Cardiac findings in asymptomatic chronic hemodialysis patients with persistently elevated cardiac troponin I levels

Monthly measurement of high-sensitivity cardiac troponins T and creatine kinase in asymptomatic chronic hemodialysis patients: A one-year prospective study

BACKGROUND

Cardiology guidelines recommend measuring high-sensitivity cardiac troponin (hs-cTn) for the diagnostic work-up of acute coronary syndromes (ACS). Many hospitals measure hs-cTnT, but preliminary data have shown that hs-cTnT is higher than normal in many hemodialysis patients without evidence of ACS. The purpose of this study was therefore to determine the hs-cTnT levels every month for 1 year in asymptomatic hemodialysis patients, in order to assess their changes over time relative to creatine kinase.

METHODS

Fourty-four hemodialysis patients (mean age 67 ± 14 years) were included. The predialysis levels of fifth-generation hs-cTnT, CK, and CK-MB were measured every month for 1 year using a Cobas® 6000 analyzer (Roche Diagnostics, Switzerland).

RESULTS

Almost 100% of hs-cTnT measurements were higher than normal (N < 14 ng/L); the mean ± SD annual level was 84 ± 59 ng/L, ranging from a minimum of 24 ± 2 to 241 ± 28 ng/L in individual patients. The mean levels of CK and CK-MB were normal. Thirteen myocardial infarctions were analyzed, which were all associated with an initial elevation in hs-cTnT >45% from the individual baseline value. By comparison, CK and CK-MB only increased in 38% and 31% of these myocardial infarctions, respectively.

DISCUSSION

hs-cTnT is persistently higher than normal in chronic hemodialysis patients. Standard algorithms for diagnosing ACS can obviously not be used and alternative diagnostic strategies need to be developed. According to our data, and given the huge variation in baseline hs-cTnT levels among patients, the use of higher cut-offs as proposed in the literature cannot be recommended. Instead, we consider that hs-cTnT should be checked at regular intervals (e.g., every 3-6 months) in order to establish individual baseline levels for hs-cTnT. This approach, in most instances, not only makes it possible to more rapidly rule-in but also to rapidly rule-out, cases of ACS in hemodialysis patients who develop cardiac symptoms.

Serial versus single troponin measurements for the prediction of cardiovascular events and mortality in stable chronic haemodialysis patients

AIM

This study aims to describe the variability of pre-dialysis troponin values in stable haemodialysis patients and compare the performance of single versus fluctuating or persistently elevated troponins in predicting a composite of mortality and cardiac arrest, myocardial infarction or stroke.

METHODS

A total of 128 stable ambulatory chronic haemodialysis patients were enrolled. Pre-dialysis troponin I was measured for three consecutive months. The patients were followed for 1 year. A troponin elevation (>0.06 μg/L) was considered high risk, and patients were classified into three risk groups: (i) patients who had normal troponin levels on all three measurements; (ii) patients with at least one elevated and one normal troponin value; and (iii) patients with elevated troponin values on all measurements.

RESULTS

A total of 81 patients had all three troponin values in the normal range; 29 had fluctuating values; 18 had all three values elevated. Twenty-seven deaths or composite events were observed: eight in the first risk group, 10 in the second and nine in the third. Persistently elevated and fluctuating troponin values were associated with higher mortality and cardiovascular event rate. Serial troponin measurement had a higher sensitivity for the composite outcome than single troponin measurement when either fluctuating or persistently elevated values were considered to confer high risk.

CONCLUSION

Most haemodialysis patients do not have elevated troponin levels at baseline. Troponin levels that remain elevated or fluctuate are associated with worse outcomes. A serial troponin measurement strategy is associated with better sensitivity and higher negative predictive value compared with single troponin measurement.

Association between Intraoperative Hypotension and Myocardial Injury after Vascular Surgery

BACKGROUND

Postoperative myocardial injury occurs frequently after noncardiac surgery and is strongly associated with mortality. Intraoperative hypotension (IOH) is hypothesized to be a possible cause. The aim of this study was to determine the association between IOH and postoperative myocardial injury.

METHODS

This cohort study included 890 consecutive patients aged 60 yr or older undergoing vascular surgery from two university centers. The occurrence of myocardial injury was assessed by troponin measurements as part of a postoperative care protocol. IOH was defined by four different thresholds using either relative or absolute values of the mean arterial blood pressure based on previous studies. Either invasive or noninvasive blood pressure measurements were used. Poisson regression analysis was used to determine the association between IOH and postoperative myocardial injury, adjusted for potential clinical confounders and multiple comparisons.

