Diagnostic performance of high-sensitive troponin T in patients with renal insufficiency

NT-proBNP and Cardiac Troponin I, but Not Cardiac Troponin T, Are Associated With 7-Year Changes in Cardiac Structure and Function in Older Adults: The ARIC Study

BACKGROUND

Higher circulating concentrations of NT-proBNP (N-terminal pro-B-type natriuretic peptide) and high-sensitivity cardiac troponin T (hs-cTnT) and I (hs-cTnI) are associated with left ventricular remodeling and with incident heart failure. The associations of these cardiac biomarkers with changes in cardiac structure and function over time are uncharacterized.

METHODS

Among 2006 participants in the ARIC prospective cohort study (Atherosclerosis Risk in Communities) who were free of overt cardiovascular disease and underwent echocardiography at study visits 5 (2011- 2013) and 7 (2018-2019), we assessed the associations of NT-proBNP, hs-cTnT, and hs-cTnI concentrations at visit 5 with changes in left ventricular structure and function between visits 5 and 7 (≈7-year change) using multivariable linear regression with the biomarkers modeled as restricted cubic splines. Models were adjusted for age, sex, race, body mass index, smoking, diabetes, hypertension, and renal function at visit 5; blood pressure and heart rate at both visits; and the baseline value of the echocardiographic parameter of interest.

RESULTS

Mean±SD age was 74±4 years at visit 5; 61% were women; and 23% were Black adults. Median (25th-75th percentile) concentrations at visit 5 of NT-proBNP, hs-cTnT, and hs-cTnI were 87 ng/L (50-157 ng/L), 9 ng/L (6-12 ng/L), and 2.6 ng/L (1.9-3.9 ng/L). In adjusted models, elevated baseline concentrations of NT-proBNP and hs-cTnI were significantly associated with 7-year decline in left ventricular systolic function (ejection fraction, longitudinal and circumferential strain) and worsening diastolic indices. In contrast, elevated baseline concentrations of hs-cTnT were not significantly associated with 7-year changes in cardiac structure, systolic function, or diastolic function (all P>0.05).

CONCLUSIONS

Higher concentrations of NT-proBNP and hs-cTnI, but not hs-cTnT, were associated with greater declines in left ventricular function over ≈7 years in late life independently of traditional cardiovascular risk factors.

Delta troponin does not distinguish acute coronary syndrome in emergency department patients with renal impairment and an initial positive troponin

Background

In emergency department (ED) patients with renal impairment, troponin concentrations can be positive without myocardial ischemia. When there is clinical concern for acute coronary syndrome (ACS), guidelines recommend obtaining a delta troponin measurement to identify acute myocardial injury. However, evidence supporting the use of delta troponin to rule in or out ACS in patients with renal impairment and initial elevated troponin levels is limited.

Methods

This retrospective, observational study assessed the diagnostic value of a 20% delta troponin cutoff in the prediction of ACS events in ED patients (estimated glomerular filtration rate [eGFR] <60 mL/min/1.72 m2) with renal impairment, clinical concern for ACS, and an initial positive troponin concentration using either conventional troponin (cTnT) or high-sensitivity troponin (hsTnT). Clinical concern for ACS was based on initial ED physician-reported diagnoses. Patients with an initial diagnosis of ST-elevation myocardial infarction were not included. A positive initial troponin was identified at a threshold of ≥0.06 ng/mL for cTnT and ≥52 ng/L for hsTnT, and delta troponin measurements were obtained within 24 h of the initial troponin. The primary composite outcome, termed ACS event, included (1) cardiac-related mortality, (2) coronary revascularization (or its recommendation), or a (3) clinically diagnosed type-1 myocardial infarction within 6 weeks of the ED presentation. Sensitivities, specificities, negative predictive values, positive predictive values, and negative and positive likelihood ratios were calculated for these 6-week ACS events.

Results

A total of 608 ED patients with renal impairment, an initial positive troponin, and clinical concern for ACS were included in the study. Of these patients, 234 had an initial positive cTnT (median eGFR 18 mL/min/1.72 m2) and 374 had an initial positive hsTnT (median eGFR 25 mL/min/1.72 m2). The overall ACS event rate was 38% in the cTnT group and 33% in the hsTnT group. In those with a negative delta, the 6-week ACS event rate was 32% when using cTnT, compared to 24% using hsTnT. Conversely, a positive delta was associated with an ACS event rate of 47% when cTnT was utilized versus 61% when hsTnT was utilized.

Conclusion

In this study, approximately one-third of ED patients with renal impairment who had an initial positive troponin and clinical concern for ACS developed ACS events at 6 weeks. A delta troponin did not appear to provide clinically meaningful assistance in the prediction or exclusion of 6-week ACS events in this cohort.

Utility of Cardiac Troponins in Patients With Chronic Kidney Disease

Cardiovascular disease is a major cause of death worldwide especially in patients with chronic kidney disease (CKD). Troponin T and troponin I are cardiac biomarkers used not only to diagnose acute myocardial infarction (AMI) but also to prognosticate cardiovascular and all-cause mortality. The diagnosis of AMI in the CKD population is challenging because of their elevated troponins at baseline. The development of high-sensitivity cardiac troponins shortens the time needed to rule in and rule out AMI in patients with normal renal function. While the sensitivity of high-sensitivity cardiac troponins is preserved in the CKD population, the specificity of these tests is compromised. Hence, diagnosing AMI in CKD remains problematic even with the introduction of high-sensitivity assays. The prognostic significance of troponins did not differ whether it is detected with standard or high-sensitivity assays. The elevation of both troponin T and troponin I in CKD patients remains strongly correlated with adverse cardiovascular and all-cause mortality, and the prognosis becomes poorer with advanced CKD stages. Interestingly, the degree of troponin elevation appears to be predictive of the rate of renal decline via unclear mechanisms though activation of the renin-angiotensin and other hormonal/oxidative stress systems remain suspect. In this review, we present the latest evidence of the use of cardiac troponins in both the diagnosis of AMI and the prognosis of cardiovascular and all-cause mortality. We also suggest strategies to improve on the diagnostic capability of these troponins in the CKD/end-stage kidney disease population.

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.

Higher troponin T serum concentrations in hospital patients without diagnosed cardiac diseases compared to a population-based cohort

OBJECTIVES

Upper reference limits of high-sensitivity cardiac troponin T (hs-cTnT) are derived from healthy, population-based cohorts, and are frequently exceeded in hospitalized patients. In this study we aim to systematically examine the differences between in-hospital patients with no diagnosed cardiac diseases and a population-based cohort.

