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

Sex steroids levels in chronic kidney disease and kidney transplant recipients: associations with disease severity and prediction of mortality

OBJECTIVE

Our objective was to characterize and evaluate prognostic implications of circulating sex steroids in patients at different stages of chronic kidney disease (CKD).

DESIGN

Prospective observational cohort study.

PATIENTS

We prospectively recruited patients with CKD III-IV, undergoing chronic dialysis and kidney transplant recipients (KTR) from a single centre in 2003-2004.

MEASUREMENTS

Two stored samples taken 3 months apart were analysed for sex hormones using liquid chromatography/tandem mass spectrometry, and the mean of the two was used for analysis. We also measured novel biomarkers troponin T and NT-proBNP. Patients were followed until death, transplant or 30 June 2013, and survival analysis performed.

RESULTS

In males, but not in females, both testosterone (P = 0·003) as well as oestradiol (P < 0·02) levels were lowest in dialysis patients and highest in KTR. Over a median follow up of 8·5 years (interquartile range 3·8-9·2), 52 men (36%) died and 24 (17%) received a kidney transplant. In Cox proportional hazards regression up to 9·6 years, an increase in total testosterone of 1 nmol/l was associated with a 9·8% (95% confidence interval 3·1-16·3) decrease in mortality independent of age, body mass index, stage of renal disease and circulating levels of NT-proBNP or troponin T. By contrast, sex steroid levels were not associated with mortality in females.

CONCLUSIONS

Testosterone levels differ across stages of kidney disease and low testosterone levels predict mortality in males, independent of established and novel predictors of mortality.

Kidney Function Alters the Relationship between Postoperative Troponin T Level and Death

Cardiac troponin T (cTnT), even at low concentrations, is a risk factor for 30-day mortality in patients undergoing noncardiac surgery, but it is uncertain whether that risk is generalizable to patients with poor kidney function. We, therefore, evaluated the relationship between cTnT concentration and kidney function on the outcome of 30-day mortality in a post hoc analysis of a prospective cohort study of patients undergoing noncardiac surgery. cTnT was measured for 3 days after surgery and considered abnormal if the peak was ≥0.02 ng/ml. Of the included 14,037 patients, 267 (1.9%) patients died within 30 days of surgery. The adjusted hazard ratios for death with an abnormal cTnT concentration were 4.37 (95% confidence intervals [95% CI], 3.21 to 6.22), 6.15 (95% CI, 2.95 to 140.9), 6.30 (95% CI, 3.12 to 21.23), 1.33 (95% CI, 0.56 to 4.85), and 1.46 (95% CI, 0.46 to 9.21) for eGFR≥60, 45 to <60, 30 to <45, 15 to <30, and <15 ml/min per 1.73 m(2) or on dialysis, respectively. Compared with patients with eGFR≥60 ml/min per 1.73 m(2), the adjusted hazard ratio was significantly lower for patients with eGFR=15 to <30 ml/min per 1.73 m(2) (interaction P value=0.02). Redefining abnormal cTnT concentration as ≥0.03 ng/ml or a change of ≥0.02 ng/ml did not alter results. Because the risk associated with postoperative cTnT levels may be different for patients with eGFR<30 ml/min per 1.73 m(2), additional research is required to determine how to interpret perioperative cTnT values for patients with low kidney function.

High-Sensitivity Troponin as a Predictor of Cardiac Events and Mortality in the Stable Dialysis Population

BACKGROUND

High-sensitivity cardiac troponin T (hs-cTnT) is a biomarker used in diagnosing myocardial injury. The clinical utility and the variation of this biomarker over time remain unclear in hemodialysis (HD) and peritoneal dialysis (PD) patients. We sought to determine whether hs-cTnT concentrations were predictive of myocardial infarction (MI) and death and to examine hs-cTnT variability over a 1-year period.

METHODS

A total of 393 nonacute HD and PD patients (70% HD and 30% PD) were followed in a prospective observational study for new MI and death.

