Troponin-I elevation in patients with increased left ventricular mass

Clinical relevance and advances in detection of translational biomarker cardiac troponin

Cardiovascular diseases (CVD) are a range of diseases, pointing the functional hindrances in the heart and blood vessels of the human system that contributes to 48.6 % of the world's adult death rate. The diagnosis of CVD relies upon the Electro Cardio Gram (ECG) and detection of muscle markers such as troponins. Among the cardiac trio, Cardiac Troponin I (cTnI) weighing 23 KiloDalton (kDa) is a sorted biomarker for CVD. cTnI remains high in the blood after 1-2 weeks of myocardial damage. Testing of cTnI in CVD patients aids in diagnosis and risk stratification of the disease. Different determination systems including optical, electrochemical, and acoustic have been put forward for monitoring the cTnI which are Point of Care (POC) that promotes simple and sensitive detection of cTnI. The modern era has paved way to high-sensitivity Troponin I (hscTnI) devices that can detect up to 0.01 ng/ml in human blood/plasma/serum. Yet, the practice of hscTnI is impracticable due to cost inefficiency. Development of new hscTnI devices with minimal investment and maximal detection range will meet the global requirement. This review gives an over view on different detection systems of cardiac troponin I which stands as a translational detection molecule for CVDs.

Low-attenuation coronary plaque burden and troponin release in chronic coronary syndrome: A mediation analysis

BACKGROUND

Coronary low-attenuation plaque (LAP) burden is a strong predictor of myocardial infarction in patients with stable chest pain. We aimed to assess the relationship between LAP burden and circulating levels of high-sensitivity cardiac troponin T (hs-cTnT), and to explore the potential underlying etiology in patients undergoing clinically indicated coronary CT angiography (CCTA).

METHODS

A comprehensive metabolic and lipid panel, as well as C-reactive protein (CRP) and hs-cTnT tests were obtained from consecutive patients with stable chest pain at the time of CCTA. Qualitative and quantitative coronary plaque analysis, CT-derived fractional flow reserve (FFR) calculation, and pericoronary adipose tissue (PCAT) attenuation measurement around the right coronary artery were performed on CCTA images. Linear regression analyses were performed to identify independent associations with hs-cTnT concentration and mediation analysis was used to assess whether ischemia or markers of inflammation mediate hs-cTnT elevation.

RESULTS

In total, 114 patients (56.3 ​± ​10.6 years, 44.7 ​% female) were enrolled. In multivariable analysis, age (β ​= ​0.04 [95%CI: 0.02; 0.06], p ​< ​0.001), female sex (β ​= ​-0.77 [95%CI: -1.20; 0.33], p ​< ​0.001), and LAP burden (β ​= ​0.03 [95%CI: 0.001; 0.06], p ​= ​0.04) were independently associated with hs-cTnT levels. Mediation analysis, on the other hand, did not identify a significant mediating effect of lesion-specific ischemia based on CT-FFR, circulating CRP levels, or PCAT values between LAP burden and hs-cTnT levels (all p ​> ​0.05).

CONCLUSION

Although ischemia and inflammation have previously been proposed to mediate the association between LAP burden and hs-cTnT levels, our results did not confirm the role of these pathophysiological pathways in patients with stable chest pain.

Defining Myocardial Infarction in trials of people receiving hemodialysis: consensus report from the SONG-HD MI Expert Working group

Cardiovascular disease is the leading cause of death in patients receiving hemodialysis. Currently there is no standardized definition of myocardial infarction (MI) for patients receiving hemodialysis. Through an international consensus process MI was established as the core CVD measure for this population in clinical trials. The Standardised Outcomes in Nephrology Group - Hemodialysis (SONG-HD) initiative convened a multidisciplinary, international working group to address the definition of MI in this population.Based on current evidence, the working group recommends using the 4th Universal Definition of MI with specific caveats with regard to the interpretation of "ischemic symptoms" and performing a baseline 12-lead electrocardiogram to facilitate interpretation of acute changes on subsequent tracings. The working group does not recommend obtaining baseline cardiac troponin values, though does recommend obtaining serial cardiac biomarkers in settings where ischemia is suspected. Application of an evidence-based uniform definition should increase the reliability and accuracy of trial results.

A comparison of echocardiographic and circulating cardiac biomarkers for predicting incident cardiovascular disease

Background

Echocardiographic measures are known predictors of cardiovascular disease (CVD) in the general population. This study compared the predictive value of such measures to that of circulating cardiac biomarkers for a composite cardiovascular disease outcome in an aging population.

Methods

In this prospective population-based cohort study, echocardiography was performed at baseline together with assessments of traditional CVD risk factors and circulating cardiac biomarkers, NT-proBNP and troponin I, in 1016 individuals all aged 70 years. Assessments were repeated at ages 75 and 80. A composite CVD outcome (myocardial infarction, heart failure or ischemic stroke) was charted over 15 years. All echocardiography variables, except for the E/A ratio, were analyzed on a continuous scale.

Results

Over 10 years, left atrial (LA) diameter, left ventricular mass index (LVMI) and high E/A ratio (>1.5) increased, while left ventricular ejection fraction (LVEF) remained unchanged. Using Cox proportional hazard analyses with time-updated variables for echocardiographic measures and traditional risk factors, an enlarged LA diameter and a low LVEF were independently related to incident CVD in 222 participants. The addition of LA diameter and LVEF to traditional risk factors increased the C-statistic by 1.5% (p = 0.008). However, the addition of troponin I and NT-proBNP to traditional risk factors increased the C-statistic by 3.0% (p<0.001).

Conclusion

An enlarged LA diameter and a low LVEF improved the prediction of incident CVD compared to traditional risk factors. However, given that troponin I and NT-proBNP improved prediction to a similar extent, the use of simple blood tests to improve clinical cardiovascular disease risk prediction is only further supported by this study.

