Prospective Evaluation of the Prognostic Implications of Improved Assay Performance With a Sensitive Assay for Cardiac Troponin I

Machine Learning Constructed Based on Patient Plaque and Clinical Features for Predicting Stent Malapposition: A Retrospective Study

BACKGROUND

Stent malapposition (SM) following percutaneous coronary intervention (PCI) for myocardial infarction continues to present significant clinical challenges. In recent years, machine learning (ML) models have demonstrated potential in disease risk stratification and predictive modeling.

HYPOTHESIS

ML models based on optical coherence tomography (OCT) imaging, laboratory tests, and clinical characteristics can predict the occurrence of SM.

METHODS

We studied 337 patients from the Affiliated Hospital of Zunyi Medical University, China, who had PCI and coronary OCT from May to October 2023. We employed nested cross-validation to partition patients into training and test sets. We developed five ML models: XGBoost, LR, RF, SVM, and NB based on calcification features. Performance was assessed using ROC curves. Lasso regression selected features from 46 clinical and 21 OCT imaging features, which were optimized with the five ML algorithms.

RESULTS

In the prediction model based on calcification features, the XGBoost model and SVM model exhibited higher AUC values. Lasso regression identified five key features from clinical and imaging data. After incorporating selected features into the model for optimization, the AUC values of all algorithmic models showed significant improvements. The XGBoost model demonstrated the highest calibration accuracy. SHAP values revealed that the top five ranked features influencing the XGBoost model were calcification length, age, coronary dissection, lipid angle, and troponin.

CONCLUSION

ML models developed using plaque imaging features and clinical characteristics can predict the occurrence of SM. ML models based on clinical and imaging features exhibited better performance.

Nanotechnology translation in vascular diseases: From design to the bench

Atherosclerosis is a systemic pathophysiological condition contributing to the development of majority of polyvascular diseases. Nanomedicine is a novel and rapidly developing science. Due to their small size, nanoparticles are freely transported in vasculature, and have been widely employed as tools in analytical imaging techniques. Furthermore, the application of nanoparticles also allows target intervention, such as drug delivery and tissue engineering regenerative methods, in the management of major vascular diseases. Therefore, by summarizing the physical and chemical characteristics of common nanoparticles used in diagnosis and treatment of vascular diseases, we discuss the details of these applications from cellular, molecular, and in vivo perspectives in this review. Furthermore, we also summarize the status and challenges of the application of nanoparticles in clinical translation. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Low-noise fluorescent detection of cardiac troponin I in human serum based on surface acoustic wave separation

Acute myocardial infarction (AMI) is a life-threatening disease when sudden blockage of coronary artery occurs. As the most specific biomarker, cardiac troponin I (cTnI) is usually checked separately to diagnose or eliminate AMI, and achieving the accurate detection of cTnI is of great significance to patients' life and health. Compared with other methods, fluorescent detection has the advantages of simple operation, high sensitivity and wide applicability. However, due to the strong fluorescence interference of biological molecules in body fluids, it is often difficult to obtain high sensitivity. In order to solve this problem, in this study, surface acoustic wave separation is designed to purify the target to achieve more sensitive detection performance of fluorescent detection. Specifically, the interference of background noise is almost completely removed on a microfluidic chip by isolating microbeads through acoustic radiation force, on which the biomarkers are captured by the immobilized detection probe. And then, the concentration of cTnI in human serum is detected by the fluorescence intensity change of the isolated functionalized beads. By this way, the detection limit of our biosensor calculated by 3σ/K method is 44 pg/mL and 0.34 ng/mL in PBS buffer and human serum respectively. Finally, the reliability of this method has been validated by comparison with clinical tests from the nephelometric analyzer in hospital.

Minor troponin T elevation and mortality in patients with atrial fibrillation presenting to the emergency department

BACKGROUND

There are limited data on the association of minor troponin elevation in unselected patients with atrial fibrillation (AF) presenting to the emergency department (ED) with adverse events. In this study, we sought to assess the early and mid-term mortality of these patients.

METHODS

In this observational study, 2911 patients with AF were admitted to the ED. They were divided into 3 groups based on peak high-sensitivity troponin (TnT) levels: normal (<15 ng/L), 15-50 ng/L and 51-100 ng/L. The primary outcomes of this study were all-cause mortality at 30 days and 1 year.

RESULTS

All-cause mortality was 6.7% (n = 196) at 30 days and 22.2% (n = 646) at 1 year. Mortality rate increased along with increasing levels of TnT irrespective of baseline covariates, primary discharge diagnosis and type of AF. A significant association between TnT levels and all-cause mortality was observed. The adjusted hazard ratio (HR) at 30 days was 6.02 (95% CI 2.62-13.83) for TnT 15-50 ng/L and 11.28 (95% CI 4.87-26.12) for TnT 51-100 ng/L (P<.001 for both) compared to TnT <15 ng/L. At 1 year, the adjusted HRs were 3.08 (95% CI 2.15-4.40) and 5.07 (95% CI 3.49-7.35), respectively (P < .001). When patients with TnT <15 ng/L were divided into two groups at the median value, TnT elevation of 10 to 14 ng/L was also associated with increased 1-year mortality (HR 2.51; 95% CI 1.09-5.74; P = .03).

CONCLUSIONS

Among patients with AF admitted to the ED, increased TnT levels were associated with increased early and mid-term all-cause mortality irrespective of baseline covariates and type of AF.

Chest pain and acute coronary syndrome in octogenarians admitted to the Emergency Department

BACKGROUND

Although chest pain and acute coronary syndrome (ACS) are among the most common complaints in the Emergency Departments (ED), little is known about this topic in the octogenarian population.

OBJECTIVES

This study aimed to describe the clinical presentation and to evaluate survival time according to the ACS type in a group of 80-year-old or over patients admitted for chest pain to an ED.

METHODS

Patients were classified according to the discharge diagnosis. A multivariable Cox regression analysis was done to assess the association between ACS type and mortality with the non-ACS chest pain group as the reference category.

RESULTS

ACS was diagnosed in 170 of the 391 patients analyzed and 51% of ACS patients were female. Within the ACS patients, 18.8% presented STEMI, 57% NSTEMI, and 24% unstable angina (UA). Most of the patients were treated conservatively. In the adjusted analysis, the incidence of death at 40 months of follow-up was higher in patients with STEMI (HR 3.24; CI 1.59-6.56) than NSTEMI (HR 2.53; CI 1.56-4.11). There was no difference between patients with UA and the non-ACS group (HR 0.64; CI 0.26-1.58), and myocardial revascularization was associated with reduced mortality risk (HR 0.45; CI 0.22-0.92).

CONCLUSIONS

A high prevalence of ACS was found among octogenarians admitted to the ED with chest pain, and the ACS type behaved as an independent predictor of mortality. Patients with UA diagnosis had a similar prognosis to patients with non-ACS chest pain, but this needs to be demonstrated by a prospective study.

Hypertension as a sequela in patients of SARS-CoV-2 infection

Background

COVID-19 is a respiratory infectious disease caused by SARS-CoV-2, and cardiovascular damage is commonly observed in affected patients. We sought to investigate the effect of SARS-CoV-2 infection on cardiac injury and hypertension during the current coronavirus pandemic.

Study design and methods

The clinical data of 366 hospitalized COVID-19-confirmed patients were analyzed. The clinical signs and laboratory findings were extracted from electronic medical records. Two independent, experienced clinicians reviewed and analyzed the data.