RESULTS

Median hs-cTnT was 57 ng/L (interquartile range, 36–101 ng/L) with no observed difference between HD and PD patients (P = 0.11). Incremental increases in mortality (P = 0.024) and MI (P = 0.001) were observed with increasing hs-cTnT quartiles. MI incidence increased significantly across quartiles in both HD and PD patients (P = 0.012 and P = 0.025, respectively), whereas mortality increased only in HD patients (P = 0.015). For every increase of 25 ng/L in hs-cTnT, the unadjusted hazard ratio (HR) was 1.10 for mortality in the whole group (95% CI, 1.04–1.16, P = 0.001) and 1.16 for MI (95% CI, 1.08–1.23, P &lt; 0.001). Adjusted HR for mortality was 1.07 (95% CI, 1.01–1.15, P = 0.04) and 1.14 for MI (95% CI, 1.06–1.22, P &lt; 0.001). Changes in hs-cTnT from baseline concentrations after 1 year were minimal (55 ng/L vs 53 ng/L, P = 0.22) even in patients who had an MI (P = 0.53).

CONCLUSIONS

hs-cTnT appears to have a useful role in predicting MI and death in the dialysis population. Over a 1-year period concentrations remained stable even in patients who sustained a new cardiac event.

Angiotensin-converting enzyme 2 activity in patients with chronic kidney disease

Background

Angiotensin-converting enzyme 2 (ACE2) is a novel regulator of the renin–angiotensin system that counteracts the adverse effects of angiotensin II. In heart failure patients, elevated plasma ACE2 activity predicted adverse events and greater myocardial dysfunction. We aimed to describe plasma ACE2 activity and its clinical associations in patients with kidney disease.

Methods

Patients recruited from a single centre comprised of chronic kidney disease Stage III/IV (CKD), haemodialysis patients and kidney transplant recipients (KTRs). Plasma ACE2 enzyme activity was measured using a fluorescent substrate assay in plasma, collected at baseline and stored at −80°C. Linear regression was performed in both males and females separately to determine the covariates associated with log-transformed ACE2.

Results

The median (interquartile range) plasma ACE2 activity in pmol/mL/min was 15.9 (8.4–26.1) in CKD (n = 59), 9.2 (3.9–18.2) in haemodialysis (n = 100) and 13.1 (5.7–21.9) in KTR (n = 80; P < 0.01). In male haemodialysis patients, ACE2 activity was 12.1 (6.8–19.6) compared with 4.4 (2.5–10.3) in females (P < 0.01). Log-transformed ACE2 plasma activity was associated with post-haemodialysis systolic blood pressure in females [β-coefficient 0.04, 95% confidence interval (95% CI) 0.01–0.06, P = 0.006]. In males, log-transformed ACE2 plasma activity was associated with B-type natriuretic peptide (β-coefficient 0.39, 95% CI 0.19–0.60, P < 0.001). Plasma ACE2 activity was not associated with mortality.

Conclusions

Plasma ACE2 activity is reduced in haemodialysis patients compared with CKD patients, and in female haemodialysis patients compared with male. The different associations of plasma ACE2 activity between male and female haemodialysis patients indicate that the role of ACE2 in cardiovascular disease may differ by gender.

Is cardiac biomarkers and left ventricular function affected by chronic kidney disease?

BACKGROUND

Cardiovascular disease is the leading cause of death in patients with chronic kidney disease (CKD). These patients may have high level of cardiac troponins in their serum irrelevant to acute coronary syndrome (ACS) that could have profound impact on patient's morbidity and mortality.

OBJECTIVES

The aim of this study was to assess the relation between level of serum creatinine (Cr) and cardiac troponins T and I, and left ventricular (LV) function (as defined by LV ejection fraction) in non-dialysis and non-acute coronary syndrome CKD patients.

MATERIALS AND METHODS

This is a prospective cross sectional study that includes 150 non-dialysis CKD patients without history of ACS in at least 1 month before the beginning of the study. Patients with history of CKD (serum Cr ≥1.5 mg/dl) of more than 6 months were selected. Patients with advanced multi-organ disease (lung disease, liver disease, cerebrovascular disease and peripheral vascular disease) and history of dialysis were excluded from the study. In each patient blood sample was obtained for analyzing serum Cr and cardiac troponin T and I (cTnT and cTnI). Also LV ejection fraction (LVEF) was measured by echocardiography in the same session.