A Case of Elevated Troponin I Level After Packed Red Blood Cell Transfusion With Normal Coronary Angiography

Other than acute coronary syndrome (ACS), many clinical conditions are associated with increased cardiac troponin I (cTnI) levels. Conditions such as pulmonary embolism, acute heart failure, myocarditis, sepsis, and renal failure are commonly reported as underlying causes. Analytical interference with the cTnI assay can also lead to falsely elevated troponin I levels. That can happen due to multiple causes such as fibrin clots, heterophile antibodies, microparticles contained in the sample, rheumatoid factor, interference by bilirubin, hemolysis, and elevated alkaline phosphatase activity. Herein, we present the case of a 66-year-old female who presented with pleuritic chest pain and had a cTnI of 35.5 ng/mL post-transfusion of three units of packed red blood cells. The patient had a complete ischemic workup for ACS, including coronary angiography, which was negative for coronary artery disease.

Biomarker Development in Cardiology: Reviewing the Past to Inform the Future

Cardiac biomarkers have become pivotal to the clinical practice of cardiology, but there remains much to discover that could benefit cardiology patients. We review the discovery of key protein biomarkers in the fields of acute coronary syndrome, heart failure, and atherosclerosis, giving an overview of the populations they were studied in and the statistics that were used to validate them. We review statistical approaches that are currently in use to assess new biomarkers and overview a framework for biomarker discovery and evaluation that could be incorporated into clinical trials to evaluate cardiovascular outcomes in the future.

The Elevated High-Sensitivity Cardiac Troponin T Pilot: Diagnoses and Outcomes

OBJECTIVE

To identify the diagnoses and outcomes associated with elevated high sensitivity cardiac troponin T (hs-cTnT) compared with the 4th-generation troponin T and to validate the Mayo Clinic hs-cTnT myocardial infarction algorithm cutoff values.

PATIENTS AND METHODS

Consecutive blood samples of patients presenting to the emergency department between July 2017 and August 2017, who had 4th-generation troponin T, were also analyzed using the hs-cTnT assay. Troponin T values, discharge diagnoses, comorbidities, and outcomes were assessed. In addition, analyses of sex-specific and hs-cTnT cutoff values were assessed.

RESULTS

Of 830 patients, 32% had an elevated 4th-generation troponin T, whereas 64% had elevated hs-cTnT. With serial sampling, 4th-generation troponin missed a chronic myocardial injury pattern and acute myocardial injury pattern in 64% and 16% of patients identified with hs-cTnT, respectively. Many of these "missed" patients had discharge diagnoses associated with cardiovascular disease, infection, or were postoperative. Five of the 6 patients with unstable angina ruled in for myocardial infarction.

CONCLUSION

There were many increases in hs-cTnT that were missed by the 4th-generation cTnT assay. Most new increases are not related to acute cardiac causes. They were more consistent with chronic myocardial injury. High-sensitivity cTnT did reclassify most patients with unstable angina as having non-ST-elevation myocardial infarction. Older age, more comorbidities, and lower hemoglobin were associated with elevated hs-cTnT. Our data also support the use of our sex-specific cutoff values.

Noninvasive Myocardial Work Indices 3 Months after ST-Segment Elevation Myocardial Infarction: Prevalence and Characteristics of Patients with Postinfarction Cardiac Remodeling

BACKGROUND

Assessment of left ventricular (LV) remodeling after ST-segment elevation myocardial infarction (STEMI) is pivotal for patient management. Noninvasive myocardial work indices obtained from echocardiography-derived strain-pressure loops provide a new tool that permits characterization of LV mechanics. We aimed at characterizing myocardial work indices in patients with LV remodeling after STEMI versus patients without remodeling.

METHODS

Six-hundred STEMI patients were retrospectively analyzed (456 men, mean age: 61 ± 11 years) and divided according to the presence of LV remodeling 3 months after the index admission (≥20% increase in LV end-diastolic volume). Noninvasive myocardial work indices were measured at 3 months after STEMI.

RESULTS

LV remodeling was observed in 150 patients (25%) who showed more impaired global myocardial work indices compared with their counterparts: work index (1,708 ± 522 mm Hg% vs 1,979 ± 450 mm Hg%; P < .001), constructive work (1,941 ± 598 mm Hg% vs 2,272 ± 519 mm Hg%; P < .001), and work efficiency (92% [range 88%-96%] vs 95% [range 93%-96%]; P < .001). In addition, patients with LV remodeling had significantly increased wasted work (116 mm Hg% [range 73-184 mm Hg%] vs 91 mm Hg% [range 61-132 mm Hg%]; P < .001). The frequency of impaired global work index, constructive and work efficiency, and increased wasted work was significantly higher among patients with LV remodeling compared with their counterparts: 21.3%, 34.7%, 34.7%, and 14.0%, respectively, versus 5.3%, 9.6%, 8.9%, and 4.9%, respectively (P < .001).

CONCLUSIONS

At 3-month follow-up after STEMI, patients with LV remodeling revealed more impaired myocardial work indices compared with patients without LV remodeling. The prevalence of impaired myocardial work indices was higher among patients with LV remodeling compared with patients without.

Impact of Left Ventricular Hypertrophy on Peak Serum Troponin T Levels in Patients With Acute Myocardial Infarction

Previous studies have reported that peak serum troponin I levels were disproportionately elevated in patients with acute anterior ST-segment elevation myocardial infarction (STEMI) and left ventricular (LV) hypertrophy (LVH) compared with those with normal LV mass. The purpose of this retrospective study was to assess the relation of peak serum troponin T levels in patients with normal LV mass and in subjects with mild, moderate, and severe LVH in patients with acute STEMI or non-ST segment elevation myocardial infarction (NSTEMI) when stratified on variables that might be expected to affect serum troponin T levels. The study population consisted of 262 patients; 91 with STEMI and 161 with NSTEMI. Serum troponin levels and 2-dimensional echocardiograms were obtained within the first 24 hours of hospitalization for STEMI or NSTEMI. There was no significant difference in serum troponin T levels in LV mass and/or LVH groups (p = 0.3210). There was no significant difference in serum troponin T levels in LV mass and/or LVH groups when these data were stratified on third variables including serum creatinine >1.2 mg/dl (p = 0.3681), LV ejection fraction <60% (p = 0.0978), STEMI (p = 0.2576), NSTEMI (p = 0.4994), and location of severe coronary stenosis (p = 0.1981). The results of this study suggest that there is no association between peak serum troponin T levels and LV mass and/or LVH groups when such groups are stratified on a third variable that may influence peak serum troponin T levels.