Results

Cardiac injury was found in 11.19% (30/268) of enrolled patients. 93.33% (28/30) of cardiac injury cases were in the severe group. The laboratory findings indicated that white blood cells, neutrophils, procalcitonin, C-reactive protein, lactate, and lactic dehydrogenase were positively associated with cardiac injury marker. Compared with healthy controls, the 190 patients without prior hypertension have higher AngⅡ level, of which 16 (8.42%) patients had a rise in blood pressure to the diagnostic criteria of hypertension during hospitalization, with a significantly increased level of the cTnI, procalcitonin, angiotensin-II (AngⅡ) than those normal blood pressure ones. Multivariate analysis indicated that elevated age, cTnI, the history of hypertension, and diabetes were independent predictors for illness severity. The predictive model, based on the four parameters and gender, has a good ability to identify the clinical severity of COVID-19 in hospitalized patients (area under the curve: 0.932, sensitivity: 98.67%, specificity: 75.68%).

Conclusion

Hypertension, sometimes accompanied by elevated cTnI, may occur in COVID-19 patients and become a sequela. Enhancing Ang II signaling, driven by SARS-CoV-2 infection, might play an important role in the renin-angiotensin system, and consequently lead to the development of hypertension in COVID-19.

Effect of Evolocumab on Type and Size of Subsequent Myocardial Infarction: A Prespecified Analysis of the FOURIER Randomized Clinical Trial

Importance

The PCSK9 inhibitor evolocumab reduced major vascular events in the Further Cardiovascular Outcomes Research With PCSK9 Inhibition in Subjects With Elevated Risk (FOURIER) trial, yet the types and sizes of myocardial outcomes in FOURIER have not been previously explored.

Objective

To assess the types and sizes of myocardial infarction (MI) and the effect of evolocumab on MI by subtype.

Design, Setting, and Participants

A prespecified analysis of a multicenter double-blind randomized clinical trial. Patients were randomized to evolocumab or placebo and followed up for a median of 2.2 years. The study included 27 564 patients with stable atherosclerotic disease receiving statin therapy. Clinical end points were evaluated by the Thrombolysis in Myocardial Infarction clinical events committee. Rates presented are 3-year Kaplan-Meier estimates. Data were collected from 2013 to 2016 and analyzed from June 2017 to December 2019.

Main Outcomes and Measures

Myocardial infarction was defined based on the third universal MI definition, and further classified according to MI type (universal MI subclass, ST-segment elevation myocardial infarction [STEMI] vs non-STEMI) and by MI size (determined by peak troponin level).

Results

A total of 27 564 patients were randomized, with a mean (SD) age of 62.5 (9.0) years, and 20 795 (75%) were male. Of these, 1107 patients experienced a total of 1288 MIs. Most MIs (68%) were atherothrombotic (type 1), with 15% from myocardial oxygen supply-demand mismatch (type 2) and 15% percutaneous coronary intervention-related (type 4). Sudden death (type 3) and coronary artery bypass grafting-related (type 5) accounted for a total of 21 MIs (<2%). Evolocumab significantly reduced the risk of first MI by 27% (4.4% vs 6.3%; hazard ratio [HR], 0.73; 95% CI, 0.65-0.82; P < .001), type 1 by 32% (2.9% vs 4.5%; HR, 0.68; 95% CI, 0.59-0.79; P < .001), and type 4 by 35% (0.8% vs 1.1%; HR, 0.65; 95% CI, 0.48-0.87; P = .004), with no effect on type 2 (0.9% vs 0.8%; HR, 1.09; 95% CI, 0.82-1.45; P = .56). Most MIs (688 [59.8%]) had troponin levels greater than or equal to 10 times the upper limit of normal. The benefit was highly significant and consistent regardless of the size of MI with a 34% reduction in MIs with troponin level greater than or equal to 10 times the upper limit of normal (2.6% vs 3.7%; HR, 0.66; 95% CI, 0.56-0.77; P < .001) and a 36% reduction in the risk of STEMI (1.0% vs 1.5%; HR, 0.64; 95% CI, 0.49-0.84; P < .001).

Conclusions and Relevance

Low-density lipoprotein cholesterol lowering with evolocumab was highly effective in reducing the risk of MI. This reduction with evolocumab included benefit across multiple subtypes of MI related to plaque rupture, smaller and larger MIs, and both STEMI and non-STEMI. These data are consistent with the known benefit of low-density lipoprotein cholesterol lowering and underscore the reduction in clinically meaningful events.

Trial Registration

ClinicalTrials.gov Identifier: NCT01764633.

Impact of troponin I level on coronary artery bypass grafting outcomes

PURPOSE

The effect of preoperative cardiac troponin level on outcomes after coronary artery bypass grafting (CABG) is unclear. We investigated the impact of preoperative cardiac troponin I (cTnI) level as well as the time interval between maximum cTnI and surgery on CABG outcomes.

METHODS

All patients who underwent isolated CABG at our institution between 2009 and 2016 and had preoperative cTnI level available were identified using our Society of Thoracic Surgeons registry. Receiver operating characteristic (ROC) analysis was performed to identify a cTnI threshold level. Subjects were divided into groups based on this value and outcomes compared.

RESULTS

A total of 608 patients were included. ROC analysis identified 5.74 µg/dL as the threshold value associated with worse postoperative outcomes. Patients with peak cTnI >5.74 µg/dL underwent CABG approximately 1 day later, had twice the risk of adverse postoperative events, and had 2.8 day longer postoperative length of stay than those with peak cTnI ≤5.74 µg/dL. cTnI level was not associated with mortality or 30-day readmission. Time interval between peak cTnI and surgery did not affect outcomes.

CONCLUSION

Elevated preoperative cTnI level beyond a certain threshold value is associated with adverse postoperative outcomes but is not a marker for increased mortality. Time from peak cTnI does not affect postoperative outcomes or mortality and may not need to be considered when deciding timing of CABG.

Comparative outcome analysis of stable mildly elevated high sensitivity troponin T in patients presenting with chest pain. A single-center retrospective cohort study

Background

The ideal high-sensitivity troponin (hsTn) cutoff for identifying those at low risk of 30 days events is debated; however, the 99th percentile overall or gender-specific upper reference limit (URL) is most commonly used. The magnitude of risk and the best management strategy for those with low-level hsTn elevation hasn't been extensively studied.

Methods

We conducted a retrospective cohort analysis including 4396 chest pain patients (542 with low-level hsTn elevation) who ruled out for myocardial infarction (MI), had a stable high-sensitivity troponin T (hsTnT) levels (defined as < 5 ng/l inter-measurements increase in hsTnT levels), and were discharged from the emergency department without further ischemic testing. The aim of the study was to compare the 30-day incidence of adverse cardiac events (ACE) between patients with undetectable high-sensitivity troponin T (hsTnT) (group 1), patients with hsTnT within the 99th percentile sex-specific URL (group 2), and patients with low-level hsTnT elevation (between the 99th percentile URL and ≤ 50 ng/l) (group 3).

Results

30-day event rates were very low 0.1%, 0.6%, and 0.4% for hsTnT groups 1, 2, and 3 respectively (overall P = 0.041, for groups 2 & 3 interaction P = 0.74). 30-day all-cause mortality, as well as 1-year all-cause and cardiovascular mortalities, occurred more frequently in those with low-level hsTnT elevation as did 1-year composite ACE.

