Using High-Sensitivity Cardiac Troponin T for Acute Cardiac Care

Improvement of Emergency Department Chest Pain Evaluation Using Hs-cTnT and a Risk Stratification Pathway

BACKGROUND

Chest pain is among the most common reasons for presentation to the emergency department (ED) worldwide. Additional studies on most cost-effective ways of differentiating serious vs. benign causes of chest pain are needed.

OBJECTIVES

Our study aimed to evaluate the effectiveness of a novel risk stratification pathway utilizing 5th generation high-sensitivity cardiac troponin T assay (Hs-cTnT) and HEART score (History, Electrocardiogram, Age, Risk factors, Troponin) in assessing nontraumatic chest pain patients in reducing ED resource utilization.

METHODS

A retrospective chart review was performed 6 months prior to and after the implementation of a novel risk stratification pathway that combined hs-cTnT with HEART score to guide evaluation of adult patients presenting with nontraumatic chest pain at a large academic quaternary care ED. Primary outcome was ED length of stay (LOS); secondary outcomes included cardiology consult rates, admission rates, number of ED boarders, and number of eloped patients.

RESULTS

A total of 1707 patients and 1529 patients were included pre- and postimplementation, respectively. Median overall ED LOS decreased from 317 to 286 min, an absolute reduction of 31 min (95% confidence interval 22-41 min), after pathway implementation (p < 0.001). Furthermore, cardiology consult rate decreased from 26.9% to 16.0% (p < 0.0001), rate of admission decreased from 30.1% to 22.7% (p < 0.0001), and number of ED boarders as a proportion of all nontraumatic chest pain patients decreased from 25.13% preimplementation to 18.63% postimplementation (p < 0.0001).

CONCLUSIONS

Implementation of our novel chest pain pathway improved numerous ED throughput metrics in the evaluation of nontraumatic chest pain patients.

High Baseline High-Sensitivity Cardiac Troponin T Concentrations and Risk of Index Acute Myocardial Infarction

OBJECTIVE

To evaluate the diagnostic performance of the previously recommended baseline high-sensitivity cardiac troponin T (hs-cTnT) thresholds of 52 and 100 ng/L in identifying patients at high risk of acute myocardial infarction (AMI).

PATIENTS AND METHODS

This study compared the positive predictive value (PPV) for index AMI of these high-risk hs-cTnT thresholds in adult patients in the emergency department undergoing hs-cTnT measurement.

RESULTS

The adjudicated MAyo Southwest Wisconsin 5th Gen Troponin T ImplementatiON cohort included 2053 patients, with 157 (7.6%) who received a diagnosis of AMI. The hs-cTnT concentrations of greater than 52 and greater than 100 ng/L resulted in PPVs of 41% (95% CI, 35%-48%) and 57% (95% CI, 48%-66%). In patients with chest discomfort, hs-cTnT concentrations greater than 52 ng/L resulted in a PPV of 66% (95% CI, 56%-76%) and hs-cTnT concentrations greater than 100 ng/L resulted in a PPV of 77% (95% CI, 65%-87%). The CV Data Mart Biomarker cohort included 143,709 patients, and 3003 (2.1%) received a diagnosis of AMI. Baseline hs-cTnT concentrations greater than 52 and greater than 100 ng/L resulted in PPVs of 12% (95% CI, 11%-12%) and 17% (95% CI, 17%-19%), respectively. In patients with chest pain and hs-cTnT concentrations greater than 52 ng/L, the PPV for MI was 17% (95% CI, 15%-18%) and in those with concentrations greater than 100 ng/L, only 22% (95% CI, 19%-25%).

CONCLUSION

In unselected patients undergoing hs-cTnT measurement, the hs-cTnT thresholds of greater than 52 and greater than 100 ng/L provide suboptimal performance for identifying high-risk patients. In patients with chest discomfort, an hs-cTnT concentration of greater than 100 ng/L, but not the European Society of Cardiology-recommended threshold of greater than 52 ng/L, provides an acceptable performance but should be used only with other clinical features.

Serial high sensitivity troponin sampling in patients with SARS-CoV-2 infection

INTRODUCTION

Multiple studies have investigated the role of cardiac troponin (cTn) in the risk stratification of patients with COVID-19. Most of these investigations are based on cTn values at presentation and do not consider the prognostic significance of cTn changes over time. This study aimed to investigate the prognostic role of serial cTn measurements in patients hospitalized with COVID-19 with samples that were not obtained for clinical indications.

METHODS

Patients hospitalized between April 2020 and March 2021 with PCR-confirmed SARS-CoV-2 infection were evaluated. Blood samples collected for any reason were stored for subsequent analysis. If clinical high sensitivity hs-cTnT (Roche) was not measured, samples were tested separately in batches. Hs-cTnI (Abbott) was also evaluated.

RESULTS

There were 228 unique patients. There were 21 (9.2 %) deaths. No patient with a low hs-cTnT (<6 ng/L) died and 1 patient with low hs-cTnI (<5 ng/L) died. Myocardial injury was associated with higher odds of death, when defined by hs-cTnT (OR: 7.88, 95 % CI: 2.04-30.40, p = 0.003) or hs-cTnI (OR: 7.46, 95 % CI: 2.68-20.77, p < 0.001). This association remained after propensity weighting. An increasing pattern was associated with higher odds of death compared to a stable pattern for hs-cTnT (OR: 5.45, 95 % CI: 1.81-16.40, p = 0.003) and hs-cTnI (OR: 4.49, 95 % CI: 1.02-19.81, p = 0.048). Among patients with myocardial injury defined by hs-cTnT, an increasing pattern was associated with higher odds of death compared to a decreasing pattern (OR: 4.80, 95 % CI: 1.16-19.97, p = 0.031).

CONCLUSIONS

Patients hospitalized with COVID-19 with myocardial injury have higher odds of death. Serial hs-cTn testing provides additional risk stratification in these patients.

Clinical Biochemistry of Serum Troponin

Accurate measurement and interpretation of serum levels of troponin (Tn) is a central part of the clinical workup of a patient presenting with chest pain suspicious for acute coronary syndrome (ACS). Knowledge of the molecular characteristics of the troponin complex and test characteristics of troponin measurement assays allows for a deeper understanding of causes of false positive and false negative test results in myocardial injury. In this review, we discuss the molecular structure and functions of the constituent proteins of the troponin complex (TnT, TnC, and TnI); review the different isoforms of Tn and where they are from; survey the evolution of clinical Tn assays, ranging from first-generation to high-sensitivity (hs); provide a primer on statistical interpretation of assay results based on different clinical settings; and discuss potential causes of false results. We also summarize the advances in technologies that may lead to the development of future Tn assays, including the development of point of care assays and wearable Tn sensors for real-time continuous measurement.

Use of the HEAR Score for 30-Day Risk-Stratification in Emergency Department Patients

BACKGROUND

The 2021 American College of Cardiology/American Heart Association chest pain guidelines recommend risk scores such as HEAR (History, Electrocardiogram, Age, Risk factors) for short-term risk stratification, yet limited data exist integrating them with high-sensitivity cardiac troponin T (hs-cTnT).