METHODS

Retrospective analyses were performed in two independent cohorts. We included 5,652 participants of the prospective population-based LIFE cohort as well as 9,300 patients having been treated at our hospital between 2014 and 2021. In both cohorts, subjects with diagnosed or suspected cardiac diseases were excluded. We used Spearman's rank correlation for correlation analyses of hs-cTnT serum concentrations and age. Sex- and age-adjusted 99th percentiles for hs-cTnT in subjects with preserved renal function were obtained in both cohorts.

RESULTS

In both cohorts, hs-cTnT serum concentrations positively correlated with age. Male sex was associated with higher hs-cTnT serum concentrations. Persons treated in hospital showed significantly higher hs-cTnT concentrations in females and males aged above 50. While in the population-based cohort only 99th percentile hs-cTnT results of females aged above 70 and males aged above 60 years exceeded the assay's upper reference limit, the 99th percentiles of in-hospital females over 40 years and males of all age groups exceeded this threshold.

CONCLUSIONS

Besides age and sex, hospitalization per se is correlated with higher serum concentrations of hs-cTnT in most age groups. Our results indicate, that unconditionally applying current hs-cTnT cut-offs to inpatients might overestimate myocardial infarction and potentially lead to overdiagnosis.

A risk model for the early diagnosis of acute myocardial infarction in patients with chronic kidney disease

Introduction

Acute myocardial infarction (AMI) remains a critical disease, characterized by a high fatality rate in several countries. In clinical practice, the incidence of AMI is increased in patients with chronic kidney disease (CKD). However, the early diagnosis of AMI in the above group of patients is still poor.

Methods

In the present study, a total of 829 patients with CKD, defined by an estimated glomerular filtration rate (eGFR) of <60 ml/min/1.73 m2 or 60-90 ml/min/1.73 m2 for patients with mildly reduced kidney function, who attended the Sichuan Provincial People's Hospital (SPPH) between January 2018 and November 2022 were enrolled. All patients underwent coronary angiography due to the presence of typical or atypical symptoms of AMI. Patients were divided into the following two groups: The training cohort, including 255 participants with AMI and 242 without AMI; and the testing cohort, including 165 and 167 subjects with and without AMI, respectively. Furthermore, a forward stepwise regression model and a multivariable logistic regression model, named SPPH-AMI-model, were constructed to select significant predictors and assist the diagnosis of AMI in patients with CKD, respectively.

Results

The following factors were evaluated in the model: Smoking status, high sensitivity cardiac troponin I, serum creatinine and uric acid levels, history of percutaneous coronary intervention and electrocardiogram. Additionally, the area under the curve (AUC) of the receiver operating characteristic curve were determined in the risk model in the training set [AUC, 0.78; 95% confidence interval (CI), 0.74-0.82] vs. the testing set (AUC, 0.74; 95% CI, 0.69-0.79) vs. the combined set (AUC, 0.76; 95% CI, 0.73-0.80). Finally, the sensitivity and specificity rates were 71.12 and 71.21%, respectively, the percentage of cases correctly classified was 71.14%, while positive and negative predictive values of 71.63 and 70.70%, respectively, were also recorded.

Discussion

The results of the current study suggested that the SPPH-AMI-model could be currently considered as the only risk scoring system for the early diagnosis of AMI in patients with CKD. This method could help clinicians and emergency physicians to quickly and accurately diagnose AMI in patients with CKD to promote the immediate and effective treatment of these patients.

Troponin Cut-Offs for Acute Myocardial Infarction in Patients with Impaired Renal Function—A Systematic Review and Meta-Analysis

Identifying acute myocardial infarction in patients with renal disease is notoriously difficult, due to atypical presentation and chronically elevated troponin. The aim of this study was to identify a specific troponin T/troponin I cut-off value for diagnosis of acute myocardial infarction in patients with renal impairment via meta-analysis. Two investigators screened 2590 publications from MEDLINE, Embase, PubMed, Web of Science, and the Cochrane library. Only studies that investigated alternative cut-offs according to renal impairment were included. Fifteen articles fulfilled the inclusion criteria. Six studies were combined for meta-analysis. The manufacturer’s upper reference level for troponin T is 14 ng/L. Based on the meta-analyses, cut-off values for troponin in patients with renal impairment with myocardial infarction was 42 ng/L for troponin I and 48 ng/L for troponin T. For patients on dialysis the troponin T cut-off is even higher at 239 ng/L. A troponin I cut-off value for dialysis patients could not be established due to lack of data. The 15 studies analyzed showed considerable diversity in study design, study population, and the definition of myocardial infarction. Further studies are needed to define a reliable troponin cut-off value for patients with kidney disease, especially in dialysis patients, and to allow necessary subanalysis.

Revisited Upper Reference Limits for Highly Sensitive Cardiac Troponin T in Relation to Age, Sex, and Renal Function

(1) Background: Highly sensitive cardiac troponin T (hs-cTnT) plays an essential role in the diagnosis of myocardial injury. The upper reference limit of the respective assay is generally applied, irrespective of age, renal function, or sex. We aimed to identify age-adjusted and sex-adjusted upper reference limits in relation to renal function in a large population-based cohort without cardiac diseases. (2) Methods: We included 5428 subjects of the population-based LIFE-Adult cohort, free of diagnosed cardiac diseases. Sex-adjusted and age-adjusted 99th percentiles for hs-cTnT in subjects with preserved renal function were obtained. (3) Results: The hs-cTnT values were higher in men of all age groups. In both sexes, an increasing age positively correlated with higher hs-cTnT values. Hs-cTnT weakly correlated with serum creatinine. The three-dimensional analysis of age, creatinine, and hs-cTnT showed no relevant additional effect of creatinine on hs-cTnT. In men aged above 60 and women above 70, the calculated 99th percentiles clearly exceeded the commonly applied thresholds. (4) Conclusion: Age and sex have a major impact on the serum concentration of hs-cTnT, while renal function does not. We propose to consider age-adjusted and sex-adjusted reference values.

High-Sensitivity Cardiac Troponin T in Patients with Severe Chronic Kidney Disease and Suspected Acute Coronary Syndrome

(1) Background: Patients with severe chronic kidney disease (CKD G4-G5) often have chronically elevated high-sensitivity cardiac troponin T (hs-cTnT) values above the 99th percentile of the upper reference limit. In these patients, optimal cutoff levels for diagnosing non-ST-elevation acute coronary syndrome (NSTE-ACS) requiring revascularization remain undefined. (2) Methods: Of 11,912 patients undergoing coronary angiography from 2012 to 2017 for suspected NSTE-ACS, 325 (3%) had severe CKD. Of these, 290 with available serial hs-cTnT measurements were included, and 300 matched patients with normal renal function were selected as a control cohort. (3) Results: In the CKD cohort, 222 patients (76%) had NSTE-ACS with indication for coronary revascularization. Diagnostic performance was high at presentation and similar to that of the control population (AUC, 95% CI: 0.81, 0.75-0.87 versus 0.85, 0.80-0.89, p = 0.68), and the ROC-derived cutoff value was 4 times higher compared to the conventional 99th percentile. Combining the ROC-derived cutoff levels for hs-cTnT at presentation and absolute 3 h changes, sensitivity increased to 98%, and PPV and NPV improved up to 93% and 86%, respectively. (4) Conclusions: In patients with severe CKD and suspected ACS, the diagnostic accuracy of hs-cTnT for the diagnosis of NSTE-ACS requiring revascularization is improved by using higher assay-specific cutoff levels combined with early absolute changes.