Conclusion

In conclusion, 30-day adverse event rates were very low in those with stable low-level hsTnT elevation who ruled out for MI and were discharged from the emergency department without further inpatient testing.

Association between high-sensitivity cardiac troponin I measured at emergency department and complications of emergency coronary artery bypass grafting

High-sensitivity cardiac troponin I (hs-cTnI) is a widely used biomarker to identify ischemic chest pain in the Emergency Department (ED), but the clinical impact on emergency coronary artery bypass grafting (eCABG) remains undetermined. We aimed to evaluate the clinical impact of hs-cTnI measured at the ED by comparing outcomes of eCABG in patients with non–ST-segment–elevation acute coronary syndrome (NSTE-ACS) which comprises unstable angina (UA) and non–ST-segment–elevation myocardial infarction (NSTEMI). From January 2012 to March 2016, 242 patients undergoing eCABG were grouped according to serum hs-cTnI level in the ED. The primary endpoint was major cardiovascular cerebral event (MACCE) defined as a composite of all-cause death, myocardial infarction, repeat revascularization, and stroke. The incidence of each MACCE composite, in addition to postoperative complications such as acute kidney injury, reoperation, atrial fibrillation, and hospital stay duration were also compared. Patients were divided into two groups: UA [<0.04 ng/mL, n = 102] and NSTEMI [≥0.04 ng/mL, n = 140]. The incidence of MACCE did not differ between the two groups. Postoperative acute kidney injury was more frequent in the NSTEMI group after adjusting for confounding factors (6.9% vs. 23.6%; odds ratio, 2.76; 95% confidence interval, 1.09–6.99; p-value = 0.032). In-hospital stay was also longer in the NSTEMI group (9.0 days vs. 15.4 days, p-value = 0.008). ECABG for UA and NSTEMI patients showed comparable outcomes, but hs-cTnI elevation at the ED may be associated with immediate postoperative complications.

Nanoscale Technologies for Prevention and Treatment of Heart Failure: Challenges and Opportunities

The adult myocardium has a limited regenerative capacity following heart injury, and the lost cells are primarily replaced by fibrotic scar tissue. Suboptimal efficiency of current clinical therapies to resurrect the infarcted heart results in injured heart enlargement and remodeling to maintain its physiological functions. These remodeling processes ultimately leads to ischemic cardiomyopathy and heart failure (HF). Recent therapeutic approaches (e.g., regenerative and nanomedicine) have shown promise to prevent HF postmyocardial infarction in animal models. However, these preclinical, clinical, and technological advancements have yet to yield substantial enhancements in the survival rate and quality of life of patients with severe ischemic injuries. This could be attributed largely to the considerable gap in knowledge between clinicians and nanobioengineers. Development of highly effective cardiac regenerative therapies requires connecting and coordinating multiple fields, including cardiology, cellular and molecular biology, biochemistry and chemistry, and mechanical and materials sciences, among others. This review is particularly intended to bridge the knowledge gap between cardiologists and regenerative nanomedicine experts. Establishing this multidisciplinary knowledge base may help pave the way for developing novel, safer, and more effective approaches that will enable the medical community to reduce morbidity and mortality in HF patients.

[Perioperative myocardial ischemia : Current aspects and concepts]

In the future an increasing number of older patients with significant comorbidities will have to undergo major surgical procedures. Perioperative cardiovascular events account for many major complications and even fatalities. While perioperative myocardial infarction (PMI) is a generally well-known and recognized complication, the less severe myocardial injury after non-cardiac surgery (MINS) has not gained widespread scientific attention until recently; however, two large observational trials (VISION 1 and VISION 2) have shown a significantly increased mortality after MINS with even subtle increases in troponin T being associated with an increased risk of death. This review summarizes the current knowledge pertaining to PMI and MINS and proposes a diagnostic and therapeutic framework for optimally guiding patients at risk through the perioperative period.

High-sensitivity cardiac troponin T as an independent predictor of stroke in patients admitted to an emergency department with atrial fibrillation

AIMS

Elevated levels of high-sensitivity cardiac troponin T (hsTnT) are associated with adverse outcomes in numerous patient populations. Their value in prediction of stroke risk in patients with atrial fibrillation (AF) is in debate.

METHODS

The study population included 2898 consecutive patients presenting with AF to the emergency department of the Department of Cardiology, Heidelberg University Hospital. Associations between hsTnT and stroke risk were assessed using multivariable Cox regression.

RESULTS

Elevated hsTnT levels (>14 ng/L) were associated with increased risk of stroke. Even after adjustment for various risk factors, elevated hsTnT remained independently associated with stroke risk in patients with AF, adjusted hazard ratio 2.35 [95% confidence interval (CI): 1.26-4.36] (P = 0.007). These results were consistent across important subgroups (age, renal function, ejection fraction, CHA2DS2-VASc score and main admission diagnosis). For hsTnT, area under the receiver-operating-characteristic curve (AUC) was 0.659 [95% CI: 0.575-0.742], compared to 0.610 [95% CI: 0.526-0.694] for the CHA2DS2-VASc score. Inclusion of hsTnT in the multivariable model for stroke risk prediction consisting of all variables of the CHA2DS2-VASc score was associated with a significant improvement of its discriminatory power.

CONCLUSION

Elevated hsTnT levels are significantly associated with higher risk of stroke and provide prognostic information independent of CHA2DS2-VASc score variables. Measurement of hsTnT may improve prediction of stroke risk in patients presenting to an emergency department with AF as compared to risk stratification based only on clinical variables.

High-Sensitivity Troponin Assays in Clinical Diagnostics of Acute Coronary Syndrome

Nowadays, measurement of cardiac troponins (cTn) in patient plasma is central for diagnosis of patients with acute coronary syndrome (ACS). High-sensitivity (hs) immunoassays have been developed that can very precisely record slightly elevated and rising plasma concentrations of cTn very early after onset of clinical symptoms. Algorithms integrate measurements of hs-cTn at onset of clinical symptoms of acute myocardial infarction (AMI), and 1 or 3 h after onset, to rule-in and rule-out AMI patients. More and more point-of-care (POC) cTn assays conquer the diagnostic market, but thorough clinical validation studies are required before potential implementation of such POC tests into hospital settings. This review provides an overview of the technical aspects, as well as diagnostic and prognostic use of cardiac troponins in AMI patients and in the healthy population.

