05). This association did not persist for GFR-adjusted hs-cTnT.

CONCLUSIONS

NT-proBNP and hs-cTnT are elevated in pediatric CKD and CKD-T patients. GFR-adjusted NT-proBNP was associated with longitudinal levels of elevated LVMI suggesting this might be a marker for early subclinical myocardial damage. A higher resolution version of the Graphical abstract is available as Supplementary information.

High-sensitive troponin T increase after hemodialysis is associated with left ventricular global longitudinal strain and ultrafiltration rate

BACKGROUND

Circulating troponin levels are both stable and higher in patients with end-stage renal disease, even in the absence of acute coronary syndrome. These patients commonly have underlying cardiac problems that frequently cause troponin elevation. The effect of hemodialysis (HD) on troponin levels has not been well elucidated. Thus, investigated herein is the relationship between the changes in troponin levels along with left ventricular deformation and volume depletion in patients with end-stage renal disease.

METHODS

Patients included were between 18 and 85 years of age and were receiving hemodialysis for at least 6 months. High sensitive cardiac troponin T (hs-cTnT) levels were studied in blood samples taken at the beginning and end of HD. Two-dimensional speckle tracking strain imaging was used to evaluate myocardial contractility.

RESULTS

Seventy patients (50.7 ± 16.9 years of age, 27 women) were included in study. The mean volume of ultrafiltration was 3260 ± 990 mL. A significant increase in circulating hs-cTnT levels was observed, as well as a prominent decrease in left ventricular global longitudinal strain (GLS) after HD (52.4 ± 40.2 ng/L vs. 66.8 ± 48.5 ng/L, p < 0.001 and 20.1 ± 3.6% vs. 16.8 ± 3.8% p < 0.001, respectively). Moreover, ultrafiltration rate and GLS were found as the strongest independent variables in relation to the relative increase in hs-cTnT.

CONCLUSIONS

Hemodialysis can cause a significant increase in hsTnT. This can jeopardize the accuracy of clinical diagnoses based on hs-TnT measurements. GLS may be used as a determinant of this hs-TnT increase. The influence of HD on the cardiovascular system should be kept in mind to prevent unnecessary interventions.

Effect of Hemodialysis on Levels of High-Sensitivity Cardiac Troponin T

Cardiac troponin (cTn) is essential for the diagnosis of an acute coronary syndrome (ACS). However, in end-stage renal disease (ESRD) baseline cTn levels are often elevated, and it is unknown whether the hemodialysis (HD) procedure affects cTn levels. This leaves clinicians unsure of how to interpret cTn in HD patients with cardiac ischemia. We therefore sought to determine if plasma levels of high-sensitivity cardiac troponin T (hs-cTnT) vary during or after HD treatment. We prospectively enrolled 10 chronic HD patients who were admitted to our institution. All participants were receiving thrice weekly HD before admission and were medically stable. Those admitted for ACS or to critical care units were excluded. Baseline hs-cTnT was measured immediately before HD. For the subsequent 6 hours, hs-cTnT was measured every 2 hours and every 3 hours thereafter for a total collection period of 24 hours. A significant decline in mean hs-cTnT was noted with HD. During HD (2 hours after HD initiation), hs-cTnT decreased by 10.7% (confidence interval 5% to 17%). Immediately after HD (4 hours after HD initiation), a decline of 12% (confidence interval 5% to 19%) was observed. Thereafter hs-cTnT began to rise. Hs-cTnT levels returned to baseline by 11 hours after HD completion and remained stable for the reminder of the study. In conclusion, HD induces a short-lived negative bias in hs-cTnT. When measured for investigation of ACS, hs-cTnT concentration should be interpreted with respect to time of dialysis and specimen collection.

Cardiac biomarkers in dialysis

Cardiovascular disease is the major cause of death, accounting for approximately 40 percent of all-cause mortality in patients receiving either hemodialysis or peritoneal dialysis. Cardiovascular risk stratification is an important aspect of managing dialysis patients as it enables early identification of high-risk patients, so therapeutic interventions can be optimized to lower cardiovascular morbidity and mortality. Biomarkers can detect early stages of cardiac injury so timely intervention can be provided. The B-type natriuretic peptides (Brain Natriuretic peptide [BNP] and N-terminal pro-B-type natriuretic peptide [NT-proBNP]) and troponins have been shown to predict mortality in dialysis patients. Suppression of tumorigenicity 2 (ST2) and galectin-3 are new emerging biomarkers in the field of heart failure in both the general and dialysis populations. This article aims to discuss the current evidence regarding cardiac biomarker use to diagnose myocardial injury and monitor the risk of major adverse cardiovascular events in patients undergoing dialysis.