Clinical utility of mean platelet volume and immature platelet fraction in acute coronary syndrome

Background

Platelets play an important role in the pathogenesis of acute coronary syndrome (ACS). Patients with ACS have an increased mean platelet volume (MPV) and immature platelet fraction (IPF) resulting in elevation of thrombotic ability. In this study, we evaluated the diagnostic performance of MPV and IPF in identifying suspected ACS patients at emergency department. Moreover, we investigated the correlation between MPV or IPF with initial troponin I (TnI), one of the current ACS biomarkers.

Methods

This was a single-center study recruiting suspected ACS patients who had acute chest pain at the emergency department. Whole blood samples were obtained from all participants and MPV and IPF were measured by Sysmex XE-5000 hematology analyzer within 20 min of blood sampling. The diagnostic values of MPV and IPF in identifying ACS were analyzed retrospectively.

Result

In this study, 63 in 104 suspected ACS patients were diagnosed as ACS (65.3%). MPV and IPF were higher in ACS patients compared to non-ACS patients (MPV: 10.7 ± 0.80 fL vs 10.0 ± 0.64 fL, p < 0.001; IPF: 3.7 ± 2.64% vs 3.1 ± 2.69%, p = 0.030). MPV and IPF were similar in unstable angina and acute myocardial infarction patients. We showed that elevation of MPV could be an independent predictive factor of ACS (odds ratio: 5.038). At the optimal cut-off value of 10.55 fL (AUC 95% CI: 0.637–0.836), the diagnostic performance of MPV in predicting ACS had an area under a receiver operating characteristic curve (AUC) of 0.736 with sensitivity and specificity of 54.2% and 82.8%, respectively. Patients with both of initial TnI and MPV higher than the established cut-off value had increased incidence (3.792 fold) for ACS development compared to patients with TnI below the cut-off value. Furthermore, diagnosing ACS with both MPV and initial TnI increased the positive predictive value from 84.2% to 86.7%. No correlation was observed between MPV or IPF and the mortality rate of ACS patients (MPV: 3.8% vs 11.1%, p = 0.300; IPF: 12.0% vs 37.5%, p = 0.054).

Conclusion

Here we show that ACS patients have higher MPV and IPF compared to non-ACS patients. We further demonstrate that MPV can be utilized as an independent predictor for early diagnosis of low-risk ACS patients who have acute chest pain.

Age-related remodeling of the JAK/STAT/SOCS signaling pathway and associated myocardial changes: From histological to molecular level

BACKGROUND

The cellular and molecular mechanisms implicated in age-associated changes in myocardial structure are of paramount importance since they cause profound alterations in the functional response and represent targets for alleviating age-related pathologies. One of these mechanisms is the JAK/STAT/SOCS signaling pathway.

AIM OF THE STUDY

The present study is designed to elucidate age-dependent changes of the myocardium to provide morphological basis displaying the pathogenesis of myocardial hypertrophy, fibrosis and inflammation with aging.

MATERIAL AND METHODS

Thirty male Sprague Dawley rats aged; 6, 30 and 36 months were used in this study. The animals were divided into three age groups, young adult, senile and very senile rats, respectively. The heart weight/body weight ratio was determined. The heart was subjected to gross morphologic examination, microscopic examination using H&E and Masson's trichrome stains and immunohistochemical examination for detection of JAK, pSTAT3, α-SMA, β-MHC and CD45. Western blotting was also carried out to detect SOCS genes. Real-time PCR was used to detect the inflammatory markers TNFα and IL1β and the hypertrophy marker α-SKA. Biochemical analysis of cardiac troponin I and creatine kinase-MB was done. Quantitative histomorphometric estimations included estimation of cardiac myocyte cross sectional area, estimation of the area percent of collagen fibers in Masson's trichrome stained sections and determination of optical density in immunostained sections. Electron microscopic examination was done to determine capillary density.

RESULTS

Jak and pSTAT3 were predominantly localized to the nuclei and exhibited progressive decline with aging, while SOCS3 activity displayed an age-related increase. The aged myocardium displayed profound age associated structural changes as well as myocardial hypertrophy, fibrosis and inflammation in senile and very senile rats.

CONCLUSION

The age-related modifications in the JAK/STAT/SOCS signaling as well as the age-associated pathological changes in myocardial structure are of particular interest as they provide further insight in age-associated heart pathologies and represent potential targets for cardioprotective and therapeutic approaches.

Evaluation of Heart Function in Patients With Hemophilia

There are conflicting reports about the protective effect of hemophilia on the occurrence of ischemic heart disease. This study focuses on evaluation of heart function in patients with hemophilia. Cross-sectional, case–control study was done on all patients with hemophilia A or B who came to hemophilia center, and data were compared to controls. The data were collected from their charts, and heart function was evaluated by 2-dimensional, Doppler and pulse tissue Doppler. The serum troponin I level was measured in all patients as a marker of myocardial damage. Fifty patients with hemophilia took part in this study. All of them were male with mean age 29.1 years. Systolic blood pressure (mean = 121.52 ± 11 vs 115.61 ± 9.81, P = .038) and diastolic (mean = 81.94 ± 4.51 vs 75.21 ± 3.95, P = .042) blood pressure were higher in the patients. Five (10%) patients had systolic hypertension and 7 (14%) patients had diastolic hypertension. The M-mode echocardiography results showed that interventricular septum in diastole in patients with hemophilia (mean 1.143 ± 0.29) was significantly thicker than the control group (mean 0.828 ± 0.22, P < .001). Tissue Doppler echocardiography showed that late diastolic velocity of septum (Aa; P = .030), systolic velocity (S) of lateral mitral valve ( P = .006), late diastolic velocity of lateral mitral (Aa) annulus ( P = .038), and late velocity of (Aa) tricuspid ( P = .004) had significant difference compared with the control group ( P < .05). Troponin enzyme level was < 0.1 in all patients. Patients with hemophilia had higher blood pressure and more hypertension. Echocardiographic study of patients with hemophilia showed some increase in septal thickness and changes in diastolic dysfunction

Cardiovascular risk is similar in patients with glomerulonephritis compared to other types of chronic kidney disease: a matched cohort study

Background

Patients with chronic kidney disease (CKD) due to glomerulonephritis (GN) are thought to be at high risk for cardiovascular disease (CVD). However, no study has examined whether GN directly contributes to CV risk beyond the effects conferred by pre-existing traditional risk factors and level of renal function.