METHODS

Retrospective, multicenter (n = 2), observational, US cohort study of consecutive emergency department patients without ST-elevation myocardial infarction who had at least one hs-cTnT (limit of quantitation [LoQ] <6 ng/L, and sex-specific 99th percentiles of 10 ng/L for women and 15 ng/L for men) measurement on clinical indications in whom HEAR scores (0-8) were calculated. The composite major adverse cardiovascular event (MACE) outcome was 30-day prognosis.

RESULTS

Among 1979 emergency department patients undergoing hs-cTnT measurement, 1045 (53%) were low risk (0-3), 914 (46%) intermediate risk (4-6), and 20 (1%) high risk (7-8) based on HEAR scores. HEAR scores were not associated with increased risk of 30-day MACE in adjusted analyses. Patients with quantifiable hs-cTnT (LoQ-99th) had an increased risk for 30-day MACE (3.4%) irrespective of HEAR scores. Those with serial hs-cTnT <99th percentile remained at low risk (range 0%-1.2%) across all HEAR score strata. Higher scores were not associated with long-term (2-year) events.

CONCLUSIONS

HEAR scores are of limited value in those with baseline hs-cTnT 99th percentile to define short-term prognosis. In those with baseline quantifiable hs-cTnT within the reference range (<99th percentile), a higher risk (>1%) for 30-day MACE exists even in those with low HEAR scores. With serial hs-cTnT measurements, HEAR scores overestimate risk when hs-cTnT remains <99th percentile.

Contrasting the potential benefits of early invasive coronary angiography in acute and chronic myocardial injury patterns

BACKGROUND

In cases of evolving myocardial injury not definitively attributed to coronary ischaemia precipitated by plaque rupture, referral for invasive coronary angiography (ICA) may be influenced by observed troponin profiles. We sought to explore association between early ICA and elevated high-sensitivity troponin T (hs-cTnT) concentrations with and without dynamic changes, to examine if there may be a hs-cTnT threshold associated with benefit from an initial ICA strategy.

METHODS

Using published studies (hs-cTnT study n = 1937, RAPID-TnT study n = 3270) and the Fourth Universal Definition of Myocardial Infarction (MI), index presentations of patients with hs-cTnT concentrations 5-14ng/L were classified as 'non-elevated' (NE). Hs-cTnT greater than upper reference limit (14ng/L) were classified as 'elevated hs-cTnT with dynamic change' (encompassing acute myocardial injury, Type 1 MI, and Type 2 MI), or 'non-dynamic hs-cTnT elevation' (chronic myocardial injury). Patients with hs-cTnT <5ng/L and/or eGFR<15mmol/L/1.73m2 were excluded. ICA was performed within 30 days of admission. Primary outcome was defined as composite endpoint of death, MI, or unstable angina at 12 months.

RESULTS

Altogether, 3620 patients comprising 837 (23.1%) with non-dynamic hs-cTnT elevations and 332 (9.2%) with dynamic hs-cTnT elevations were included. Primary outcome was significantly higher with dynamic and non-dynamic hs-cTnT elevations (Dynamic: HR: 4.13 95%CI:2.92-5.82; p<0.001 Non-dynamic: HR: 2.39 95% confidence interval [CI]:1.74-3.28, p<0.001). Hs-cTnT thresholds where benefit from initial ICA strategy appeared to emerge was observed at 110ng/L and 50ng/L in dynamic and non-dynamic elevations, respectively.

CONCLUSION

Early ICA appears to portend benefit in hs-cTnT elevations with and without dynamic changes, and at lower hs-cTnT threshold in non-dynamic hs-cTnT elevation. Differences compel further investigation.

Risk factor associations with individual myocardial infarction subtypes and acute non-ischemic myocardial injury in the Multi-Ethnic Study of Atherosclerosis (MESA): Design and rationale

BACKGROUND

Despite different prevalence, pathobiology, and prognosis between etiologically distinct myocardial infarction (MI) subtypes, prospective study of risk factor for MI in large NHLBI-sponsored cardiovascular cohorts is limited to acute MI as a singular entity. Therefore, we sought to utilize the Multi-Ethnic Study of Atherosclerosis (MESA), a large prospective primary prevention cardiovascular study, to define the incidence and risk factor profile of individual myocardial injury subtypes.

METHODS

We describe the rationale and design of re-adjudicating 4,080 events that occurred over the first 14 years of follow-up in MESA for the presence and subtype of myocardial injury as defined by the Fourth Universal Definition of MI: MI type 1 to 5, acute non-ischemic myocardial injury, and chronic myocardial injury. The project utilizes a 2-physician adjudication process via examination of medical records, abstracted data collection forms, cardiac biomarker results, and electrocardiograms of all relevant clinical events. Comparison of the magnitude and direction of associations between baseline traditional and novel cardiovascular risk factors with incident and recurrent acute MI subtypes and acute non-ischemic myocardial injury events will be made.

CONCLUSIONS

This project will result in one of the first large prospective cardiovascular cohort with modern classification of acute MI subtypes, as well as a full accounting of non-ischemic myocardial injury events, with implications for numerous ongoing and future studies in MESA. By creating precise MI phenotypes, and defining their epidemiology, this project will allow for discovery of novel pathobiology-specific risk factors, allow for development of more accurate risk prediction, and suggest more targeted preventive strategies.

Diagnosis and prognosis of type 2 myocardial infarction using objective evidence of acute myocardial ischemia: a validation study

BACKGROUND

Differentiating type 2 myocardial infarction from myocardial injury can be difficult. In addition, the presence of objective evidence of myocardial ischemia may facilitate identification of high-risk type 2 myocardial infarction patients.

METHODS

Observational cohort study of adult emergency department patients undergoing hs-cTnT measurement. Patients with ≥1 hs-cTnT>99th percentile were adjudicated following the Fourth Universal Definition of Myocardial Infarction. Patients were categorized as "subjective type 2 myocardial infarction" when ischemic symptoms were the lone criteria supporting type 2 myocardial infarction, or "objective type 2 myocardial infarction" when there was ≥1 objective clinical feature (electrocardiography, imaging, angiography) of acute myocardial ischemia. The primary outcome was mortality.

RESULTS

A total of 857 patients were included, amongst which 55 (6.4%) were classified as subjective type 2 myocardial infarction, 36 (4.2%) as objective type 2 myocardial infarction, and 702 (82%) as myocardial injury. Those with objective type 2 myocardial infarction had a higher risk of mortality during the index presentation (17% vs. 1.7%, p<0.0001; HR 11.1 95% CI 3.7-33.4) and at 2-year follow-up (47% vs. 31%, p=0.04; HR 1.92, 95% CI 1.17-3.14) than those with myocardial injury. Objective type 2 myocardial infarction had a higher mortality than subjective type 2 myocardial infarction at index presentation (17% vs. 2.0%, p=0.01) and at 1- (25% vs. 9.1%, p=0.04) and 3-months (31% vs. 13%, p=0.04) follow-up. There were no mortality differences between subjective type 2 myocardial infarction and myocardial injury.

CONCLUSION

In patients diagnosed with type 2 myocardial infarction, those with objective evidence of myocardial ischemia have significantly worse outcomes compared to those with myocardial injury and subjective type 2 myocardial infarction. A more rigorous type 2 myocardial infarction definition that emphasizes these criteria may facilitate diagnosis and risk-stratification.