High-sensitivity cardiac troponin T levels in the emergency department in patients with chest pain but no myocardial infarction

BACKGROUND

High-sensitivity cardiac troponin T (hs-cTnT) was recently introduced into clinical practice. The increased sensitivity has decreased the specificity. We aimed to determine the predictors for and prevalence of hs-cTnT levels above the 99th percentile in a stable population of patients without myocardial infarction (MI) who sought medical attention for chest pain in the emergency department.

METHODS

We included 11,847 patients with chest pain and at least one hs-cTnT measurement during 2011 and 2012. Patients with any acute reasons for an elevated hs-cTnT level were excluded. We used logistic regression to calculate adjusted odds ratios with 95% confidence intervals for the association between patient characteristics and hs-cTnT levels of >14ng/L. We also determined 50th, 75th, 97.5th, and 99th percentile values of hs-cTnT levels in relation to age, sex, estimated glomerular filtration rate (eGFR), and presence or absence of comorbidities.

RESULTS

In total, 1360 (11%) patients had hs-cTnT levels of >14ng/L. Men had higher troponin levels than women, and older patients had higher levels than younger patients. The strongest predictor of an elevated troponin level was a reduced eGFR. The 99th percentile for hs-cTnT among all men and among women <50years of age with normal renal function was 20 and 12ng/L, respectively; this level increased to 44 and 36ng/L, respectively, at the age of 70-79years.

CONCLUSIONS

A hs-cTnT level above the 99th percentile in patients with chest pain but no MI is common and is related to sex, age, and eGFR.

The effect of hemodialysis on cardiac enzyme levels and echocardiographic parameters

BACKGROUND

Cardiac troponins are specific and sensitive markers of myocardial damage. Troponin levels may increase without an obvious active cardiac disease in hemodialysis patients. In this study, we aimed to investigate the effect of a single hemodialysis session on echocardiographic parameters and cardiac enzyme levels, including cTn-I, creatine phosphokinase (CPK), and creatine kinase-MB (CK-MB).

PATIENTS AND METHODS

Forty patients under chronic hemodialysis treatment enrolled in this prospective study. All the patients had a physical examination and underwent echocardiography before and after hemodialysis. cTn-I, CPK and CK-MB levels were also determined before and after hemodialysis in all patients.

RESULTS

Post-dialysis cTn-I levels were significantly higher compared to pre-dialysis levels (p = 0.03). cTn-I levels increased in 26 patients, did not change in 1 patient and decreased in 13 patients after hemodialysis when compared to the values determined before hemodialysis. There was no significant increase in CPK and CK-MB levels after dialysis. Statistically significant changes were detected in the end-systolic diameter of the left ventricle, end-diastolic diameter of left ventricle, ejection fraction, diameter of the left atrium, diameter of the right atrium, pulmonary artery pressure and end-diastolic diameter of the right ventricle. However, there was no significant relation between these echocardiographic changes and ultrafiltration volume, blood flow rate, age, and gender.

CONCLUSIONS

Hemodialysis leads to an increase in cTnI levels. However, the effect of increased cTnI levels on survival rates in hemodialysis patients with underlying coronary artery disease has not yet been determined. Prospective multi-center studies with large sample size are required to clarify this issue.