High-sensitivity troponins in dialysis patients: variation and prognostic value

Background

Dialysis patients have a high prevalence of cardiovascular mortality but also elevated cardiac troponins (cTns) even without signs of cardiac ischaemia. The study aims to assess variation and prognostic value of high-sensitivity cTnI and cTnT in prevalent dialysis patients.

Methods

In 198 prevalent haemodialysis (HD) and 78 peritoneal dialysis (PD) patients, 4-monthly serum troponin I and T measurements were obtained. Reference change values (RCVs) were used for variability assessment and competing-risk regression models for survival analyses; maximal follow-up was 50 months.

Results

HD and PD patients had similar troponin levels [median (interquartile range) troponin I: 25 ng/L (14–43) versus 21 ng/L (11–37), troponin T: 70 ng/L (44–129) versus 67 ng/L (43–123)]. Of troponin I and T levels, 42% versus 98% were above the decision level of myocardial infarction. RCVs were +68/−41% (troponin I) and +29/−23% (troponin T). Increased variability of troponins related to higher age, male sex, protein-energy wasting and congestive heart failure, but not ischaemic heart disease or dialysis form. Elevated troponin T, but not troponin I, predicted death after adjusting for confounders.

Conclusions

A large proportion of prevalent dialysis patients without current established or ongoing cardiac events have elevated levels of high-sensitivity cTns. Mortality risk was doubled in patients with persistently high troponin T levels. The large intraindividual variation of cTns suggests that serial measurements and reference change levels may be used to improve diagnostic utility. However, evidence-based recommendations require more data from large studies of dialysis patients with cardiac events.

Value of the high-sensitivity troponin T assay for diagnosis of acute myocardial infarction in patients with and without renal insufficiency

BACKGROUND

Cardiac troponins are important markers for diagnosis of acute myocardial infarction (AMI) in general population; however, chronically-elevated troponins levels are often seen in patients with renal insufficiency, which reduce their diagnostic accuracy. The aim of our study was to access the diagnostic values of initial high-sensitive cardiac troponin T (hs-cTnT) and relative change of hs-cTnT for AMI in patients with and without renal insufficiency.

METHODS

Cardiac care unit patients with elevated hs-cTnT levels in 2017-2018 were enrolled. Receiver operating characteristic (ROC) curves were used to evaluate initial hs-cTnT levels and relative changes after 3 h of enrollment for diagnosis of AMI in patients with estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² (low), and eGFR ≥ 60 mL/min/1.73 m² (normal).

RESULTS

Of 359 patients, 240 patients had low eGFR, and 119 patients had normal eGFR. The area under the ROC curve (AUC) for the initial hs-cTnT levels was 0.58 (95% CI, 0.5-0.65, p = 0.053) among patients with low eGFR and 0.54 (95% CI, 0.4-0.67, p = 0.612) among patients with normal eGFR. AUCs for relative changes of hs-cTnT were 0.82 (95% CI, 0.76-0.88, p < 0.001) in patients with low eGFR and 0.82 (95% CI, 0.71-0.91, p < 0.001) in patients with normal eGFR. Optimal cutoff values for the relative changes in hs-cTnT were 16% and 12% in patients with low eGFR and normal eGFR, respectively.

CONCLUSIONS

Relative changes in hs-cTnT levels had better diagnostic accuracy than initial hs-cTnT levels.

Ideal high sensitivity troponin baseline cutoff for patients with renal dysfunction

OBJECTIVE

High-sensitivity cardiac troponin assays (hs-cTn) aid in diagnosis of myocardial infarction (MI). These assays have lower specificity for non-ST Elevation MI (NSTEMI) in patients with renal disease. Our objective was to determine an optimized cutoff for patients with renal disease.

METHODS

We conducted an a priori secondary analysis of a prospective FDA study in adults with suspected MI presenting to 29 academic urban EDs between 4/2015 and 4/2016. Blood was drawn 0, 1, 2-3, and 6-9 h after ED arrival. We recorded cTn and estimated glomerular filtrate rate (eGFR) by Chronic Kidney Disease Epidemiology Collaboration equation. The primary endpoint was NSTEMI (Third Universal Definition of MI), adjudicated by physicians blinded to hs-cTn results. We generated an adjusted hscTn rule-in cutoff to increase specificity.

RESULTS

2505 subjects were enrolled; 234 were excluded. Patients were mostly male (55.7%) and white (57.2%), median age was 56 years 472 patients [20.8%] had an eGFR <60 mL/min/1.73 m2. In patients with eGFR <15 mL/min/1.73 m2, a baseline rule-in cutoff of 120 ng/L led to a specificity of 85.0% and Positive Predictive Value (PPV) of 62.5% with 774 patients requiring further observation. Increasing the cutoff to 600 ng/L increased specificity and PPV overall and in every eGFR subgroup (specificity and PPV 93.3% and 78.9%, respectively for eGFR <15 mL/min/1.73m²), while increasing the number (79) of patients requiring observation.

CONCLUSIONS

An eGFR-adjusted baseline rule-in threshold for the Siemens Atellica hs-cTnI improves specificity with identical sensitivity. Further study in a prospective cohort with higher rates of renal disease is warranted.

Associations between estimated glomerular filtration rate and cardiac biomarkers

BACKGROUND

Chronic kidney disease (CKD) is associated with an increased cardiovascular disease (CVD) mortality risk. Elevation of cardiac biomarkers in patients with renal dysfunction is ambiguous in the diagnosis of CVD. The purpose of this study was to investigate the associations between estimated glomerular filtration rate (eGFR) and cardiac biomarkers, and the influence of renal dysfunction on the cardiac biomarkers.

METHODS

We examined the cross-sectional associations of eGFR with cardiac troponin I (cTnI), creatine kinase (CK), CK-MB, lactic dehydrogenase (LDH), hydroxybutyrate dehydrogenase (HBDH), and brain natriuretic peptide (BNP) in 812 adults and 215 child. Spearman correlation and logistic regression analysis were performed to evaluate the associations.

