Diagnostic specificity and prognostic value of cardiac troponins in asymptomatic chronic haemodialysis patients: a three year prospective study

High-Sensitivity Troponin for Suspected Acute Coronary Syndrome in Patients With Chronic Kidney Disease Versus Patients Without Chronic Kidney Disease

BACKGROUND

Heart disease is the leading cause of death in the United States. Patients with acute coronary syndrome (ACS) who have chronic kidney disease (CKD) have a twofold increase in mortality compared to patients with normal kidney function. Patients with CKD tend to have elevated baseline high-sensitivity cardiac troponin-T (hs-cTnT) levels. We studied patients with or without CKD to find out if a higher baseline hs-cTnT influenced the change in hs-cTnT (delta) when ruling in or ruling out ACS.

METHODS

Eighty-nine patients were included in this study (29 with CKD; 60 without CKD). Delta hs-cTnT was dichotomized based on those who had delta of ≥ 5, or < 5. We calculated the positive predictive values, negative predictive values, sensitivities and specificities. Shapiro-Wilk test and independent t-test were used for the continuous variables. Mann-Whitney U test was used to examine the variables between the two groups. Chi-square test was used to compare the categorical variables between the two groups.

RESULTS

The mean ages of patients with CKD and without CKD were 61.2 and 58.9 years, respectively (P = 0.508). We found that although there were differences in the sensitivities, specificities, positive predictive values and negative predictive values of delta hs-cTnT > 5 for ACS between the patients with CKD and without CKD, the differences were not statistically significant. Subgroup analysis showed that in patients with CKD, the positive predictive values and sensitivities of delta hs-cTnT > 5 for CAD requiring percutaneous coronary intervention (PCI) and stent were significantly higher compared to the patients without CKD (82.4% vs. 27.3%, and 82.4% vs. 40.0%, respectively) (P < 0.05).

CONCLUSIONS

In calculating delta hs-cTnT to rule in or rule out ACS, the presence of CKD does not influence the delta. Patients with CKD and a delta hs-cTnT > 5 have significantly higher risk of undergoing PCI.

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.

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.

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.

Increases of cardiac troponin in conditions other than acute coronary syndrome and heart failure

BACKGROUND

Although cardiac troponin (cTn) is a cornerstone marker in the assessment and management of patients with acute coronary syndrome (ACS) and heart failure (HF), cTn is not diagnostically specific for any single myocardial disease process. This narrative review discusses increases in cTn that result from acute and chronic diseases, iatrogenic causes, and myocardial injury other than ACS and HF.

CONTENT

Increased cTn concentrations have been reported in cardiac, vascular, and respiratory disease and in association with infectious processes. In cases involving acute aortic dissection, cerebrovascular accident, treatment in an intensive care unit, and upper gastrointestinal bleeding, increased cTn predicts a longer time to diagnosis and treatment, increased length of hospital stay, and increased mortality. cTn increases are diagnostically and prognostically useful in patients with cardiac inflammatory diseases and in patients with respiratory disease; in respiratory disease cTn can help identify patients who would benefit from aggressive management. In chronic renal failure patients the diagnostic sensitivity of cTn for ACS is decreased, but cTn is prognostic for the development of cardiovascular disease. cTn also provides useful information when increases are attributable to various iatrogenic causes and blunt chest trauma.

SUMMARY

Information on the diagnostic and prognostic uses of cTn in conditions other than ACS and heart failure is accumulating. Although increased cTn in settings other than ACS or heart failure is frequently considered a clinical confounder, the astute physician must be able to interpret cTn as a dynamic marker of myocardial damage, using clinical acumen to determine the source and significance of any reported cTn increase.