Cardiac troponin T before and after kidney transplantation: determinants and implications for posttransplant survival

Pretransplant cardiac troponin T(cTnT(pre) ) is a significant predictor of survival postkidney transplantation. We assessed correlates of cTnT levels pre- and posttransplantation and their relationship with recipient survival. A total of 1206 adult recipients of kidney grafts between 2000 and 2010 were included. Pretransplant cTnT was elevated (≥0.01 ng/mL) in 56.4%. Higher cTnT(pre) was associated with increased risk of posttransplant death/cardiac events independent of cardiovascular risk factors. Elevated cTnT(pre) declined rapidly posttransplant and was normal in 75% of recipients at 3 weeks and 88.6% at 1 year. Elevated posttransplant cTnT was associated with reduced patient survival (cTnT(3wks) : HR = 5.575, CI 3.207-9.692, p < 0.0001; cTnT(1year) : 3.664, 2.129-6.305, p < 0.0001) independent of age, diabetes, pretransplant dialysis, heart disease and allograft function. Negative/positive predictive values for high cTnT(3wks) were 91.4%/50% respectively. Normalization of cTnT posttransplant was associated with reduced risk. Variables related to elevated cTnT posttransplant included pretransplant diabetes, older age, time on dialysis, high cTnT(pre) and lower graft function. Patients with delayed graft function and those with GFR < 30 mL/min at 3 weeks were more likely to have an elevated cTnT(3wks) and remained at high risk. When allografts restore sufficient kidney function cTnT normalizes and patient survival improves. Lack of normalization of cTnT posttransplant identifies a group of individuals with high risk of death/cardiac events.

Biomarkers in hemodialysis patients

Patients with chronic kidney disease (CKD) are, compared to the general population, at higher risk of cardiovascular disease (CVD), including sudden death, coronary artery disease (CAD), congestive heart failure (HF), stroke, and peripheral artery disease. The presence of CVD is independently associated with kidney function decline. Renal insufficiency is a strong and independent predictor of mortality in patients with different CKD stages. The interplay of traditional and nontraditional risk factors is complex such that risk factor profiles are different in CKD patients. Seemingly, paradoxical associations between traditional risk factors and cardiovascular outcome complicate efforts to identify real cardiovascular etiology in these patients. Additional tools are often required to aid clinical assessment of cardiovascular risk. Recently, a number of cardiovascular biomarkers were identified as predictors of outcome in CVD. These may be used to guide early diagnosis and therapy for CVD or may predict outcome in CKD. This review focuses on the potential diagnostic and prognostic use of some important new biomarkers including brain natriuretic peptide (BNP), cardiac troponins (cTns), inflammatory markers, adhesion molecules, and asymmetric dimethylarginine (ADMA) in CKD as well as those patients with end-stage renal failure.

[Cardiac markers in different degrees of chronic kidney disease: influence of inflammation and previous heart disease]

BACKGROUND AND OBJECTIVE

Troponin T (TnT), brain natriuretic peptide (BNP) and its precursor (NT-proBNP) are useful markers of acute coronary events and heart failure. The aim of this study was to analyze the influence of chronic renal failure, inflammation and heart disease in these biomarkers.

PATIENTS AND METHODS

In 266 patients with different stages of chronic renal diseases, the following parameters were measured: cardiac markers (TnT, BNP and NT-proBNP), renal function, inflammatory markers (hsCRP, fibrinogen, albumin, uric acid and white blood cells). We recorded the cardiovascular history. Ventricular dysfunction and left ventricular hypertrophy were assessed by echocardiography.

RESULTS

A significant correlation between cardiac markers and inflammatory parameters such as fibrinogen, hsCRP and albumin was found. Age (OR 1.05, P = .021), serum albumin (OR: 0.06, P=.006), ischemic heart disease (OR: 8.17, P=.0092) and renal failure (OR: 1.67, P=.05) were predictors of higher BNP levels. Age (OR 1.05, P=.0097), serum albumin (OR: 0.12, P=.001), ischemic heart disease (OR: 3.43, P=.034), renal failure (OR: 1, 65, P=.036) and heart failure (OR: 4.33, P=.0312) were predictors of elevated NT-proBNP. Previous ischemic heart disease alone increased TnT levels (OR: 6.51, P=.0012).

CONCLUSIONS

Age, previous cardiac disease and inflammation increase cardiac marker levels in patients with different stages of renal disease, but the degree of renal failure is an important factor influencing NT-proBNP levels. However, ischemic heart disease alone increases the levels of TnT.