Use and Prognostic Implications of Cardiac Troponin in COVID-19

Myocardial injury is common in patients with COVID-19 and is associated with an adverse prognosis. Cardiac troponin (cTn) is used to detect myocardial injury and assist with risk stratification in this population. SARS-CoV-2 infection can play a role in the pathogenesis of acute myocardial injury due to both direct and indirect damage to the cardiovascular system. Despite the initial concerns about an increased incidence of acute myocardial infarction (MI), most cTn increases are related to chronic myocardial injury due to comorbidities and/or acute nonischemic myocardial injury. This review will discuss the latest findings on this topic.

High-Sensitivity Cardiac Troponin T Elevation in Hypertrophic Cardiomyopathy Is Associated With Ventricular Arrhythmias

OBJECTIVE

To investigate the relationship between high-sensitivity cardiac troponin T (hs-cTnT) levels and sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy (HCM).

METHODS

A referral HCM population with prospectively obtained hs-cTnT concentration from March 1, 2018, to April 23, 2020, was reviewed. Patients with end-stage renal disease or an abnormal hs-cTnT level not collected in an outpatient protocolled fashion were excluded. The hs-cTnT level was compared with demographic characteristics, comorbidities, conventional HCM-associated SCD risk factors, imaging, exercise testing, and prior cardiac events.

RESULTS

Of 112 included patients, 69 (62%) had an elevated hs-cTnT concentration. The level of hs-cTnT correlated with known risk factors for SCD, including nonsustained ventricular tachycardia (P=.049) and septal thickness (P=.02). When patients were stratified by having a normal vs an elevated hs-cTnT concentration, patients with elevated hs-cTnT concentration were more likely to have experienced an implantable cardioverter-defibrillator discharge for ventricular arrhythmia, ventricular arrhythmia with hemodynamic instability, or cardiac arrest (incidence rate ratio, 2.96; 95% CI, 1.11 to 10.2). When sex-specific hs-cTnT cutoffs were removed, this association was no longer present (incidence rate ratio, 1.50; 95% CI, 0.66 to 3.60).

CONCLUSION

In a protocolized, outpatient HCM population, hs-cTnT elevations were common and were associated with more arrhythmic expressivity of the HCM substrate as indicated by previous ventricular arrhythmias and appropriate implantable cardioverter-defibrillator shocks only when sex-specific hs-cTnT cutoffs were used. Further research should use different hs-cTnT reference values by sex to determine whether an elevated hs-cTnT value is an independent risk factor for SCD in patients with HCM.

Artificial intelligence-augmented electrocardiography for left ventricular systolic dysfunction in patients undergoing high-sensitivity cardiac troponin T

AIMS

Our goal was to evaluate a previously validated artificial intelligence-augmented electrocardiography (AI-ECG) screening tool for left ventricular systolic dysfunction (LVSD) in patients undergoing high-sensitivity-cardiac troponin T (hs-cTnT).

METHODS AND RESULTS

Retrospective application of AI-ECG for LVSD in emergency department (ED) patients undergoing hs-cTnT. AI-ECG scores (0-1) for probability of LVSD (left ventricular ejection fraction ≤ 35%) were obtained. An AI-ECG score ≥0.256 indicates a positive screen. The primary endpoint was a composite of post-discharge major adverse cardiovascular events (MACEs) at two years follow-up. Among 1977 patients, 248 (13%) had a positive AI-ECG. When compared with patients with a negative AI-ECG, those with a positive AI-ECG had a higher risk for MACE [48 vs. 21%, P < 0.0001, adjusted hazard ratio (HR) 1.39, 95% confidence interval (CI) 1.11-1.75]. This was largely because of a higher rate of deaths (32 vs. 14%, P < 0.0001; adjusted HR 1.26, 95% 0.95-1.66) and heart failure hospitalizations (26 vs. 6.1%, P < 0.001; adjusted HR 1.75, 95% CI 1.25-2.45). Together, hs-cTnT and AI-ECG resulted in the following MACE rates and adjusted HRs: hs-cTnT < 99th percentile and negative AI-ECG: 116/1176 (11%; reference), hs-cTnT < 99th percentile and positive AI-ECG: 28/107 (26%; adjusted HR 1.54, 95% CI 1.01-2.36), hs-cTnT > 99th percentile and negative AI-ECG: 233/553 (42%; adjusted HR 2.12, 95% CI 1.66, 2.70), and hs-cTnT > 99th percentile and positive AI-ECG: 91/141 (65%; adjusted HR 2.83, 95% CI 2.06, 3.87).

CONCLUSION

Among ED patients evaluated with hs-cTnT, a positive AI-ECG for LVSD identifies patients at high risk for MACE. The conjoint use of hs-cTnT and AI-ECG facilitates risk stratification.

Structural Cardiac Abnormalities in Patients with Atrial Fibrillation/Flutter and Myocardial Injury

BACKGROUND

High-sensitivity cardiac troponin (hs-cTnT) is often increased in patients with atrial fibrillation/flutter, portending a poor prognosis. The etiologies for these increases have not been systematically investigated. Our aim was to define prevalence/significance of structural cardiac abnormalities in patients with atrial fibrillation/flutter and high-sensitivity cardiac troponin T (hs-cTnT) increases.

METHODS

This is a retrospective observational cohort study of patients with atrial fibrillation/flutter diagnosis with hs-cTnT measurements, echocardiograms, and coronary angiograms. Myocardial injury was defined as hs-cTnT >10 ng/L for women and >15 ng/L for men. Cases with myocardial injury were adjudicated according to the Fourth Universal Definition of Myocardial Infarction.

RESULTS

Patients with definite causes for increased hs-cTnT (n = 875) were tabulated but not evaluated further; common diagnoses were type 1 myocardial infarction, critical illness, and known heart failure. Of the remaining 401, increased hs-cTnT was present in 336 (84%) patients. Of those, 78% had nonischemic myocardial injury, the remaining (n = 75, 22%) had type 2 myocardial infarction. Patients with elevated hs-cTnT had greater left ventricular mass index, left ventricular filling pressures, and right ventricular systolic pressure. They more frequently had significant coronary artery disease (47% vs 31%, P = .016), especially in type 2 myocardial infarction. With logistic regression, age, sex (F), diabetes, left ventricular mass index, e' medial velocity, and right ventricular systolic pressure were independent determinants of myocardial injury. One-year mortality was higher in patients with myocardial injury.

CONCLUSIONS

Structural heart abnormalities are common in patients with atrial fibrillation/flutter and increased hs-cTnT. Causes of myocardial injury should be elucidated in each patient to craft appropriate therapies.

Absence of Significant Myocardial Injury following Elective Direct Current Cardioversion for Atrial Fibrillation

Background

Direct current (DC) cardioversion is used to terminate cardiac arrhythmias. Current guidelines list cardioversion as a cause of myocardial injury.

Objective

This study determined whether external DC cardioversion results in myocardial injury measured by serial changes in high-sensitivity cardiac troponin T (hs-cTnT) and high-sensitivity cardiac troponin I (hs-cTnI).