RESULTS

For adults, lower eGFR _CKD-EPI had significantly higher cTnI, CK-MB, LDH, HBDH, and BNP. There were negative correlations between eGFR_CKD-EPI and cTnI, CK-MB, LDH, HBDH, and BNP. After adjustment for potential confounders, as compared with eGFR_CKD-EPI  ≥ 90 mL/min/1.73 m² , eGFR_CKD-EPI  < 60 mL/min/1.73 m² remained associated with a 2.83 (1.08-7.41) [ratio (95% CI)] times higher cTnI and a 6.50 (2.32-18.22) [ratio (95% CI)] times higher HBDH. For child, lower eGFR_Schwartz had significant higher CK and CK-MB. There were negative correlations between eGFR_Schwartz and CK, and eGFR_Schwartz and CK-MB. After adjustment for potential confounders, as compared with eGFR_Schwartz  ≥ 90 mL/min/1.73 m² , eGFR_Schwartz  < 90 mL/min/1.73 m² revealed no significant higher CVD biomarkers.

CONCLUSION

Reduced eGFR is associated with elevated cTnI and HBDH among adults without clinically evident CVD, but not child.

Optimal cut-off value of high-sensitivity troponin I in diagnosing myocardial infarction in patients with end-stage renal disease

End-stage renal disease (ESRD) is a major risk factor for cardiovascular disease and the prognosis after myocardial infarction (MI) is dismal. Although cardiac troponin is a key diagnostic test, troponin levels are often elevated in ESRD patients without evidence of MI. Thus, this study attempted to determine the optimal diagnostic value of high-sensitivity troponin I (hsTnI) by dialysis modality in ESRD patients.Medical records of adult dialysis patients who visited tertiary emergency department (ED) were collected retrospectively. Diagnosis of MI was made according to the fourth universal definition of MI. The cut-off values were calculated using a receiver operating characteristic (ROC) curve.Medical records of 1144 patients were analyzed and MI was diagnosed in 82 patients (75 on hemodialysis and 7 on peritoneal dialysis). The optimal cut-off value of hsTnI in hemodialysis patients was 75 ng/L, with 93.33% sensitivity and 60.76% specificity. Area under the curve (AUC) was .870 (95% confidence interval (CI) .833-.906). The optimal cut-off value of hsTnI in peritoneal dialysis patients was 144 ng/L, with 100.00% sensitivity and 83.10% specificity. AUC was .943 (95% CI .893-.992).The dialysis modality should also be considered when diagnosing MI using hsTnI in ESRD patients.

The Asia-Pacific Society of Cardiology (APSC) Expert Committee Consensus Recommendations for Assessment of Suspected Acute Coronary Syndrome Using High-Sensitivity Cardiac Troponin T in the Emergency Department

The Asia-Pacific Society of Cardiology (APSC) high-sensitivity troponin T (hs-TnT) consensus recommendations and rapid algorithm were developed to provide guidance for healthcare professionals in the Asia-Pacific region on assessing patients with suspected acute coronary syndrome (ACS) using a hs-TnT assay. Experts from Asia-Pacific convened in 2 meetings to develop evidence-based consensus recommendations and an algorithm for appropriate use of the hs-TnT assay. The Expert Committee defined a cardiac troponin assay as a high-sensitivity assay if the total imprecision is ≤10% at the 99th percentile of the upper reference limit and measurable concentrations below the 99th percentile are attainable with an assay at a concentration value above the assay's limit of detection for at least 50% of healthy individuals. Recommendations for single-measurement rule-out/rule-in cutoff values, as well as for serial measurements, were also developed. The Expert Committee also adopted similar hs-TnT cutoff values for men and women, recommended serial hs-TnT measurements for special populations, and provided guidance on the use of point-of-care troponin T devices in individuals suspected of ACS. These recommendations should be used in conjunction with all available clinical evidence when making the diagnosis of ACS.

Cardiac Troponins for the Diagnosis of Acute Myocardial Infarction in Chronic Kidney Disease

Background Patients with chronic kidney disease ( CKD ) are at high risk of myocardial infarction. Cardiac troponins are the biomarkers of choice for the diagnosis of acute myocardial infarction ( AMI ) without ST -segment elevation ( NSTE ). In patients with CKD , troponin levels are often chronically elevated, which reduces their diagnostic utility when NSTE - AMI is suspected. The aim of this study was to derive a diagnostic algorithm for serial troponin measurements in patients with CKD and suspected NSTE - AMI . Methods and Results Two cohorts, 1494 patients from a prospective cohort study with high-sensitivity troponin I (hs- cTnI ) measurements and 7059 cases from a clinical registry with high-sensitivity troponin T (hs- cTnT ) measurements, were analyzed. The prospective cohort comprised 280 CKD patients (estimated glomerular filtration rate <60 mL/min/1.73 m²). The registry data set contained 1581 CKD patients. In both cohorts, CKD patients were more likely to have adjudicated NSTE - AMI than non- CKD patients. The specificities of hs- cTnI and hs- cTnT to detect NSTE - AMI were reduced with CKD (0.82 versus 0.91 for hs- cTnI and 0.26 versus 0.73 for hs- cTnT ) but could be restored by applying optimized cutoffs to either the first or a second measurement after 3 hours. The best diagnostic performance was achieved with an algorithm that incorporates serial measurements and rules in or out AMI in 69% (hs- cTnI ) and 55% (hs- cTnT ) of CKD patients. Conclusions The diagnostic performance of high-sensitivity cardiac troponins in patients with CKD with suspected NSTE - AMI is improved by use of an algorithm based on admission troponin and dynamic changes in troponin concentration.

Clinical Significance of Circulating Cardiomyocyte-Specific Cell-Free DNA in Patients With Heart Failure: A Proof-of-Concept Study

We investigated clinical significance of cell-free DNA (cfDNA) in heart failure. This study enrolled 32 heart failure patients and 28 control subjects. Total cfDNA levels were not different between groups (P = 0.343). Bisulfite-digital polymerase chain reaction using the unmethylated FAM101A locus demonstrated that cardiomyocyte-specific cfDNA was significantly elevated in heart failure patients compared with control subjects (median 0.99 [interquartile range 0.77-1.98] vs 0 [0-0.91] copies/mL; P = 0.003). Cardiomyocyte-specific cfDNA significantly discriminated heart failure patients from control subjects (area under the receiver operating characteristic curve, 0.716; P = 0.003) and was positively correlated with troponin I (r = 0.438; P = 0.003) but not with B-type natriuretic peptide (r = 0.275; P = 0.058). cfDNA may be a novel biomarker to measure cardiomyocyte death in heart failure.