MicroRNAs in patients on chronic hemodialysis (MINOS study)

BACKGROUND AND OBJECTIVES

Diagnosis of acute myocardial injury with biomarkers is difficult in patients with advanced renal failure. Circulating microRNAs are promising new biomarkers of myocardial injury. It is unknown whether levels of microRNAs are affected in patients undergoing hemodialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

High-sensitivity cardiac troponin T (hsTnT) and cardiac-enriched miR-499 were measured in 41 patients with ESRD undergoing hemodialysis and 41 controls.

RESULTS

Levels of hsTnT and miR-499 were highly elevated in patients with ESRD compared with controls (>80-fold increase; P<0.001). Among patients with ESRD, 98% had positive hsTnT levels and 46% had positive miR-499 levels. Levels of troponins were not affected by hemodialysis. However, miR-499 levels were decreased after hemodialysis (6.5-fold decrease; P=0.002).

CONCLUSIONS

Both miR-499 and troponins are elevated in patients with advanced renal failure. However, whereas levels of troponins are unaffected by hemodialysis, this is not the case for miR-499. Therefore, these observations mitigate the potential of miR-499 as a marker of myocardial injury in patients with ESRD.

Increased cardiac troponin T levels are related to inflammatory markers and various indices of renal function in chronic renal disease patients

BACKGROUND/OBJECTIVES

Cardiovascular disease begins early in the course of chronic kidney disease (CKD), and the glomerular filtration rate (GFR) is an independent risk factor for it. There is little information on cardiac troponin concentrations in patients with CKD who have not commenced dialysis. Factors associated with this deleterious process are not completely understood, and we aimed to determine associated laboratory abnormalities of increased cardiac troponin T (cTnT) in patients with CKD.

METHODS

In this study, 104 patients (65 males and 39 females with mean age of 65 ± 15 years) were recruited. A detailed clinical history was recorded and routine biochemical variables and cTnT levels were measured. GFR was estimated (44.62 ± 14.38 mL/min/1.73 m(2)) using the modification of diet in renal disease study formula.

RESULTS

cTnT is correlated with blood urea (r = 0.262, p < 0.05), uric acid (r = 0.399, p < 0.001), blood phosphorus (r = 0.550, p < 0.001), triglyceride (r = 0.329, p = 0.011), C-reactive protein (CRP; r = 0.768, p < 0.001), renal resistive index (RRI; r = 0.412, p = 0.017), and GFR (r = -0.755, p = 0.011). On stepwise multiple regression analysis, increased CRP (≥12 mg/L), uric acid (≥5 mg/L), and RRI (≥0.70) were independent variables for increased cTnT status (r(2) = 0.053, p < 0.05).

CONCLUSION

Increased cTnT not only shows ongoing inflammation but also is a sensitive marker of functioning renal mass. It is strongly correlated with factors influencing the decline in renal function; thus, it can be used as a renal risk parameter.

Elevated cardiac troponin T contributes to prediction of worse in-hospital outcomes after endovascular therapy for acute limb ischemia

INTRODUCTION

The present study evaluated whether elevated cardiac troponin T (cTnT) was predictive of an increased risk for death or amputation in patients with acute lower limb ischemia (ALI). ALI is one of the most frequent causes of amputation, with mortality rates for ALI ranging from 15% to 20%.

METHODS

This study included 254 consecutive ALI patients (155 men, 99 women; mean age, 71.6 ± 13.2 years) presenting with Rutherford categories I, IIA, or IIB according to the classification for ALI.

RESULTS

ALI was caused by thromboembolism (29.5%), local arterial thrombosis (53.1%), or bypass graft occlusion (16.9%). Restoration of arterial blood flow was obtained by an endovascular approach, with a primary success rate of 98.4%. Rates were low for in-hospital mortality (3.9%) and amputation (5.1%). Patients who died or required amputation more frequently presented with elevated cTnT ≥0.01 ng/mL (52.2% vs 25.5%, P = .01) and impaired renal function (chronic kidney disease stage 3-5; 60.9% vs 38.1%; P = .04). After controlling for age, sex, C-reactive protein, renal function, presence or absence of coronary artery disease, and traditional vascular risk factors, as well as the interval between symptom onset and revascularization, the relationship between cTnT and a worse in-hospital outcome remained significant (hazard ratio, 3.4; 95% confidence interval, 1.3-8.5; P = .010).