Methods

This was a prospective study of patients undergoing elective external DC cardioversion for atrial fibrillation. hs-cTnT and hs-cTnI were measured precardioversion and at least 6 hours postcardioversion. Myocardial injury was present when there were significant changes in both hs-cTnT and hs-cTnI.

Results

Ninety-eight subjects were analyzed. Median cumulative energy delivered was 121.9 (interquartile range [IQR] 102.2-302.7) J. Multiple cases 23 (23.5%) required 300 J or more. Maximum cumulative energy delivered was 2455.1 J. There were small significant changes in both hs-cTnT (median precardioversion 12 [IQR 7-19) ng/L], median postcardioversion 13 [IQR 8-21] ng/L; P < .001) and hs-cTnI (median precardioversion 5 [IQR 3-10) ng/L], median postcardioversion 7 [IQR 3.6-11) ng/L; P < .001). Results were similar in patients with high-energy shocks and did not vary based on precardioversion values. Only 2 (2%) cases met criteria for myocardial injury.

Conclusion

DC cardioversion resulted in a small but statistically significant changes in hs-cTnT and hs-cTnI in 2% of patients studied irrespective of shock energy. Patients with marked troponin elevations after elective cardioversion should be assessed for other causes of myocardial injury. It should not be assumed the myocardial injury was from the cardioversion.

High-Sensitivity Cardiac Troponin and the 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guidelines for the Evaluation and Diagnosis of Acute Chest Pain

The 2021 American Heart Association/American College of Cardiology/American Society of Echocardiography/American College of Chest Physicians/Society for Academic Emergency Medicine/Society of Cardiovascular Computed Tomography/Society for Cardiovascular Magnetic Resonance guidelines for the evaluation and diagnosis of acute chest pain make important recommendations that include the recognition of high-sensitivity cardiac troponin (hs-cTn) as the preferred biomarker, endorsement of 99th percentile upper reference limits to define myocardial injury, and the use of clinical decision pathways, as well as acknowledgment of the uniqueness of women and other patient subsets. Details on how to integrate hs-cTn into clinical practice are less extensively addressed. Clinicians should be aware of some of the analytical aspects related to hs-cTn assays regarding the limit of detection and the limit of quantitation and how they are used clinically, especially for the single sample strategy to rule out acute myocardial infarction. Likewise, it is important for clinicians to understand issues related to the derivation of the 99th percentile upper reference limit; the value of sex-specific 99th percentile upper reference limits; how to use changing concentrations (deltas) to facilitate diagnosis and risk stratification of patients with suspected acute coronary syndrome, including the differentiation of acute from chronic myocardial injury; and how to best integrate the use of hs-cTn with clinical decision pathways. With the use of hs-cTn, conditions such as type 2 myocardial infarction become more common, whereas others such as unstable angina become less frequent but still occur. Sections relating to these issues are included.

Major adverse cardiovascular events after diagnosis of myocardial injury and types 1 and 2 myocardial infarction

AIMS

Limited US outcome data exist among patients with myocardial injury and types 1 and 2 myocardial infarction (MI) evaluated with high-sensitivity cardiac troponin (hs-cTn).

METHODS AND RESULTS

This is an observational US cohort study of emergency department (ED) patients undergoing hs-cTnT measurement. Cases with ≥1 hs-cTnT increase >99th percentile were adjudicated following the Fourth Universal Definition of MI. Post-discharge major adverse cardiovascular events (MACE) included death, MI, heart failure (HF) hospitalization, stroke or transient ischaemic attack, and new-onset atrial fibrillation or flutter during 2 years follow-up. Among 2002 patients, 857 (43%) had ≥1 hs-cTnT >99th percentile. Among these, 702 (81.9%) had myocardial injury, 64 (7.5%) had type 1 MI, and 91 (10.6%) had type 2 MI. Compared with patients without myocardial injury, type 2 MI [8.4 vs. 50%; adjusted hazard ratio (HR) 2.31, 95% confidence interval (CI) 1.49-3.58] and myocardial injury (8.4 vs. 47%; adjusted HR 3.13, 95% CI 2.39-4.09) had a higher risk of MACE, in large part because of death and HF hospitalizations. Compared with patients with type 1 MI, type 2 MI (23 vs. 50%; adjusted HR 2.24; 95% CI 1.23-4.10) and myocardial injury (23 vs. 47%; adjusted HR 2.02; 95% CI 1.20-3.40) also have a higher risk of MACE.

CONCLUSION

Among unselected US ED patients undergoing hs-cTnT measurement, most increases are due to myocardial injury, and type 2 MI is more frequent than type 1 MI. Patients with myocardial injury and type 2 MI have morbid outcomes, in large part due to death and HF.

Late Outcomes of Patients With Prehospital ST-Segment Elevation and Appropriate Cardiac Catheterization Laboratory Nonactivation

Background Patients with suspected ST-segment-elevation myocardial infarction (STEMI) and cardiac catheterization laboratory nonactivation (CCL-NA) or cancellation have reportedly similar crude and higher adjusted risks of death compared with those with CCL activation, though reasons for these poor outcomes are not clear. We determined late clinical outcomes among patients with prehospital ECG STEMI criteria who had CCL-NA compared with those who had CCL activation. Methods and Results We identified consecutive prehospital ECG transmissions between June 2, 2010 to October 6, 2016. Diagnoses according to the Fourth Universal Definition of myocardial infarction (MI), particularly rates of myocardial injury, were adjudicated. The primary outcome was all-cause death. Secondary outcomes included cardiovascular death/MI/stroke and noncardiovascular death. To explore competing risks, cause-specific hazard ratios (HRs) were obtained. Among 1033 included ECG transmissions, there were 569 (55%) CCL activations and 464 (45%) CCL-NAs (1.8% were inappropriate CCL-NAs). In the CCL activation group, adjudicated index diagnoses included MI (n=534, 94%, of which 99.6% were STEMI and 0.4% non-STEMI), acute myocardial injury (n=15, 2.6%), and chronic myocardial injury (n=6, 1.1%). In the CCL-NA group, diagnoses included MI (n=173, 37%, of which 61% were non-STEMI and 39% STEMI), chronic myocardial injury (n=107, 23%), and acute myocardial injury (n=47, 10%). At 2 years, the risk of all-cause death was higher in patients who had CCL-NA compared with CCL activation (23% versus 7.9%, adjusted risk ratio, 1.58, 95% CI, 1.24-2.00), primarily because of an excess in noncardiovascular deaths (adjusted HR, 3.56, 95% CI, 2.07-6.13). There was no significant difference in the adjusted risk for cardiovascular death/MI/stroke between the 2 groups (HR, 1.23, 95% CI, 0.87-1.73). Conclusions CCL-NA was not primarily attributable to missed STEMI, but attributable to "masquerading" with high rates of non-STEMI and myocardial injury. These patients had worse late outcomes than patients who had CCL activation, mainly because of higher rates of noncardiovascular deaths.