Reduction in Subtypes and Sizes of Myocardial Infarction With Ticagrelor in PEGASUS-TIMI 54

Background Ticagrelor reduced cardiovascular death, myocardial infarction (MI), or stroke in patients with prior MI in PEGASUS-TIMI 54 (Prevention of Cardiovascular Events [eg, Death From Heart or Vascular Disease, Heart Attack, or Stroke] in Patients With Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin). MI can occur in diverse settings and with varying severity; therefore, understanding the types and sizes of MI events prevented is of clinical importance. Methods and Results MIs were adjudicated by a blinded clinical events committee and categorized by subtype and fold elevation of peak cardiac troponin over the upper limit of normal. A total of 1042 MIs occurred in 898 of the 21 162 randomized patients over a median follow-up of 33 months. The majority of the MIs (76%) were spontaneous (Type 1), with demand MI (Type 2) and stent thrombosis (Type 4b) accounting for 13% and 9%, respectively; sudden death (Type 3), percutaneous coronary intervention-related (Type 4a) and coronary artery bypass graft-related (Type 5) each accounted for <1%. Half of MIs (520, 50%) had a peak troponin ≥10x upper limit of normal and 21% of MIs (220) had a peak troponin ≥100× upper limit of normal. A total of 21% (224) were ST-segment-elevation MI STEMI. Overall ticagrelor reduced MI (4.47% versus 5.25%, hazard ratio 0.83, 95% confidence interval 0.72-0.95, P=0.0055). The benefit was consistent among the subtypes, including a 31% reduction in MIs with a peak troponin ≥100× upper limit of normal (hazard ratio 0.69, 95% confidence interval 0.53-0.92, P=0.0096) and a 40% reduction in ST-segment elevation MI (hazard ratio 0.60, 95% confidence interval 0.46-0.78, P=0.0002). Conclusions In stable outpatients with prior MI, the majority of recurrent MIs are spontaneous and associated with a high biomarker elevation. Ticagrelor reduces the MI consistently among subtypes and sizes including large MIs and ST-segment elevation MI. Clinical Trial Registration URL: https://www.clinicaltrials.gov . Unique identifier: NCT01225562.

N-terminal pro-B-type natriuretic peptide and microsize myocardial infarction risk in the reasons for geographic and racial differences in stroke study

Background

N-terminal pro B-type peptide (NT-proBNP) has been associated with risk of myocardial infarction (MI), but less is known about the relationship between NT-proBNP and very small non ST-elevation MI, also known as microsize MI. These events are now routinely detectable with modern troponin assays and are emerging as a large proportion of all MI. Here, we sought to compare the association of NT-proBNP with risk of incident typical MI and microsize MI in the REasons for Geographic and Racial Differences in Stroke (REGARDS) Study.

Methods

The REGARDS Study is a national cohort of 30,239 US community-dwelling black and white adults aged ≥ 45 years recruited from 2003 to 2007. Expert-adjudicated outcomes included incident typical MI (definite/probable MI with peak troponin ≥ 0.5 μg/L), incident microsize MI (definite/probable MI with peak troponin < 0.5 μg/L), and incident fatal CHD. Using a case-cohort design, we estimated the hazard ratio of the outcomes as a function of baseline NT-proBNP. Competing risk analyses tested whether the associations of NT-proBNP differed between the risk of incident microsize MI and incident typical MI as well as if the association of NT-proBNP differed between incident non-fatal microsize MI and incident non-fatal typical MI, while accounting for incident fatal coronary heart disease (CHD) as well as heart failure (HF).

Results

Over a median of 5 years of follow-up, there were 315 typical MI, 139 microsize MI, and 195 incident fatal CHD. NT-proBNP was independently and strongly associated with all CHD endpoints, with significantly greater risk observed for incident microsize MI, even after removing individuals with suspected HF prior to or coincident with their incident CHD event.

Conclusion

NT-proBNP is associated with all MIs, but is a more powerful risk factor for microsize than typical MI.

Electronic supplementary material

The online version of this article (10.1186/s12872-018-0806-4) contains supplementary material, which is available to authorized users.

Low-level troponin elevations following a reduced troponin I cutoff: Increased resource utilization without improved outcomes

OBJECTIVE

The study sought to evaluate changes in mortality and resource utilization in patients with low level troponin elevations following a reduction in the cutoff for normal troponin I (TnI) from 0.5 ng/mL to the 99th percentile (0.06 ng/mL).

METHODS

This was an interrupted time series comparing emergency department (ED) patients with possible acute coronary syndrome (ACS) and TnI values 0.06-0.5 ng/mL before and after an institutional decrease in the TnI cutoff. The primary outcome was overall mortality at 90 days. Secondary outcomes included rates of rehospitalization, subsequent ACS, and coronary intervention within 90 days, as well as rates of anticoagulation, cardiology consultation, cardiac testing, and coronary intervention during the index visit. Outcomes for the pre-cutoff change group (control) and post-cutoff change group (post) were compared using tests of proportions and odds ratios.

RESULTS

The study included a total of 1058 subjects with 529 in each cohort. No significant differences in 90 day outcomes were observed between groups, including mortality (13.2% post vs 14.1% control, OR 0.93 [95% CI: 0.65-1.34], p = 0.705). During the index visit, the post-group demonstrated higher rates of cardiology consultation (55.4% vs 41.2%, OR 1.77 [1.39-2.26], p < 0.0001) and cardiac stress testing (16.4% vs 10.6%, OR 1.66 [1.16-2.38], p = 0.006), but no significant differences in coronary intervention or short-term mortality were observed.

CONCLUSION

A reduction in the TnI cutoff to the 99th percentile did not change mortality or rates of coronary intervention in ED patients with low level troponin elevations, but significantly increased the use of cardiology resources.

Prognostic Utility of a Modified HEART Score in Chest Pain Patients in the Emergency Department

BACKGROUND

The TRAPID-AMI trial study (High-Sensitivity Troponin-T Assay for Rapid Rule-Out of Acute Myocardial Infarction) evaluated high-sensitivity cardiac troponin-T (hs-cTnT) in a 1-hour acute myocardial infarction (AMI) exclusion algorithm. Our study objective was to evaluate the prognostic utility of a modified HEART score (m-HS) within this trial.

METHODS AND RESULTS

Twelve centers evaluated 1282 patients in the emergency department for possible AMI from 2011 to 2013. Measurements of hs-cTnT (99th percentile, 14 ng/L) were performed at 0, 1, 2, and 4 to 14 hours. Evaluation for major adverse cardiac events (MACEs) occurred at 30 days (death or AMI). Low-risk patients had an m-HS≤3 and had either hs-cTnT<14 ng/L over serial testing or had AMI excluded by the 1-hour protocol. By the 1-hour protocol, 777 (60%) patients had an AMI excluded. Of those 777 patients, 515 (66.3%) patients had an m-HS≤3, with 1 (0.2%) patient having a MACE, and 262 (33.7%) patients had an m-HS≥4, with 6 (2.3%) patients having MACEs (P=0.007). Over 4 to 14 hours, 661 patients had a hs-cTnT<14 ng/L. Of those 661 patients, 413 (62.5%) patients had an m-HS≤3, with 1 (0.2%) patient having a MACE, and 248 (37.5%) patients had an m-HS≥4, with 5 (2.0%) patients having MACEs (P=0.03).

CONCLUSIONS

Serial testing of hs-cTnT over 1 hour along with application of an m-HS identified a low-risk population that might be able to be directly discharged from the emergency department.

Improved risk stratification of patients with acute coronary syndromes using a combination of hsTnT, NT-proBNP and hsCRP with the GRACE score

Background:

Clinical scores and biomarkers improve risk stratification of patients with acute coronary syndromes. However, little is known about their value in patients referred for coronary angiography.

Methods:

Consecutive patients admitted at four Swiss university hospitals with a diagnosis of acute coronary syndrome were enrolled into the SPUM-ACS Biomarker Cohort between 2009 and 2012. Patients were followed at 30 days and 1 year with assessment of adjudicated events including all-cause mortality and the composite of all-cause mortality or non-fatal recurrent myocardial infarction.