Methods

Matched cohort study using the previously described prospective CanPREDDICT study cohort. 2187 patients with CKD (eGFR 15–45 ml/min/m²) from 25 Canadian centres were divided into GN vs non-GN cause of CKD. Patients on immunotherapy for GN were not included in the study. Standardized measures of CV risk factors, biomarkers and CV outcomes were recorded over 3 years of follow-up, with the primary outcome measure being time to first all-cause CV event.

Results

In the overall cohort, CV events occurred in 25 (8.7%) of the GN group and 338 (17.8%) of the non-GN group (HR 0.45, 95% CI 0.30–0.67, p < 0.01). In a Cox regression multivariable model that included age, sex, prior diabetes and CVD, baseline eGFR and onset of renal replacement therapy, the risk of CV events was similar in the GN and non-GN groups (HR 0.71, 95% CI 0.47–1.08, p = 0.11). GN and non-GN patients were matched by age and using a propensity score including sex, prior diabetes and CVD and baseline eGFR. In the matched group, the risk of CV events was similar in GN vs non-GN patients (N = 25/271 (9.2%) in both groups, HR 1.01, 95% CI 0.05–1.77, p = 0.9). An interaction analysis showed that CRP, ACR and troponin conferred differing amounts of CV risk in the GN and non-GN groups.

Conclusions

Patients with advanced CKD due to GN have a high 8.7% absolute 3-year risk of CVD, attributable to prior CV risk factors and level of kidney function rather than the GN disease itself.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0511-z) contains supplementary material, which is available to authorized users.

Cardiac Troponins in Dogs and Cats

Cardiac troponins are sensitive and specific markers of myocardial injury. The troponin concentration can be thought of as a quantitative measure of the degree of injury sustained by the heart, however, it provides no information on the cause of injury or the mechanism of troponin release. Conventionally, the cardiac troponins have been used for diagnosis of acute myocardial infarction in humans and have become the gold standard biomarkers for this indication. They have become increasingly recognized as an objective measure of cardiomyocyte status in both cardiac and noncardiac disease, supplying additional information to that provided by echocardiography and ECG. Injury to cardiomyocytes can occur through a variety of mechanisms with subsequent release of troponins. Independent of the underlying disease or the mechanism of troponin release, the presence of myocardial injury is associated with an increased risk of death. As increasingly sensitive assays are introduced, the frequent occurrence of myocardial injury is becoming apparent, and our understanding of its causes and importance is constantly evolving. Presently troponins are valuable for detecting a subgroup of patients with higher risk of death. Future research is needed to clarify whether troponins can serve as monitoring tools guiding treatment, whether administering more aggressive treatment to patients with evidence of myocardial injury is beneficial, and whether normalizing of troponin concentrations in patients presenting with evidence of myocardial injury is associated with reduced risk of death.

Electrocardiographic Left Ventricular Hypertrophy as a Predictor for Nonsignificant Coronary Artery Disease in Patients With Non-ST-Segment Elevation Myocardial Infarction

Left ventricular hypertrophy (LVH) can lead to subendocardial ischemia by altering the coronary blood flow and its transmural myocardial distribution in the setting of increased oxygen demand. We hypothesized that electrocardiographic LVH predicts nonsignificant coronary artery disease (CAD) in patients with non-ST-segment elevation myocardial infarction (NSTEMI). We performed a retrospective analysis of 406 consecutive patients with NSTEMI who underwent coronary angiography. The LVH was diagnosed using Sokolow-Lyon and Cornell voltage criteria. Nonsignificant CAD was defined as stenosis less than 50% in the left main and 70% in any other coronary arteries. Of the 406 patients, 100 (25%) patients had electrocardiographic LVH and 99 (24%) patients had nonsignificant CAD. Patients with electrocardiographic LVH had a higher prevalence of nonsignificant CAD (32% vs 22%, P = .04) and a lower rate of in-hospital revascularization (45% vs 69%, P < .001) than those without LVH. On multivariate analysis, electrocardiographic LVH was an independent predictor of nonsignificant CAD (odds ratio 1.94; 95% confidence interval 1.12-3.35; P = .02). In conclusion, electrocardiographic LVH is an independent predictor of nonsignificant CAD and associated with a lower rate of in-hospital revascularization in patients with NSTEMI.

Impact of left ventricular hypertrophy on troponin release during acute myocardial infarction: new insights from a comprehensive translational study

BACKGROUND

Biomarkers are frequently used to estimate infarct size (IS) as an endpoint in experimental and clinical studies. Here, we prospectively studied the impact of left ventricular (LV) hypertrophy (LVH) on biomarker release in clinical and experimental myocardial infarction (MI).

METHODS AND RESULTS

ST-segment elevation myocardial infarction (STEMI) patients (n=140) were monitored for total creatine kinase (CK) and cardiac troponin I (cTnI) over 72 hours postinfarction and were examined by cardiac magnetic resonance (CMR) at 1 week and 6 months postinfarction. MI was generated in pigs with induced LVH (n=10) and in sham-operated pigs (n=8), and serial total CK and cTnI measurements were performed and CMR scans conducted at 7 days postinfarction. Regression analysis was used to study the influence of LVH on total CK and cTnI release and IS estimated by CMR (gold standard). Receiver operating characteristic (ROC) curve analysis was performed to study the discriminatory capacity of the area under the curve (AUC) of cTnI and total CK in predicting LV dysfunction. Cardiomyocyte cTnI expression was quantified in myocardial sections from LVH and sham-operated pigs. In both the clinical and experimental studies, LVH was associated with significantly higher peak and AUC of cTnI, but not with differences in total CK. ROC curves showed that the discriminatory capacity of AUC of cTnI to predict LV dysfunction was significantly worse for patients with LVH. LVH did not affect the capacity of total CK to estimate IS or LV dysfunction. Immunofluorescence analysis revealed significantly higher cTnI content in hypertrophic cardiomyocytes.