Rapid Exclusion of Acute Myocardial Injury and Infarction with a Single High Sensitivity Cardiac Troponin T in the Emergency Department: a Multicenter United States Evaluation

BACKGROUND

There are good data to support using a single high-sensitivity cardiac troponin T (hs-cTnT) below the limit of detection (LoD) of 5 ng/L to exclude acute myocardial infarction. Per the United States (US) Food and Drug Administration (FDA), hs-cTnT can only report to the limit of quantitation (LoQ) of 6 ng/L, a threshold for which there is limited data. Our goal was to determine whether a single hs-cTnT below the LoQ of 6 ng/L is a safe strategy to identify patients at low-risk for acute myocardial injury and infarction.

METHODS

The efficacy (proportion identified as low-risk based on baseline hs-cTnT<6 ng/L) of identifying low-risk patients was examined in a multicenter (n=22 sites) US cohort study of emergency department patients undergoing at least one hs-cTnT (CV Data Mart Biomarker cohort). We then determined the performance of a single hs-cTnT<6 ng/L (biomarker alone) to exclude acute myocardial injury (subsequent hs-cTnT >99^th percentile in those with an initial hs-cTnT<6 ng/L). The clinically intended rule-out strategy combining a nonischemic electrocardiogram with a baseline hs-cTnT<6 ng/L was subsequently tested in an adjudicated cohort in which the diagnostic performance for ruling-out acute myocardial infarction and safety (myocardial infarction or death at 30-days) were evaluated.

RESULTS

A total of 85,610 patients were evaluated in the CV Data Mart Biomarker cohort, amongst which 24,646 (29%) had a baseline hs-cTnT<6 ng/L. Women were more likely than men to have hs-cTnT<6 ng/L (38% vs. 20%, p<0.0001). Among 11,962 patients with baseline hs-cTnT<6 ng/L and serial measurements, only 1.2% developed acute myocardial injury, resulting in a negative predictive value of 98.8% (95% CI 98.6, 99.0) and sensitivity of 99.6% (95% CI 99.5, 99.6). In the adjudicated cohort, a nonischemic electrocardiogram with hs-cTnT<6 ng/L identified 33% of patients (610 of 1849) as low-risk and resulted in a negative predictive value and sensitivity of 100% and a 30-day rate of 0.2% for 30-day myocardial infarction or death.

CONCLUSIONS

A single hs-cTnT below the LoQ of 6 ng/L is a safe and rapid method to identify a substantial number of patients at very low risk for acute myocardial injury and infarction.

High-Sensitivity Troponin T Testing for Pediatric Patients in the Emergency Department

Debate exists on the usefulness of high-sensitivity cardiac troponin (hs-cTn) testing in pediatric patients due to the perceived low incidence of myocardial injury and lack of data concerning its efficacy. We evaluated the contribution of an increased hs-cTnT above the 99th percentile upper-reference limit (URL) to clinical diagnoses made in pediatric patients presenting to the emergency department (ED). Retrospective cohort study including patients aged 0-18 years presenting to the ED from 2018 to 2020 where hs-cTnT was measured. Sex-specific 99th percentile URLs of 15 and 10 ng/L for males and females, respectively, were used, with concentrations above these thresholds considered indicative of myocardial injury. Overall, 356 patients were identified in whom hs-cTnT concentrations were measured during ED clinical evaluation. Hs-cTnT was increased above the 99th percentile on presentation in 36 patients (10.1%). Twelve patients (3.4%) had a clinical cardiac diagnosis made. Hs-cTnT was increased in 6 of these (50.0%). Serial hs-cTnT from 106 patients with an initial hs-cTnT < 99th percentile was subsequently elevated in 5 (4.6%); none of whom had a final clinical cardiac diagnosis. Hs-cTnT has high specificity, but low sensitivity when used as a screening tool for myocardial injury when the gold standard is mostly clinical assessment. In present practice, however, they do not appear to track well with clinical diagnoses. Further studies are needed to more clearly define the role of hs-cTnT in this patient population.

Distinct etiologies of high-sensitivity troponin T elevation predict different mortality risks for patients hospitalized with COVID-19

Background

Cardiovascular events in the context of COVID-19 infection increase the risk of negative patient outcomes, but large cohort studies describing this association are limited. The purpose of the current study was to investigate the potential associations between cardiovascular events and mortality in patients hospitalized due to COVID-19.

Methods

A retrospective chart review was performed in 2450 patients hospitalized for confirmed COVID-19 infection within a single hospital network between March 15 and June 15, 2020. Logistic regression analysis was used to identify predictors of mortality.

Results

In the study population, 57% of patients had elevated high sensitivity troponin (hs-TnT) levels. Acute heart failure occurred in 23% of patients and arrhythmias were observed in 8% of patients. Of the 1401 patients with elevated hs-TnT levels, a primary cardiac etiology (e.g., myocardial infarction) was identified in 653 (47%) patients. In the remaining 748 (53%) patients, there was evidence of a primary non-cardiac etiology for hs-TnT elevation such as renal failure (n = 304) and critical illness (n = 286). Elevated hs-TnT was associated with increased risk of mortality. A significantly higher mortality rate was observed for hs-TnT elevation associated with a primary cardiac etiology (OR 4.6, 95% CI: 2.7–7.6; P < 0.001) than a primary non-cardiac etiology (OR 2.7, 95% CI: 1.6–4.5; P < 0.001).

Conclusions

Elevated hs-TnT in the context of COVID-19 infection is associated with a significantly increased mortality risk. Hs-TnT elevation in the context of a primary cardiac etiology confers a nearly 2-fold higher mortality risk than hs-TnT elevation due to a primary non-cardiac etiology.

Pathology: Hub and Integrator of Modern, Multidisciplinary [Precision] Oncology

Every profession has an essential, behind-the-scenes component without which it cannot function. Medicine is no exception. Pathologists are one of medicine's group of specialists whose work as diagnosticians is critical for patient care. This article describes the multifaceted role that pathologists play in oncology practice and cancer research. To do so, we will highlight the role of pathologists in a typical "day-in-the-life" of a patient's journey in cancer care. Clinicians, clinical trialists, radiologists, researchers, and pathologists, all work together to provide optimal, multidisciplinary care for patients with cancer.

Analytical and Clinical Considerations in Implementing the Roche Elecsys Troponin T Gen 5 STAT Assay

OBJECTIVES

To evaluate the analytical and clinical performance characteristics of the fifth-generation troponin T reagent.

METHODS

Troponin T was measured in 2,332 paired serum and plasma samples from emergency department and hospital patients using the fourth- and fifth-generation reagents. Testing was repeated after recentrifugation to determine the frequency of analytical outliers and percentage of patients with elevated values for each assay. We conducted separate experiments to determine the effects of biotin and hemolysis interference, as well as measure interinstrument variability, for fifth-generation troponin T.

RESULTS

Analytic outliers occurred more frequently using the fifth-generation reagent (3.4%) compared with the fourth-generation reagent (1.0%). The frequency of elevated troponin T above the 99th percentile upper reference limit was 26% for the fourth-generation reagent and 52% for the fifth-generation reagent. Clinically significant assay interference by biotin was observed at 20 ng/mL, but hemolysis interference was not observed until an H index of 150. Instrument-to-instrument variability between e411 and e601/602 instrument platforms is predicted to confound clinical interpretation of troponin changes.

CONCLUSIONS

Analytical outliers and instrument-to-instrument variability are the two analytical variables most likely to confound interpretation of changes in fifth-generation troponin T results over time.