Results:

Events and biomarkers were analysed in 1892 patients (52.4% with ST-segment elevation myocardial infarction, 43.3% with non-ST-segment elevation myocardial infarction and 4.3% with unstable angina). Death at 30 days occurred in 35 patients (1.9%) and at 1 year in 80 patients (4.3%). The choice of troponin assay (conventional versus high sensitivity) to calculate the Global Registry of Acute Coronary Events (GRACE) score did not affect risk prediction. The prognostic accuracy of the GRACE score was improved when combined with three individual biomarkers including high sensitivity troponin T (hsTnT), N-terminal-pro B-type natriuretic peptide (NT-proBNP) and high sensitivity C-reactive protein (hsCRP) to yield a 9% increment (C-statistic 0.73–>0.82) for the discrimination of short-term risk for all-cause mortality. In contrast, the novel biomarkers placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and the ratio sFlt-1/PlGF did not improve risk stratification.

Conclusions:

In patients with acute coronary syndrome referred for coronary angiography, combinations of biomarkers including hsTnT, NT-proBNP and hsCRP with the GRACE score enhanced risk discrimination.

Clinical Trials Registration:

NCT01000701

Report of the European Society of Cardiology Cardiovascular Round Table regulatory workshop update of the evaluation of new agents for the treatment of acute coronary syndrome: Executive summary

Regulatory authorities interpret the results of randomized controlled trials according to published principles. The European Medicines Agency (EMA) is planning a revision of the 2000 and 2003 guidance documents on clinical investigation of new medicinal products for the treatment of acute coronary syndrome (ACS) to achieve consistency with current knowledge in the field. This manuscript summarizes the key output from a collaborative workshop, organized by the Cardiovascular Round Table and the European Affairs Committee of the European Society of Cardiology, involving clinicians, academic researchers, trialists, European and US regulators, and pharmaceutical industry researchers. Specific questions in four key areas were selected as priorities for changes in regulatory guidance: patient selection, endpoints, methodologic issues and issues related to the research for novel agents. Patients with ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI) should be studied separately for therapies aimed at the specific pathophysiology of either condition, particularly for treatment of the acute phase, but can be studied together for other treatments, especially long-term therapy. Unstable angina patients should be excluded from acute phase ACS trials. In general, cardiovascular death and reinfarction are recommended for primary efficacy endpoints; other endpoints may be considered if specifically relevant for the therapy under study. New agents or interventions should be tested against a background of evidence-based therapy with expanded follow-up for safety assessment. In conclusion, new guidance documents for randomized controlled trials in ACS should consider changes regarding patient and endpoint selection and definitions, and trial designs. Specific requirements for the evaluation of novel pharmacological therapies need further clarification.

High-Sensitivity Cardiac Troponin Concentrations in Patients with Chest Discomfort: Is It the Heart or the Kidneys As Well?

BACKGROUND

High-sensitivity cardiac troponins (hs-cTn) are the preferred biomarkers to detect myocardial injury, making them promising risk-stratifying tools for patients with symptoms of chest pain. However, circulating hs-cTn are also elevated in other conditions like renal dysfunction, complicating appropriate interpretation of low-level hs-cTn concentrations.

METHODS

A cross-sectional analysis was performed in 1864 patients with symptoms of chest discomfort from the cardiology outpatient department who underwent cardiac computed tomographic angiography (CCTA). Serum samples were analyzed using hs-cTnT and hs-cTnI assays. Renal function was measured by the estimated glomerular filtration rate (eGFR), established from serum creatinine and cystatin C. On follow-up, the incidence of adverse events was assessed.

RESULTS

Median hs-cTnT and hs-cTnI concentrations were 7.2(5.8-9.2) ng/L and 2.6(1.8-4.1) ng/L, respectively. Multivariable regression analysis revealed that both assay results were more strongly associated with eGFR (hs-cTnT:stβ:-0.290;hs-cTnI:stβ:-0.222) than with cardiac imaging parameters, such as coronary calcium score, CCTA plaque severity score and left ventricular mass (all p<0.01). Furthermore, survival analysis indicated lower relative risks in patients with normal compared to reduced renal function for hs-cTnT [HR(95%CI), 1.02(1.00-1.03) compared to 1.07(1.05-1.09)] and hs-cTnI [1.01(1.00-1.01) compared to 1.02(1.01-1.02)] (all p<0.001).

CONCLUSION

In patients with chest discomfort, we identified an independent influence of renal function on hs-cTn concentrations besides CAD, that affected the association of hs-cTn concentrations with adverse events. Estimating renal function is therefore warranted when interpreting baseline hs-cTn concentrations.

Troponin levels within the normal range and probability of inducible myocardial ischemia and coronary events in patients with acute chest pain

BACKGROUND/OBJECTIVES

Patients with suspected acute coronary syndromes and negative cardiac troponin (cTn) levels are deemed at low risk. Our aim was to assess the effect of cTn levels on the frequency of inducible myocardial ischemia and subsequent coronary events in patients with acute chest pain and cTn levels within the normal range.

METHODS

We evaluated 4474 patients with suspected acute coronary syndromes, nondiagnostic electrocardiograms and serial cTnI levels below the diagnostic threshold for myocardial necrosis using a conventional or a sensitive cTnI assay. The end points were the probability of inducible myocardial ischemia and coronary events (i.e., coronary death, myocardial infarction or coronary revascularization within 3 months).

RESULTS

The probability of inducible myocardial ischemia was significantly higher in patients with detectable peak cTnI levels (25%) than in those with undetectable concentrations (14.6%, p<0.001). These results were consistent regardless of the type of cTnI assay, the type of stress testing modality, or the timing for cTnI measurement, and remained significant after multivariate adjustment (odds ratio [OR] 1.47, 95% confidence interval [CI] 1.21-1.79, p<0.001). The rate of coronary events at 3 months was also significantly higher in patients with detectable cTnI levels (adjusted OR 2.08, 95% CI 1.64-2.64, p<0.001).

CONCLUSIONS

Higher cTnI levels within the normal range were associated with a significantly increased probability of inducible myocardial ischemia and coronary events in patients with suspected acute coronary syndromes and seemingly negative cTnI.

Acute cardiac injury events ≤30 days after laboratory-confirmed influenza virus infection among U.S. veterans, 2010-2012

BACKGROUND

Cardiac injury is a known potential complication of influenza infection. Because U.S. veterans cared for at the U.S. Department of Veterans Affairs are older and have more cardiovascular disease (CVD) risk factors than the general U.S. population, veterans are at risk for cardiac complications of influenza infection. We investigated biomarkers of cardiac injury characteristics and associated cardiac events among veterans who received cardiac biomarker testing ≤30 days after laboratory-confirmed influenza virus infection.

METHODS

Laboratory-confirmed influenza cases among veterans cared for at U.S. Department of Veterans Affairs' facilities for October 2010-December 2012 were identified using electronic medical records (EMRs). Influenza confirmation was based on respiratory specimen viral culture or antigen or nucleic acid detection. Acute cardiac injury (ACI) was defined as an elevated cardiac biomarker (troponin I or creatinine kinase isoenzyme MB) >99 % of the upper reference limit occurring ≤30 days after influenza specimen collection. EMRs were reviewed for demographics, CVD history and risk factors, and ACI-associated cardiac events.