CONCLUSIONS

ALI patients frequently have elevated cTnT, which is associated with increased in-hospital mortality and amputation. Even small cTnT elevations predict a markedly increased risk of worse in-hospital outcome; however, the overall mortality and amputation rate in our study was low.

The comparison of cardiac biomarkers positivities in hemodialysis patients without acute coronary syndrome

AIM

We aimed to compare heart-type fatty acid-binding proteins (H-FAB) and other cardiac biomarkers to determine the most reliable cardiac marker in hemodialysis (HD) patients without acute coronary syndrome (ACS).

MATERIALS AND METHODS

Sixty HD patients without ACS were included the study. Blood samples were taken before HD session for measurement of H-FAB, troponin I, troponin T, creatine kinase-MB (CK-MB) isoforms.

RESULTS

Mean age of patients was 55 ± 15 years. Males were 55%. Mean serum level of blood urea nitrogen was 75 ± 15 mg/dL, mean serum level of creatinine was 8.3 ± 2.5 mg/dL, mean serum level of hematocrit was 33 ± 5%, mean ejection fraction was 54 ± 9%, and mean left ventricular mass index (LVMI) was 136 ± 54 g/m(2). H-FAB was positive in 32%, troponin T in 20%, troponin I in 12%, and CK-MB in 5% of all patients. Three or four of all parameters were not positive together in any patient. While 5% of patients had positive troponin T with H-FAB, 3% of patients had positive troponin T with troponin I and 2% of patients had positive troponin I with H-FAB.

CONCLUSION

Our study found that CK-MB had the lowest positivity in the HD patients without ACS. H-FAB had the highest rate of positivity in all markers. If only one marker is assessed it should be CK-MB. But using two parameters in HD patients in ACS diagnosis increases the reliability of diagnosis. If we use two biomarkers it should be CK-MB and troponin I.

Biomonitors of cardiac injury and performance: B-type natriuretic peptide and troponin as monitors of hemodynamics and oxygen transport balance

Serum biomarkers, such as B-type natriuretic peptide and troponin, are frequently measured in the cardiac intensive care unit. A review of the evidence supporting monitoring of these biomarkers is presented.

DESIGN

A search of MEDLINE, PubMed, and the Cochrane Database was conducted to find literature regarding the use of B-type natriuretic peptide and troponin in the cardiac intensive care setting. Adult and pediatric data were considered.

RESULTS AND CONCLUSION

Both B-type natriuretic peptide and troponin have demonstrated utility in the intensive care setting but there is no conclusive evidence at this time that either biomarker can be used to guide inpatient management of children with cardiac disease. Although B-type natriuretic peptide and troponin concentrations can alert clinicians to myocardial stress, injury, or hemodynamic alterations, the levels can also be elevated in a variety of clinical scenarios, including sepsis. Observational studies have demonstrated that perioperative measurement of these biomarkers can predict postoperative mortality and complications.

RECOMMENDATION AND LEVEL OF EVIDENCE

(class IIb, level of evidence B): The use of B-type natriuretic peptide and/or troponin measurements in the evaluation of hemodynamics and postoperative outcome in pediatric cardiac patients may be beneficial.

New features of troponin testing in different clinical settings

Cardiac troponin levels are routinely measured for diagnosing acute myocardial infarction. Cardiac troponin measurements also provide information concerning prognosis and the effect of early intervention in patients with acute coronary syndromes. The recent development of highly sensitive cardiac troponin assays permits detection of very low circulating levels. Use of sensitive troponin assays improves overall diagnostic accuracy in patients with suspected acute coronary syndromes, and these assays provide strong prognostic information in stable coronary artery disease and chronic heart failure. However, increased sensitivity comes with a cost of decreased specificity, and serial testing, as well as clinical context and judgment, is likely to become increasingly important in the interpretation of troponin assay results.

Clinical applications of highly sensitive troponin assays

Cardiac troponin is the biomarker of choice for the diagnosis of acute myocardial infarction. Recent consensus recommendations have adopted a concentration of troponin above the 99th percentile of a healthy population to diagnose myocardial infarction. Until recently, there was no assay capable of achieving recommended precision; however, with the development of "highly sensitive" troponin assays, it is now possible to accurately measure troponin concentrations at and below the current 99th percentile of a healthy population. These assays have enormous potential in not only identifying more patients with acute myocardial infarction, and providing superior risk prediction in those so afflicted, in addition highly sensitive troponins assays may be useful for long-term risk assessment of the patient with coronary disease. In this article, we will review the clinical applications, novel concepts, challenges, and limitations of using highly sensitive troponins assays.