CONCLUSIONS

Peak and AUC of cTnI both significantly overestimate IS in the presence of LVH, owing to the higher troponin content per cardiomyocyte. In the setting of LVH, cTnI release during STEMI poorly predicts postinfarction LV dysfunction. LV mass should be taken into consideration when IS or LV function are estimated by troponin release.

The calculation of the cardiac troponin T 99th percentile of the reference population is affected by age, gender, and population selection: a multicenter study in Italy

BACKGROUND

The aim of this study is to determine the 99th upper-reference limit (URL) for cardiac troponin T (cTnT) in Italian apparently healthy subjects.

METHODS

The reference population was selected from 5 cities: Bolzano (n=290), Milano (CAMELIA-Study, n=287), Montignoso (MEHLP-Study, n=306), Pisa (n=182), and Reggio Calabria (MAREA-Study, n=535). Subjects having cardiac/systemic acute/chronic diseases were excluded. Participants to MEHLP project underwent cardiac imaging investigation. High-sensitive cTnT was measured with Cobas-e411 (Roche Diagnostics).

RESULTS

We enrolled 1600 healthy subjects [54.6% males; age range 10-90years; mean (SD): 36.4 (21.2) years], including 34.6% aged <20years, 54.5% between 20 and 64years, and 10.9% over 65years. In the youngest the 99th URL was 10.9ng/L in males and 6.8ng/L in females; in adults 23.2ng/L and 10.2ng/L; and in elderly 36.8ng/L and 28.6ng/L. After the exclusion of outliers the 99th URL values were significantly decreased (P<0.05) in particular those of the oldest (13.8ng/L and 14ng/L). MEHLP participants were divided in healthy and asymptomatic, according to known cardiovascular risk factors (HDL, LDL, glucose, C-reactive protein): the 99th URL of cTnT values of these subgroups was significantly different (19.5 vs. 22.7, P<0.05).

CONCLUSIONS

99th URL of cTnT values was strongly affected by age, gender, selection of subjects and the statistical evaluation of outliers.

Cardiac troponin I associated with the development of unrecognized myocardial infarctions detected with MRI

BACKGROUND

Late enhancement MRI (LE-MRI) and cardiac troponin I (cTnI) are sensitive methods to detect subclinical myocardial injury. We sought to investigate the relation between plasma concentrations of cTnI measured with a high-sensitivity assay (hs-cTnI) and the development of unrecognized myocardial infarctions (UMIs) detected with LE-MRI.

METHODS

After approval from the ethics committee and written informed consent were obtained, LE-MRI was performed on 248 randomly selected community-living 70-year-old volunteers and hs-cTnI was determined with a highly sensitive premarket assay. Five years later these individuals were invited to a second LE-MRI, and 176 of them (82 women, 94 men), who did not have a hospital diagnosis of MI, constitute the present study population. LE-MR images were analyzed by 2 radiologists independently and in a consensus reading, blinded to any information on previous disease or assessments.

RESULTS

New or larger UMIs were detected in 37 participants during follow-up. Plasma concentrations of hs-cTnI at 70 years of age, which were mainly within what is considered to be the reference interval, were related to new or larger UMIs at 75 years of age with an odds ratio of 1.98 per 1 unit increase in ln-transformed cTnI (95% CI, 1.17-3.35; P = 0.010). Plasma concentrations of hs-cTnI at 70 years of age were associated with the volumes of the UMIs detected at 75 years of age (P = 0.028).

CONCLUSIONS

hs-cTnI in 70-year-old community-living women and men was associated with the development of MRI-detected UMIs within 5 years.

Relation of highly sensitive cardiac troponin T in hypertrophic cardiomyopathy to left ventricular mass and cardiovascular risk

Elevated cardiac troponin can be seen in patients with left ventricular (LV) hypertrophy and in asymptomatic subjects with a high a priori risk of cardiovascular disease (CVD). In hypertrophic cardiomyopathy (HC) troponin can be detected as well, but little is known about the contribution of LV mass, on the one hand, and the long-term risk of CVD, on the other. In an observational single-center study of 62 patients with HC, without a history of CVD, we assessed the Framingham Heart 10-year risk score (FH10yrs), LV mass index (LVMI) using magnetic resonance imaging, and highly sensitive cardiac troponin T (hs-cTnT). Hs-cTnT (>3 ng/L) was detectable in 74% of patients (46 of 62). Hs-cTnT was elevated in 26% (16 of 62) of patients (ninety-ninth percentile reference limit of 14 ng/L or more). From 3 to 14 ng/L, patients were older, more often had hypertension, and the FH10yrs was higher. Hs-cTnT correlated positively with LVMI (p<0.001) and maximal wall thickness (p<0.001). In addition, LVMI and hypertension were independently associated with increasing hs-cTnT concentrations in linear regression. Using multivariate binary logistic regression, both LVMI and FH10yrs were independently associated with detectable hs-cTnT levels. In contrast, only LVMI was associated with elevated hs-cTnT levels. In conclusion, hs-cTnT was detectable in 3 quarters and elevated in a quarter of our patients with HC. Although detectable hs-cTnT is associated with both LV mass and CVD risk, elevated hs-cTnT relates to LV mass only. This indicates that hypertrophy more than the risk of CVD seems the most important drive for hs-cTnT to occur in these patients.

Elevated troponin predicts long-term adverse cardiovascular outcomes in hypertensive crisis: a retrospective study

BACKGROUND

Hypertensive crisis is associated with poor clinical outcomes. Elevated troponin, frequently observed in hypertensive crisis, may be attributed to myocardial supply-demand mismatch or obstructive coronary artery disease (CAD). However, in patients presenting with hypertensive crisis and an elevated troponin, the prevalence of CAD and the long-term adverse cardiovascular outcomes are unknown.