RESULTS

Among 38,197 patients with influenza testing results, 4,469 (12 %) had a positive result; 600 of those patients had cardiac biomarker testing performed ≤30 days after influenza testing, and 143 (24 %) had one or more elevated cardiac biomarkers. Among these 143, median age was 73 years (range 44-98 years), and 98 (69 %) were non-Hispanic white. All patients had one or more CVD risk factors, and 98 (69 %) had a history of CVD. Eighty-six percent of ACI-associated events occurred within 3 days of influenza specimen collection date. Seventy patients (49 %) had documented or probable acute myocardial infarction, 8 (6 %) acute congestive heart failure, 6 (4 %) myocarditis, and 4 (3 %) atrial fibrillation. Eleven (8 %) had non-cardiac explanations for elevated cardiac biomarkers, and 44 (31 %) had no documented explanation. Sixty-eight (48 %) patients had received influenza vaccination during the related influenza season.

CONCLUSION

Among veterans with laboratory-confirmed influenza infection and cardiac biomarker testing ≤30 days after influenza testing, approximately 25 % had evidence of ACI, the majority within 3 days. Approximately half were myocardial infarctions. Our findings emphasize the importance of considering ACI associated with influenza infection among patients at high risk, including this older population with prevalent CVD risk factors.

Perioperative myocardial injury in patients receiving cardiac output-guided haemodynamic therapy: a substudy of the OPTIMISE Trial

BACKGROUND

Evidence suggests that cardiac output-guided haemodynamic therapy algorithms improve outcomes after high-risk surgery, but there is some concern that this could promote acute myocardial injury. We evaluated the incidence of myocardial injury in a perioperative goal-directed therapy trial.

METHODS

Patients undergoing major gastrointestinal surgery (n=723) were randomly assigned to cardiac output-guided haemodynamic therapy (intervention group) or usual care as part of the OPTIMISE trial. At four participating sites, 288 patients were enrolled in a biomarker substudy. Serum high-sensitivity cardiac troponin I (TnI) concentration and N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration were measured before and at 24 and 72 h after surgery.

RESULTS

Median preoperative TnI and NT-ProBNP concentrations were 4.3 ng litre(-1) and 144 pg ml(-1), respectively. After surgery, 67 (46%) patients in the intervention group and 68 (48%) patients receiving usual care had TnI concentrations above the 99th centile upper reference limit (P=0.82). Peak serum TnI concentration was similar in the intervention and usual care groups (median [interquartile range]: 10.0 [5.3-21.5] vs 7.8 [5.0-21.8] ng litre(-1); P=0.85), and no differences were observed in serum TnI concentrations over 72 h (repeated-measures anova, P=0.51). Likewise, there were no differences in peak NT-proBNP concentration between intervention and usual care groups (645 [362-1169] vs 659 [381-1028] pg ml(-1); P=0.86) or in serial NT-proBNP concentrations over 72 h (P=0.20).

CONCLUSIONS

Myocardial injury is common among patients undergoing major gastrointestinal surgery. In this study, the frequency was not affected by cardiac output-guided fluid and low-dose inotropic therapy.

Correlation between lipid profile and troponin I test results in patients with chest pain in Nepal

OBJECTIVE

To study the usefulness of traditional lipid profile levels in screening subjects who had developed chest pain due to cardiac event as indicated by a positive troponin I test.

METHODS

In this retrospective study data of the 430 patients presented to the emergency department with symptoms of cardiac ischemia who underwent both troponin and lipid profiles tests were compared with the lipid profiles of 165 normal healthy subjects (controls). The troponin was detected qualitatively when a specimen contains troponin I (cTnI) above the 99th percentile (TnI>0.5 ng/mL). The total cholesterol, high density lipoproteins cholesterol, very low density lipoproteins and triacyl glycerol levels were also analyzed and low density lipoprotein level was calculated using Friedewald's formula.

RESULTS

Patients with chest pain and positive troponin test (with confirmed cardiac event) were found to have significantly elevated levels of total cholesterol, triacyl glycerol levels, low density lipoprotein level and significantly reduced high density lipoproteins cholesterol levels when compared to the patients who experienced only chest pain (negative troponin) and healthy controls.

CONCLUSIONS

Traditional lipid profile levels is still can be used in screening populations to identify the subjects with high risk of developing cardiac event in case if the laboratory set up has not troponin test facilities.

Prognostic implications of low level cardiac troponin elevation using high-sensitivity cardiac troponin T

BACKGROUND

High-sensitivity cardiac troponin T (hsTnT) is used in many countries, but is not available in the United States. Prior evidence has been viewed as inconclusive as to whether low cardiac troponin T (cTnT) concentrations detected with hsTnT are prognostically meaningful compared with fourth-generation cTnT.

HYPOTHESIS

The aim of this study was to assess the prognostic performance of low-level cTnT elevations using the hsTnT assay compared with the assay (fourth-generation) currently available in the United States.

METHODS

We measured serum cTnT in 4160 patients with non-ST-elevation acute coronary syndrome using both the hsTnT and fourth-generation assays. Patients were stratified at the 99th percentile cut point for each assay.

RESULTS

Patients with baseline hsTnT ≥14 ng/L (n = 3697) vs <14 ng/L were at higher 30-day risk of cardiovascular death (CVD) or myocardial infarction (MI) (9.1% vs 1.9%, P < 0.0001). After adjusting for all other elements of the Thrombolysis In Myocardial Infarction risk score, hsTnT ≥14 carried a 5.2-fold higher risk of CVD/MI (95% confidence interval [CI]: 2.6-10.1, P < 0.0001). Low levels of hsTnT (14-50 ng/L) also revealed increased risk (CVD/MI: 6.4%, P = 0.002). Importantly, patients with negative fourth-generation cTnT but positive hsTnT were at 4.5-times higher risk of CVD/MI (95% CI: 1.9-11.0, P = 0.0008) than patients with negative hsTnT. In contrast, patients with a negative hsTnT but positive fourth-generation cTnT result had a lower rate of CVD/MI than with a positive hsTnT (1.3% vs 8.2%, P = 0.0005).

CONCLUSIONS

Low-level increases in cTnT detected using the hsTnT assay identified patients at a meaningfully higher risk and who might otherwise be missed, and improves upon risk stratification using the cTnT assay currently available in the United States.

Patients with atrial fibrillation complicated by coronary artery disease. Is a single value of sensitive cardiac troponin I on admission enough?

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia in the general population. Cardiac troponin I (cTnI) can be elevated in patients with AF without coexisting coronary artery disease (CAD). The aim of this study was to characterize the diagnostic accuracy and clinical usefulness of a cTnI assay for the diagnosis of CAD in patients with AF.

METHODS

Patients with AF undergoing coronary angiography were included in the study. The workflow chart encompassed measuring of cTnI in all patients at admission and after 6 h.

RESULTS

Patients with CAD were older (73.8 ± 7.6 vs. 65.3 ± 12.9 years) than patients without CAD; for all other characteristics, no significant differences were observed. Of the patients, 39 had CAD [12 patients one-vessel disease (VD), 14 patients 2-VD, 13 patients 3-VD] and 16 patients had acute myocardial infarction and were undergoing percutaneous coronary intervention. There was no significant difference in cTnI concentrations between patients without and with CAD at admission (0.02 vs. 0.03 ng/ml, respectively); however, a difference was noted after 6 h (0.03 vs. 0.06 ng/ml, respectively).

CONCLUSION

AF patients both without and with CAD showed similar cTnI concentrations at admission. A second validation of cTnI is mandatory for all patients.

Highly Sensitive Troponin and Critical Illness Insurance: Have the Goalposts Moved Again?

