Clinical implications of high-sensitivity cardiac troponins

Effect of transitioning from conventional cardiac troponin to high-sensitivity cardiac troponin on resource utilization- a single center experience

BACKGROUND

Compared to conventional cardiac troponin (cTn), the high-sensitivity cardiac troponin (hs-cTn) assay is associated with improved detection of myocardial infarction (MI).

METHODS

We performed a descriptive retrospective analysis of resource utilization at Rush University Medical Center over the transition period (July 1, 2021) from a cTn to a hs-cTn assay. Inclusion criteria included emergency department (ED) encounters between January 1 to December 31, 2021, with chief complaints of "chest pain" or "dyspnea" with associated troponin orders. The primary endpoint was the percentage of ED discharges. Secondary endpoints included the number of cardiac studies ordered. Univariable comparisons of these endpoints were performed using Student's t-test for continuous variables and Chi-square tests for binary/categorical variables.

RESULTS

A total of 5113 encounters were analyzed. Hs-cTn was associated with an overall increase in ED patient discharges with negative troponin tests (44.1% vs. 29.9%, P < 0.01). In terms of cardiac testing per encounter, hs-cTn was associated with significant increases in the number of troponin tests (1.9 vs. 1.6, P < 0.01), electrocardiograms (3.0 vs. 2.9, P = 0.01), and echocardiograms (0.5 vs. 0.4, P < 0.01). There was a significant decrease in the utilization of stress testing (0.21 vs. 0.26, P < 0.01). There was a significant increase in total coronary angiography use during the hs-cTn period compared to cTn (227/2471 (9.2%) vs. 195/2642 (7.4%), P = 0.02).

CONCLUSION

Transitioning from cTn to hs-cTn was associated with significantly increased ED discharges and an increase in troponin tests, ECG, echocardiograms, and coronary angiograms. There was a decrease in the number of stress tests.

Trending Cardiac Biomarkers During Pregnancy in Women With Cardiovascular Disease

BACKGROUND

Clinical utility of cardiac biomarker testing during pregnancy in women with preexisting cardiac disease is not well known. We studied the levels and temporal trends of NT-proBNP (N-terminal pro-B-type natriuretic peptide) and hs-cTnI (high-sensitivity cardiac troponin I) throughout pregnancy in women with preexisting cardiac disease and sought to assess the association between NT-proBNP and hs-cTnI and pregnancy outcomes.

METHODS

Three hundred seven pregnant women with preexisting cardiac disease were prospectively recruited. Mixed-effects linear regression analysis was used to compare the NT-proBNP and hs-cTnI levels between time periods and subgroups. Logistic regression analysis adjusted for maternal age and CARPREG II (Cardiac Disease in Pregnancy) risk score assessed the association between NT-proBNP levels and adverse events.

RESULTS

Geometric mean NT-proBNP (95% CI) was stable through pregnancy with a transient significant increase with labor and delivery (101.4 pg/mL [87.1-118.1], 90.2 pg/mL [78.5-103.6], 153.6 pg/mL [126.8-186.1], and 112.2 pg/mL [94.2-133.7] for first/second trimester, third trimester, labor/delivery and postpartum, respectively). We observed a statistically significant difference in the NT-proBNP between women with preserved versus decreased systemic ventricular function, structurally normal versus abnormal heart, modified World Health Organization class 1, 2 versus modified World Health Organization class 3, 4 and no congenital heart disease versus congenital heart disease. Compared to those without events, median (interquartile range) NT-proBNP levels were significantly higher in those who had heart failure (204 pg/mL [51-450] versus 55 pg/mL [31-97]; P=0.001) and preeclampsia (98 pg/mL [40-319] versus 55 pg/mL [31-99]; P=0.027). NT-proBNP, adjusted for age and CARPREG II risk score, was significantly associated with combined heart failure and preeclampsia (adjusted odds ratio, 2.14 [95% CI, 1.48-3.10] per log NT-proBNP increase; P<0.001). NT-proBNP <200 pg/mL had a specificity of 91% and negative predictive value of 95% in predicting combined heart failure and preeclampsia.

CONCLUSIONS

NT-proBNP remains steady over the course of pregnancy with a transient increase during labor and delivery with higher levels in subgroups of stable cardiac patients. NT-proBNP level of 200 pg/mL can be used in the diagnosis of heart failure/preeclampsia in the pregnant cardiac population.