RESULT

There was a positive non-parametric relation between serum Cr and cTnT (p = 0.028). However there were no relation between serum Cr, cTnI (p = 0.57) and LVEF (p = 0.188).

CONCLUSION

In patients with CKD, serum Cr level has an impact on cTnT, but has no impact on cTnI and LVEF.

Troponin I levels and postoperative myocardial infarction following renal transplantation

BACKGROUND

The relationship of routine postoperative troponin I (TnI) monitoring in kidney transplant recipients and in-hospital myocardial infarction (MI) is not known.

METHODS

This observational study evaluated the prevalence of abnormal postoperative TnI (Ortho Clinical Diagnostics assay) in 376 consecutive kidney or kidney/pancreas transplant recipients. In-hospital MI was adjudicated using the universal definition. Rates of death and coronary revascularizations at 1 year were studied. Logistic regression analysis was performed to identify independent predictors of abnormal TnI.

RESULTS

Ninety-five (25%) recipients had abnormal TnI (>0.04 ng/ml) following transplantation. Abnormal TnI levels were more common in older (mean age: 52.2 ± 13.4 vs. 48.3 ± 13.2 years, p = 0.01), diabetic (57.9 vs. 45.6%, p = 0.04), and prior coronary artery disease (31.6 vs. 20.3%, p = 0.02) patients. In-hospital MI occurred in 6 patients (1.6%). All subsequent in-hospital cardiovascular events occurred in the abnormal postoperative TnI group; most in those with TnI levels >1 ng/ml. Previous coronary artery disease was the only independent predictor of a postoperative TnI level >1 ng/ml in multivariate analysis (odds ratio 4.61, 95% confidence interval 1.49-14.32). At 1 year there was no significant difference in death (3.2 vs. 1.8%, p = 0.42) and borderline significant difference in coronary revascularization (5.3 vs. 1.4%, p = 0.049) in abnormal versus normal TnI groups.

CONCLUSIONS

In-hospital MI was infrequent, but abnormal TnI highly prevalent following renal transplantation. Normal TnI levels following renal transplantation had a high negative predictive value in excluding patients likely to develop subsequent postoperative MI. The role of a higher TnI cut-off for screening for postoperative MI in high-risk subgroups deserves future prospective evaluation.

Cardiorenal syndrome: biomarkers linking kidney damage with heart failure

All the vital organs of the body share information by virtue of various biological mediators. Primary pathology of a major organ can lead to dysfunction of the other. Cardiorenal syndrome is an important example of such organ crosstalk. Primary dysfunction of the heart or kidney can lead to injury of the other organ. As molecular injury occurs prior to clinical dysfunction, effective interventions can be planned if one can detect this organ dysfunction at an earlier stage by virtue of some biological markers. Such biomarkers can be substances in urine, serum, imaging maneuvers or any other quantifiable parameters. Some currently available biomarkers are not sensitive enough to provide timely diagnosis of the disorder. An important research priority is the development of newer biomarkers or a panel of biomarkers for the early diagnosis of organ dysfunction, as well as nature of injury, guidance for therapeutic interventions and prognosis. Many newer biomarkers have been studied for both heart and kidney dysfunction. This article focuses on newer biomarkers for the cardiorenal syndrome.

Serial increased cardiac troponin T predicts mortality in asymptomatic patients treated with chronic haemodialysis

Background

A single detectable cardiac troponin predicts mortality in patients treated with dialysis. There are limited data on changes in troponin concentration over time and the clinical implications of serial troponin measurement.

Methods

Serial cardiac troponin T (cTnT) was assayed five times over 12 months in a prospective cohort study of patients with end-stage kidney disease treated with haemodialysis. A concentration of cTnT ≥0.04 μg/L was considered increased. Mortality and cardiovascular events were analysed by survival analysis, according to the serial troponin results.