OBJECTIVE

We sought to assess the impact of elevated troponin on cardiovascular outcomes and evaluate the role of troponin as a predictor of obstructive CAD in patients with hypertensive crisis.

METHODS

Patients who presented with hypertensive crisis (n = 236) were screened retrospectively. Baseline and follow-up data including the event rates were obtained using electronic patient records. Those without an assay for cardiac Troponin I (cTnI) (n = 65) were excluded. Of the remaining 171 patients, those with elevated cTnI (cTnI ≥ 0.12 ng/ml) (n = 56) were compared with those with normal cTnI (cTnI < 0.12 ng/ml) (n = 115) at 2 years for the occurrence of major adverse cardiac or cerebrovascular events (MACCE) (composite of myocardial infarction, unstable angina, hypertensive crisis, pulmonary edema, stroke or transient ischemic attack).

RESULTS

At 2 years, MACCE occurred in 40 (71.4%) patients with elevated cTnI compared with 44 (38.3%) patients with normal cTnI [hazard ratio: 2.77; 95% confidence interval (CI): 1.79-4.27; P < 0.001]. Also, patients with elevated cTnI were significantly more likely to have underlying obstructive CAD (odds ratio: 8.97; 95% CI: 1.4-55.9; P < 0.01).

CONCLUSION

In patients with hypertensive crisis, elevated cTnI confers a significantly greater risk of long-term MACCE, and is a strong predictor of obstructive CAD.

Optimal fluid control can normalize cardiovascular risk markers and limit left ventricular hypertrophy in thrice weekly dialysis patients

Increased hemodialysis frequency can make fluid overload easier to treat, although most patients are still treated thrice weekly. Chronic fluid overload is associated with left ventricular hypertrophy and elevated serum cardiac biomarkers, recognized as mortality risk factors. Serum cardiac troponin T (cTnT), N-terminal prohormone brain natriuretic peptide (NT-proBNP), left ventricular mass index by cardiac magnetic imaging, and ambulatory blood pressure was measured in 30 thrice weekly hemodiafiltration patients. Time-averaged fluid overload (TAFO) was quantified by bioimpedance spectroscopy. In the study group, left ventricular hypertrophy was found to be 26% by cardiac magnetic resonance. Ambulatory blood pressure was 130 mmHg (112-151) requiring a low equivalent dose of medication of 0.25 units (0-1). Significantly, lower levels of left ventricular mass index (P < 0.05) were associated in those patients with TAFO <1 L or NT-proBNP <1200 pg/mL or cTnT <0.1 ug/L. In the subgroups, 16 patients had normal cTnT (<0.03 ug/L), 16 patients had NT-proBNP <400 pg/mL, and 20 patients had TAFO <1 L. Nine patients had both cTnT <0.03 ug/L and NT-proBNP <400 pg/mL. Normally hydrated thrice-weekly hemodiafiltration patients can have cardiac biomarker and TAFO levels indistinguishable from the normal healthy population. Obtaining TAFO by bioimpedance monitoring can offer a practical alternative to serum cardiac biomarkers.

Fluctuation of spuriously elevated troponin I: a case report

Serum troponin is a useful laboratory study for the diagnosis of acute myocardial infarction. However, elevations can also be seen in a variety of other diseases processes. Falsely positive troponin values caused by interference with current troponin assays have been reported. We report a unique case that demonstrates the fluctuation of falsely elevated troponin correlating with hemoglobin, serving as a marker of heterophile antibody levels. A 74-year-old gentleman presented to our Emergency Department with a several-day history of increasing shortness of breath associated with a new-onset chest pain and a troponin I level of 77.28 ng/mL. Throughout his stay, fluctuations in measured troponin levels correlated strongly with fluctuations in hemoglobin levels. Several investigations confirmed false elevated troponin levels secondary to heterophile antibody interference. We conclude that hemoglobin trending in our patient represented a surrogate measure of his heterophile antibody titers with time and that fluctuations in these levels correlated with respective fluctuations in the falsely elevated troponin levels.

A review of causes and systemic approach to cardiac troponin elevation

The first American College of Cardiology/European Society of Cardiology task force published recommendations for a universal definition of myocardial infarction (MI) in 2000 based on the measurement of troponin (Tn). Although this rapid and highly sensitive blood test is certainly valuable in the appropriate setting, its widespread use in variety of clinical scenarios may lead to the detection of Tn elevation in absence of thrombotic acute coronary syndrome. In 2007, the joint European Society of Cardiology/American College of Cardiology Foundation/American Heart Association/World Heart Federation task force proposed a new definition for acute MI based on detection of Tn and associated clinical evidence. The goal of this article is to review the universal definition of acute MI and to differentiate type 1 MI, type 2 MI, and non-acute coronary syndrome Tn elevations. The prognosis and a clinical approach to this differential diagnosis will be developed.

Subtle myocardial damage associated with diagnostic coronary angiography alone

AIMS

To evaluate the frequency, predictors and prognostic significance of elevation in cardiac troponin I (cTnI) after coronary angiography (CAG).

METHODS AND RESULTS

A series of 296 consecutive patients with normal pre-procedural cTnI levels and undergoing elective CAG at our centre were prospectively analysed. Positive cTnI elevation was defined as >0.06 ng/ml. Positive cTnI elevation was observed in 44 patients (14.8%), but CK-MB was elevated in only four patients (1.3%) after the procedure. The risk of cTnI elevation was independently associated with left ventricular hypertrophy (odds ratio [OR] 5.52; 95% confidence interval [CI], 2.54 to 12.02; P<0.001), inexperienced operator (OR 10.83; 95% CI, 2.47 to 47.43; P=0.002) and the amount of contrast agent (OR 1.12; 95% CI, 1.03 to 1.23; P=0.009 for each 10 ml increase), whereas it was not associated with the severity of coronary artery disease. At one year, however, postprocedural elevation of cTnI was not associated with an increased risk of death (2.3% vs. 0.8%, P=0.384) or myocardial infarction (2.3% vs. 2.0%, P=0.623).

CONCLUSIONS

A minor elevation of cTnI is observed commonly after CAG, which might be associated with left ventricular hypertrophy, operator's experience and the amount of contrast used; however, it does not influence 1-year events rates.