An elevated cardiac troponin is a sine qua non for the clinical diagnosis of myocardial infarction. The sensitivity of troponin assays has improved repeatedly since troponin entered clinical use in the late 1990s. Its most recent iteration, "highly sensitive" troponin will shortly enter clinical use in North America. It is able to detect amounts of troponin 10 times smaller than the current assay. As a result, more myocardial infarctions will be diagnosed. This may have an impact on the number of critical illness claims for heart attack.

Prognostic performance of a high-sensitivity assay for cardiac troponin I after non-ST elevation acute coronary syndrome: Analysis from MERLIN-TIMI 36

BACKGROUND

Newer troponin assays offer the ability to quantify circulating troponin levels at an order of magnitude lower than contemporary assays, fueling continued debate over the prognostic implications of very low-level increases in concentration. We evaluated the prognostic implications of low-level increases in cardiac troponin I (cTnI) using an investigational single-molecule high-sensitivity assay in patients with acute coronary syndrome (ACS).

METHODS

We measured cTnI using both a high-sensitivity troponin I (hsTnI) assay (Erenna, Singulex, 99(th) percentile 9 pg/ml) and a current generation sensitive assay (TnI-Ultra, Siemens, 99(th) percentile 40 pg/ml) at baseline in 1807 patients with non-ST elevation ACS and compared their prognostic ability for adverse cardiovascular events at 30 days and one year.

RESULTS

Among patients with TnI-Ultra<99(th) percentile, patients with elevated hsTnI (≥ 9 pg/ml) had a significantly higher risk than patients with hsTnI<9 pg/ml: cardiovascular death (CVD) or myocardial infarction (MI) at one year (7.0% vs 3.8%; p<0.001, hazard ratio (HR) 2.05, confidence interval (CI) 1.23-3.41); including a higher risk of CVD (3.5% vs 1.5%, p<0.001) and MI (5.0% vs 2.8%, p<0.001) individually. This higher risk of CVD/MI was independent of clinical risk stratification using the TIMI Risk Score (adj. HR 1.76, CI 1.05-2.90). Moreover, hsTnI showed a trend toward a gradient of risk even below the hsTnI 99 percentile.

CONCLUSIONS

Low-level cardiac troponin detected using a single-molecule technique, below the cutpoint of a contemporary sensitive assay, identified a significant gradient of risk. These findings support the prognostic relevance of low-level cardiac troponin elevation with increasingly sensitive assays in patients with ACS.

High-sensitivity cardiac troponin T in patients with intermittent claudication and its relation with cardiovascular events and all-cause mortality--the CAVASIC Study

BACKGROUND

Serum concentrations of high-sensitivity cardiac troponin T (hs-cTnT) are elevated in various diseases. The role of this marker in peripheral arterial disease (PAD) has not been fully investigated.

METHODS

Hs-cTnT was measured in the CAVASIC Study, a male cohort of 235 patients diagnosed with intermittent claudication and 249 age- and diabetes-matched controls. Patients with symptomatic PAD were prospectively followed for a median time of 7 years. The association of hs-cTnT with PAD, cardiovascular disease (CVD) at baseline as well as incident CVD and all-cause mortality during follow-up was analyzed.

RESULTS

Detectable hs-cTnT was associated with an 84% higher probability for symptomatic PAD at baseline: OR = 1.84, 95%CI 1.05-3.21, p = 0.03. Inclusion of ln-NT-proBNP or prevalent CVD abolished this association (both OR = 1.22, p = 0.52). However, detectable hs-cTnT was associated with prevalent CVD (n = 69) in PAD patients independent from ln-NT-proBNP: OR = 3.42, p = 0.001. In the adjusted Cox regression analysis detectable (HR = 2.15, p = 0.05) and especially hs-cTnT ≥ 14 ng/L (HR = 5.06, p < 0.001) were predictive for all-cause mortality (n = 39) independent from ln-NT-proBNP. Furthermore, hs-cTnT ≥ 14 ng/L was significantly associated with incident CVD (n = 66): HR = 3.15, 95%CI 1.26-7.89, p = 0.01.

CONCLUSIONS

This study in male patients with intermittent claudication and age- and diabetes-matched controls revealed hs-cTnT to be associated with PAD and prevalent CVD. The latter association was even significant after considering NT-proBNP. Prospectively, in PAD patients hs-cTnT was predictive for incident cardiovascular diseases and all-cause mortality. Thus, hs-cTnT could be a surrogate marker for cardiomyocyte damage also in symptomatic PAD patients.

"Troponin elevation in coronary ischemia and necrosis"

Detection of a rise and/or fall of cardiac troponin (cTn) is the cornerstone in the diagnosis of myocardial infarction (MI). For the acute risk, it is hypothesized that cTn mirrors activated coagulation and platelet reactivity and indicates the presence of a ruptured plaque, which may help to identify patients at high risk who benefit particularly from aggressive pharmacological treatment and early invasive strategy. High-sensitivity assays using the 99th percentile as the threshold for positivity can achieve sensitivity at presentation of 90 % or more, and performance further improves with subsequent measurements within 3 to 6 h. By 3 h, negative predictive values of almost 100 % have been reported. However, use of assays with higher sensitivity lead ultimately to a loss of clinical specificity. Thus, other conditions than MI, such as stroke, pulmonary embolism, sepsis, acute perimyocarditis, Takotsubo, acute heart failure and tachycardia also can go with elevated troponin levels. The detection of brief rise and subsequent fall of troponin concentration in marathon runners, and even in healthy subjects, after a standardized exercise test has cast doubts on the hypothesis that troponin is released only upon irreversible damage. This kind of troponin leakage may originate from a cytosolic compartment of the cells and not from the necrosis of thin filaments.

[Essential cardiac biomarkers in myocardial infarction and heart failure]

With the discovery of novel biomarkers in cardiovascular diseases, over the past decades considerable improvements in diagnosis, risk stratification and patient care could be achieved; however, despite extensive research, only few biomarkers have met the requirements of significantly improving diagnostic or prognostic approaches. Among the most established markers are cardiac troponins and natriuretic peptides, which are recommended in current guidelines for myocardial infarction or heart failure and are routinely used in clinical practice. Cardiac troponins T and I are the preferred biomarkers of choice for definition of myocardial infarction and proved to be prognostically relevant not only in acute coronary syndrome but also in non-cardiac diseases. The natriuretic peptides B-type natriuretic peptide (BNP) and amino-terminal pro-B-type natriuretic peptide (NT-proBNP) aid in diagnosis, risk stratification and monitoring of heart failure. In recent years several new promising markers have been proposed which might add incremental clinical information, most notably copeptin and growth differentiation factor (GDF) 15; however, larger studies are still required before recommendations for routine clinical use can be made.

Clinical criteria replenish high-sensitive troponin and inflammatory markers in the stratification of patients with suspected acute coronary syndrome

OBJECTIVES

In patients with suspected acute coronary syndrome (ACS), rapid triage is essential. The aim of this study was to establish a tool for risk prediction of 30-day cardiac events (CE) on admission. 30-day cardiac events (CE) were defined as early coronary revascularization, subsequent myocardial infarction, or cardiovascular death within 30 days.