Results

From 100 patients who provided a baseline sample for cTnT, 81 completed five serial measurements. The analysis of patients who completed serial cTnT measurements demonstrated that 28 patients (35%) had normal cTnT concentrations in all five samples, 20 patients (24%) had between one and four increased cTnT measurements and 33 patients (41%) had increased concentrations of cTnT in all five samples. The 1.7-y patient survival was 100%, 90% and 78% for patients with zero, one to four, or five out of five concentrations of cTnT increased, respectively ( P = 0.037), and the corresponding cardiovascular event-free survival was 100%, 91% and 78%, respectively ( P = 0.027).

Conclusions

Serial measurements of cTnT concentration were frequently increased in patients receiving haemodialysis. The number of abnormal measurements over time predicted mortality and cardiovascular adverse events.

Survival of patients on the kidney transplant wait list: relationship to cardiac troponin T

Patients waiting for a kidney transplant have high mortality despite careful preselection. Herein, we assessed whether cardiac troponin T (cTnT) can help stratify risk in patients selected for kidney transplantation. cTnT levels were measured in all kidney transplant candidates but the results were not used for patient selection. Among 644 patients placed on the kidney waiting list from 9/2004 to 12/2006, 61% had elevated cTnT levels (>0.01 ng/mL). Higher levels related to diabetes, longer time on dialysis, history of cardiovascular disease and low serum albumin. High cTnT also related to cardiac anomalies, including left ventricular hypertrophy (LVH), wall motion abnormalities and stress-inducible ischemia by dobutamine echo (DSE). However, 54% of patients without these cardiac findings had elevated cTnT. Increasing cTnT levels were associated with reduced survival (HR = 1.729, CI (1.25-2.39), p = 0.01) independently of low serum albumin (0.449 (0.24-0.83), p = 0.011) and history of stroke (3.368 (1.47-7.73), p = 0.0004). The results of the DSE and/or coronary angiography did not relate significantly to survival. However, high cTnT identified patients with abnormal echo findings and poor survival. Wait listed patients with normal cTnT have excellent survival irrespective of other factors. In contrast, high cTnT levels are strongly predictive of poor survival in the kidney transplant waiting list.

Effect of hemodialysis on traditional and innovative cardiac markers

The diagnostic approach to acute coronary syndrome (ACS) is challenging in patients with impaired renal function since most serum biomarkers are commonly increased in this clinical setting. Cardiac troponin T (cTnT), creatine kinase isoenzyme MB (CK MB), myoglobin, and ischemia modified albumin (IMA), were assayed in 45 patients prehemodialysis (pre-HD) and posthemodialysis (post-HD), and results were adjusted for hemoconcentration. The pre-HD values of serum IMA and cTnT were above the respective diagnostic thresholds (IMA<85 K units/L; cTnT <0.03 ng/mL) in six (13%) and 27 (60%) patients undergoing chronic HD, respectively. A significant (105.0 vs. 79.0 K units/L, P<0.0001) and variable (+38%; 95% confidence interval [CI], 12-65%) increase of serum IMA was observed post-HD, whereas the other biomarkers significantly decreased (cTnT: 0.029 vs. 0.044 ng/mL, P=0.016; CK-MB: 2.33 vs. 2.50 microg/L, P<0.0001; myoglobin: 128.1 vs. 148.7 microg/L, P<0.0001). Biomarkers of myocardial injury, especially cTnT and IMA, might be used in HD patients, provided that an appropriate diagnostic interpretation is guarantee, according to individual baseine value, metabolism, and time of sampling. Moreover, IMA might be reliably applied to stratify the long-term risk of these patients, but not for diagnosing an ACS during or immediately post-HD.

Cardiac biomarkers in haemodialysis patients: the prognostic value of amino-terminal pro-B-type natriuretic peptide and cardiac troponin T

Cardiac biomarkers such as amino-terminal pro-B-type natriuretic peptide (NT-proBNP) and cardiac troponin T (cTNT) provide information on cardiovascular morbidity and mortality in patients with normal renal function. In a considerable number of chronic haemodialysis patients, both biomarkers - NT-proBNP and cTNT - are elevated despite the absence of cardiac ischaemia. The elevation of cardiac biomarkers in chronic haemodialysis patients is of prognostic value with respect to cardiovascular morbidity and mortality. They provide a useful rationale for the screening of occult cardiac disease and optimization of the dialysis procedure with respect to volume control.