Clinical Relevance of Troponin T Profile Following Cardiac Surgery

Background: Peak post-operative cardiac troponin T (cTnT) independently predicts mid- and long-term outcome of cardiac surgery patients. A few studies however have reported two peaks of cTnT over the first 48–72 h following myocardial reperfusion. The aim of the current study was to better understand underlying reasons of these different cTnT profiles and their possible relevance in terms of clinical outcome.

Methods: All consecutive adult cardiac surgical procedures performed with an extra-corporeal circulation during a >6 years period were retrospectively evaluated. Patients with a myocardial infarction (MI) < 8 days were excluded. cTnT profile of patients with at least one value ≥1 ng/mL value were categorized according to the time occurrence of the peak value. Univariable and multivariable analysis were performed to identify factors influencing early vs. late increase of cTnT values, and to verify the correlation of early vs. late increase with clinical outcome.

Results: Data of 5,146 patients were retrieved from our prospectively managed registry. From 953 with at least one cTnT value ≥1 ng/mL, peak occurred ≤ 6 h (n = 22), >6 to ≤ 12 h (n = 366), >12 to ≤ 18 h (n = 176), >18 to ≤ 24 h (171), >24 h (218). Age (OR: 1.023; CI: 1.016–1.030) and isolated CABG (OR: 1.779; CI: 1.114–2.839) were independent predictors of a late increase of cTnT over a limit of 1 ng/ml (p < 0.05), whereas isolated valve procedures (OR: 0.685; CI: 0.471–0.998) and cross-clamp duration (OR: 0.993; CI: 0.990–0.997) independently predicted an early elevation (p < 0.05). Delayed elevation as opposed to early elevation correlated with a higher rate of post-operative complications including MI (19.8 vs. 7.2%), new renal insufficiency (16.3 vs. 6.7%), MACCE (32.0 vs. 15.5%), or death (7.4 vs. 4.4%).

Conclusion: Profile of cTnT elevation following cardiac surgery depends on patients' intrinsic factors, type of surgery and duration of cross-clamp time. Delayed increase is of higher clinically relevance than prompt post-operative elevation.

Renal Dysfunction Influences the Diagnostic and Prognostic Performance of High-Sensitivity Cardiac Troponin I

Measures of cardiac troponin (cTn) may have lower specificity for myocardial infarction in patients with CKD. We examined the diagnostic accuracy of baseline and serial high-sensitivity cTnI (hs-cTnI) measurements for myocardial infarction and 30- and 180-day mortality according to renal function. hs-cTnI was measured (Abbott assay) using sex-specific 99th percentiles (women, 16 ng/L; men, 34 ng/L) in 1555 adults presenting to the emergency department with symptoms suggesting ischemia (NCT02060760). Myocardial infarction was adjudicated along universal definition classification. Renal function did not significantly affect sensitivity or negative predictive values. Specificity decreased with impaired renal function from 93%-95% with normal function (eGFR≥90 ml/min per 1.73 m2; n=722) to 57%-61% with severely impaired renal function (eGFR<30 ml/min per 1.73 m2; n=81) and 40%-41% on dialysis (n=78). Positive predictive values decreased with decreasing renal function from 51%-57% with normal function to 27%-42% with severely impaired function and 15%-32% on dialysis. Receiver operating characteristic curve areas trended lower at baseline and 3 hours with renal impairment. Mortality increased significantly with increasing hs-cTnI tertile (1.3%, 6.0%, and 10.4%, respectively). Patients with hs-cTnI concentration exceeding concentrations in the 99th percentiles had a mortality rate (11.7%) significantly higher than that of patients with concentrations between 99th percentile concentrations and limit of detection (6.2%) or below limit of detection (1.1%). Renal dysfunction and dialysis reduced the rule-in performance but not the rule-out performance of hs-cTnI for myocardial infarction, and mortality increased in patients with higher hs-cTnI concentrations and any level of renal dysfunction.

Contemporary Emergency Department Management of Patients with Chest Pain: A Concise Review and Guide for the High-Sensitivity Troponin Era

This article synthesizes current best evidence for the evaluation of patients with suspected acute coronary syndrome (ACS) using high-sensitivity troponin assays, enabling physicians to effectively incorporate them into practice. Unlike conventional assays, high-sensitivity assays can precisely measure blood cardiac troponin concentrations in the vast majority of healthy individuals, facilitating the creation of rapid diagnostic algorithms. Very low troponin concentrations on presentation accurately rule out acute myocardial infarction (AMI) and enable the discharge of approximately 20% of patients after a single test, whereas an additional 30%-40% of patients can be safely discharged after short-interval serial sampling in as little as 1 or 2 hours. In contrast, highly abnormal troponin concentrations on presentation (more than 5 times the upper reference limit) or rapidly rising levels on serial testing can rapidly rule in AMI with high specificity. However, approximately one-third of patients remain in a biomarker-indeterminate "observation zone" even after serial sampling. These patients pose a disposition challenge to clinicians because although the differential diagnosis of elevated troponin concentrations is broad, these patients have an increased risk for short-term major adverse cardiac events. Use of repeated serial troponin sampling and structured clinical prediction tools may assist disposition for these patients, because no validated pathways currently exist to guide clinicians. Ongoing research to tailor diagnostic thresholds to individual patient characteristics may enable improved diagnostic accuracy and usher in a new era of personalized medicine in the evaluation of suspected ACS.

[Not Available]

Zusammenfassung. Verbessertes Verständnis der menschlichen Physiologie und technische Fortschritte haben zu einer breiten Verwendung von Labordiagnostik in der klinischen Aufarbeitung eines Patienten geführt. Diese Entwicklungen gingen jedoch mit der Verbreitung von falschen Mythen und Missverständnissen einher, die humane und ökonomische Ressourcen konsumieren sowie das klinische Denken und – nicht zuletzt – den Patienten gefährden. Das Ziel dieses Artikels ist es daher, eine Übersicht über typische Beispiele von falschen Dogmen über in der Notfallmedizin häufig verwendete Laborwerte zu geben.

B-Type Natriuretic Peptide and Cardiac Troponin I Are Associated With Adverse Outcomes in Stable Kidney Transplant Recipients

BACKGROUND

Approximately 200 000 kidney transplant recipients are living in the United States; they are at increased risk for cardiovascular and other adverse outcomes. Biomarkers predicting these outcomes are needed. Using specimens collected during the Folic Acid for Vascular Outcome Reduction in Transplantation trial, we determined whether plasma levels of B-type natriuretic peptide (BNP) and cardiac troponin I are associated with adverse outcomes in stable kidney transplant recipients.