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.

High-Sensitivity Cardiac Troponin T for the Detection of Myocardial Injury and Risk Stratification in COVID-19

BACKGROUND

Limited data exist on high-sensitivity cardiac troponin (hs-cTn) for risk-stratification in COVID-19.

METHODS

We conducted a multicenter, retrospective, observational, US-based study of COVID-19 patients undergoing hs-cTnT. Outcomes included short-term mortality (in-hospital and 30-days post-discharge) and a composite of major adverse events, including respiratory failure requiring mechanical ventilation, cardiac arrest, and shock within the index presentation and/or mortality during the index hospitalization or within 30-days post-discharge.

RESULTS

Among 367 COVID-19 patients undergoing hs-cTnT, myocardial injury was identified in 46%. They had a higher risk for mortality (20% vs 12%, P < 0.0001; unadjusted HR 4.44, 95% CI 2.13-9.25, P < 0.001) and major adverse events (35% vs. 11%, P < 0.0001; unadjusted OR 4.29, 95% CI 2.50-7.40, P < 0.0001). Myocardial injury was associated with major adverse events (adjusted OR 3.84, 95% CI 2.00-7.36, P < 0.0001) but not mortality. Baseline (adjusted OR 1.003, 95% CI 1.00-1.007, P = 0.047) and maximum (adjusted OR 1.005, 95% CI 1.001-1.009, P = 0.0012) hs-cTnT were independent predictors of major adverse events. Most (95%) increases were due to myocardial injury, with 5% (n = 8) classified as type 1 or 2 myocardial infarction. A single hs-cTnT <6 ng/L identified 26% of patients without mortality, with a 94.9% (95% CI 87.5-98.6) negative predictive value and 93.1% sensitivity (95% CI 83.3-98.1) for major adverse events in those presenting to the ED.

CONCLUSIONS

Myocardial injury is frequent and prognostic in COVID-19. While most hs-cTnT increases are modest and due to myocardial injury, they have important prognostic implications. A single hs-cTnT <6 ng/L at presentation may facilitate the identification of patients with a favorable prognosis.

Circulating microRNAs after a 24-h ultramarathon run in relation to muscle damage markers in elite athletes

Ultra-endurance sports are growing in popularity but can be associated with adverse health effects, such as exercise-induced muscle damage (EIMD), which can lead to exertional rhabdomyolysis. Circulating microRNAs (miRNAs) may be useful to approach the degree of EIMD. We aimed to (1) investigate the relevance of circulating miRNAs as biomarkers of muscle damage and (2) examine the acute response of skeletal/cardiac muscle and kidney biomarkers to a 24-h run in elite athletes. Eleven elite athletes participated in the 24-h run World Championships. Counter-movement jump (CMJ), creatine kinase (CK), myoglobin (Mb), creatinine (Cr), high-sensitive cardiac troponin T (hs-cTnT), and muscle-specific miRNA (myomiR) levels were measured before, immediately after, and 24 and 48h after the race. CMJ height was reduced immediately after the race (-84.0 ± 25.2%, p < 0.001) and remained low at 24 h (-43.6 ± 20.4%, p = 0.002). We observed high CK activity (53 239 ± 63 608 U/L, p < 0.001) immediately after the race, and it remained elevated 24h after (p < 0.01). Circulating myomiR levels (miR-1-3p, miR-133a-3p, miR-133b, miR-208a-3p, miR-208b-3p, and miR-499a-5p) were elevated immediately after the 24-h run (fold changes: 18-124,723, p<0.001) and significantly (p < 0.05) correlated or tended to significantly (p < 0.07) correlate with the reduction in CMJ height at 24 h. We found no significant correlation between CMJ height loss at 24 h and CK (p = 0.23) or Mb (p = 0.41) values. All elite ultramarathon runners included in our study were diagnosed with exertional rhabdomyolysis after the 24-h ultramarathon race. MyomiR levels may be useful to approach the degree of muscle damage.

Clinical Impact of High-Sensitivity Cardiac Troponin T Implementation in the Community

BACKGROUND

Limited U.S. data exist regarding high-sensitivity cardiac troponin (cTn) implementation.

OBJECTIVES

This study sought to evaluate the impact of high-sensitivity cardiac troponin T (cTnT) implementation.

METHODS

Observational U.S. cohort study of emergency department (ED) patients undergoing measurement of cTnT during the transition from 4th (pre-implementation March 12, 2018, to September 11, 2018) to 5th generation (Gen) cTnT (post-implementation September 12, 2018, to March 11, 2019). Diagnoses were adjudicated following the Fourth Universal Definition of Myocardial Infarction (MI). Resources evaluated included length of stay, hospitalizations, and cardiac testing.

RESULTS

In this study, 3,536 unique patients were evaluated, including 2,069 and 2,491 ED encounters pre- and post-implementation. Compared with 4th Gen cTnT, encounters with ≥1 cTnT >99th percentile increased using 5th Gen cTnT (15% vs. 47%; p < 0.0001). Acute MI (3.3% vs. 8.1%; p < 0.0001) and myocardial injury (11% vs. 38%; p < 0.0001) increased. Although type 1 MIs increased (1.7% vs. 2.9%; p = 0.0097), the overall MI increase was largely due to more type 2 MIs (1.6% vs. 5.2%; p < 0.0001). Women were less likely than men to have MI using 4th Gen cTnT (2.3% vs. 4.4%; p = 0.008) but not 5th Gen cTnT (7.7% vs. 8.5%; p = 0.46). Overall length of stay and stress testing were reduced, and angiography was increased (all p < 0.05). Among those without cTnT increases, there were more ED discharges and a reduction in length of stay, echocardiography, and stress tests (all p < 0.05).

CONCLUSIONS

High-sensitivity cTnT implementation resulted in a marked increase in myocardial injury and MI, particularly in women and patients with type 2 MI. Despite this, except for angiography, overall resource use did not increase. Among those without cTnT increases, there were more ED discharges and fewer cardiac tests.

Cardiac Abnormalities in COVID-19 and Relationship to Outcome

OBJECTIVE

To characterize the clinical and transthoracic echocardiographic features and 30-day outcomes of hospitalized patients with coronavirus disease 2019 (COVID-19).

METHODS

Retrospective cohort study that included consecutive inpatients with COVID-19 infection who underwent clinically indicated transthoracic echocardiography at 10 sites in the Mayo Clinic Health System between March 10 and August 5, 2020. Echocardiography was performed at bedside by cardiac sonographers according to an abbreviated protocol. Echocardiographic results, demographic characteristics, laboratory findings, and clinical outcomes were analyzed.

RESULTS

There were 179 patients, aged 59.8±16.9 years and 111 (62%) men; events within 30 days occurred in 70 (39%) patients, including prolonged hospitalization in 43 (24%) and death in 27 (15%). Echocardiographic abnormalities included left ventricular ejection fraction less than 50% in 29 (16%), regional wall motion abnormalities in 26 (15%), and right ventricular systolic pressure (RVSP) of 35 or greater mm Hg in 44 (44%) of 101 in whom it was measured. Myocardial injury, defined as the presence of significant troponin level elevation accompanied by new ventricular dysfunction or electrocardiographic abnormalities, was present in 13 (7%). Prior echocardiography was available in 36 (20%) patients and pre-existing abnormalities were seen in 28 (78%) of these. In a multivariable age-adjusted model, area under the curve of 0.81, prior cardiovascular disease, troponin level, D-dimer level, and RVSP were related to events at 30 days.