RESULTS

Depending on the definition used, IOH occurred in 12 to 81% of the patients. Postoperative myocardial injury occurred in 131 (29%) patients with IOH as defined by a mean arterial pressure less than 60 mmHg, compared with 87 (20%) patients without IOH (P = 0.001). After adjustment for potential confounding factors including mean heart rates, a 40% decrease from the preinduction mean arterial blood pressure with a cumulative duration of more than 30 min was associated with postoperative myocardial injury (relative risk, 1.8; 99% CI, 1.2 to 2.6, P < 0.001). Shorter cumulative durations (less than 30 min) were not associated with myocardial injury. Postoperative myocardial infarction and death within 30 days occurred in 26 (6%) and 17 (4%) patients with IOH as defined by a mean arterial pressure less than 60 mmHg, compared with 12 (3%; P = 0.08) and 15 (3%; P = 0.77) patients without IOH, respectively.

CONCLUSIONS

In elderly vascular surgery patients, IOH defined as a 40% decrease from the preinduction mean arterial blood pressure with a cumulative duration of more than 30 min was associated with postoperative myocardial injury.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Factors related to silent myocardial damage in hemodialysis patients

BACKGROUND

Both traditional and non-traditional risk factors play a role for the development of cardiovascular disease in hemodialysis patients. However, a specific relationship between these risk factors and silent myocardial damage is unknown.

METHODS

Demographic, anthropometric, clinical, and laboratory data were collected. Silent myocardial damage was defined by elevated cardiac troponin I values above cutoff values.

RESULTS

In total, 113 hemodialysis patients were included. Cardiac troponin I concentrations were below cutoff value (<2.3 ng/mL) in 103 (91.2%) patients (Group 1), whereas 10 (8.8%) patients had elevated concentrations (Group 2). Group 1 patients had higher levels of hemoglobin (p = 0.002) and high-density lipoprotein cholesterol (p = 0.002) and lower C-reactive protein (p = 0.003) and tumor necrosis factor-alpha (p = 0.005) levels, as well as less incidence of left ventricular hypertrophy (p = 0.045), when compared to Group 2 patients. Diabetes mellitus (Beta = +0.160, p = 0.021), left ventricular hypertrophy (Beta = +0.247, p < 0.0001), uncontrolled blood pressure (Beta = +0.170, p = 0.016), normalized protein equivalent of total nitrogen appearance (Beta = -0.230, p = 0.001), hemoglobin (Beta = -0.302, p < 0.0001), and tumor necrosis factor-alpha (Beta = +0.506, p < 0.0001) were found to be independently associated with cardiac troponin I levels in multiple linear regression analysis.

CONCLUSIONS

Both traditional and non-traditional risk factors are related with silent myocardial damage, which is considered to an antecedent of major cardiovascular events. Hemodialysis patients, even when asymptomatic, must be closely followed up for the presence of these risk factors.

Troponin I is a predictor of acute cardiac events in the immediate postoperative renal transplant period

BACKGROUND

Patients on the renal transplant waiting list and renal transplant recipients have an increased risk of premature cardiovascular (CV) disease and death.

METHODS

We performed a prospective observational study in 331 kidney or kidney-pancreas transplant recipients to test whether Troponin I (TnI), determined at time of engraftment, can help to identify patients at risk for a major adverse cardiac event (MACE) in the immediate postoperative period. Logistic regression analysis was used to test if pretransplant TnI is a predictor of MACE within 3 months after transplantation.

RESULTS

Eleven patients (3.3%) developed a MACE during the first 2 weeks after transplantation. In patients with a CV history (23.6%), the incidence of MACE increased to 13.4%. In univariate analysis, age (odds ratio [OR] 1.062, P=0.04), TnI (OR 1.12, P=0.0042), HbA1c (OR 1.879, P=0.0076), and CV history (absent vs. present OR 0.027, P=0.0006) were associated with MACE. TnI remained an independent predictor after adjusting for every other significant variable. When we restricted the analysis to patients with a CV history, TnI was the only statistically significant variable associated with MACE.

CONCLUSION

Elevated TnI, immediately pretransplant, is an independent predictor of MACE in the immediate posttransplant period, particularly in patients with CV history.