METHODS

Five hundred ten subjects were selected randomly from the 4110 Folic Acid for Vascular Outcome Reduction in Transplantation participants. This cohort was then enriched for all additional subjects with adverse outcomes (death, dialysis-dependent kidney failure (DDKF), and cardiovascular outcomes) for a total of 1131 participants studied. Quartiles of BNP and high-sensitivity cardiac troponin I (hs-cTnI) were included in adjusted models. Combinations of normal and elevated hs-cTnI (>26.2 ng/L) and BNP (>100 pg/mL) were also studied.

RESULTS

Median concentrations (interquartile ranges) were 5.6 (3.3-10.5) ng/L for hs-cTnI and 39 (15, 94) pg/mL for BNP. Hazard ratios for each adverse outcome were higher with higher quartiles of BNP after adjustment and remained statistically significant after adding hs-cTnI to the model. The highest quartile hazard ratio for DDKF was 2.47 (95% confidence interval [95% CI], 1.21-5.05). Simultaneous elevations of BNP and hs-cTnI over clinical cutoffs were strongly associated with adverse outcomes with hazard ratios 8.8 (95% CI, 3.4-23.1) for DDKF and 6.3 (95% CI, 2.7-15.0) for cardiovascular outcomes.

CONCLUSIONS

Higher BNP is associated with mortality and cardiovascular and kidney outcomes in stable kidney transplant recipients. Elevated BNP and hs-cTnI identify candidates for targeted risk reduction.

Improving the diagnostic accuracy of acute myocardial infarction with the use of high-sensitive cardiac troponin T in different chronic kidney disease stages

High-sensitive cardiac troponin T (hs-TnT) is a critical biomarker in diagnosis of acute myocardial infarction (AMI). However, CKD individuals usually have elevated hs-TnT even in the absence of AMI. Our study aimed to explore the optimal cutoff-value of hs-TnT and further to improve diagnostic accuracy of AMI in CKD patients. Clinical data of 489 patients were collected from the maintained database between September 2010 and June 2014. CKD patients with AMI were assigned to CKD+AMI group and CKD patients without AMI were assigned to CKD group. Receiver operating characteristic curves were utilized to derive the optimal cutoff-value. In CKD+STEMI and CKD group, hs-TnT was increased with descending eGFR. In CKD+NSTEMI group, hs-TnT showed an upward trend with increasing SYNTAX Score. In patients with CKD+STEMI, hs-TnT was significantly correlated with SYNTAX Score in CKD stage 2, stage 4 and in total. In CKD patients, the optimal cutoff-value of hs-TnT for diagnosis of AMI was 129.45 ng/l with 75.2% sensitivity and 83.2% specificity. The cutoff-value appeared to be hs-TnT level of 99.55ng/l in CKD stage 3, 129.45 ng/l in CKD stage 4, 105.50 ng/l in CKD stage 5 and 149.35 ng/l in dialysis patients, respectively. In different stages of CKD, eGFR-range-specific optimal cutoff-values should be considered.

Advances in Cardiac Biomarkers of Acute Coronary Syndrome

Acute coronary syndrome (ACS) encompasses a pathophysiological spectrum of cardiovascular diseases, all of which have significant morbidity and mortality. ACS was once considered an acute condition; however, new treatment strategies and improvements in biomarker assays have led to ACS being an acute and chronic disease. Cardiac troponin is the preferred biomarker for the diagnosis of myocardial infarction, and there is considerable interest and efforts toward development and implementation of high-sensitivity cardiac troponin (hs-cTn) assays worldwide. Analytical and clinical performance characteristics of hs-cTn assays as well as testing limitations are important for laboratorians and clinicians to understand in order to utilize testing appropriately. Furthermore, expanding the clinical utility of hs-cTn into other cohorts such as asymptomatic community dwelling populations, heart failure, and chronic kidney disease populations supports novel opportunities for improved short- and long-term prognosis.

Challenging the 99th percentile: A lower troponin cutoff leads to low mortality of chest pain patients

BACKGROUND

Rule-out of non-ST-elevation myocardial infarction is based on consecutive measurements of cardiac troponins using the 99th percentile of the respective assay as cutoff. The new ESC guidelines alternatively offer rapid 1h algorithms with lower cutoffs than the 99th percentile for rule-out of non-ST-elevation myocardial infarction. We aimed to compare a recently introduced 1h algorithm based on a high-sensitivity cardiac troponin I (hs-TnI) cutoff of 6ng/L at 0h and 1h to the current standard of care using the 99th percentile (27ng/L) as cutoff with reference to follow-up events in a large chest pain cohort.

METHODS

Hs-TnI was measured at three time points (0h, 1h and 3h) in 1625 patients presenting with suspected myocardial infarction to the emergency department of the University-Medical Center Hamburg-Eppendorf. Seventy-five patients with ST-elevation myocardial infarction were excluded from the analysis. All-cause mortality, cardiac death, acute myocardial infarction, revascularization and cardiac rehospitalization after 12months were assessed.

RESULTS

Patients ruled out by the 1h algorithm showed significantly less cardiac rehospitalizations (12.84% vs. 17.66%; p<0.001), and overall mortality (1.30% vs 3.46%, p<0.001) compared to using the 99th percentile as cutoff. The majority of deaths were caused by non-cardiac reasons. Cardiac deaths were rare using the 1h algorithm (0.21%).

CONCLUSION

The commonly used 99th percentile as cutoff neglects patients with a high risk in the setting of acute chest pain.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT02355457).

Strategies to overcome misdiagnosis of type 1 myocardial infarction using high sensitive cardiac troponin assays

High sensitive cardiac troponin assays have become the gold standard in the diagnosis of an acute type 1 myocardial infarction (MI) in the absence of ST-segment elevation. Several acute or chronic conditions that impact cardiac troponin levels in the absence of a MI might lead to a misdiagnosis of MI. For example, patients with impaired renal function as well as elderly patients often present with chronically increased cardiac troponin levels. Therefore, the diagnosis of MI type 1 based on the 99th percentile upper limit of normal threshold is more difficult in these patients. Different diagnostic approaches might help to overcome this limitation of reduced MI specificity of sensitive troponin assays. First, serial troponin measurement helps to differentiate chronic from acute troponin elevations. Second, specific diagnostic cut-offs, optimized for a particular patient group, like elderly patients, are able to regain specificity. Such an individualized use and interpretation of sensitive cardiac troponin measurements improves diagnostic accuracy and reduces the amount of misdiagnosed MI type 1.