CONCLUSION

Bedside Doppler assessment of RVSP appears promising for short-term risk stratification in hospitalized patients with COVID-19 infection undergoing clinically indicated echocardiography. Pre-existing echocardiographic abnormalities were common; caution should be exercised in attributing such abnormalities to the COVID-19 infection in this comorbid patient population.

Gradient-Based Rapid Digital Immunoassay for High-Sensitivity Cardiac Troponin T (hs-cTnT) Detection in 1 μL Plasma

Rapid and sensitive detection of biomarkers is the key to the diagnosis of acute diseases. One example is the detection of troponin in myocardial infarction. Here, we report a gradient-based digital immunoassay method, which can achieve high-sensitivity cardiac troponin T (hs-cTnT) detection with only 1 μL of plasma sample. We designed a multizone microfluidic channel functionalized with capture antibody specific to troponin. Taking advantage of limited sample volume, a troponin concentration gradient is created along the channel because of binding induced depletion. We quantified the concentration gradient by counting the detection antibody conjugated gold nanoparticles bound to different test zones with optical imaging. Differential counting between the zones removes most common noises and nonspecific bindings. The total analytical time is about 30 min, and the limit of quantification is 6.2 ng/L. We examined 41 clinical plasma samples from 15 patients and the change in hs-cTnT concentration in serial samples showed good linear correlation with clinical results (R² = 0.98). Therefore, this simple and sensitive gradient-based digital immunoassay method is a promising technology for clinical hs-cTnT detection and could be adapted for detection of other biomarkers.

Atherosclerotic Cardiovascular Disease Risk Stratification Based on Measurements of Troponin and Coronary Artery Calcium

BACKGROUND

Low values of high-sensitivity cardiac troponin (hs-cTn) and coronary artery calcium (CAC) scores of zero are associated with a low risk for atherosclerotic cardiovascular disease (ASCVD).

OBJECTIVES

The purpose of this study was to evaluate baseline hs-cTnT and CAC in relation to ASCVD.

METHODS

Baseline hs-cTnT (limit of detection [LoD] 3 ng/l) and CAC measurements were analyzed across participants age 45 to 84 years without clinical cardiovascular disease from the prospective MESA (Multi-Ethnic Study of Atherosclerosis) in relationship to incident ASCVD.

RESULTS

Among 6,749 participants, 1,002 ASCVD events occurred during a median follow-up of 15 years. Participants with detectable CAC (20.1 vs. 5.0 events per 1,000 person-years; adjusted hazard ratio [HR]: 2.35; 95% confidence interval [CI]: 2.0 to 2.76; p < 0.001) and detectable hs-cTnT (15.4 vs. 5.2 per 1,000 person-years; adjusted HR: 1.47; 95% CI: 1.21 to 1.77; p < 0.001) had higher rates of ASCVD than those with undetectable results. Individuals with undetectable hs-cTnT (32%) had similar risk for ASCVD as did those with a CAC of zero (50%) (5.2 vs. 5.0 per 1,000 person-years). Together, hs-cTnT and CAC (discordance 38%) resulted in the following ASCVD event rates: hs-cTnT < LoD/CAC = 0: 2.8 per 1,000 person-years (reference), hs-cTnT ≥ LoD/CAC = 0: 6.8 per 1,000 person-years (HR: 1.59; 95% CI: 1.17 to 2.16; p = 0.003), hs-cTnT < LoD/CAC > 0: 11.1 per 1,000 person-years (HR: 2.74; 95% CI: 1.96 to 3.83; p < 0.00001), and hs-cTnT ≥ LoD/CAC > 0: 22.6 per 1,000 person-years (HR: 3.50; 95% CI: 2.60 to 4.70; p < 0.00001).

CONCLUSIONS

An undetectable hs-cTnT identifies patients with a similar, low risk for ASCVD as those with a CAC score of zero. The increased risk among those with discordant results supports their conjoined use for risk prediction.

Early kinetic profiles of troponin I and T measured by high-sensitivity assays in patients with myocardial infarction

The early concentration kinetic profiles of cardiac troponin in patients with non-ST-elevated myocardial infarction (NSTEMI) measured by high-sensitivity cardiac troponin I (hs-cTnI) and T (hs-cTnT) assays have not been described. In intermediate-to-high-risk of NSTEMI patients we measured serial cTn concentrations on ED arrival, at 1, 2, 3, 6-12, 24 and 48-hours with hs-cTnI and hs-cTnT assays. Log-normal curves were fitted to concentrations from time from symptom onset, and the time to rule-out decision thresholds estimated (hs-cTnI: 2 ng/L and 5 ng/L; hs-cTnT: 5 ng/L). Among 164 patients there were 58 NSTEMI. The hs-cTnI to hs-cTnT ratio increased linearly over the first 6-12 h following symptom onset. The estimated times from symptom onset to the 2 ng/L and 5 ng/L thresholds for hs-cTnI were 1.8 (0.1-3.1) and 1.9 (1.1-3.5) hours, and to the 5 ng/L threshold for hs-cTnT 1.9 (1.1-3.8) hours. The estimated time to exceed 5 ng/L was ≥3 hours in 32.6% (95%CI: 20.0% to 48.1%) cases for hs-cTnI and 33.3% (19.6% to 50.0%) for hs-cTnT. cTnI concentrations increased at a much more rapid rate than cTnT concentrations in patients with NSTEMI. Concentrations of a high proportion of patients took longer than 3 hours from symptom onset to exceed the 5 ng/L rule-out decision threshold.

The 99th percentile upper reference limit for the 5th generation cardiac troponin T assay in the United States

BACKGROUND

Determining diagnostic thresholds for cardiac troponin assays is key to interpreting their clinical performance. We describe the calculation of 99th percentile upper reference limits (URLs) for the Elecsys® Troponin T Gen 5 (TnT Gen 5) assay.

METHODS

Plasma and serum samples from healthy US participants were prospectively evaluated using TnT Gen 5 Short Turn Around Time and 18-min assays on cobas e 411 and cobas e 601 analyzers (Roche Diagnostics); with, up to 8 TnT Gen 5 results per participant.

RESULTS

A total of 10,402 TnT Gen 5 results from 1301 participants were included (50.4% female). Across 9 calculation methods, overall 99th percentile URL was 19.2 ng/l (females, 13.5-13.6 ng/l; males, 21.4-22.2 ng/l). Across different sample/assay/analyzer combinations, overall 99th percentile URLs ranged from 18.4-20.2 ng/l. Median TnT Gen 5 results increased with age, were higher in males, and ranged from 3.0-3.7 ng/l across races/ethnicities and from 3.0-3.6 ng/l across body mass index (BMI) classes. Applying additional exclusion criteria (N-terminal pro-brain natriuretic peptide, BMI and estimated glomerular filtration rate) resulted in lower 99th percentile URLs (overall, 16.9 ng/l; females, 11.8 ng/l; males, 18.5 ng/l).