Association of Maximum Troponin Levels With Diagnosis of Acute Myocardial Infarction and Elevated Risk of Mortality

Background: Cardiac troponins I and T are highly sensitive and specific markers for acute myocardial infarction (AMI). However, a wide range of non-AMI conditions can also cause significant elevations in cardiac troponins. Given the deleterious impact of misdiagnosis of AMI, the ability to risk-stratify patients who present with an elevated troponin is paramount. We hypothesized that the maximum troponin level would be more predictive of mortality and the diagnosis of AMI than the initial troponin level or change in troponin level. Methods: Patient records from a 9-hospital system (n=30,173) in Texas were reviewed during a 24-month period in 2016-2017. Data collected for patients aged ≥40 years included International Classification of Diseases, Tenth Revision diagnoses, troponin I, demographic data (age, sex, smoking history, and chronic medical conditions), and death during hospitalization. We used logistic regression with the Firth penalized likelihood approach to determine the predictive ability of initial, maximum, and change in troponin level for mortality and the diagnosis of AMI. Results: Demographic characteristics of our cohort included a median age of 70 years, with 48.05% male and 51.95% female. The most common preexisting risk factor was hypertension in 78.81% of the cohort. Notable findings from the logistic regression include the predictive ability of maximum troponin on the odds of death by 0.7% for each unit of increase in troponin value. Also, the odds of AMI increased by 3.1% for each unit of increase in the maximum troponin value. Conclusion: Regardless of the level, a detectable amount of troponin in the serum results in a significantly elevated risk of mortality. Many patients with elevated troponin levels leave the hospital without a specific diagnosis, which can lead to poor outcomes because a detectable troponin does not represent a no-risk population. Our study demonstrates that maximum troponin level is a more sensitive and specific predictor of mortality than initial or change in troponin. Similarly, maximum troponin is the most predictive of AMI vs other causes of troponin elevation, likely because of the correlation between rising troponin levels and cardiomyocyte damage. Further studies are needed to correlate maximum troponin levels and clinical manifestations, which may be helpful in redefining AMI so that AMI can be distinguished more easily from non-AMI diagnoses.

Low risk patients with acute atrial fibrillation and elevated high-sensitivity troponin do not have increased incidence of pathological stress tests

OBJECTIVES

Many patients with atrial fibrillation (AF) or atrial flutter (AFL) and rapid ventricular response (RVR) have elevated high-sensitivity troponin T (hsTnT) values. Elevated hsTnT is an independent risk marker for cardiovascular events and mortality. The aim was to examine if AF/AFL patients with RVR and elevated hsTnT have an increased incidence of pathological cardiac stress tests, indicating need of further evaluation for coronary artery disease (CAD). Design: We prospectively included 90 AF/AFL patients without known heart failure and CAD presenting with AF/AFL and RVR. Half of the patients had elevated hsTnT (cases) and half had levels below the 99th percentile (controls). All patients were discharged in sinus rhythm. After approximately one week in sinus rhythm a new hsTnT was analysed and the patients performed a bicycle exercise stress test within the 30 day follow-up. The primary endpoint was a pathological stress test confirmed by a pathological SPECT myocardial perfusion imaging or a coronary angiography. Results: None of the controls reached the primary endpoint. Two patients (4%) out of the 45 cases reached the primary endpoint (p = .49 vs controls), but only one was found to have significant CAD at subsequent coronary angiography. Conclusion: Patients with paroxysmal AF/AFL, without a history of CAD and heart failure, who present with a RVR and minor hsTnT elevations were not found to have an increased incidence of pathological stress tests compared to patients with hsTnT values below the 99th percentile.

Short-term effects of ambient air pollution and outdoor temperature on biomarkers of myocardial damage, inflammation and oxidative stress in healthy adults

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The mechanisms whereby ambient air pollution and temperature changes promote cardiac events remain incompletely described. Seventy-three nonsmoking healthy adults (mean age 23.3, SD 5.4 years) were followed with up to four repeated visits across 15 months in Beijing in 2014–2016. Biomarkers relevant to myocardial damage (high-sensitivity cardiac troponin I [hs-cTnI]), inflammation (growth differentiation factor-15 [GDF-15]), and oxidative stress (8-hydroxy-2′-deoxyguanosine [8-OHdG]) were measured at each visit, while ambient air pollution and temperature were monitored throughout the study. Linear mixed-effects models coupled with distributed lag nonlinear models were used to assess the impacts of each exposure measure on study outcomes. During follow-up, average daily concentrations of fine particulate matter and outdoor temperature were 62.9 µg/m³ (8.1–331.0 µg/m³) and 10.1 °C (−6.5°C to 29.5°C). Serum hs-cTnI levels were detectable in 18.2% of blood samples, with 27.4% of individuals having ≥1 detectable values. Higher levels of ambient particulates and gaseous pollutants (per interquartile range) up to 14 days before clinical visits were associated with significant alterations in hs-cTnI levels of 22.9% (95% CI, 6.4, 39.4) to 154.7% (95% CI, 94.4, 215.1). These changes were accompanied by elevations of circulating GDF-15 and urinary 8-OHdG levels. Both low (5th percentile, −2.5 °C) and high (95th percentile, 24.8°C) outdoor temperatures, with breakpoint at ~13.0°C as the reference level, were also associated with elevations of hs-cTnI levels. Short-term exposure to ambient air pollution and temperature was associated with cardiac troponin, a biomarker of myocardial damage, along with increased inflammation and oxidative stress responses. These findings extend our understanding of the biological mechanisms linking pervasive environmental exposure to adverse cardiac events.