Troponin elevations in patients with chronic cardiovascular disease: An analysis of current evidence and significance

Serum troponin elevation above the 99^th percentile of the upper reference limit in healthy subjects (<0.01 ng/ml measured using currently available high-sensitivity cardiac troponin laboratory assays) is required to establish the diagnosis the diagnosis of myocardial necrosis in acute cardiovascular syndromes, as well as guide prognosis and therapy. In the perioperative period, for patients with cardiac disease undergoing noncardiac surgery, it is a particularly critical biomarker universally used to assess the myocardial damage. The value of troponin testing and elevation (as well as its significance) in patients with chronic cardiac valvular, vascular, and renal disease is relatively less well understood. This evidence-based review seeks to examine the currently available data assessing the significance of troponin elevation in certain chronic valvular and other disease states.

Neutrophil to lymphocyte ratio might help prediction of acute myocardial infarction in patients with elevated serum creatinine

Background and Objective:

Diagnostic performance of troponin assays is affected by renal insufficiency. Neutrophil to lymphocyte ratio(NLR) is an independent predictor of acute coronary syndrome. Our objective was to evaluate performance of NLR in diagnosing acute myocardial infarction (AMI) among patients with elevated serum creatinine.

Methods:

Patients with elevated creatinine levels evaluated for coronary artery disease were included (n=284). Patients were divided into two groups according to having AMI or non-specific chest pain. AMI diagnosis was made based on clinical and laboratory data, including serial EKG and cardiac enzymes, ECHO and coronary angiography.

Results:

Troponin, neutrophil, and NLR were found to be higher in patients with AMI, compared to patients without AMI (P= 0.001, P= 0.001 and P=0.028, respectively). ROC curve analysis for NLR in diagnosing AMI was significant (AUC: 0.607; P=0.003). Sensitivity, specificity, LR +, LR-, PPV and NPV for NLR>7.4 were found as 42.3%, 74.7%, 1.68%, 0.77%, 77% and 40%, respectively. Logistic regression analysis revealed that patients whose NLR>7.4 were 2.18 times as likely to have AMI.

Conclusions:

NLR can be used as an independent predictor of AMI in patients with renal insufficiency. This seems to get more important in the era of high sensitivity troponin assays. Our results might also help in early diagnosis of AMI in this high risk population while serial cardiac enzyme results are pending.

Relationship between high sensitivity troponins and estimated glomerular filtration rate

BACKGROUND

Diagnosis of acute coronary syndrome may be challenging because of high troponin concentrations in patients with chronic kidney disease.

OBJECTIVE

the aim of this study is to investigate the difference between high sensitivity troponin T and troponin I in four groups of patients separated according to eGFR values and the effect of renal function both on troponin T and troponin I.

METHODS

119 outpatients were divided into 4 groups according to their eGFR values as Group 1: eGFR<30, Group 2: eGFR between 30 and 60, Group 3: eGFR between 60 and 90 and Group 4: eGFR >90mL/min/1.73m(2). The cardiac troponin T and I concentrations were measured concurrently.

RESULTS

Troponin T values of all patients who have eGFR values lower than 30mL/min/1.73m(2) were above the decision point, but cTnI values of only 2 patients were above the decision limit (40ng/L) in this group. There was a strong and significant negative relationship between eGFR and hs-cTnT [log(y)=2.3-0.72log(x); R(2)=0.625] whereas there was no significant relationship between eGFR and hs-cTnI [log(y)=1.28-0.08log(x); R(2)=0.013] when eGFR was taken into consideration as a continuous variable.

CONCLUSION

In this study, we found that cTnT increases with decreasing eGFR values, but cTnI is not affected by the change in eGFR values.

Diagnosis of Acute Myocardial Infarction in Hemodialysis Patients With High-Sensitivity Cardiac Troponin T Assay

Context

Cardiac troponins have become the gold standard for diagnosing acute myocardial infarction (AMI) in the general population; however, their diagnostic accuracy for hemodialysis (HD) patients presenting with chest pain or dyspnea is uncertain.

Objective

To examine the diagnostic accuracy of high-sensitivity cardiac troponin T (hs-cTnT) assay for AMI in HD patients.

Design

In this prospective study, we enrolled 670 consecutive stable HD patients presenting with chest pain or dyspnea on routine predialysis therapy in the nephrology department. Receiver operating characteristic (ROC) curves were used to examine the diagnostic accuracy of hs-cTnT levels at enrollment in HD patients presenting with chest pain or dyspnea, and the dynamic change in these levels after 3 hours.

Results

Acute myocardial infarction was the adjudicated final diagnosis in 12% of HD patients. Among patients with a final diagnosis other than AMI, 97% had a plasma hs-cTnT concentration above the 99th percentile. At the time of enrollment, the area under the ROC curve of hs-cTnT levels for diagnosis of AMI was 0.68 (95% confidence interval [CI], 0.62–0.74; P &lt; .001) with a cutoff value of 107.7 ng/L; the relative change after 3 hours was 0.90 (95% CI, 0.82–0.96, P &lt; .001) with a cutoff value of 24%, and the absolute change was 0.88 (95% CI, 0.82–0.94, P &lt; .001) with a cutoff value of 32.6 ng/L. The prognostic value for 40-day mortality varied with the magnitude of elevation in hs-cTnT levels.

Conclusions

Tracking the dynamic change in hs-cTnT levels during the short term significantly increased this measure's diagnostic accuracy for AMI in HD patients.

The appropriate troponin T level associated with coronary occlusions in chronic kidney disease patients

Background

High-sensitivity troponin T (HS Trop T) plays an important role as a diagnostic marker for acute coronary syndrome. It is also related to cardiovascular outcomes. HS Trop T levels may be varied in individuals with renal dysfunction. This study aimed to find the appropriate HS Trop T cutoff points in chronic kidney disease (CKD) patients who had coronary artery occlusion.

Patients and methods

The study was conducted at the Emergency Department, Ramathibodi Hospital, Mahidol University, Thailand. CKD patients stage 3–5 who had HS Trop T levels after 2 hours of chest pain and had coronary angiographic results were enrolled. Patients were divided into two groups: those who had significant occlusion of more than 70% of a coronary artery as the coronary artery disease (CAD) group and the non-CAD group.

Results

In total, 210 patients met the study criteria. There were 132 patients (62.86%) who had significant stenosis of coronary arteries by coronary angiograms. The average age (standard deviation) of all patients was 71.02 (9.49) years. HS Trop T levels were significantly higher in all CKD patients with CAD than the non-CAD group (0.4973 versus 0.0384 ng/mL). Sex and HS Trop T levels were significantly associated with CAD by multivariate logistic regression analysis. The HS Trop T level of 0.041 ng/mL gave sensitivity and specificity of 65.91% and 75.65%, respectively, for CAD.

Conclusion

The HS Trop T level of 0.041 ng/mL provided diagnostic properties for established coronary artery occlusion in CKD patients.