The utility of troponin measurement to detect myocardial infarction: review of the current findings

Myocardial infarction (MI) is defined by the presence of myocardial necrosis in combination with clinical evidence of myocardial ischemia. Cardiac troponins are regulatory proteins within the myocardium that are released into the circulation when damage to the myocyte has occurred. Therefore, serum troponin is an exquisitely sensitive marker of myocardial injury and is necessary for establishing the diagnosis of MI. High-sensitivity troponin assays are improving the diagnostic accuracy and rapid detection of myocardial infarction. The early identification of MI is vital for the institution of anti-thrombotic therapy to limit myocardial damage and preserve cardiac function. Troponin has both diagnostic and prognostic significance in the setting of acute coronary syndrome (ACS). Increased troponin levels in the absence of ACS should prompt an evaluation for an alternative, non-thrombotic mechanism of troponin elevation and direct management at the underlying cause. This review describes the role of troponin in the evaluation of patients with suspected myocardial infarction.

Prognostic utility of cardiac troponin in heart failure: a novel role for an established biomarker

Many individual variables are predictive of an increased risk of mortality and morbidity in heart failure. These include a range of data from patient demographics, clinical findings, comorbidities and invasive and noninvasive parameters. Some of these markers, for example the B-type natriuretic peptides, have been identified as independently predictive in large, robust, multivariable analyses. However, many markers have had less vigorous scrutiny and were identified in small cohorts after only univariate or limited multivariable analyses. Recently, cardiac troponins have emerged as potential biomarkers for patients with heart failure. In this article, we consider the utility of cardiac troponins in heart failure and propose what role they may play in improving the risk stratification of this disease.

Persistent cardiac troponin I elevation in stabilized patients after an episode of acute coronary syndrome predicts long-term mortality

BACKGROUND

In patients with non-ST-elevation acute coronary syndrome, any troponin elevation is associated with an increased risk for cardiovascular events. However, the prevalence and prognostic importance of persistent troponin elevation in stabilized patients after an episode of non-ST-elevation acute coronary syndrome are unknown and were therefore assessed in this study.

METHODS AND RESULTS

Cardiac troponin I (cTnI) was measured in 1092 stabilized patients at 6 weeks and 3 and 6 months after enrollment in the FRagmin and Fast Revascularization during InStability in Coronary artery disease (FRISC-II) trial. cTnI was analyzed with the Access AccuTnI assay with the application of different prognostic cutoffs. Outcomes were assessed through 5 years. Elevated cTnI levels >0.01 microg/L were found in 48% of the study patients at 6 weeks, in 36% at 6 months, and in 26% at all 3 measurements. cTnI elevation was associated with increased age and other cardiovascular high-risk features. The lowest tested cTnI cutoff (0.01 microg/L) was prognostically most useful and was independently predictive of mortality (hazard ratio, 2.1 [95% confidence interval, 1.3 to 3.3]; P=0.001) on multivariable analysis adjusted for cardiovascular risk factors and randomization to an invasive versus noninvasive treatment strategy, whereas it was related to myocardial infarction only on univariate analysis.

CONCLUSIONS

Persistent minor cTnI elevation can be detected frequently in patients stabilized after an episode of non-ST-elevation acute coronary syndrome with the use of a sensitive assay. Elevated cTnI levels >0.01 microg/L predict mortality during long-term follow-up. Our results emphasize the importance of further troponin testing in non-ST-elevation acute coronary syndrome patients after hospital discharge.

Use and Misuse of Cardiac Troponins in Clinical Practice

Cardiac troponins are very sensitive and specific markers of myocardial injury. Elevated troponin levels in the setting of acute coronary syndrome are diagnostic of acute myocardial infarction and provide guidance to clinicians with regard to appropriate use of intensive medical and revascularization therapies. However, elevated troponin levels are commonly seen in several noncoronary ischemia presentations and create considerable confusion among clinicians in these settings. In this review article, we discuss the utility of troponins in various clinical settings and present a "common sense" approach to interpreting troponin elevation outside the setting of acute coronary syndrome.

Cardiac troponin I concentration is commonly increased in nondialysis patients with CKD: experience with a sensitive assay

BACKGROUND

Cardiac troponin (cTn) concentrations commonly are increased in patients with chronic kidney disease (CKD) in the absence of an acute coronary syndrome. cTn T (cTnT) concentration reportedly is increased more commonly than cTn I (cTnI). Using a sensitive cTnI assay, we studied cTnI concentrations in predialysis patients with CKD who did not have an acute coronary event.

STUDY DESIGN

Observational cohort study.

SETTING AND PARTICIPANTS

Nondialysis patients with CKD attending an outpatient clinic.

PREDICTOR

Plasma cTnI was measured using the cTnI-Ultra assay (Bayer HealthCare LLC, Diagnostics Division, Tarrytown, NY), the same manufacturer's standard cTnI assay, and a cTnT assay (Roche Diagnostics PLC, East Sussex, UK).

OUTCOMES AND MEASUREMENTS

Prevalence of increased cTn concentration, effect of clinical variables on cTnI-Ultra concentration, and independent associations between cTn assays and all-cause mortality by using multiple regression modeling.

RESULTS

Plasma cTnI-Ultra concentration exceeded the upper limit of normal in 33% of patients compared with 18% with the cTnI-standard assay and 43% with the cTnT assay. Age, vascular disease, parathyroid hormone concentration, and left ventricular mass, but not kidney function, had independent effects on plasma cTnI-Ultra concentrations. There were 39 deaths during follow-up. Survival was decreased in patients with baseline cTnI-Ultra concentrations of 0.040 ng/mL or greater (54% versus 83%; P < 0.001), cTnI-standard concentrations of 0.07 ng/mL or greater (55% versus 78%; P = 0.02), and cTnT concentrations of 0.01 ng/mL or greater (59% versus 89%; P < 0.001). Only cTnT concentration was an independent predictor of death.

LIMITATION

Only all-cause mortality was recorded.

CONCLUSION

Using a sensitive assay, we found that the prevalence of increased cTnI concentrations in patients with CKD is similar to that observed for cTnT. cTnT concentration, but not cTnI, was independently associated with death.