METHODS AND RESULTS

This single-centre, prospective cohort study included 377 consecutive patients presenting to the emergency department with suspected ACS and for whom troponin T measurements were requested on clinical grounds. Fifteen biomarkers were analyzed in the admission sample, and clinical parameters were assessed by the TIMI risk score for unstable angina/Non-ST myocardial infarction and the GRACE risk score. Sixty-nine (18%) patients presented with and 308 (82%) without ST-elevations, respectively. Coronary angiography was performed in 165 (44%) patients with subsequent percutaneous coronary intervention--accounting for the majority of CE--in 123 (33%) patients, respectively. Eleven out of 15 biomarkers were elevated in patients with CE compared to those without. High-sensitive troponin T (hs-cTnT) was the best univariate biomarker to predict CE in Non-ST-elevation patients (AUC 0.80), but did not yield incremental information above clinical TIMI risk score (AUC 0.80 vs 0.82, p = 0.69). Equivalence testing of AUCs of risk models and non-inferiority testing demonstrated that the clinical TIMI risk score alone was non-inferior to its combination with hs-cTnT in predicting CE.

CONCLUSIONS

In patients presenting without ST-elevations, identification of those prone to CE is best based on clinical assessment based on TIMI risk score criteria and hs-cTnT.

Prognostic Performance of a High-Sensitivity Cardiac Troponin I Assay in Patients with Non–ST-Elevation Acute Coronary Syndrome

BACKGROUND

High-sensitivity assays for cardiac troponin enable more precise measurement of very low concentrations and improved diagnostic accuracy. However, the prognostic value of these measurements, particularly at low concentrations, is less well defined.

METHODS

We evaluated the prognostic performance of a new high-sensitivity cardiac troponin I (hs-cTnI) assay (Abbott ARCHITECT) compared with the commercial fourth generation cTnT assay in 4695 patients with non–ST-segment elevation acute coronary syndromes (NSTE-ACS) from the EARLY-ACS (Early Glycoprotein IIb/IIIa Inhibition in NSTE-ACS) and SEPIA-ACS1-TIMI 42 (Otamixaban for the Treatment of Patients with NSTE-ACS) trials. The primary endpoint was cardiovascular death or new myocardial infarction (MI) at 30 days. Baseline cardiac troponin was categorized at the 99th percentile reference limit (26 ng/L for hs-cTnI; 10 ng/L for cTnT) and at sex-specific 99th percentiles for hs-cTnI.

RESULTS

All patients at baseline had detectable hs-cTnI compared with 94.5% with detectable cTnT. With adjustment for all other elements of the TIMI risk score, patients with hs-cTnI ≥99th percentile had a 3.7-fold higher adjusted risk of cardiovascular death or MI at 30 days relative to patients with hs-cTnI &lt;99th percentile (9.7% vs 3.0%; odds ratio, 3.7; 95% CI, 2.3–5.7; P &lt; 0.001). Similarly, when stratified by categories of hs-cTnI, very low concentrations demonstrated a graded association with cardiovascular death or MI (P-trend &lt; 0.001). Use of sex-specific cutpoints did not improve prognostic performance. Patients with negative fourth generation cTnT (&lt;10 ng/L) but hs-cTnI ≥26 ng/L were at increased risk of cardiovascular death/MI compared to those with hs-cTnI &lt;26 ng/L (9.2% vs 2.9%, P = 0.002).

CONCLUSIONS

Application of this hs-cTnI assay identified a clinically relevant higher risk of recurrent events among patients with NSTE-ACS, even at very low troponin concentrations.

Quantitative point-of-care troponin T measurement for diagnosis and prognosis in patients with a suspected acute myocardial infarction

Improvement of prehospital triage is essential to ensure rapid management of patients with acute myocardial infarction (AMI). This study evaluates the feasibility of prehospital quantitative point-of-care cardiac troponin T (POC-cTnT) analysis, its ability to identify patients with AMI, and its capacity to predict mortality. The study was performed in the Central Denmark Region from May 2010 to May 2011. As a supplement to electrocardiography, a prehospital POC-cTnT measurement was performed by a paramedic in patients with suspected AMI. AMI was diagnosed according to the universal definition of myocardial infarction using the ninety-ninth percentile upper reference level as diagnostic cut point. The paramedics performed POC-cTnT measurements in 985 subjects with a symptom duration of 70 minutes (95% CI, 35 to 180); of whom, 200 (20%) had an AMI. The prehospital sample was obtained 88 minutes (range, 58 to 131) before the sample made on admission to the hospital. The sensitivity for detection of patients with an AMI was 39% (95% CI, 32% to 46%) and the diagnostic accuracy of the POC-cTnT values was 0.67 (95% CI, 0.64 to 0.71). Adjusted survival analysis showed a strong significant association between elevated prehospital POC-cTnT level above the detection level of 50 ng/L and mortality in patients with a suspected AMI irrespective of whether an AMI was diagnosed. In conclusion, large-scale quantitative prehospital POC-cTnT testing by paramedics is feasible. An elevated prehospital POC-cTnT value contains diagnostic information and is highly predictive of mortality in patients with a suspected AMI.

Incremental Prognostic Value of Biomarkers beyond the GRACE (Global Registry of Acute Coronary Events) Score and High-Sensitivity Cardiac Troponin T in Non-ST-Elevation Acute Coronary Syndrome

BACKGROUND

Guidelines recommend the use of validated risk scores and a high-sensitivity cardiac troponin assay for risk assessment in non-ST-elevation acute coronary syndrome (NSTE-ACS). The incremental prognostic value of biomarkers in this context is unknown.

METHODS

We calculated the Global Registry of Acute Coronary Events (GRACE) score and measured the circulating concentrations of high-sensitivity cardiac troponin T (hs-cTnT) and 8 selected cardiac biomarkers on admission in 1146 patients with NSTE-ACS. We used an hs-cTnT threshold at the 99th percentile of a reference population to define increased cardiac marker in the score. The magnitude of the increase in model performance when individual biomarkers were added to GRACE was assessed by the change (Δ) in the area under the receiver-operating characteristic curve (AUC), integrated discrimination improvement (IDI), and category-free net reclassification improvement [NRI(&gt;0)].

RESULTS

Seventy-eight patients reached the combined end point of 6-month all-cause mortality or nonfatal myocardial infarction. The GRACE score alone had an AUC of 0.749. All biomarkers were associated with the risk of the combined end point and offered statistically significant improvement in model performance when added to GRACE (likelihood ratio test P ≤ 0.015). Growth differentiation factor 15 [ΔAUC 0.039, IDI 0.049, NRI(&gt;0) 0.554] and N-terminal pro–B-type natriuretic peptide [ΔAUC 0.024, IDI 0.027, NRI(&gt;0) 0.438] emerged as the 2 most promising biomarkers. Improvements in model performance upon addition of a second biomarker were small in magnitude.

CONCLUSIONS

Biomarkers can add prognostic information to the GRACE score even in the current era of high-sensitivity cardiac troponin assays. The incremental information offered by individual biomarkers varies considerably, however.

High-sensitivity cardiac troponins: no more 'negatives'

According to recently published expert guidelines, cardiac troponins are the only accepted biomarkers to define acute myocardial infarction. New high sensitivity cardiac troponin assays provide exciting opportunities for early rule-out and rule-in strategies and for identifying high-risk patients early in their presentation to guide early treatment and intervention. This review briefly discusses the history of troponin testing, before going on to cover clinical uses of the new highly sensitive assays in the early assessment of acute myocardial infection. Common clinical pitfalls with the use of these assays are discussed, as is the use of highly sensitive troponins more widely as prognostic markers. Likely future developments in this area are discussed.