Can High-Sensitivity Troponins Predict Future Hypertension? A Systematic Literature Review

Hypertension (HT) is associated with cardiovascular events and increased mortality, and identification of persons at risk in due time is therefore important. Finding a biomarker to identify those at risk will enable early preventive treatment, and high-sensitivity cardiac troponin (hs-cTn) seems to be a highly relevant candidate. To gather the existing knowledge on the association between hs-cTn and future HT, a systematic literature review was conducted following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) reporting guidelines and using the PICOS system. Medline was searched until August 2018. Of 45 extracted papers, eleven papers were eligible for the study. None were randomized controlled trials. Three studies assessed hs-cTnI, eight studies assessed hs-cTnT. All studies found statistically significant associations between hs-cTn concentrations and future HT, but the studies included different types of blood pressure (diastolic, systolic, diurnal). Due to differences in troponin assay construction and test capability, a direct comparison of test performance in terms of specificity, sensitivity and predictive values was not possible, and a specific hs-cTn cutoff value for HT prediction could therefore not be defined. Furthermore, a number of conditions known to affect troponin concentrations (e.g. gender, renal function, and co-morbidities) were not sufficiently studied. All retrieved studies found significant associations between hs-cTn concentrations and future HT; although the findings are promising, the studies were too heterogeneous, and many conditions affecting troponin concentrations needs investigation at these low concentrations before hs-cTn can be considered a useful HT predictor.

High-sensitivity troponin assays: development and utility in a modern health-care system

Introduction: The introduction of cardiac troponin (cTn) assays have revolutionized the diagnosis and management of acute myocardial infarction in Emergency Departments worldwide. Its success has led to significant research and development investment in this area culminating in the development of newer high-sensitivity cardiac troponin assays (hs-cTn). While these newer assays allow for more rapid diagnosis by decreasing the time interval between serial data points, there is an inevitable trade off between increasing sensitivity and specificity. This review examines in detail the introduction and implementation of hs-cTN and its implications for clinical practice.Areas covered: This article reviews the history and development of high-sensitivity troponin assays and their application to clinical practice and current evidence base. It also discusses both the positive and negative aspects of the continuing increasing sensitivity of biochemical assays and the translation of this into clinical practice. Potential future developments are also discussed.Expert commentary: It is clear that there are many benefits to detecting extremely low concentration of cardiac troponin including the development of rapid rule out algorithms and the cost and time-saving advantages associated with the quicker movement of patients through the health-care system. It is important to note however that detecting troponin at very low concentrations also dramatically increases the false-positive rates and leads to a potentially large increase in invasive testing and diagnosis of myocardial infarction.

Smartphone-app based point-of-care testing for myocardial infarction biomarker cTnI using an autonomous capillary microfluidic chip with self-aligned on-chip focusing (SOF) lenses

Cardiovascular disease is one of the most common causes of mortality in the world. Most of the diagnostic processes usually require bulky instruments and trained professionals, which cannot meet the demand for fast, early and regular bedside diagnosis. In this paper, a bespoke app on a smartphone and an autonomous capillary microfluidic chip (ACMC) are combined to realize the point-of-care testing of cardiac troponin I (cTnI). The smartphone-app-ACMC platform was based on the sandwich immunofluorescence principle and featured self-aligned on-chip focusing (SOF) lenses which can avoid the complex optical coupling process. The operator only needs to introduce 100 μl sample into the ACMC, where the priming, time-delaying, mixing and washing steps for the assay can be accomplished automatically. With the help of the bespoke app and a palm-sized optical attachment, the smartphone can capture fluorescence images, process fluorescence intensity information, output detection results and save the results for long-term monitoring. Our results showed that within 12 min, the detection limit of 78 pg ml-1 and 94 pg ml-1 for cTnI was attained in buffer and spiked human serum, respectively. Our proposed platform has the potential to be applied in the POCT field especially for some resource-limited settings.