Effect of hemodialysis, coronary artery disease and diabetes on cardiac troponin T: a prospective survey over one year

Background:

Limited data is available about the effects of hemodialysis sessions, coronary artery disease (CAD), and diabetes on serum cardiac troponin T (cTnT) levels in patients with end-stage renal disease (ESRD).

Objectives:

To test whether hemodialysis could be associated with an increase in cTnT concentration. To evaluate if coronary artery disease (CAD) or diabetes are associated with higher cTnT levels in ESRD.

Methods:

Serum cTnT levels were measured immediately before and after dialysis 3 times over 1 year (0, 6, and 12 months).

Results:

A total of 100 ESRD patients without acute coronary syndrome (mean age of 58.5 years, 34% with diabetes, and 37% with CAD) gave 267 pre-dialysis and 260 post-dialysis blood samples. The mean (standard deviation) pre-dialysis cTnT levels were 0.06 (0.12), 0.05 (0.06), and 0.07 (0.07) mcg/L at 0, 6, and 12 months, respectively. The post-dialysis cTnT levels were similar on average. Among 259 samples with cTnT measured both before and after dialysis, 79 (30.5%) showed a decrease in serum cTnT, 97 (37.5%) showed an increase and 83 (32%) showed no change following dialysis. Mean cTnT was higher in CAD than in non-CAD patients. We observed no significant difference in mean cTnT levels between diabetic and non-diabetic patients.

Conclusions:

cTnT levels were not affected by individual hemodialysis sessions, and remained stable around 0.06 mcg/L over a 1-year period in ESRD patients. Random cTnT levels were higher in stable CAD patients undergoing hemodialysis.

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.

Cardiac Troponin T Circulates in the Free, Intact Form in Patients with Kidney Failure

Background: The clinical significance of the increased concentrations of cardiac troponins observed in patients with end stage renal disease (ESRD) in the absence of an acute coronary syndrome (ACS) is controversial. One proposed explanation is that immunoreactive fragments of cardiac troponin T (cTnT) accumulate in ESRD. We used gel-filtration chromatography (GFC) to ascertain whether fragments of cTnT, which could cross-react in the commercial diagnostic immunoassay (Roche Diagnostics), were the cause of the increased cTnT in the serum of patients with ESRD.

Methods: We subjected sera from ESRD patients (n = 21) receiving dialysis and having increased cTnT concentrations to size-separation GFC. We detected cTnT in the chromatography fractions by use of the same antibodies used in the commercial assay for serum cTnT.

Results: In all patients, cTnT immunoreactivity eluted as a major, homogeneous peak in an identical position between the peaks of serum prolactin [relative molecular mass (Mr) 23 000] and albumin (Mr 67 000): the elution pattern of cTnT in samples obtained from ACS patients was identical to that of the ESRD patients. There was no evidence that low–molecular-mass (Mr &lt;23 000) cTnT fragments were the cause of the increased cTnT in the patients studied.

Conclusions: The form of cTnT observed in the serum of patients with kidney failure and immunoreactive in the diagnostic assay is predominantly the free intact form, as in patients with ACS. Our data are consistent with the view that circulating cTnT in renal failure reflects cardiac pathology.

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.

Treatment of acute coronary syndromes in patients who have chronic kidney disease

Patients with CKD and CAD have traditionally been a difficult population to diagnose and treat in the setting of ACS. In addition to having poorer outcomes post-ACS, data are lacking regarding best treatments available. Aggressive interventional and medical treatments in this group with already poor outcomes are not necessarily contraindicated and should always be considered. The appalling outcome for CKD patients post-ACS is improved by many therapies shown to benefit in the non-CKD patients. Data suggest that troponins are useful markers in CKD patients, that major bleeding is not increased with the use of GP IIb-IIIa antagonists, that thrombolytics have been used successfully in CKD patients, and that PCI electively and as a primary treatment for ACS is successful and probably more beneficial to treatment.

[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.

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.