Recent advances in the diagnosis and treatment of acute myocardial infarction

The Third Universal Definition of Myocardial Infarction (MI) requires cardiac myocyte necrosis with an increase and/or a decrease in a patient’s plasma of cardiac troponin (cTn) with at least one cTn measurement greater than the 99^th percentile of the upper normal reference limit during: (1) symptoms of myocardial ischemia; (2) new significant electrocardiogram (ECG) ST-segment/T-wave changes or left bundle branch block; (3) the development of pathological ECG Q waves; (4) new loss of viable myocardium or regional wall motion abnormality identified by an imaging procedure; or (5) identification of intracoronary thrombus by angiography or autopsy. Myocardial infarction, when diagnosed, is now classified into five types. Detection of a rise and a fall of troponin are essential to the diagnosis of acute MI. However, high sensitivity troponin assays can increase the sensitivity but decrease the specificity of MI diagnosis. The ECG remains a cornerstone in the diagnosis of MI and should be frequently repeated, especially if the initial ECG is not diagnostic of MI.

There have been significant advances in adjunctive pharmacotherapy, procedural techniques and stent technology in the treatment of patients with MIs. The routine use of antiplatelet agents such as clopidogrel, prasugrel or ticagrelor, in addition to aspirin, reduces patient morbidity and mortality. Percutaneous coronary intervention (PCI) in a timely manner is the primary treatment of patients with acute ST segment elevation MI. Drug eluting coronary stents are safe and beneficial with primary coronary intervention. Treatment with direct thrombin inhibitors during PCI is non-inferior to unfractionated heparin and glycoprotein IIb/IIIa receptor antagonists and is associated with a significant reduction in bleeding. The intra-coronary use of a glycoprotein IIb/IIIa antagonist can reduce infarct size. Pre- and post-conditioning techniques can provide additional cardioprotection. However, the incidence and mortality due to MI continues to be high despite all these recent advances. The initial ten year experience with autologous human bone marrow mononuclear cells (BMCs) in patients with MI showed modest but significant increases in left ventricular (LV) ejection fraction, decreases in LV end-systolic volume and reductions in MI size. These studies established that the intramyocardial or intracoronary administration of stem cells is safe. However, many of these studies consisted of small numbers of patients who were not randomized to BMCs or placebo. The recent LateTime, Time, and Swiss Multicenter Trials in patients with MI did not demonstrate significant improvement in patient LV ejection fraction with BMCs in comparison with placebo. Possible explanations include the early use of PCI in these patients, heterogeneous BMC populations which died prematurely from patients with chronic ischemic disease, red blood cell contamination which decreases BMC renewal, and heparin which decreases BMC migration. In contrast, cardiac stem cells from the right atrial appendage and ventricular septum and apex in the SCIPIO and CADUCEUS Trials appear to reduce patient MI size and increase viable myocardium. Additional clinical studies with cardiac stem cells are in progress.

Optimal Cutoff Levels of More Sensitive Cardiac Troponin Assays for the Early Diagnosis of Myocardial Infarction in Patients With Renal Dysfunction

Supplemental Digital Content is available in the text.

Background—

It is unknown whether more sensitive cardiac troponin (cTn) assays maintain their clinical utility in patients with renal dysfunction. Moreover, their optimal cutoff levels in this vulnerable patient population have not previously been defined.

Methods and Results—

In this multicenter study, we examined the clinical utility of 7 more sensitive cTn assays (3 sensitive and 4 high-sensitivity cTn assays) in patients presenting with symptoms suggestive of acute myocardial infarction. Among 2813 unselected patients, 447 (16%) had renal dysfunction (defined as Modification of Diet in Renal Disease–estimated glomerular filtration rate <60 mL·min⁻¹·1.73 m⁻²). The final diagnosis was centrally adjudicated by 2 independent cardiologists using all available information, including coronary angiography and serial levels of high-sensitivity cTnT. Acute myocardial infarction was the final diagnosis in 36% of all patients with renal dysfunction. Among patients with renal dysfunction and elevated baseline cTn levels (≥99th percentile), acute myocardial infarction was the most common diagnosis for all assays (range, 45%–80%). In patients with renal dysfunction, diagnostic accuracy at presentation, quantified by the area under the receiver-operator characteristic curve, was 0.87 to 0.89 with no significant differences between the 7 more sensitive cTn assays and further increased to 0.91 to 0.95 at 3 hours. Overall, the area under the receiver-operator characteristic curve in patients with renal dysfunction was only slightly lower than in patients with normal renal function. The optimal receiver-operator characteristic curve–derived cTn cutoff levels in patients with renal dysfunction were significantly higher compared with those in patients with normal renal function (factor, 1.9–3.4).

Conclusions—

More sensitive cTn assays maintain high diagnostic accuracy in patients with renal dysfunction. To ensure the best possible clinical use, assay-specific optimal cutoff levels, which are higher in patients with renal dysfunction, should be considered.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00470587.

D-dimer to rule out pulmonary embolism in renal insufficiency

BACKGROUND

D-dimer levels are often elevated in renal insufficiency. The diagnostic accuracy of D-dimer to rule out pulmonary embolism in patients with renal insufficiency is unclear.

METHODS

We evaluated the data of patients presenting to our Emergency Department and receiving computed tomography angiography to rule out pulmonary embolism with measurement of D-dimer and creatinine. Glomerular filtration rate was calculated using the Chronic Kidney Disease Epidemiology Collaboration formula.

RESULTS

There were 1305 patients included; 1067 (82%) had an estimated glomerular filtration rate (eGFR) exceeding 60 mL/min, 209 (16%) 30-60 mL/min, and 29 (2%) <30 mL/min. One hundred fifty-two patients (12%) had D-dimer below 500 μg/L. eGFR (R = -0.1122) correlated significantly with D-dimer (P <.0001). One hundred sixty-nine patients (13%) were found to have pulmonary embolism. Sensitivity of D-dimer for patients with an eGFR >60 mL/min was 96% (confidence interval [CI], 0.93-0.99) and 100% (CI, 100-100) for those with 30-60 mL/min, while specificity decreased significantly with impaired renal function. Area under the curve of the receiver operating characteristic for D-dimer was 0.734 in patients with an eGFR of >60 mL/min, and 0.673 for 30-60 mL/min.

CONCLUSIONS

D-dimer levels were elevated in patients with an eGFR <60 mL/min, but proved to be highly sensitive for the exclusion of pulmonary embolism. However, because almost all patients with impaired renal function had elevated D-dimer irrespective of the presence of pulmonary embolism, studies should be performed to determine renal function-adjusted D-dimer cutoffs.