CONCLUSION

Our findings facilitate the interpretation of TnT Gen 5 results in US clinical practice.

Detection of subclinical cardiotoxicity in sarcoma patients receiving continuous doxorubicin infusion or pre-treatment with dexrazoxane before bolus doxorubicin

Background

Continuous infusion of doxorubicin or dexrazoxane pre-treatment prior to bolus doxorubicin are proven strategies to protect against doxorubicin-induced cardiotoxicity. Recently, global longitudinal peak systolic strain (GLS) measured with speckle tracking echocardiography (STE) and high-sensitivity troponin T (hs-TnT) have been validated as sensitive indicators of doxorubicin-induced cardiotoxicity. Here, we asked whether changes in hs-TnT and/or GLS can be detected in patients who were treated with continuous infusion of doxorubicin or pre-treated with dexrazoxane followed by bolus doxorubicin.

Methods

Twenty-nine patients with newly diagnosed sarcoma were assigned to receive either 72-h doxorubicin infusion or dexrazoxane pre-treatment before bolus doxorubicin. Eight patients received dexrazoxane pre-treatment; eleven patients received continuous doxorubicin infusion; ten patients crossed over from continuous infusion to dexrazoxane. Bloods were collected for hs-TnT at baseline, 24 h or 72 h after initiation of doxorubicin treatment in each chemotherapy cycle. All blood samples were assayed in batch using hs-TnT kit from Roche diagnostics. 2D Echo and STE were performed before doxorubicin, after cycle 3, and at the end of chemotherapy.

Results

Seven patients in the cross-over group have at least one hs-TnT measurement between 5 ng/L to 10 ng/L during and after chemotherapy. Ten patients have at least one hs-TnT measurement above 10 ng/ml during and after chemotherapy (six in dexrazoxane group, three in continuous infusion group, one in cross-over group). The average hs-TnT level increases with each additional cycle of doxorubicin treatment. Eight patients had a more than 5% reduction in LVEF at the end of chemotherapy (four in dexrazoxane group, three in continuous infusion group, and one in cross-over group). Four out of these eight patients had a change of GLS by more than 15% (three in the dexrazoxane group).

Conclusion

Elevation in hs-TnT levels were observed in more than 59% of patients who had received either continuous doxorubicin infusion or dexrazoxane pre-treatment before bolus doxorubicin. However, changes in LVEF and GLS were less frequently observed. Thus, continuous doxorubicin infusion or dexrazoxane pre-treatment do not completely ameliorate subclinical doxorubicin-induced cardiotoxicity as detected by more sensitive techniques.

Evaluating Tiered Hemolysis Thresholds to Facilitate Rapid Reporting of High-Sensitivity Cardiac Troponin

Background

Cardiac troponin (cTn) assays are used for the diagnosis of acute myocardial infarction and frequently require serial measurements. Recollection of unacceptable specimens for hemolysis can delay results and disrupt timing of serial measurements. This study was designed to assess the influence of hemolysis on a high-sensitivity cTnT assay in granular detail at clinically important concentrations. These were used in consultation with the clinical practice to evaluate risk-based thresholds for acceptable amounts of hemolysis.

Methods

Plasma pools ranging from &lt;10 to &gt;100 ng/L cTnT were spiked with hemolysate to various degrees of hemolysis and measured using the Elecsys Troponin T Gen 5 STAT assay. The impact of accepting expanded hemolysis thresholds was completed using retrospective data of 12225 serial cTnT results and an additional 4651 baseline cTnT results.

Results

The mean percent change in cTnT was consistent for a given degree of hemolysis regardless of the initial nonhemolyzed cTnT concentration. Tiered hemolysis thresholds were evaluated for low-risk patients (apparent cTnT ≤8 ng/L), intermediate-risk patients (thresholds for 9–37 ng/L, 38–66 ng/L, and 67–99 ng/L cTnT), and high-risk patients (≥100 ng/L cTnT). The influence of tiered hemolysis thresholds was calculated for patients with serial (0 and 2 h) cTnT results, which demonstrated that the majority of 2-h delta interpretations were unchanged. Implementation of tiered thresholds dramatically decreased recollections for hemolyzed cTnT samples.

Conclusion

Tiered hemolysis cutoffs minimized disruption to patient care for low- and high-risk patients, while maintaining the integrity of serial measurements for those with intermediate cTnT concentrations.

[A review on the clinical application of high-sensitivity cardiac troponin T in neonatal diseases]

In recent years, high-sensitivity cardiac troponin T (hs-cTnT) has been recognized as an effective marker for myocardial injury in adults and can be used to diagnose acute myocardial injury and predict major adverse cardiovascular events. It is the gold standard for the diagnosis of acute myocardial infarction in adults. Neonates are a special group, and due to the changes of various physiological processes during the perinatal period, many laboratory markers used in adults may have a low clinical value in neonates. So far, for example, there is still no suitable cardiac serum biomarker that can reflect the true condition of neonatal myocardial injury. In recent years, new breakthroughs have been made in the application of hs-cTnT in the field of neonates. In order to fully understand the role of hs-cTnT in neonatal diseases, this article reviews the research advances in the biological and physiological features of hs-cTnT and its application in neonates.

High-Sensitivity Troponin and the Application of Risk Stratification Thresholds in Patients With Suspected Acute Coronary Syndrome

Supplemental Digital Content is available in the text.

Guidelines acknowledge the emerging role of high-sensitivity cardiac troponin (hs-cTnl) for risk stratification and the early rule-out of myocardial infarction, but multiple thresholds have been described. We evaluate the safety and effectiveness of risk stratification thresholds in patients with suspected acute coronary syndrome.

SCAI clinical expert consensus statement on the classification of cardiogenic shock: This document was endorsed by the American College of Cardiology (ACC), the American Heart Association (AHA), the Society of Critical Care Medicine (SCCM), and the Society of Thoracic Surgeons (STS) in April 2019

BACKGROUND

The outcome of cardiogenic shock complicating myocardial infarction has not appreciably changed in the last 30 years despite the development of various percutaneous mechanical circulatory support options. It is clear that there are varying degrees of cardiogenic shock but there is no robust classification scheme to categorize this disease state.

METHODS

A multidisciplinary group of experts convened by the Society for Cardiovascular Angiography and Interventions was assembled to derive a proposed classification schema for cardiogenic shock. Representatives from cardiology (interventional, advanced heart failure, noninvasive), emergency medicine, critical care, and cardiac nursing all collaborated to develop the proposed schema.

RESULTS

A system describing stages of cardiogenic shock from A to E was developed. Stage A is "at risk" for cardiogenic shock, stage B is "beginning" shock, stage C is "classic" cardiogenic shock, stage D is "deteriorating", and E is "extremis". The difference between stages B and C is the presence of hypoperfusion which is present in stages C and higher. Stage D implies that the initial set of interventions chosen have not restored stability and adequate perfusion despite at least 30 minutes of observation and stage E is the patient in extremis, highly unstable, often with cardiovascular collapse.

CONCLUSION

This proposed classification system is simple, clinically applicable across the care spectrum from pre-hospital providers to intensive care staff but will require future validation studies to assess its utility and potential prognostic implications.