Role of biochemical markers in diagnosis of myocardial infarction

An ideal cardiac biochemical marker should have not only high sensitivity but also high specificity to myocardial infarction. The creatine kinase-MB, a relatively specific cardiac marker, could be elevated in situations other than acute myocardial infarction, such as renal failure, muscular injury, and myopathy. Although these are more specific than creatine kinase-MB, cardiac troponins have also been reported to be elevated in conditions other than acute myocardial infarction, such as chronic renal failure, acute myocarditis, cardiomyopathy, congestive heart failure, pulmonary embolism, rhabdomyolysis, sepsis, and left ventricular hypertrophy. With the ongoing research in this field, future holds hopes of finding an ideally specific marker of myocardial infarction, but until then biochemical markers should be used in conjunction with clinical assessment and electrocardiography in making the diagnosis of myocardial infarction, and the patients should not be treated merely on the basis of elevated serum levels of cardiac biochemical markers.

Prevalence and determinants of troponin T elevation in the general population

BACKGROUND

The prevalence and determinants of cardiac troponin T (cTnT) elevation in the general population are unknown, and the significance of minimally increased cTnT remains controversial. Our objective was to determine the prevalence and determinants of cTnT elevation in a large, representative sample of the general population.

METHODS AND RESULTS

cTnT was measured from stored plasma samples in 3557 subjects of the Dallas Heart Study, a population-based sample. cTnT elevation (> or =0.01 microg/L) was correlated with clinical variables and cardiac MRI findings. The sample weight-adjusted prevalence of cTnT elevation in the general population was 0.7%. In univariable analyses, cTnT elevation was associated with older age, black race, male sex, coronary artery calcium by electron beam CT, a composite marker of congestive heart failure (CHF), left ventricular hypertrophy (LVH), diabetes mellitus (DM), and chronic kidney disease (CKD) (P<0.001 for each). Subjects with minimally increased (0.01 to 0.029 microg/L) and increased (> or =0.03 microg/L) cTnT had a similar prevalence of these characteristics. In multivariable logistic regression analysis, LVH, CHF, DM, and CKD were independently associated with cTnT elevation.

CONCLUSIONS

In the general population, cTnT elevation is rare in subjects without CHF, LVH, CKD, or DM, suggesting that the upper limit of normal for the immunoassay should be <0.01 microg/L. Even minimally increased cTnT may represent subclinical cardiac injury and have important clinical implications, a hypothesis that should be tested in longitudinal outcome studies.

The new definition of myocardial infarction and the impact of troponin determination on clinical practice

OBJECTIVE

To discuss the more controversial clinical and laboratory aspects in the application of the new biochemical diagnostic standard for myocardial infarction, 4 years after its introduction, and to make some suggestions, which could allow for a more realistic application of the new definition in the current clinical practice.

METHODS

Studies published in the last 4 years in the most important cardiology and laboratory medicine journals (including proceedings of the international meetings), discussing advantages and limits of the new definition of myocardial infarction, were reviewed and pertinent data were discussed and compared with similar information available in literature.

RESULTS AND CONCLUSIONS

Although the exact status of implementation of the new definition of myocardial infarction cannot yet be known, the trend toward such recommendation is evolving significantly, even if at different rates in different countries. To make the transition smoother, major educational efforts are required to disseminate the conceptual reasoning behind the new guidelines. On the other hand, more knowledge is needed for some relevant issues, such as the different analytical performance of cardiac troponin assays or the prognostic significance of biomarker changes after a percutaneous coronary intervention.

Cardiac Troponins and Renal Function in Nondialysis Patients with Chronic Kidney Disease

Background: Serum cardiac troponin concentrations are commonly increased in end-stage renal disease (ESRD) in the absence of an acute coronary syndrome (ACS). The data on cardiac troponin I (cTnI) are more variable than those for cardiac troponin T (cTnT). There is little information on cardiac troponin concentrations in patients with chronic kidney disease (CKD) who have not commenced dialysis.

Methods: We studied 222 patients: 56 had stage 3 (moderate CKD); 70 stage 4 (severe CKD); and 96 stage 5 (kidney failure). Patients underwent echocardiography and were followed prospectively for a median of 19 months; all-cause mortality was recorded.

Results: Overall, serum cTnT was increased above the 99th percentile reference limit in 43% of all CKD patients studied, compared with 18% for cTnI. Serum cTnT and cTnI concentrations were more commonly increased in the presence of more severe CKD (11 and 6 patients in stage 3, 27 and 8 in stage 4, and 57 and 24 in stage 5 (P &lt;0.0001 and &lt;0.02, respectively). Among 38 patients with detectable cTnI, 32 had detectable cTnT (rs = 0.67; P&lt;0.0001). There was evidence that decreasing estimated glomerular filtration rate increased the odds of having detectable cTnT (P &lt;0.001) but not cTnI (P = 0.128). There was no evidence to support an adjusted association of detectable cardiac troponins with increasing left ventricular mass index. Increased cTnT (P = 0.0097), but not cTnI, was associated with decreased survival.

Conclusions: Increased cTnT and cTnI concentrations are relatively common in predialysis CKD patients, in the absence of an ACS, including among those with stage 3 disease. The presence of left ventricular hypertrophy alone does not explain these data. Detectable cTnT was a marker of decreased survival.

Biochemical markers of cardiac diseases

This article reviews the current contribution of the determination of biochemical markers to clinical cardiology and discusses some important developments in this field. Biochemical markers play a pivotal role in the diagnosis and management of patients with acute coronary syndrome (ACS), as witnessed by the incorporation of cardiac troponins into new international guidelines for patients with ACS and in the redefinition of myocardial infarction. Despite the success of cardiac troponins, there is still a need for development of early markers that can reliably rule out ACS from the emergency room at presentation and detect myocardial ischemia also in the absence of irreversible myocyte injury. Under investigation are two classes of indicators: markers of early injury/ischemia and markers of coronary plaque instability and disruption. Finally, with the characterization of the cardiac natriuretic peptides, Laboratory Medicine is also assuming part in the assessment of cardiac function.